From 9cb9e37c33173c16cbafd345f43e43b5a550537d Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Mon, 19 Sep 2022 17:29:59 +0200
Subject: Add structs, enums for `mdast`

---
 src/compiler.rs | 1924 -------------------------------------------------------
 src/lib.rs      |   45 +-
 src/mdast.rs    | 1047 ++++++++++++++++++++++++++++++
 src/to_html.rs  | 1922 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/to_mdast.rs |   40 ++
 5 files changed, 3046 insertions(+), 1932 deletions(-)
 delete mode 100644 src/compiler.rs
 create mode 100644 src/mdast.rs
 create mode 100644 src/to_html.rs
 create mode 100644 src/to_mdast.rs

(limited to 'src')

diff --git a/src/compiler.rs b/src/compiler.rs
deleted file mode 100644
index eaa15ee..0000000
--- a/src/compiler.rs
+++ /dev/null
@@ -1,1924 +0,0 @@
-//! Turn events into a string of HTML.
-use crate::event::{Event, Kind, Name};
-use crate::util::{
-    constant::{SAFE_PROTOCOL_HREF, SAFE_PROTOCOL_SRC},
-    decode_character_reference::{decode_named, decode_numeric},
-    encode::encode,
-    gfm_tagfilter::gfm_tagfilter,
-    normalize_identifier::normalize_identifier,
-    sanitize_uri::{sanitize, sanitize_with_protocols},
-    skip,
-    slice::{Position, Slice},
-};
-use crate::{LineEnding, Options};
-use alloc::{
-    format,
-    string::{String, ToString},
-    vec,
-    vec::Vec,
-};
-use core::str;
-
-/// Link, image, or footnote call.
-/// Resource or reference.
-/// Reused for temporary definitions as well, in the first pass.
-#[derive(Debug)]
-struct Media {
-    /// Whether this represents an image (`true`) or a link or definition
-    /// (`false`).
-    image: bool,
-    /// The text between the brackets (`x` in `![x]()` and `[x]()`).
-    ///
-    /// Not interpreted.
-    label_id: Option<(usize, usize)>,
-    /// The result of interpreting the text between the brackets
-    /// (`x` in `![x]()` and `[x]()`).
-    ///
-    /// When this is a link, it contains further text content and thus HTML
-    /// tags.
-    /// Otherwise, when an image, text content is also allowed, but resulting
-    /// tags are ignored.
-    label: Option<String>,
-    /// The string between the explicit brackets of the reference (`y` in
-    /// `[x][y]`), as content.
-    ///
-    /// Not interpreted.
-    reference_id: Option<(usize, usize)>,
-    /// The destination (url).
-    ///
-    /// Interpreted string content.
-    destination: Option<String>,
-    /// The destination (url).
-    ///
-    /// Interpreted string content.
-    title: Option<String>,
-}
-
-/// Representation of a definition.
-#[derive(Debug)]
-struct Definition {
-    /// Identifier.
-    id: String,
-    /// The destination (url).
-    ///
-    /// Interpreted string content.
-    destination: Option<String>,
-    /// The title.
-    ///
-    /// Interpreted string content.
-    title: Option<String>,
-}
-
-/// GFM table: column alignment.
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
-enum GfmTableAlign {
-    /// No alignment.
-    ///
-    /// ```markdown
-    ///   | | aaa |
-    /// > | | --- |
-    ///       ^^^
-    /// ```
-    None,
-    /// Left alignment.
-    ///
-    /// ```markdown
-    ///   | | aaa |
-    /// > | | :-- |
-    ///       ^^^
-    /// ```
-    Left,
-    /// Center alignment.
-    ///
-    /// ```markdown
-    ///   | | aaa |
-    /// > | | :-: |
-    ///       ^^^
-    /// ```
-    Center,
-    /// Right alignment.
-    ///
-    /// ```markdown
-    ///   | | aaa |
-    /// > | | --: |
-    ///       ^^^
-    /// ```
-    Right,
-}
-
-/// Context used to compile markdown.
-#[allow(clippy::struct_excessive_bools)]
-#[derive(Debug)]
-struct CompileContext<'a> {
-    // Static info.
-    /// List of events.
-    pub events: &'a [Event],
-    /// List of bytes.
-    pub bytes: &'a [u8],
-    /// Configuration.
-    pub options: &'a Options,
-    // Fields used by handlers to track the things they need to track to
-    // compile markdown.
-    /// Rank of heading (atx).
-    pub heading_atx_rank: Option<usize>,
-    /// Buffer of heading (setext) text.
-    pub heading_setext_buffer: Option<String>,
-    /// Whether raw (flow) (code (fenced), math (flow)) or code (indented) contains data.
-    pub raw_flow_seen_data: Option<bool>,
-    /// Number of raw (flow) fences.
-    pub raw_flow_fences_count: Option<usize>,
-    /// Whether we are in code (text).
-    pub raw_text_inside: bool,
-    /// Whether we are in image text.
-    pub image_alt_inside: bool,
-    /// Marker of character reference.
-    pub character_reference_marker: Option<u8>,
-    /// Whether we are expecting the first list item marker.
-    pub list_expect_first_marker: Option<bool>,
-    /// Stack of media (link, image).
-    pub media_stack: Vec<Media>,
-    /// Stack of containers.
-    pub tight_stack: Vec<bool>,
-    /// List of definitions.
-    pub definitions: Vec<Definition>,
-    /// List of definitions.
-    pub gfm_footnote_definitions: Vec<(String, String)>,
-    pub gfm_footnote_definition_calls: Vec<(String, usize)>,
-    pub gfm_footnote_definition_stack: Vec<(usize, usize)>,
-    /// Whether we are in a GFM table head.
-    pub gfm_table_in_head: bool,
-    /// Current GFM table alignment.
-    pub gfm_table_align: Option<Vec<GfmTableAlign>>,
-    /// Current GFM table column.
-    pub gfm_table_column: usize,
-    // Fields used to influance the current compilation.
-    /// Ignore the next line ending.
-    pub slurp_one_line_ending: bool,
-    /// Whether to encode HTML.
-    pub encode_html: bool,
-    // Configuration
-    /// Line ending to use.
-    pub line_ending_default: LineEnding,
-    // Intermediate results.
-    /// Stack of buffers.
-    pub buffers: Vec<String>,
-    /// Current event index.
-    pub index: usize,
-}
-
-impl<'a> CompileContext<'a> {
-    /// Create a new compile context.
-    pub fn new(
-        events: &'a [Event],
-        bytes: &'a [u8],
-        options: &'a Options,
-        line_ending: LineEnding,
-    ) -> CompileContext<'a> {
-        CompileContext {
-            events,
-            bytes,
-            heading_atx_rank: None,
-            heading_setext_buffer: None,
-            raw_flow_seen_data: None,
-            raw_flow_fences_count: None,
-            raw_text_inside: false,
-            character_reference_marker: None,
-            list_expect_first_marker: None,
-            media_stack: vec![],
-            definitions: vec![],
-            gfm_footnote_definitions: vec![],
-            gfm_footnote_definition_calls: vec![],
-            gfm_footnote_definition_stack: vec![],
-            gfm_table_in_head: false,
-            gfm_table_align: None,
-            gfm_table_column: 0,
-            tight_stack: vec![],
-            slurp_one_line_ending: false,
-            image_alt_inside: false,
-            encode_html: true,
-            line_ending_default: line_ending,
-            buffers: vec![String::new()],
-            index: 0,
-            options,
-        }
-    }
-
-    /// Push a buffer.
-    pub fn buffer(&mut self) {
-        self.buffers.push(String::new());
-    }
-
-    /// Pop a buffer, returning its value.
-    pub fn resume(&mut self) -> String {
-        self.buffers.pop().expect("Cannot resume w/o buffer")
-    }
-
-    /// Push a str to the last buffer.
-    pub fn push(&mut self, value: &str) {
-        self.buffers
-            .last_mut()
-            .expect("Cannot push w/o buffer")
-            .push_str(value);
-    }
-
-    /// Add a line ending.
-    pub fn line_ending(&mut self) {
-        let eol = self.line_ending_default.as_str().to_string();
-        self.push(&eol);
-    }
-
-    /// Add a line ending if needed (as in, there’s no eol/eof already).
-    pub fn line_ending_if_needed(&mut self) {
-        let tail = self
-            .buffers
-            .last()
-            .expect("at least one buffer should exist")
-            .as_bytes()
-            .last();
-
-        if !matches!(tail, None | Some(b'\n' | b'\r')) {
-            self.line_ending();
-        }
-    }
-}
-
-/// Turn events and codes into a string of HTML.
-pub fn compile(events: &[Event], bytes: &[u8], options: &Options) -> String {
-    let mut index = 0;
-    let mut line_ending_inferred = None;
-
-    // First, we figure out what the used line ending style is.
-    // Stop when we find a line ending.
-    while index < events.len() {
-        let event = &events[index];
-
-        if event.kind == Kind::Exit
-            && (event.name == Name::BlankLineEnding || event.name == Name::LineEnding)
-        {
-            line_ending_inferred = Some(LineEnding::from_str(
-                Slice::from_position(bytes, &Position::from_exit_event(events, index)).as_str(),
-            ));
-            break;
-        }
-
-        index += 1;
-    }
-
-    // Figure out which line ending style we’ll use.
-    let line_ending_default = if let Some(value) = line_ending_inferred {
-        value
-    } else {
-        options.default_line_ending.clone()
-    };
-
-    let mut context = CompileContext::new(events, bytes, options, line_ending_default);
-    let mut definition_indices = vec![];
-    let mut index = 0;
-    let mut definition_inside = false;
-
-    // Handle all definitions first.
-    // We must do two passes because we need to compile the events in
-    // definitions which come after references already.
-    //
-    // To speed things up, we collect the places we can jump over for the
-    // second pass.
-    //
-    // We don’t need to handle GFM footnote definitions like this, because
-    // unlike normal definitions, what they produce is not used in calls.
-    // It would also get very complex, because footnote definitions can be
-    // nested.
-    while index < events.len() {
-        let event = &events[index];
-
-        if definition_inside {
-            handle(&mut context, index);
-        }
-
-        if event.kind == Kind::Enter {
-            if event.name == Name::Definition {
-                handle(&mut context, index); // Also handle start.
-                definition_inside = true;
-                definition_indices.push((index, index));
-            }
-        } else if event.name == Name::Definition {
-            definition_inside = false;
-            definition_indices.last_mut().unwrap().1 = index;
-        }
-
-        index += 1;
-    }
-
-    index = 0;
-    let jump_default = (events.len(), events.len());
-    let mut definition_index = 0;
-    let mut jump = definition_indices
-        .get(definition_index)
-        .unwrap_or(&jump_default);
-
-    while index < events.len() {
-        if index == jump.0 {
-            index = jump.1 + 1;
-            definition_index += 1;
-            jump = definition_indices
-                .get(definition_index)
-                .unwrap_or(&jump_default);
-        } else {
-            handle(&mut context, index);
-            index += 1;
-        }
-    }
-
-    // No section to generate.
-    if !context.gfm_footnote_definition_calls.is_empty() {
-        generate_footnote_section(&mut context);
-    }
-
-    debug_assert_eq!(context.buffers.len(), 1, "expected 1 final buffer");
-    context
-        .buffers
-        .get(0)
-        .expect("expected 1 final buffer")
-        .to_string()
-}
-
-/// Handle the event at `index`.
-fn handle(context: &mut CompileContext, index: usize) {
-    context.index = index;
-
-    if context.events[index].kind == Kind::Enter {
-        enter(context);
-    } else {
-        exit(context);
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter].
-fn enter(context: &mut CompileContext) {
-    match context.events[context.index].name {
-        Name::CodeFencedFenceInfo
-        | Name::CodeFencedFenceMeta
-        | Name::MathFlowFenceMeta
-        | Name::DefinitionLabelString
-        | Name::DefinitionTitleString
-        | Name::GfmFootnoteDefinitionPrefix
-        | Name::HeadingAtxText
-        | Name::HeadingSetextText
-        | Name::Label
-        | Name::MdxEsm
-        | Name::MdxFlowExpression
-        | Name::MdxTextExpression
-        | Name::MdxJsxFlowTag
-        | Name::MdxJsxTextTag
-        | Name::ReferenceString
-        | Name::ResourceTitleString => on_enter_buffer(context),
-
-        Name::BlockQuote => on_enter_block_quote(context),
-        Name::CodeIndented => on_enter_code_indented(context),
-        Name::CodeFenced | Name::MathFlow => on_enter_raw_flow(context),
-        Name::CodeText | Name::MathText => on_enter_raw_text(context),
-        Name::Definition => on_enter_definition(context),
-        Name::DefinitionDestinationString => on_enter_definition_destination_string(context),
-        Name::Emphasis => on_enter_emphasis(context),
-        Name::Frontmatter => on_enter_frontmatter(context),
-        Name::GfmFootnoteDefinition => on_enter_gfm_footnote_definition(context),
-        Name::GfmFootnoteCall => on_enter_gfm_footnote_call(context),
-        Name::GfmStrikethrough => on_enter_gfm_strikethrough(context),
-        Name::GfmTable => on_enter_gfm_table(context),
-        Name::GfmTableBody => on_enter_gfm_table_body(context),
-        Name::GfmTableCell => on_enter_gfm_table_cell(context),
-        Name::GfmTableHead => on_enter_gfm_table_head(context),
-        Name::GfmTableRow => on_enter_gfm_table_row(context),
-        Name::GfmTaskListItemCheck => on_enter_gfm_task_list_item_check(context),
-        Name::HtmlFlow => on_enter_html_flow(context),
-        Name::HtmlText => on_enter_html_text(context),
-        Name::Image => on_enter_image(context),
-        Name::Link => on_enter_link(context),
-        Name::ListItemMarker => on_enter_list_item_marker(context),
-        Name::ListOrdered | Name::ListUnordered => on_enter_list(context),
-        Name::Paragraph => on_enter_paragraph(context),
-        Name::Resource => on_enter_resource(context),
-        Name::ResourceDestinationString => on_enter_resource_destination_string(context),
-        Name::Strong => on_enter_strong(context),
-        _ => {}
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit].
-fn exit(context: &mut CompileContext) {
-    match context.events[context.index].name {
-        Name::CodeFencedFenceMeta
-        | Name::MathFlowFenceMeta
-        | Name::MdxJsxTextTag
-        | Name::MdxTextExpression
-        | Name::Resource => {
-            on_exit_drop(context);
-        }
-        Name::MdxEsm | Name::MdxFlowExpression | Name::MdxJsxFlowTag => on_exit_drop_slurp(context),
-        Name::CharacterEscapeValue | Name::CodeTextData | Name::Data | Name::MathTextData => {
-            on_exit_data(context);
-        }
-        Name::AutolinkEmail => on_exit_autolink_email(context),
-        Name::AutolinkProtocol => on_exit_autolink_protocol(context),
-        Name::BlankLineEnding => on_exit_blank_line_ending(context),
-        Name::BlockQuote => on_exit_block_quote(context),
-        Name::CharacterReferenceMarker => on_exit_character_reference_marker(context),
-        Name::CharacterReferenceMarkerNumeric => {
-            on_exit_character_reference_marker_numeric(context);
-        }
-        Name::CharacterReferenceMarkerHexadecimal => {
-            on_exit_character_reference_marker_hexadecimal(context);
-        }
-        Name::CharacterReferenceValue => on_exit_character_reference_value(context),
-        Name::CodeFenced | Name::CodeIndented | Name::MathFlow => on_exit_raw_flow(context),
-        Name::CodeFencedFence | Name::MathFlowFence => on_exit_raw_flow_fence(context),
-        Name::CodeFencedFenceInfo => on_exit_raw_flow_fence_info(context),
-        Name::CodeFlowChunk | Name::MathFlowChunk => on_exit_raw_flow_chunk(context),
-        Name::CodeText | Name::MathText => on_exit_raw_text(context),
-        Name::Definition => on_exit_definition(context),
-        Name::DefinitionDestinationString => on_exit_definition_destination_string(context),
-        Name::DefinitionLabelString => on_exit_definition_label_string(context),
-        Name::DefinitionTitleString => on_exit_definition_title_string(context),
-        Name::Emphasis => on_exit_emphasis(context),
-        Name::Frontmatter => on_exit_frontmatter(context),
-        Name::GfmAutolinkLiteralEmail => on_exit_gfm_autolink_literal_email(context),
-        Name::GfmAutolinkLiteralMailto => on_exit_gfm_autolink_literal_mailto(context),
-        Name::GfmAutolinkLiteralProtocol => on_exit_gfm_autolink_literal_protocol(context),
-        Name::GfmAutolinkLiteralWww => on_exit_gfm_autolink_literal_www(context),
-        Name::GfmAutolinkLiteralXmpp => on_exit_gfm_autolink_literal_xmpp(context),
-        Name::GfmFootnoteCall => on_exit_gfm_footnote_call(context),
-        Name::GfmFootnoteDefinitionLabelString => {
-            on_exit_gfm_footnote_definition_label_string(context);
-        }
-        Name::GfmFootnoteDefinitionPrefix => on_exit_gfm_footnote_definition_prefix(context),
-        Name::GfmFootnoteDefinition => on_exit_gfm_footnote_definition(context),
-        Name::GfmStrikethrough => on_exit_gfm_strikethrough(context),
-        Name::GfmTable => on_exit_gfm_table(context),
-        Name::GfmTableBody => on_exit_gfm_table_body(context),
-        Name::GfmTableCell => on_exit_gfm_table_cell(context),
-        Name::GfmTableHead => on_exit_gfm_table_head(context),
-        Name::GfmTableRow => on_exit_gfm_table_row(context),
-        Name::GfmTaskListItemCheck => on_exit_gfm_task_list_item_check(context),
-        Name::GfmTaskListItemValueChecked => on_exit_gfm_task_list_item_value_checked(context),
-        Name::HardBreakEscape | Name::HardBreakTrailing => on_exit_break(context),
-        Name::HeadingAtx => on_exit_heading_atx(context),
-        Name::HeadingAtxSequence => on_exit_heading_atx_sequence(context),
-        Name::HeadingAtxText => on_exit_heading_atx_text(context),
-        Name::HeadingSetextText => on_exit_heading_setext_text(context),
-        Name::HeadingSetextUnderlineSequence => on_exit_heading_setext_underline_sequence(context),
-        Name::HtmlFlow | Name::HtmlText => on_exit_html(context),
-        Name::HtmlFlowData | Name::HtmlTextData => on_exit_html_data(context),
-        Name::Image | Name::Link => on_exit_media(context),
-        Name::Label => on_exit_label(context),
-        Name::LabelText => on_exit_label_text(context),
-        Name::LineEnding => on_exit_line_ending(context),
-        Name::ListOrdered | Name::ListUnordered => on_exit_list(context),
-        Name::ListItem => on_exit_list_item(context),
-        Name::ListItemValue => on_exit_list_item_value(context),
-        Name::Paragraph => on_exit_paragraph(context),
-        Name::ReferenceString => on_exit_reference_string(context),
-        Name::ResourceDestinationString => on_exit_resource_destination_string(context),
-        Name::ResourceTitleString => on_exit_resource_title_string(context),
-        Name::Strong => on_exit_strong(context),
-        Name::ThematicBreak => on_exit_thematic_break(context),
-        _ => {}
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:`*`.
-///
-/// Buffers data.
-fn on_enter_buffer(context: &mut CompileContext) {
-    context.buffer();
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`BlockQuote`][Name::BlockQuote].
-fn on_enter_block_quote(context: &mut CompileContext) {
-    context.tight_stack.push(false);
-    context.line_ending_if_needed();
-    context.push("<blockquote>");
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`CodeIndented`][Name::CodeIndented].
-fn on_enter_code_indented(context: &mut CompileContext) {
-    context.raw_flow_seen_data = Some(false);
-    context.line_ending_if_needed();
-    context.push("<pre><code>");
-}
-
-/// Handle [`Enter`][Kind::Enter]:{[`CodeFenced`][Name::CodeFenced],[`MathFlow`][Name::MathFlow]}.
-fn on_enter_raw_flow(context: &mut CompileContext) {
-    context.raw_flow_seen_data = Some(false);
-    context.line_ending_if_needed();
-    // Note that no `>` is used, which is added later (due to info)
-    context.push("<pre><code");
-    context.raw_flow_fences_count = Some(0);
-
-    if context.events[context.index].name == Name::MathFlow {
-        context.push(" class=\"language-math math-display\"");
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:{[`CodeText`][Name::CodeText],[`MathText`][Name::MathText]}.
-fn on_enter_raw_text(context: &mut CompileContext) {
-    context.raw_text_inside = true;
-    if !context.image_alt_inside {
-        context.push("<code");
-        if context.events[context.index].name == Name::MathText {
-            context.push(" class=\"language-math math-inline\"");
-        }
-        context.push(">");
-    }
-    context.buffer();
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Definition`][Name::Definition].
-fn on_enter_definition(context: &mut CompileContext) {
-    context.buffer();
-    context.media_stack.push(Media {
-        image: false,
-        label: None,
-        label_id: None,
-        reference_id: None,
-        destination: None,
-        title: None,
-    });
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`DefinitionDestinationString`][Name::DefinitionDestinationString].
-fn on_enter_definition_destination_string(context: &mut CompileContext) {
-    context.buffer();
-    context.encode_html = false;
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Emphasis`][Name::Emphasis].
-fn on_enter_emphasis(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("<em>");
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Frontmatter`][Name::Frontmatter].
-fn on_enter_frontmatter(context: &mut CompileContext) {
-    context.buffer();
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmFootnoteDefinition`][Name::GfmFootnoteDefinition].
-fn on_enter_gfm_footnote_definition(context: &mut CompileContext) {
-    context.tight_stack.push(false);
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmFootnoteCall`][Name::GfmFootnoteCall].
-fn on_enter_gfm_footnote_call(context: &mut CompileContext) {
-    context.media_stack.push(Media {
-        image: false,
-        label_id: None,
-        label: None,
-        reference_id: None,
-        destination: None,
-        title: None,
-    });
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmStrikethrough`][Name::GfmStrikethrough].
-fn on_enter_gfm_strikethrough(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("<del>");
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmTable`][Name::GfmTable].
-fn on_enter_gfm_table(context: &mut CompileContext) {
-    // Find the alignment.
-    let mut index = context.index;
-    let mut in_delimiter_row = false;
-    let mut align = vec![];
-
-    while index < context.events.len() {
-        let event = &context.events[index];
-
-        if in_delimiter_row {
-            if event.kind == Kind::Enter {
-                // Start of alignment value: set a new column.
-                if event.name == Name::GfmTableDelimiterCellValue {
-                    align.push(
-                        if context.events[index + 1].name == Name::GfmTableDelimiterMarker {
-                            GfmTableAlign::Left
-                        } else {
-                            GfmTableAlign::None
-                        },
-                    );
-                }
-            } else {
-                // End of alignment value: change the column.
-                if event.name == Name::GfmTableDelimiterCellValue {
-                    if context.events[index - 1].name == Name::GfmTableDelimiterMarker {
-                        let align_index = align.len() - 1;
-                        align[align_index] = if align[align_index] == GfmTableAlign::Left {
-                            GfmTableAlign::Center
-                        } else {
-                            GfmTableAlign::Right
-                        }
-                    }
-                }
-                // Done!
-                else if event.name == Name::GfmTableDelimiterRow {
-                    break;
-                }
-            }
-        } else if event.kind == Kind::Enter && event.name == Name::GfmTableDelimiterRow {
-            in_delimiter_row = true;
-        }
-
-        index += 1;
-    }
-
-    // Generate.
-    context.gfm_table_align = Some(align);
-    context.line_ending_if_needed();
-    context.push("<table>");
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmTableBody`][Name::GfmTableBody].
-fn on_enter_gfm_table_body(context: &mut CompileContext) {
-    context.push("<tbody>");
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmTableCell`][Name::GfmTableCell].
-fn on_enter_gfm_table_cell(context: &mut CompileContext) {
-    let column = context.gfm_table_column;
-    let align = context.gfm_table_align.as_ref().unwrap();
-
-    if column >= align.len() {
-        // Capture cell to ignore it.
-        context.buffer();
-    } else {
-        let value = align[column];
-        context.line_ending_if_needed();
-
-        if context.gfm_table_in_head {
-            context.push("<th");
-        } else {
-            context.push("<td");
-        }
-
-        match value {
-            GfmTableAlign::Left => context.push(" align=\"left\""),
-            GfmTableAlign::Right => context.push(" align=\"right\""),
-            GfmTableAlign::Center => context.push(" align=\"center\""),
-            GfmTableAlign::None => {}
-        }
-
-        context.push(">");
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmTableHead`][Name::GfmTableHead].
-fn on_enter_gfm_table_head(context: &mut CompileContext) {
-    context.line_ending_if_needed();
-    context.push("<thead>");
-    context.gfm_table_in_head = true;
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmTableRow`][Name::GfmTableRow].
-fn on_enter_gfm_table_row(context: &mut CompileContext) {
-    context.line_ending_if_needed();
-    context.push("<tr>");
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`GfmTaskListItemCheck`][Name::GfmTaskListItemCheck].
-fn on_enter_gfm_task_list_item_check(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("<input type=\"checkbox\" disabled=\"\" ");
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`HtmlFlow`][Name::HtmlFlow].
-fn on_enter_html_flow(context: &mut CompileContext) {
-    context.line_ending_if_needed();
-    if context.options.allow_dangerous_html {
-        context.encode_html = false;
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`HtmlText`][Name::HtmlText].
-fn on_enter_html_text(context: &mut CompileContext) {
-    if context.options.allow_dangerous_html {
-        context.encode_html = false;
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Image`][Name::Image].
-fn on_enter_image(context: &mut CompileContext) {
-    context.media_stack.push(Media {
-        image: true,
-        label_id: None,
-        label: None,
-        reference_id: None,
-        destination: None,
-        title: None,
-    });
-    context.image_alt_inside = true; // Disallow tags.
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Link`][Name::Link].
-fn on_enter_link(context: &mut CompileContext) {
-    context.media_stack.push(Media {
-        image: false,
-        label_id: None,
-        label: None,
-        reference_id: None,
-        destination: None,
-        title: None,
-    });
-}
-
-/// Handle [`Enter`][Kind::Enter]:{[`ListOrdered`][Name::ListOrdered],[`ListUnordered`][Name::ListUnordered]}.
-fn on_enter_list(context: &mut CompileContext) {
-    let events = &context.events;
-    let mut index = context.index;
-    let mut balance = 0;
-    let mut loose = false;
-    let name = &events[index].name;
-
-    while index < events.len() {
-        let event = &events[index];
-
-        if event.kind == Kind::Enter {
-            balance += 1;
-        } else {
-            balance -= 1;
-
-            if balance < 3 && event.name == Name::BlankLineEnding {
-                // Blank line directly after a prefix:
-                //
-                // ```markdown
-                // > | -␊
-                //      ^
-                //   |   a
-                // ```
-                let mut at_prefix = false;
-                // Blank line directly after item, which is just a prefix.
-                //
-                // ```markdown
-                // > | -␊
-                //      ^
-                //   | - a
-                // ```
-                let mut at_empty_list_item = false;
-                // Blank line at block quote prefix:
-                //
-                // ```markdown
-                // > | * >␊
-                //        ^
-                //   | * a
-                // ```
-                let mut at_empty_block_quote = false;
-
-                if balance == 1 {
-                    let mut before = index - 2;
-
-                    if events[before].name == Name::ListItem {
-                        before -= 1;
-
-                        if events[before].name == Name::SpaceOrTab {
-                            before -= 2;
-                        }
-
-                        if events[before].name == Name::BlockQuote
-                            && events[before - 1].name == Name::BlockQuotePrefix
-                        {
-                            at_empty_block_quote = true;
-                        } else if events[before].name == Name::ListItemPrefix {
-                            at_empty_list_item = true;
-                        }
-                    }
-                } else {
-                    let mut before = index - 2;
-
-                    if events[before].name == Name::SpaceOrTab {
-                        before -= 2;
-                    }
-
-                    if events[before].name == Name::ListItemPrefix {
-                        at_prefix = true;
-                    }
-                }
-
-                if !at_prefix && !at_empty_list_item && !at_empty_block_quote {
-                    loose = true;
-                    break;
-                }
-            }
-
-            // Done.
-            if balance == 0 && event.name == *name {
-                break;
-            }
-        }
-
-        index += 1;
-    }
-
-    context.tight_stack.push(!loose);
-    context.line_ending_if_needed();
-    // Note: no `>`.
-    context.push(if *name == Name::ListOrdered {
-        "<ol"
-    } else {
-        "<ul"
-    });
-    context.list_expect_first_marker = Some(true);
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`ListItemMarker`][Name::ListItemMarker].
-fn on_enter_list_item_marker(context: &mut CompileContext) {
-    if context.list_expect_first_marker.take().unwrap() {
-        context.push(">");
-    }
-
-    context.line_ending_if_needed();
-
-    context.push("<li>");
-    context.list_expect_first_marker = Some(false);
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Paragraph`][Name::Paragraph].
-fn on_enter_paragraph(context: &mut CompileContext) {
-    let tight = context.tight_stack.last().unwrap_or(&false);
-
-    if !tight {
-        context.line_ending_if_needed();
-        context.push("<p>");
-    }
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Resource`][Name::Resource].
-fn on_enter_resource(context: &mut CompileContext) {
-    context.buffer(); // We can have line endings in the resource, ignore them.
-    context.media_stack.last_mut().unwrap().destination = Some("".to_string());
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`ResourceDestinationString`][Name::ResourceDestinationString].
-fn on_enter_resource_destination_string(context: &mut CompileContext) {
-    context.buffer();
-    // Ignore encoding the result, as we’ll first percent encode the url and
-    // encode manually after.
-    context.encode_html = false;
-}
-
-/// Handle [`Enter`][Kind::Enter]:[`Strong`][Name::Strong].
-fn on_enter_strong(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("<strong>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`AutolinkEmail`][Name::AutolinkEmail].
-fn on_exit_autolink_email(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        Some("mailto:"),
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        false,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`AutolinkProtocol`][Name::AutolinkProtocol].
-fn on_exit_autolink_protocol(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        None,
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        false,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`HardBreakEscape`][Name::HardBreakEscape],[`HardBreakTrailing`][Name::HardBreakTrailing]}.
-fn on_exit_break(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("<br />");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`BlankLineEnding`][Name::BlankLineEnding].
-fn on_exit_blank_line_ending(context: &mut CompileContext) {
-    if context.index == context.events.len() - 1 {
-        context.line_ending_if_needed();
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`BlockQuote`][Name::BlockQuote].
-fn on_exit_block_quote(context: &mut CompileContext) {
-    context.tight_stack.pop();
-    context.line_ending_if_needed();
-    context.slurp_one_line_ending = false;
-    context.push("</blockquote>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceMarker`][Name::CharacterReferenceMarker].
-fn on_exit_character_reference_marker(context: &mut CompileContext) {
-    context.character_reference_marker = Some(b'&');
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceMarkerHexadecimal`][Name::CharacterReferenceMarkerHexadecimal].
-fn on_exit_character_reference_marker_hexadecimal(context: &mut CompileContext) {
-    context.character_reference_marker = Some(b'x');
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceMarkerNumeric`][Name::CharacterReferenceMarkerNumeric].
-fn on_exit_character_reference_marker_numeric(context: &mut CompileContext) {
-    context.character_reference_marker = Some(b'#');
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceValue`][Name::CharacterReferenceValue].
-fn on_exit_character_reference_value(context: &mut CompileContext) {
-    let marker = context
-        .character_reference_marker
-        .take()
-        .expect("expected `character_reference_kind` to be set");
-    let slice = Slice::from_position(
-        context.bytes,
-        &Position::from_exit_event(context.events, context.index),
-    );
-    let value = slice.as_str();
-
-    let value = match marker {
-        b'#' => decode_numeric(value, 10),
-        b'x' => decode_numeric(value, 16),
-        b'&' => decode_named(value),
-        _ => panic!("impossible"),
-    };
-
-    context.push(&encode(&value, context.encode_html));
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`CodeFlowChunk`][Name::CodeFlowChunk],[`MathFlowChunk`][Name::MathFlowChunk]}.
-fn on_exit_raw_flow_chunk(context: &mut CompileContext) {
-    context.raw_flow_seen_data = Some(true);
-    context.push(&encode(
-        &Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        // Must serialize to get virtual spaces.
-        .serialize(),
-        context.encode_html,
-    ));
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`CodeFencedFence`][Name::CodeFencedFence],[`MathFlowFence`][Name::MathFlowFence]}.
-fn on_exit_raw_flow_fence(context: &mut CompileContext) {
-    let count = if let Some(count) = context.raw_flow_fences_count {
-        count
-    } else {
-        0
-    };
-
-    if count == 0 {
-        context.push(">");
-        context.slurp_one_line_ending = true;
-    }
-
-    context.raw_flow_fences_count = Some(count + 1);
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`CodeFencedFenceInfo`][Name::CodeFencedFenceInfo].
-///
-/// Note: math (flow) does not support `info`.
-fn on_exit_raw_flow_fence_info(context: &mut CompileContext) {
-    let value = context.resume();
-    context.push(" class=\"language-");
-    context.push(&value);
-    context.push("\"");
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`CodeFenced`][Name::CodeFenced],[`CodeIndented`][Name::CodeIndented],[`MathFlow`][Name::MathFlow]}.
-fn on_exit_raw_flow(context: &mut CompileContext) {
-    // One special case is if we are inside a container, and the raw (flow) was
-    // not closed (meaning it runs to the end).
-    // In that case, the following line ending, is considered *outside* the
-    // fenced code and block quote by micromark, but CM wants to treat that
-    // ending as part of the code.
-    if let Some(count) = context.raw_flow_fences_count {
-        // No closing fence.
-        if count == 1
-            // In a container.
-            && !context.tight_stack.is_empty()
-            // Empty (as the closing is right at the opening fence)
-            && !matches!(context.events[context.index - 1].name, Name::CodeFencedFence | Name::MathFlowFence)
-        {
-            context.line_ending();
-        }
-    }
-
-    // But in most cases, it’s simpler: when we’ve seen some data, emit an extra
-    // line ending when needed.
-    if context
-        .raw_flow_seen_data
-        .take()
-        .expect("`raw_flow_seen_data` must be defined")
-    {
-        context.line_ending_if_needed();
-    }
-
-    context.push("</code></pre>");
-
-    if let Some(count) = context.raw_flow_fences_count.take() {
-        if count < 2 {
-            context.line_ending_if_needed();
-        }
-    }
-
-    context.slurp_one_line_ending = false;
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`CodeText`][Name::CodeText],[`MathText`][Name::MathText]}.
-fn on_exit_raw_text(context: &mut CompileContext) {
-    let result = context.resume();
-    let mut bytes = result.as_bytes().to_vec();
-
-    // If we are in a GFM table, we need to decode escaped pipes.
-    // This is a rather weird GFM feature.
-    if context.gfm_table_align.is_some() {
-        let mut index = 0;
-        let mut len = bytes.len();
-
-        while index < len {
-            if index + 1 < len && bytes[index] == b'\\' && bytes[index + 1] == b'|' {
-                bytes.remove(index);
-                len -= 1;
-            }
-
-            index += 1;
-        }
-    }
-
-    let mut trim = false;
-    let mut index = 0;
-    let mut end = bytes.len();
-
-    if end > 2 && bytes[index] == b' ' && bytes[end - 1] == b' ' {
-        index += 1;
-        end -= 1;
-        while index < end && !trim {
-            if bytes[index] != b' ' {
-                trim = true;
-                break;
-            }
-            index += 1;
-        }
-    }
-
-    if trim {
-        bytes.remove(0);
-        bytes.pop();
-    }
-
-    context.raw_text_inside = false;
-    context.push(str::from_utf8(&bytes).unwrap());
-
-    if !context.image_alt_inside {
-        context.push("</code>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:*.
-///
-/// Resumes, and ignores what was resumed.
-fn on_exit_drop(context: &mut CompileContext) {
-    context.resume();
-}
-
-/// Handle [`Exit`][Kind::Exit]:*.
-///
-/// Resumes, ignores what was resumed, and slurps the following line ending.
-fn on_exit_drop_slurp(context: &mut CompileContext) {
-    context.resume();
-    context.slurp_one_line_ending = true;
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`CodeTextData`][Name::CodeTextData],[`Data`][Name::Data],[`CharacterEscapeValue`][Name::CharacterEscapeValue]}.
-fn on_exit_data(context: &mut CompileContext) {
-    context.push(&encode(
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        context.encode_html,
-    ));
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`Definition`][Name::Definition].
-fn on_exit_definition(context: &mut CompileContext) {
-    context.resume();
-    let media = context.media_stack.pop().unwrap();
-    let indices = media.reference_id.unwrap();
-    let id =
-        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str());
-
-    context.definitions.push(Definition {
-        id,
-        destination: media.destination,
-        title: media.title,
-    });
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`DefinitionDestinationString`][Name::DefinitionDestinationString].
-fn on_exit_definition_destination_string(context: &mut CompileContext) {
-    let buf = context.resume();
-    context.media_stack.last_mut().unwrap().destination = Some(buf);
-    context.encode_html = true;
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`DefinitionLabelString`][Name::DefinitionLabelString].
-fn on_exit_definition_label_string(context: &mut CompileContext) {
-    // Discard label, use the source content instead.
-    context.resume();
-    context.media_stack.last_mut().unwrap().reference_id =
-        Some(Position::from_exit_event(context.events, context.index).to_indices());
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`DefinitionTitleString`][Name::DefinitionTitleString].
-fn on_exit_definition_title_string(context: &mut CompileContext) {
-    let buf = context.resume();
-    context.media_stack.last_mut().unwrap().title = Some(buf);
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`Emphasis`][Name::Emphasis].
-fn on_exit_emphasis(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("</em>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`Frontmatter`][Name::Frontmatter].
-fn on_exit_frontmatter(context: &mut CompileContext) {
-    context.resume();
-    context.slurp_one_line_ending = true;
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralEmail`][Name::GfmAutolinkLiteralEmail].
-fn on_exit_gfm_autolink_literal_email(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        Some("mailto:"),
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        true,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralMailto`][Name::GfmAutolinkLiteralMailto].
-fn on_exit_gfm_autolink_literal_mailto(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        None,
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        true,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralProtocol`][Name::GfmAutolinkLiteralProtocol].
-fn on_exit_gfm_autolink_literal_protocol(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        None,
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        true,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralWww`][Name::GfmAutolinkLiteralWww].
-fn on_exit_gfm_autolink_literal_www(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        Some("http://"),
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        true,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralXmpp`][Name::GfmAutolinkLiteralXmpp].
-fn on_exit_gfm_autolink_literal_xmpp(context: &mut CompileContext) {
-    generate_autolink(
-        context,
-        None,
-        Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .as_str(),
-        true,
-    );
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteCall`][Name::GfmFootnoteCall].
-fn on_exit_gfm_footnote_call(context: &mut CompileContext) {
-    let indices = context.media_stack.pop().unwrap().label_id.unwrap();
-    let id =
-        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str());
-    let safe_id = sanitize(&id.to_lowercase());
-    let mut call_index = 0;
-
-    // See if this has been called before.
-    while call_index < context.gfm_footnote_definition_calls.len() {
-        if context.gfm_footnote_definition_calls[call_index].0 == id {
-            break;
-        }
-        call_index += 1;
-    }
-
-    // New.
-    if call_index == context.gfm_footnote_definition_calls.len() {
-        context.gfm_footnote_definition_calls.push((id, 0));
-    }
-
-    // Increment.
-    context.gfm_footnote_definition_calls[call_index].1 += 1;
-
-    // No call is output in an image alt, though the definition and
-    // backreferences are generated as if it was the case.
-    if context.image_alt_inside {
-        return;
-    }
-
-    context.push("<sup><a href=\"#");
-    if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
-        context.push(&encode(value, context.encode_html));
-    } else {
-        context.push("user-content-");
-    }
-    context.push("fn-");
-    context.push(&safe_id);
-    context.push("\" id=\"");
-    if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
-        context.push(&encode(value, context.encode_html));
-    } else {
-        context.push("user-content-");
-    }
-    context.push("fnref-");
-    context.push(&safe_id);
-    if context.gfm_footnote_definition_calls[call_index].1 > 1 {
-        context.push("-");
-        context.push(
-            &context.gfm_footnote_definition_calls[call_index]
-                .1
-                .to_string(),
-        );
-    }
-    context.push("\" data-footnote-ref=\"\" aria-describedby=\"footnote-label\">");
-
-    context.push(&(call_index + 1).to_string());
-    context.push("</a></sup>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteDefinitionLabelString`][Name::GfmFootnoteDefinitionLabelString].
-fn on_exit_gfm_footnote_definition_label_string(context: &mut CompileContext) {
-    context
-        .gfm_footnote_definition_stack
-        .push(Position::from_exit_event(context.events, context.index).to_indices());
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteDefinitionPrefix`][Name::GfmFootnoteDefinitionPrefix].
-fn on_exit_gfm_footnote_definition_prefix(context: &mut CompileContext) {
-    // Drop the prefix.
-    context.resume();
-    // Capture everything until end of definition.
-    context.buffer();
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteDefinition`][Name::GfmFootnoteDefinition].
-fn on_exit_gfm_footnote_definition(context: &mut CompileContext) {
-    let value = context.resume();
-    let indices = context.gfm_footnote_definition_stack.pop().unwrap();
-    context.tight_stack.pop();
-    context.gfm_footnote_definitions.push((
-        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str()),
-        value,
-    ));
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmStrikethrough`][Name::GfmStrikethrough].
-fn on_exit_gfm_strikethrough(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("</del>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTable`][Name::GfmTable].
-fn on_exit_gfm_table(context: &mut CompileContext) {
-    context.gfm_table_align = None;
-    context.line_ending_if_needed();
-    context.push("</table>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTableBody`][Name::GfmTableBody].
-fn on_exit_gfm_table_body(context: &mut CompileContext) {
-    context.line_ending_if_needed();
-    context.push("</tbody>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTableCell`][Name::GfmTableCell].
-fn on_exit_gfm_table_cell(context: &mut CompileContext) {
-    let align = context.gfm_table_align.as_ref().unwrap();
-
-    if context.gfm_table_column < align.len() {
-        if context.gfm_table_in_head {
-            context.push("</th>");
-        } else {
-            context.push("</td>");
-        }
-    } else {
-        // Stop capturing.
-        context.resume();
-    }
-
-    context.gfm_table_column += 1;
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTableHead`][Name::GfmTableHead].
-fn on_exit_gfm_table_head(context: &mut CompileContext) {
-    context.gfm_table_in_head = false;
-    context.line_ending_if_needed();
-    context.push("</thead>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTableRow`][Name::GfmTableRow].
-fn on_exit_gfm_table_row(context: &mut CompileContext) {
-    let mut column = context.gfm_table_column;
-    let len = context.gfm_table_align.as_ref().unwrap().len();
-
-    // Add “phantom” cells, for body rows that are shorter than the delimiter
-    // row (which is equal to the head row).
-    while column < len {
-        on_enter_gfm_table_cell(context);
-        on_exit_gfm_table_cell(context);
-        column += 1;
-    }
-
-    context.gfm_table_column = 0;
-    context.line_ending_if_needed();
-    context.push("</tr>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTaskListItemCheck`][Name::GfmTaskListItemCheck].
-fn on_exit_gfm_task_list_item_check(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("/>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`GfmTaskListItemValueChecked`][Name::GfmTaskListItemValueChecked].
-fn on_exit_gfm_task_list_item_value_checked(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("checked=\"\" ");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`HeadingAtx`][Name::HeadingAtx].
-fn on_exit_heading_atx(context: &mut CompileContext) {
-    let rank = context
-        .heading_atx_rank
-        .take()
-        .expect("`heading_atx_rank` must be set in headings");
-
-    context.push("</h");
-    context.push(&rank.to_string());
-    context.push(">");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`HeadingAtxSequence`][Name::HeadingAtxSequence].
-fn on_exit_heading_atx_sequence(context: &mut CompileContext) {
-    // First fence we see.
-    if context.heading_atx_rank.is_none() {
-        let rank = Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        )
-        .len();
-        context.line_ending_if_needed();
-        context.heading_atx_rank = Some(rank);
-        context.push("<h");
-        context.push(&rank.to_string());
-        context.push(">");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`HeadingAtxText`][Name::HeadingAtxText].
-fn on_exit_heading_atx_text(context: &mut CompileContext) {
-    let value = context.resume();
-    context.push(&value);
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`HeadingSetextText`][Name::HeadingSetextText].
-fn on_exit_heading_setext_text(context: &mut CompileContext) {
-    let buf = context.resume();
-    context.heading_setext_buffer = Some(buf);
-    context.slurp_one_line_ending = true;
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`HeadingSetextUnderlineSequence`][Name::HeadingSetextUnderlineSequence].
-fn on_exit_heading_setext_underline_sequence(context: &mut CompileContext) {
-    let text = context
-        .heading_setext_buffer
-        .take()
-        .expect("`heading_atx_rank` must be set in headings");
-    let head = Slice::from_position(
-        context.bytes,
-        &Position::from_exit_event(context.events, context.index),
-    )
-    .head();
-    let rank = if head == Some(b'-') { "2" } else { "1" };
-
-    context.line_ending_if_needed();
-    context.push("<h");
-    context.push(rank);
-    context.push(">");
-    context.push(&text);
-    context.push("</h");
-    context.push(rank);
-    context.push(">");
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`HtmlFlow`][Name::HtmlFlow],[`HtmlText`][Name::HtmlText]}.
-fn on_exit_html(context: &mut CompileContext) {
-    context.encode_html = true;
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`HtmlFlowData`][Name::HtmlFlowData],[`HtmlTextData`][Name::HtmlTextData]}.
-fn on_exit_html_data(context: &mut CompileContext) {
-    let slice = Slice::from_position(
-        context.bytes,
-        &Position::from_exit_event(context.events, context.index),
-    );
-    let value = slice.as_str();
-
-    let encoded = if context.options.gfm_tagfilter && context.options.allow_dangerous_html {
-        encode(&gfm_tagfilter(value), context.encode_html)
-    } else {
-        encode(value, context.encode_html)
-    };
-
-    context.push(&encoded);
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`Label`][Name::Label].
-fn on_exit_label(context: &mut CompileContext) {
-    let buf = context.resume();
-    context.media_stack.last_mut().unwrap().label = Some(buf);
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`LabelText`][Name::LabelText].
-fn on_exit_label_text(context: &mut CompileContext) {
-    context.media_stack.last_mut().unwrap().label_id =
-        Some(Position::from_exit_event(context.events, context.index).to_indices());
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`LineEnding`][Name::LineEnding].
-fn on_exit_line_ending(context: &mut CompileContext) {
-    if context.raw_text_inside {
-        context.push(" ");
-    } else if context.slurp_one_line_ending
-        // Ignore line endings after definitions.
-        || (context.index > 1
-            && (context.events[context.index - 2].name == Name::Definition
-                || context.events[context.index - 2].name == Name::GfmFootnoteDefinition))
-    {
-        context.slurp_one_line_ending = false;
-    } else {
-        context.push(&encode(
-            Slice::from_position(
-                context.bytes,
-                &Position::from_exit_event(context.events, context.index),
-            )
-            .as_str(),
-            context.encode_html,
-        ));
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`ListOrdered`][Name::ListOrdered],[`ListUnordered`][Name::ListUnordered]}.
-fn on_exit_list(context: &mut CompileContext) {
-    context.tight_stack.pop();
-    context.line_ending();
-    context.push(if context.events[context.index].name == Name::ListOrdered {
-        "</ol>"
-    } else {
-        "</ul>"
-    });
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`ListItem`][Name::ListItem].
-fn on_exit_list_item(context: &mut CompileContext) {
-    let tight = context.tight_stack.last().unwrap_or(&false);
-    let before_item = skip::opt_back(
-        context.events,
-        context.index - 1,
-        &[
-            Name::BlankLineEnding,
-            Name::BlockQuotePrefix,
-            Name::LineEnding,
-            Name::SpaceOrTab,
-            // Also ignore things that don’t contribute to the document.
-            Name::Definition,
-            Name::GfmFootnoteDefinition,
-        ],
-    );
-    let previous = &context.events[before_item];
-    let tight_paragraph = *tight && previous.name == Name::Paragraph;
-    let empty_item = previous.name == Name::ListItemPrefix;
-
-    context.slurp_one_line_ending = false;
-
-    if !tight_paragraph && !empty_item {
-        context.line_ending_if_needed();
-    }
-
-    context.push("</li>");
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`ListItemValue`][Name::ListItemValue].
-fn on_exit_list_item_value(context: &mut CompileContext) {
-    if context.list_expect_first_marker.unwrap() {
-        let slice = Slice::from_position(
-            context.bytes,
-            &Position::from_exit_event(context.events, context.index),
-        );
-        let value = slice.as_str().parse::<u32>().ok().unwrap();
-
-        if value != 1 {
-            context.push(" start=\"");
-            context.push(&value.to_string());
-            context.push("\"");
-        }
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:{[`Image`][Name::Image],[`Link`][Name::Link]}.
-fn on_exit_media(context: &mut CompileContext) {
-    let mut is_in_image = false;
-    let mut index = 0;
-
-    // Skip current.
-    let end = context.media_stack.len() - 1;
-    while index < end {
-        if context.media_stack[index].image {
-            is_in_image = true;
-            break;
-        }
-        index += 1;
-    }
-
-    context.image_alt_inside = is_in_image;
-
-    let media = context.media_stack.pop().unwrap();
-    let label = media.label.unwrap();
-    let id = media.reference_id.or(media.label_id).map(|indices| {
-        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str())
-    });
-
-    let definition_index = if media.destination.is_none() {
-        id.and_then(|id| {
-            let mut index = 0;
-
-            while index < context.definitions.len() {
-                if context.definitions[index].id == id {
-                    return Some(index);
-                }
-
-                index += 1;
-            }
-
-            None
-        })
-    } else {
-        None
-    };
-
-    if !is_in_image {
-        if media.image {
-            context.push("<img src=\"");
-        } else {
-            context.push("<a href=\"");
-        };
-
-        let destination = if let Some(index) = definition_index {
-            context.definitions[index].destination.as_ref()
-        } else {
-            media.destination.as_ref()
-        };
-
-        if let Some(destination) = destination {
-            let url = if context.options.allow_dangerous_protocol {
-                sanitize(destination)
-            } else {
-                sanitize_with_protocols(
-                    destination,
-                    if media.image {
-                        &SAFE_PROTOCOL_SRC
-                    } else {
-                        &SAFE_PROTOCOL_HREF
-                    },
-                )
-            };
-            context.push(&url);
-        }
-
-        if media.image {
-            context.push("\" alt=\"");
-        };
-    }
-
-    if media.image {
-        context.push(&label);
-    }
-
-    if !is_in_image {
-        context.push("\"");
-
-        let title = if let Some(index) = definition_index {
-            context.definitions[index].title.clone()
-        } else {
-            media.title
-        };
-
-        if let Some(title) = title {
-            context.push(" title=\"");
-            context.push(&title);
-            context.push("\"");
-        };
-
-        if media.image {
-            context.push(" /");
-        }
-
-        context.push(">");
-    }
-
-    if !media.image {
-        context.push(&label);
-
-        if !is_in_image {
-            context.push("</a>");
-        }
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`Paragraph`][Name::Paragraph].
-fn on_exit_paragraph(context: &mut CompileContext) {
-    let tight = context.tight_stack.last().unwrap_or(&false);
-
-    if *tight {
-        context.slurp_one_line_ending = true;
-    } else {
-        context.push("</p>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`ReferenceString`][Name::ReferenceString].
-fn on_exit_reference_string(context: &mut CompileContext) {
-    // Drop stuff.
-    context.resume();
-
-    context.media_stack.last_mut().unwrap().reference_id =
-        Some(Position::from_exit_event(context.events, context.index).to_indices());
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`ResourceDestinationString`][Name::ResourceDestinationString].
-fn on_exit_resource_destination_string(context: &mut CompileContext) {
-    let buf = context.resume();
-    context.media_stack.last_mut().unwrap().destination = Some(buf);
-    context.encode_html = true;
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`ResourceTitleString`][Name::ResourceTitleString].
-fn on_exit_resource_title_string(context: &mut CompileContext) {
-    let buf = context.resume();
-    context.media_stack.last_mut().unwrap().title = Some(buf);
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`Strong`][Name::Strong].
-fn on_exit_strong(context: &mut CompileContext) {
-    if !context.image_alt_inside {
-        context.push("</strong>");
-    }
-}
-
-/// Handle [`Exit`][Kind::Exit]:[`ThematicBreak`][Name::ThematicBreak].
-fn on_exit_thematic_break(context: &mut CompileContext) {
-    context.line_ending_if_needed();
-    context.push("<hr />");
-}
-
-/// Generate a footnote section.
-fn generate_footnote_section(context: &mut CompileContext) {
-    context.line_ending_if_needed();
-    context.push("<section data-footnotes=\"\" class=\"footnotes\"><");
-    if let Some(ref value) = context.options.gfm_footnote_label_tag_name {
-        context.push(&encode(value, context.encode_html));
-    } else {
-        context.push("h2");
-    }
-    context.push(" id=\"footnote-label\" ");
-    if let Some(ref value) = context.options.gfm_footnote_label_attributes {
-        context.push(value);
-    } else {
-        context.push("class=\"sr-only\"");
-    }
-    context.push(">");
-    if let Some(ref value) = context.options.gfm_footnote_label {
-        context.push(&encode(value, context.encode_html));
-    } else {
-        context.push("Footnotes");
-    }
-    context.push("</");
-    if let Some(ref value) = context.options.gfm_footnote_label_tag_name {
-        context.push(&encode(value, context.encode_html));
-    } else {
-        context.push("h2");
-    }
-    context.push(">");
-    context.line_ending();
-    context.push("<ol>");
-
-    let mut index = 0;
-    while index < context.gfm_footnote_definition_calls.len() {
-        generate_footnote_item(context, index);
-        index += 1;
-    }
-
-    context.line_ending();
-    context.push("</ol>");
-    context.line_ending();
-    context.push("</section>");
-    context.line_ending();
-}
-
-/// Generate a footnote item from a call.
-fn generate_footnote_item(context: &mut CompileContext, index: usize) {
-    let id = &context.gfm_footnote_definition_calls[index].0;
-    let safe_id = sanitize(&id.to_lowercase());
-
-    // Find definition: we’ll always find it.
-    let mut definition_index = 0;
-    while definition_index < context.gfm_footnote_definitions.len() {
-        if &context.gfm_footnote_definitions[definition_index].0 == id {
-            break;
-        }
-        definition_index += 1;
-    }
-
-    debug_assert_ne!(
-        definition_index,
-        context.gfm_footnote_definitions.len(),
-        "expected definition"
-    );
-
-    context.line_ending();
-    context.push("<li id=\"");
-    if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
-        context.push(&encode(value, context.encode_html));
-    } else {
-        context.push("user-content-");
-    }
-    context.push("fn-");
-    context.push(&safe_id);
-    context.push("\">");
-    context.line_ending();
-
-    // Create one or more backreferences.
-    let mut reference_index = 0;
-    let mut backreferences = String::new();
-    while reference_index < context.gfm_footnote_definition_calls[index].1 {
-        if reference_index != 0 {
-            backreferences.push(' ');
-        }
-        backreferences.push_str("<a href=\"#");
-        if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
-            backreferences.push_str(&encode(value, context.encode_html));
-        } else {
-            backreferences.push_str("user-content-");
-        }
-        backreferences.push_str("fnref-");
-        backreferences.push_str(&safe_id);
-        if reference_index != 0 {
-            backreferences.push('-');
-            backreferences.push_str(&(reference_index + 1).to_string());
-        }
-        backreferences.push_str("\" data-footnote-backref=\"\" aria-label=\"");
-        if let Some(ref value) = context.options.gfm_footnote_back_label {
-            backreferences.push_str(&encode(value, context.encode_html));
-        } else {
-            backreferences.push_str("Back to content");
-        }
-        backreferences.push_str("\" class=\"data-footnote-backref\">↩");
-        if reference_index != 0 {
-            backreferences.push_str("<sup>");
-            backreferences.push_str(&(reference_index + 1).to_string());
-            backreferences.push_str("</sup>");
-        }
-        backreferences.push_str("</a>");
-
-        reference_index += 1;
-    }
-
-    let value = context.gfm_footnote_definitions[definition_index].1.clone();
-    let bytes = value.as_bytes();
-    let mut byte_index = bytes.len();
-    // Move back past EOL.
-    while byte_index > 0 && matches!(bytes[byte_index - 1], b'\n' | b'\r') {
-        byte_index -= 1;
-    }
-    // Check if it ends in `</p>`.
-    // This is a bit funky if someone wrote a safe paragraph by hand in
-    // there.
-    // But in all other cases, `<` and `>` would be encoded, so we can be
-    // sure that this is generated by our compiler.
-    if byte_index > 3
-        && bytes[byte_index - 4] == b'<'
-        && bytes[byte_index - 3] == b'/'
-        && bytes[byte_index - 2] == b'p'
-        && bytes[byte_index - 1] == b'>'
-    {
-        let (before, after) = bytes.split_at(byte_index - 4);
-        let mut result = String::new();
-        result.push_str(str::from_utf8(before).unwrap());
-        result.push(' ');
-        result.push_str(&backreferences);
-        result.push_str(str::from_utf8(after).unwrap());
-        context.push(&result);
-    } else {
-        context.push(&value);
-        context.line_ending_if_needed();
-        context.push(&backreferences);
-    }
-    context.line_ending_if_needed();
-    context.push("</li>");
-}
-
-/// Generate an autolink (used by unicode autolinks and GFM autolink literals).
-fn generate_autolink(
-    context: &mut CompileContext,
-    protocol: Option<&str>,
-    value: &str,
-    is_gfm_literal: bool,
-) {
-    let mut is_in_link = false;
-    let mut index = 0;
-
-    while index < context.media_stack.len() {
-        if !context.media_stack[index].image {
-            is_in_link = true;
-            break;
-        }
-        index += 1;
-    }
-
-    if !context.image_alt_inside && (!is_in_link || !is_gfm_literal) {
-        context.push("<a href=\"");
-        let url = if let Some(protocol) = protocol {
-            format!("{}{}", protocol, value)
-        } else {
-            value.to_string()
-        };
-
-        let url = if context.options.allow_dangerous_protocol {
-            sanitize(&url)
-        } else {
-            sanitize_with_protocols(&url, &SAFE_PROTOCOL_HREF)
-        };
-
-        context.push(&url);
-        context.push("\">");
-    }
-
-    context.push(&encode(value, context.encode_html));
-
-    if !context.image_alt_inside && (!is_in_link || !is_gfm_literal) {
-        context.push("</a>");
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index 0b1a571..669660b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,26 +1,37 @@
 //! Public API of micromark.
 //!
-//! This module exposes [`micromark`][] (and [`micromark_with_options`][]).
-//! `micromark` is a safe way to transform (untrusted?) markdown into HTML.
-//! `micromark_with_options` allows you to configure how markdown is turned into
-//! HTML, such as by allowing dangerous HTML when you trust it.
+//! This module exposes primarily [`micromark`][].
+//! It also exposes [`micromark_with_options`][] and [`micromark_to_mdast`][].
+//!
+//! *   [`micromark`][]
+//!     — safe way to transform (untrusted?) markdown into HTML
+//! *   [`micromark_with_options`][]
+//!     — like `micromark` but lets you configure how markdown is turned into
+//!     HTML, such as allowing dangerous HTML or turning on/off
+//!     different constructs (GFM, MDX, and the like)
+//! *   [`micromark_to_mdast`][]
+//!     — like `micromark_with_options` but compiles to a syntax tree
 #![no_std]
 
 extern crate alloc;
 
-mod compiler;
 mod construct;
 mod event;
+pub mod mdast;
 mod parser;
 mod resolve;
 mod state;
 mod subtokenize;
+mod to_html;
+mod to_mdast;
 mod tokenizer;
 mod util;
 
-use crate::compiler::compile;
-use crate::parser::parse;
 use alloc::{boxed::Box, fmt, string::String};
+use mdast::Root;
+use parser::parse;
+use to_html::compile as to_html;
+use to_mdast::compile as to_mdast;
 
 /// Type of line endings in markdown.
 #[derive(Clone, Debug, Default, Eq, PartialEq)]
@@ -1154,5 +1165,23 @@ pub fn micromark(value: &str) -> String {
 /// ```
 pub fn micromark_with_options(value: &str, options: &Options) -> Result<String, String> {
     let (events, bytes) = parse(value, options)?;
-    Ok(compile(&events, bytes, options))
+    Ok(to_html(&events, bytes, options))
+}
+
+/// Turn markdown into a syntax tree.
+///
+/// ## Errors
+///
+/// `to_mdast` never errors with normal markdown because markdown does not have
+/// syntax errors, so feel free to `unwrap()`.
+/// However, MDX does have syntax errors.
+/// When MDX is turned on, there are several errors that can occur with how
+/// JSX, expressions, or ESM are written.
+///
+/// ## Examples
+///
+/// To do.
+pub fn micromark_to_mdast(value: &str, options: &Options) -> Result<Root, String> {
+    let (events, bytes) = parse(value, options)?;
+    Ok(to_mdast(&events, bytes, options))
 }
diff --git a/src/mdast.rs b/src/mdast.rs
new file mode 100644
index 0000000..b60e891
--- /dev/null
+++ b/src/mdast.rs
@@ -0,0 +1,1047 @@
+//! [mdast][] syntax tree.
+//!
+//! [mdast]: https://github.com/syntax-tree/mdast
+
+// To do: example.
+// To do: math.
+
+use alloc::{string::String, vec::Vec};
+
+/// One place in a source file.
+#[derive(Clone, Debug)]
+pub struct Point {
+    /// 1-indexed integer representing a line in a source file.
+    pub line: usize,
+    /// 1-indexed integer representing a column in a source file.
+    pub column: usize,
+    /// 0-indexed integer representing a character in a source file.
+    pub offset: usize,
+}
+
+/// Location of a node in a source file.
+#[derive(Clone, Debug)]
+pub struct Position {
+    /// Represents the place of the first character of the parsed source region.
+    pub start: Point,
+    /// Represents the place of the first character after the parsed source
+    /// region, whether it exists or not.
+    pub end: Point,
+}
+
+/// Explicitness of a reference.
+#[derive(Clone, Debug)]
+pub enum ReferenceKind {
+    /// The reference is implicit, its identifier inferred from its content.
+    Shortcut,
+    /// The reference is explicit, its identifier inferred from its content.
+    Collapsed,
+    /// The reference is explicit, its identifier explicitly set.
+    Full,
+}
+
+/// Represents how phrasing content is aligned.
+#[derive(Clone, Debug)]
+pub enum AlignKind {
+    /// See the `left` value of the `text-align` CSS property.
+    Left,
+    /// See the `right` value of the `text-align` CSS property.
+    Right,
+    /// See the `center` value of the `text-align` CSS property.
+    Center,
+    /// Phrasing content is aligned as defined by the host environment.
+    None,
+}
+
+/// Node type.
+#[derive(Clone, Debug)]
+pub enum Kind {
+    /// Root node.
+    Root,
+    /// Paragraph node.
+    Paragraph,
+    /// Heading node.
+    Heading,
+    /// Thematic break node.
+    ThematicBreak,
+    /// Block quote node.
+    BlockQuote,
+    /// List node.
+    List,
+    /// List item node.
+    ListItem,
+    /// Html node.
+    Html,
+    /// Code node.
+    Code,
+    /// Definition node.
+    Definition,
+    /// Text node.
+    Text,
+    /// Emphasis node.
+    Emphasis,
+    /// Strong node.
+    Strong,
+    /// Code (inline) node.
+    InlineCode,
+    /// Break node.
+    Break,
+    /// Link node.
+    Link,
+    /// Image node.
+    Image,
+    /// Link reference node.
+    LinkReference,
+    /// Image reference node.
+    ImageReference,
+    /// Footnote definition node.
+    FootnoteDefinition,
+    /// Footnote reference node.
+    FootnoteReference,
+    /// Table node.
+    Table,
+    /// Table row node.
+    TableRow,
+    /// Table cell node.
+    TableCell,
+    /// Strong node.
+    Delete,
+    /// Yaml node.
+    Yaml,
+    /// Toml node.
+    Toml,
+    /// MDX: ESM node.
+    MdxjsEsm,
+    /// MDX: expression (flow).
+    MdxFlowExpression,
+    /// MDX: expression (phrasing).
+    MdxTextExpression,
+    /// MDX: JSX element (flow).
+    MdxJsxFlowElement,
+    /// MDX: JSX element (phrasing).
+    MdxJsxTextElement,
+    /// MDX: JSX attribute expression.
+    MdxJsxExpressionAttribute,
+    /// MDX: JSX attribute.
+    MdxJsxAttribute,
+    /// MDX: JSX attribute value expression.
+    MdxJsxAttributeValueExpression,
+}
+
+/// Document content.
+#[derive(Clone, Debug)]
+pub enum DocumentContent {
+    /// Container content.
+    Container(ContainerContent),
+    /// Frontmatter content.
+    Frontmatter(FrontmatterContent),
+}
+
+/// Container content.
+#[derive(Clone, Debug)]
+pub enum ContainerContent {
+    /// Block quote.
+    BlockQuote(BlockQuote),
+    /// Flow content.
+    Flow(FlowContent),
+    /// Footnote definition.
+    FootnoteDefinition(FootnoteDefinition),
+    /// MDX: JSX element (container).
+    JsxElement(MdxJsxFlowElement),
+    /// List.
+    List(List),
+}
+
+/// Frontmatter content.
+#[derive(Clone, Debug)]
+pub enum FrontmatterContent {
+    /// MDX.js ESM.
+    Esm(MdxjsEsm),
+    /// Toml.
+    Toml(Toml),
+    /// Yaml.
+    Yaml(Yaml),
+}
+
+/// Phrasing content.
+#[derive(Clone, Debug)]
+pub enum PhrasingContent {
+    /// Break.
+    Break(Break),
+    /// Code (phrasing).
+    Code(InlineCode),
+    /// Delete.
+    Delete(Delete),
+    /// Emphasis.
+    Emphasis(Emphasis),
+    // MDX: expression (text).
+    Expression(MdxTextExpression),
+    /// Footnote reference.
+    FootnoteReference(FootnoteReference),
+    /// Html (phrasing).
+    Html(Html),
+    /// Image.
+    Image(Image),
+    /// Image reference.
+    ImageReference(ImageReference),
+    // MDX: JSX element (text).
+    JsxElement(MdxJsxTextElement),
+    /// Link.
+    Link(Link),
+    /// Link reference.
+    LinkReference(LinkReference),
+    /// Strong
+    Strong(Strong),
+    /// Text.
+    Text(Text),
+}
+
+/// Flow content.
+#[derive(Clone, Debug)]
+pub enum FlowContent {
+    /// Code (flow).
+    Code(Code),
+    /// Content.
+    Content(ContentContent),
+    // MDX: expression (flow).
+    Expression(MdxFlowExpression),
+    /// Heading.
+    Heading(Heading),
+    /// Html (flow).
+    Html(Html),
+    /// Table.
+    Table(Table),
+    /// Thematic break.
+    ThematicBreak(ThematicBreak),
+}
+
+/// Table content.
+#[derive(Clone, Debug)]
+pub enum TableContent {
+    /// Table row.
+    Row(TableRow),
+}
+
+/// Row content.
+#[derive(Clone, Debug)]
+pub enum RowContent {
+    /// Table cell.
+    Cell(TableCell),
+}
+
+/// List content.
+#[derive(Clone, Debug)]
+pub enum ListContent {
+    /// List item.
+    Item(ListItem),
+}
+
+/// Content.
+#[derive(Clone, Debug)]
+pub enum ContentContent {
+    /// Definition.
+    Definition(Definition),
+    /// Paragraph.
+    Paragraph(Paragraph),
+}
+
+/// MDX: attribute content.
+#[derive(Clone, Debug)]
+pub enum AttributeContent {
+    /// MDX: JSX attribute expression.
+    Expression(MdxJsxExpressionAttribute),
+    /// MDX: JSX attribute.
+    Property(MdxJsxAttribute),
+}
+
+/// MDX: attribute value.
+#[derive(Clone, Debug)]
+pub enum AttributeValue {
+    /// Expression value.
+    Expression(MdxJsxAttributeValueExpression),
+    /// Static value.
+    Literal(String),
+}
+
+/// Document.
+///
+/// ```markdown
+/// > | a
+///     ^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Root {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Root`.
+    /// Content model.
+    pub children: Vec<DocumentContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Paragraph.
+///
+/// ```markdown
+/// > | a
+///     ^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Paragraph {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Paragraph`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Heading.
+///
+/// ```markdown
+/// > | # a
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Heading {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Heading`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Extra.
+    /// Rank (between `1` and `6`, both including).
+    pub depth: u8,
+}
+
+/// Thematic break.
+///
+/// ```markdown
+/// > | ***
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct ThematicBreak {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::ThematicBreak`.
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Block quote.
+///
+/// ```markdown
+/// > | > a
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct BlockQuote {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::BlockQuote`.
+    /// Content model.
+    pub children: Vec<ContainerContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// List.
+///
+/// ```markdown
+/// > | * a
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct List {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::List`.
+    /// Content model.
+    pub children: Vec<ListContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Extra.
+    /// Ordered (`true`) or unordered (`false`).
+    pub ordered: bool,
+    /// Starting number of the list.
+    /// `None` when unordered.
+    pub start: Option<u8>,
+    /// One or more of its children are separated with a blank line from its
+    /// siblings (when `true`), or not (when `false`).
+    pub spread: bool,
+}
+
+/// List item.
+///
+/// ```markdown
+/// > | * a
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct ListItem {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::ListItem`.
+    /// Content model.
+    pub children: Vec<ContainerContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Extra.
+    /// The item contains two or more children separated by a blank line
+    /// (when `true`), or not (when `false`).
+    pub spread: bool,
+    /// GFM: whether the item is done (when `true`), not done (when `false`),
+    /// or indeterminate or not applicable (`None`).
+    pub checked: Option<bool>,
+}
+
+/// Html (flow or phrasing).
+///
+/// ```markdown
+/// > | <a>
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Html {
+    // Text.
+    /// Node type.
+    pub kind: Kind, // `Kind::Html`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Code (flow).
+///
+/// ```markdown
+/// > | ~~~
+///     ^^^
+/// > | a
+///     ^^^
+/// > | ~~~
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Code {
+    // Text.
+    /// Node type.
+    pub kind: Kind, // `Kind::Code`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Extra.
+    /// The language of computer code being marked up.
+    pub lang: Option<String>,
+    /// Custom info relating to the node.
+    pub meta: Option<String>,
+}
+
+/// Definition.
+///
+/// ```markdown
+/// > | [a]: b
+///     ^^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Definition {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::Definition`.
+    /// Positional info.
+    pub position: Option<Position>,
+    // Resource.
+    /// URL to the referenced resource.
+    pub url: String,
+    /// Advisory info for the resource, such as something that would be
+    /// appropriate for a tooltip.
+    pub title: Option<String>,
+    // Association.
+    /// Value that can match another node.
+    /// `identifier` is a source value: character escapes and character references
+    /// are *not* parsed.
+    /// Its value must be normalized.
+    pub identifier: String,
+    /// `label` is a string value: it works just like `title` on a link or a
+    /// `lang` on code: character escapes and character references are parsed.
+    ///
+    /// To normalize a value, collapse markdown whitespace (`[\t\n\r ]+`) to a
+    /// space, trim the optional initial and/or final space, and perform
+    /// case-folding.
+    pub label: Option<String>,
+}
+
+/// Text.
+///
+/// ```markdown
+/// > | a
+///     ^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Text {
+    // Text.
+    /// Node type.
+    pub kind: Kind, // `Kind::Text`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Emphasis.
+///
+/// ```markdown
+/// > | *a*
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Emphasis {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Emphasis`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Strong.
+///
+/// ```markdown
+/// > | **a**
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Strong {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Strong`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Code (phrasing).
+///
+/// ```markdown
+/// > | `a`
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct InlineCode {
+    // Text.
+    /// Node type.
+    pub kind: Kind, // `Kind::InlineCode`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Break.
+///
+/// ```markdown
+/// > | a\
+///      ^
+///   | b
+/// ```
+#[derive(Clone, Debug)]
+pub struct Break {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::Break`.
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Link.
+///
+/// ```markdown
+/// > | [a](b)
+///     ^^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Link {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Link`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Resource.
+    /// URL to the referenced resource.
+    pub url: String,
+    /// Advisory info for the resource, such as something that would be
+    /// appropriate for a tooltip.
+    pub title: Option<String>,
+}
+
+/// Image.
+///
+/// ```markdown
+/// > | ![a](b)
+///     ^^^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Image {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::Image`.
+    /// Positional info.
+    pub position: Option<Position>,
+    // Alternative.
+    /// Equivalent content for environments that cannot represent the node as
+    /// intended.
+    pub alt: String,
+    // Resource.
+    /// URL to the referenced resource.
+    pub url: String,
+    /// Advisory info for the resource, such as something that would be
+    /// appropriate for a tooltip.
+    pub title: Option<String>,
+}
+
+/// Link reference.
+///
+/// ```markdown
+/// > | [a]
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct LinkReference {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::LinkReference`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Reference.
+    /// Explicitness of a reference.
+    pub reference_kind: ReferenceKind,
+    // Association.
+    /// Value that can match another node.
+    /// `identifier` is a source value: character escapes and character references
+    /// are *not* parsed.
+    /// Its value must be normalized.
+    pub identifier: String,
+    /// `label` is a string value: it works just like `title` on a link or a
+    /// `lang` on code: character escapes and character references are parsed.
+    ///
+    /// To normalize a value, collapse markdown whitespace (`[\t\n\r ]+`) to a
+    /// space, trim the optional initial and/or final space, and perform
+    /// case-folding.
+    pub label: Option<String>,
+}
+
+/// Image reference.
+///
+/// ```markdown
+/// > | ![a]
+///     ^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct ImageReference {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::ImageReference`.
+    /// Positional info.
+    pub position: Option<Position>,
+    // Alternative.
+    /// Equivalent content for environments that cannot represent the node as
+    /// intended.
+    pub alt: String,
+    // Reference.
+    /// Explicitness of a reference.
+    pub reference_kind: ReferenceKind,
+    // Association.
+    /// Value that can match another node.
+    /// `identifier` is a source value: character escapes and character references
+    /// are *not* parsed.
+    /// Its value must be normalized.
+    pub identifier: String,
+    /// `label` is a string value: it works just like `title` on a link or a
+    /// `lang` on code: character escapes and character references are parsed.
+    ///
+    /// To normalize a value, collapse markdown whitespace (`[\t\n\r ]+`) to a
+    /// space, trim the optional initial and/or final space, and perform
+    /// case-folding.
+    pub label: Option<String>,
+}
+
+/// Footnote definition (GFM).
+///
+/// ```markdown
+/// > | [^a]: b
+///     ^^^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct FootnoteDefinition {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::FootnoteDefinition`.
+    /// Content model.
+    pub children: Vec<ContainerContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Association.
+    /// Value that can match another node.
+    /// `identifier` is a source value: character escapes and character references
+    /// are *not* parsed.
+    /// Its value must be normalized.
+    pub identifier: String,
+    /// `label` is a string value: it works just like `title` on a link or a
+    /// `lang` on code: character escapes and character references are parsed.
+    ///
+    /// To normalize a value, collapse markdown whitespace (`[\t\n\r ]+`) to a
+    /// space, trim the optional initial and/or final space, and perform
+    /// case-folding.
+    pub label: Option<String>,
+}
+
+/// Footnote reference (GFM).
+///
+/// ```markdown
+/// > | [^a]
+///     ^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct FootnoteReference {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::FootnoteReference`.
+    /// Positional info.
+    pub position: Option<Position>,
+    // Association.
+    /// Value that can match another node.
+    /// `identifier` is a source value: character escapes and character references
+    /// are *not* parsed.
+    /// Its value must be normalized.
+    pub identifier: String,
+    /// `label` is a string value: it works just like `title` on a link or a
+    /// `lang` on code: character escapes and character references are parsed.
+    ///
+    /// To normalize a value, collapse markdown whitespace (`[\t\n\r ]+`) to a
+    /// space, trim the optional initial and/or final space, and perform
+    /// case-folding.
+    pub label: Option<String>,
+}
+
+/// Table (GFM).
+///
+/// ```markdown
+/// > | | a |
+///     ^^^^^
+/// > | | - |
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Table {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Table`.
+    /// Content model.
+    pub children: Vec<TableContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // Extra.
+    /// Represents how cells in columns are aligned.
+    pub align: Vec<AlignKind>,
+}
+
+/// Table row (GFM).
+///
+/// ```markdown
+/// > | | a |
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct TableRow {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::TableRow`.
+    /// Content model.
+    pub children: Vec<RowContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Table cell (GFM).
+///
+/// ```markdown
+/// > | | a |
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct TableCell {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::TableCell`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Delete (GFM).
+///
+/// ```markdown
+/// > | ~~a~~
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Delete {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::Delete`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Yaml (frontmatter).
+///
+/// ```markdown
+/// > | ---
+///     ^^^
+/// > | a: b
+///     ^^^^
+/// > | ---
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Yaml {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::Yaml`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// Toml (frontmatter).
+///
+/// ```markdown
+/// > | +++
+///     ^^^
+/// > | a: b
+///     ^^^^
+/// > | +++
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct Toml {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::Toml`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// MDX: ESM.
+///
+/// ```markdown
+/// > | import a from 'b'
+///     ^^^^^^^^^^^^^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxjsEsm {
+    // Literal.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxjsEsm`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// MDX: expression (flow).
+///
+/// ```markdown
+/// > | {a}
+///     ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxFlowExpression {
+    // Literal.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxFlowExpression`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// MDX: expression (text).
+///
+/// ```markdown
+/// > | a {b}
+///       ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxTextExpression {
+    // Literal.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxTextExpression`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// MDX: JSX element (container).
+///
+/// ```markdown
+/// > | <a />
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxJsxFlowElement {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxJsxFlowElement`.
+    /// Content model.
+    pub children: Vec<ContainerContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // JSX element.
+    /// Name.
+    ///
+    /// Fragments have no name.
+    pub name: Option<String>,
+    /// Attributes.
+    pub attributes: Vec<AttributeContent>,
+}
+
+/// MDX: JSX element (text).
+///
+/// ```markdown
+/// > | <a />.
+///     ^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxJsxTextElement {
+    // Parent.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxJsxTextElement`.
+    /// Content model.
+    pub children: Vec<PhrasingContent>,
+    /// Positional info.
+    pub position: Option<Position>,
+    // JSX element.
+    /// Name.
+    ///
+    /// Fragments have no name.
+    pub name: Option<String>,
+    /// Attributes.
+    pub attributes: Vec<AttributeContent>,
+}
+
+/// MDX: JSX attribute expression.
+///
+/// ```markdown
+/// > | <a {...b} />
+///        ^^^^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxJsxExpressionAttribute {
+    // Literal.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxJsxExpressionAttribute`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+/// MDX: JSX attribute.
+///
+/// ```markdown
+/// > | <a b />
+///        ^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxJsxAttribute {
+    // Void.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxJsxAttribute`.
+    /// Positional info.
+    pub position: Option<Position>,
+    /// Key.
+    pub name: String,
+    /// Value.
+    pub value: Option<AttributeValue>,
+}
+
+/// MDX: JSX attribute value expression.
+///
+/// ```markdown
+/// > | <a b={c} />
+///          ^^^
+/// ```
+#[derive(Clone, Debug)]
+pub struct MdxJsxAttributeValueExpression {
+    // Literal.
+    /// Node type.
+    pub kind: Kind, // `Kind::MdxJsxAttributeValueExpression`.
+    /// Content model.
+    pub value: String,
+    /// Positional info.
+    pub position: Option<Position>,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use alloc::{string::ToString, vec};
+
+    #[test]
+    fn test() {
+        let text = Text {
+            kind: Kind::Text,
+            value: "a".to_string(),
+            position: Some(Position {
+                start: Point {
+                    line: 1,
+                    column: 1,
+                    offset: 0,
+                },
+                end: Point {
+                    line: 1,
+                    column: 2,
+                    offset: 1,
+                },
+            }),
+        };
+
+        let paragraph = Paragraph {
+            kind: Kind::Paragraph,
+            children: vec![PhrasingContent::Text(text)],
+            position: Some(Position {
+                start: Point {
+                    line: 1,
+                    column: 1,
+                    offset: 0,
+                },
+                end: Point {
+                    line: 1,
+                    column: 2,
+                    offset: 1,
+                },
+            }),
+        };
+
+        assert_eq!(paragraph.children.len(), 1);
+        assert!(matches!(&paragraph.children[0], PhrasingContent::Text(_)));
+    }
+}
diff --git a/src/to_html.rs b/src/to_html.rs
new file mode 100644
index 0000000..43be6a7
--- /dev/null
+++ b/src/to_html.rs
@@ -0,0 +1,1922 @@
+//! Turn events into a string of HTML.
+use crate::event::{Event, Kind, Name};
+use crate::util::{
+    constant::{SAFE_PROTOCOL_HREF, SAFE_PROTOCOL_SRC},
+    decode_character_reference::{decode_named, decode_numeric},
+    encode::encode,
+    gfm_tagfilter::gfm_tagfilter,
+    normalize_identifier::normalize_identifier,
+    sanitize_uri::{sanitize, sanitize_with_protocols},
+    skip,
+    slice::{Position, Slice},
+};
+use crate::{LineEnding, Options};
+use alloc::{
+    format,
+    string::{String, ToString},
+    vec,
+    vec::Vec,
+};
+use core::str;
+
+/// Link, image, or footnote call.
+/// Resource or reference.
+/// Reused for temporary definitions as well, in the first pass.
+#[derive(Debug)]
+struct Media {
+    /// Whether this represents an image (`true`) or a link or definition
+    /// (`false`).
+    image: bool,
+    /// The text between the brackets (`x` in `![x]()` and `[x]()`).
+    ///
+    /// Not interpreted.
+    label_id: Option<(usize, usize)>,
+    /// The result of interpreting the text between the brackets
+    /// (`x` in `![x]()` and `[x]()`).
+    ///
+    /// When this is a link, it contains further text content and thus HTML
+    /// tags.
+    /// Otherwise, when an image, text content is also allowed, but resulting
+    /// tags are ignored.
+    label: Option<String>,
+    /// The string between the explicit brackets of the reference (`y` in
+    /// `[x][y]`), as content.
+    ///
+    /// Not interpreted.
+    reference_id: Option<(usize, usize)>,
+    /// The destination (url).
+    ///
+    /// Interpreted string content.
+    destination: Option<String>,
+    /// The destination (url).
+    ///
+    /// Interpreted string content.
+    title: Option<String>,
+}
+
+/// Representation of a definition.
+#[derive(Debug)]
+struct Definition {
+    /// Identifier.
+    id: String,
+    /// The destination (url).
+    ///
+    /// Interpreted string content.
+    destination: Option<String>,
+    /// The title.
+    ///
+    /// Interpreted string content.
+    title: Option<String>,
+}
+
+/// GFM table: column alignment.
+// To do: share with `mdast`.
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+enum GfmTableAlign {
+    /// No alignment.
+    ///
+    /// ```markdown
+    ///   | | aaa |
+    /// > | | --- |
+    ///       ^^^
+    /// ```
+    None,
+    /// Left alignment.
+    ///
+    /// ```markdown
+    ///   | | aaa |
+    /// > | | :-- |
+    ///       ^^^
+    /// ```
+    Left,
+    /// Center alignment.
+    ///
+    /// ```markdown
+    ///   | | aaa |
+    /// > | | :-: |
+    ///       ^^^
+    /// ```
+    Center,
+    /// Right alignment.
+    ///
+    /// ```markdown
+    ///   | | aaa |
+    /// > | | --: |
+    ///       ^^^
+    /// ```
+    Right,
+}
+
+/// Context used to compile markdown.
+#[allow(clippy::struct_excessive_bools)]
+#[derive(Debug)]
+struct CompileContext<'a> {
+    // Static info.
+    /// List of events.
+    pub events: &'a [Event],
+    /// List of bytes.
+    pub bytes: &'a [u8],
+    /// Configuration.
+    pub options: &'a Options,
+    // Fields used by handlers to track the things they need to track to
+    // compile markdown.
+    /// Rank of heading (atx).
+    pub heading_atx_rank: Option<usize>,
+    /// Buffer of heading (setext) text.
+    pub heading_setext_buffer: Option<String>,
+    /// Whether raw (flow) (code (fenced), math (flow)) or code (indented) contains data.
+    pub raw_flow_seen_data: Option<bool>,
+    /// Number of raw (flow) fences.
+    pub raw_flow_fences_count: Option<usize>,
+    /// Whether we are in code (text).
+    pub raw_text_inside: bool,
+    /// Whether we are in image text.
+    pub image_alt_inside: bool,
+    /// Marker of character reference.
+    pub character_reference_marker: Option<u8>,
+    /// Whether we are expecting the first list item marker.
+    pub list_expect_first_marker: Option<bool>,
+    /// Stack of media (link, image).
+    pub media_stack: Vec<Media>,
+    /// Stack of containers.
+    pub tight_stack: Vec<bool>,
+    /// List of definitions.
+    pub definitions: Vec<Definition>,
+    /// List of definitions.
+    pub gfm_footnote_definitions: Vec<(String, String)>,
+    pub gfm_footnote_definition_calls: Vec<(String, usize)>,
+    pub gfm_footnote_definition_stack: Vec<(usize, usize)>,
+    /// Whether we are in a GFM table head.
+    pub gfm_table_in_head: bool,
+    /// Current GFM table alignment.
+    pub gfm_table_align: Option<Vec<GfmTableAlign>>,
+    /// Current GFM table column.
+    pub gfm_table_column: usize,
+    // Fields used to influance the current compilation.
+    /// Ignore the next line ending.
+    pub slurp_one_line_ending: bool,
+    /// Whether to encode HTML.
+    pub encode_html: bool,
+    // Configuration
+    /// Line ending to use.
+    pub line_ending_default: LineEnding,
+    // Intermediate results.
+    /// Stack of buffers.
+    pub buffers: Vec<String>,
+    /// Current event index.
+    pub index: usize,
+}
+
+impl<'a> CompileContext<'a> {
+    /// Create a new compile context.
+    pub fn new(
+        events: &'a [Event],
+        bytes: &'a [u8],
+        options: &'a Options,
+        line_ending: LineEnding,
+    ) -> CompileContext<'a> {
+        CompileContext {
+            events,
+            bytes,
+            heading_atx_rank: None,
+            heading_setext_buffer: None,
+            raw_flow_seen_data: None,
+            raw_flow_fences_count: None,
+            raw_text_inside: false,
+            character_reference_marker: None,
+            list_expect_first_marker: None,
+            media_stack: vec![],
+            definitions: vec![],
+            gfm_footnote_definitions: vec![],
+            gfm_footnote_definition_calls: vec![],
+            gfm_footnote_definition_stack: vec![],
+            gfm_table_in_head: false,
+            gfm_table_align: None,
+            gfm_table_column: 0,
+            tight_stack: vec![],
+            slurp_one_line_ending: false,
+            image_alt_inside: false,
+            encode_html: true,
+            line_ending_default: line_ending,
+            buffers: vec![String::new()],
+            index: 0,
+            options,
+        }
+    }
+
+    /// Push a buffer.
+    pub fn buffer(&mut self) {
+        self.buffers.push(String::new());
+    }
+
+    /// Pop a buffer, returning its value.
+    pub fn resume(&mut self) -> String {
+        self.buffers.pop().expect("Cannot resume w/o buffer")
+    }
+
+    /// Push a str to the last buffer.
+    pub fn push(&mut self, value: &str) {
+        self.buffers
+            .last_mut()
+            .expect("Cannot push w/o buffer")
+            .push_str(value);
+    }
+
+    /// Add a line ending.
+    pub fn line_ending(&mut self) {
+        let eol = self.line_ending_default.as_str().to_string();
+        self.push(&eol);
+    }
+
+    /// Add a line ending if needed (as in, there’s no eol/eof already).
+    pub fn line_ending_if_needed(&mut self) {
+        let tail = self
+            .buffers
+            .last()
+            .expect("at least one buffer should exist")
+            .as_bytes()
+            .last();
+
+        if !matches!(tail, None | Some(b'\n' | b'\r')) {
+            self.line_ending();
+        }
+    }
+}
+
+/// Turn events and bytes into a string of HTML.
+pub fn compile(events: &[Event], bytes: &[u8], options: &Options) -> String {
+    let mut index = 0;
+    let mut line_ending_inferred = None;
+
+    // First, we figure out what the used line ending style is.
+    // Stop when we find a line ending.
+    while index < events.len() {
+        let event = &events[index];
+
+        if event.kind == Kind::Exit
+            && (event.name == Name::BlankLineEnding || event.name == Name::LineEnding)
+        {
+            line_ending_inferred = Some(LineEnding::from_str(
+                Slice::from_position(bytes, &Position::from_exit_event(events, index)).as_str(),
+            ));
+            break;
+        }
+
+        index += 1;
+    }
+
+    // Figure out which line ending style we’ll use.
+    let line_ending_default =
+        line_ending_inferred.unwrap_or_else(|| options.default_line_ending.clone());
+
+    let mut context = CompileContext::new(events, bytes, options, line_ending_default);
+    let mut definition_indices = vec![];
+    let mut index = 0;
+    let mut definition_inside = false;
+
+    // Handle all definitions first.
+    // We must do two passes because we need to compile the events in
+    // definitions which come after references already.
+    //
+    // To speed things up, we collect the places we can jump over for the
+    // second pass.
+    //
+    // We don’t need to handle GFM footnote definitions like this, because
+    // unlike normal definitions, what they produce is not used in calls.
+    // It would also get very complex, because footnote definitions can be
+    // nested.
+    while index < events.len() {
+        let event = &events[index];
+
+        if definition_inside {
+            handle(&mut context, index);
+        }
+
+        if event.kind == Kind::Enter {
+            if event.name == Name::Definition {
+                handle(&mut context, index); // Also handle start.
+                definition_inside = true;
+                definition_indices.push((index, index));
+            }
+        } else if event.name == Name::Definition {
+            definition_inside = false;
+            definition_indices.last_mut().unwrap().1 = index;
+        }
+
+        index += 1;
+    }
+
+    index = 0;
+    let jump_default = (events.len(), events.len());
+    let mut definition_index = 0;
+    let mut jump = definition_indices
+        .get(definition_index)
+        .unwrap_or(&jump_default);
+
+    while index < events.len() {
+        if index == jump.0 {
+            index = jump.1 + 1;
+            definition_index += 1;
+            jump = definition_indices
+                .get(definition_index)
+                .unwrap_or(&jump_default);
+        } else {
+            handle(&mut context, index);
+            index += 1;
+        }
+    }
+
+    // No section to generate.
+    if !context.gfm_footnote_definition_calls.is_empty() {
+        generate_footnote_section(&mut context);
+    }
+
+    debug_assert_eq!(context.buffers.len(), 1, "expected 1 final buffer");
+    context
+        .buffers
+        .get(0)
+        .expect("expected 1 final buffer")
+        .to_string()
+}
+
+/// Handle the event at `index`.
+fn handle(context: &mut CompileContext, index: usize) {
+    context.index = index;
+
+    if context.events[index].kind == Kind::Enter {
+        enter(context);
+    } else {
+        exit(context);
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter].
+fn enter(context: &mut CompileContext) {
+    match context.events[context.index].name {
+        Name::CodeFencedFenceInfo
+        | Name::CodeFencedFenceMeta
+        | Name::MathFlowFenceMeta
+        | Name::DefinitionLabelString
+        | Name::DefinitionTitleString
+        | Name::GfmFootnoteDefinitionPrefix
+        | Name::HeadingAtxText
+        | Name::HeadingSetextText
+        | Name::Label
+        | Name::MdxEsm
+        | Name::MdxFlowExpression
+        | Name::MdxTextExpression
+        | Name::MdxJsxFlowTag
+        | Name::MdxJsxTextTag
+        | Name::ReferenceString
+        | Name::ResourceTitleString => on_enter_buffer(context),
+
+        Name::BlockQuote => on_enter_block_quote(context),
+        Name::CodeIndented => on_enter_code_indented(context),
+        Name::CodeFenced | Name::MathFlow => on_enter_raw_flow(context),
+        Name::CodeText | Name::MathText => on_enter_raw_text(context),
+        Name::Definition => on_enter_definition(context),
+        Name::DefinitionDestinationString => on_enter_definition_destination_string(context),
+        Name::Emphasis => on_enter_emphasis(context),
+        Name::Frontmatter => on_enter_frontmatter(context),
+        Name::GfmFootnoteDefinition => on_enter_gfm_footnote_definition(context),
+        Name::GfmFootnoteCall => on_enter_gfm_footnote_call(context),
+        Name::GfmStrikethrough => on_enter_gfm_strikethrough(context),
+        Name::GfmTable => on_enter_gfm_table(context),
+        Name::GfmTableBody => on_enter_gfm_table_body(context),
+        Name::GfmTableCell => on_enter_gfm_table_cell(context),
+        Name::GfmTableHead => on_enter_gfm_table_head(context),
+        Name::GfmTableRow => on_enter_gfm_table_row(context),
+        Name::GfmTaskListItemCheck => on_enter_gfm_task_list_item_check(context),
+        Name::HtmlFlow => on_enter_html_flow(context),
+        Name::HtmlText => on_enter_html_text(context),
+        Name::Image => on_enter_image(context),
+        Name::Link => on_enter_link(context),
+        Name::ListItemMarker => on_enter_list_item_marker(context),
+        Name::ListOrdered | Name::ListUnordered => on_enter_list(context),
+        Name::Paragraph => on_enter_paragraph(context),
+        Name::Resource => on_enter_resource(context),
+        Name::ResourceDestinationString => on_enter_resource_destination_string(context),
+        Name::Strong => on_enter_strong(context),
+        _ => {}
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit].
+fn exit(context: &mut CompileContext) {
+    match context.events[context.index].name {
+        Name::CodeFencedFenceMeta
+        | Name::MathFlowFenceMeta
+        | Name::MdxJsxTextTag
+        | Name::MdxTextExpression
+        | Name::Resource => {
+            on_exit_drop(context);
+        }
+        Name::MdxEsm | Name::MdxFlowExpression | Name::MdxJsxFlowTag => on_exit_drop_slurp(context),
+        Name::CharacterEscapeValue | Name::CodeTextData | Name::Data | Name::MathTextData => {
+            on_exit_data(context);
+        }
+        Name::AutolinkEmail => on_exit_autolink_email(context),
+        Name::AutolinkProtocol => on_exit_autolink_protocol(context),
+        Name::BlankLineEnding => on_exit_blank_line_ending(context),
+        Name::BlockQuote => on_exit_block_quote(context),
+        Name::CharacterReferenceMarker => on_exit_character_reference_marker(context),
+        Name::CharacterReferenceMarkerNumeric => {
+            on_exit_character_reference_marker_numeric(context);
+        }
+        Name::CharacterReferenceMarkerHexadecimal => {
+            on_exit_character_reference_marker_hexadecimal(context);
+        }
+        Name::CharacterReferenceValue => on_exit_character_reference_value(context),
+        Name::CodeFenced | Name::CodeIndented | Name::MathFlow => on_exit_raw_flow(context),
+        Name::CodeFencedFence | Name::MathFlowFence => on_exit_raw_flow_fence(context),
+        Name::CodeFencedFenceInfo => on_exit_raw_flow_fence_info(context),
+        Name::CodeFlowChunk | Name::MathFlowChunk => on_exit_raw_flow_chunk(context),
+        Name::CodeText | Name::MathText => on_exit_raw_text(context),
+        Name::Definition => on_exit_definition(context),
+        Name::DefinitionDestinationString => on_exit_definition_destination_string(context),
+        Name::DefinitionLabelString => on_exit_definition_label_string(context),
+        Name::DefinitionTitleString => on_exit_definition_title_string(context),
+        Name::Emphasis => on_exit_emphasis(context),
+        Name::Frontmatter => on_exit_frontmatter(context),
+        Name::GfmAutolinkLiteralEmail => on_exit_gfm_autolink_literal_email(context),
+        Name::GfmAutolinkLiteralMailto => on_exit_gfm_autolink_literal_mailto(context),
+        Name::GfmAutolinkLiteralProtocol => on_exit_gfm_autolink_literal_protocol(context),
+        Name::GfmAutolinkLiteralWww => on_exit_gfm_autolink_literal_www(context),
+        Name::GfmAutolinkLiteralXmpp => on_exit_gfm_autolink_literal_xmpp(context),
+        Name::GfmFootnoteCall => on_exit_gfm_footnote_call(context),
+        Name::GfmFootnoteDefinitionLabelString => {
+            on_exit_gfm_footnote_definition_label_string(context);
+        }
+        Name::GfmFootnoteDefinitionPrefix => on_exit_gfm_footnote_definition_prefix(context),
+        Name::GfmFootnoteDefinition => on_exit_gfm_footnote_definition(context),
+        Name::GfmStrikethrough => on_exit_gfm_strikethrough(context),
+        Name::GfmTable => on_exit_gfm_table(context),
+        Name::GfmTableBody => on_exit_gfm_table_body(context),
+        Name::GfmTableCell => on_exit_gfm_table_cell(context),
+        Name::GfmTableHead => on_exit_gfm_table_head(context),
+        Name::GfmTableRow => on_exit_gfm_table_row(context),
+        Name::GfmTaskListItemCheck => on_exit_gfm_task_list_item_check(context),
+        Name::GfmTaskListItemValueChecked => on_exit_gfm_task_list_item_value_checked(context),
+        Name::HardBreakEscape | Name::HardBreakTrailing => on_exit_break(context),
+        Name::HeadingAtx => on_exit_heading_atx(context),
+        Name::HeadingAtxSequence => on_exit_heading_atx_sequence(context),
+        Name::HeadingAtxText => on_exit_heading_atx_text(context),
+        Name::HeadingSetextText => on_exit_heading_setext_text(context),
+        Name::HeadingSetextUnderlineSequence => on_exit_heading_setext_underline_sequence(context),
+        Name::HtmlFlow | Name::HtmlText => on_exit_html(context),
+        Name::HtmlFlowData | Name::HtmlTextData => on_exit_html_data(context),
+        Name::Image | Name::Link => on_exit_media(context),
+        Name::Label => on_exit_label(context),
+        Name::LabelText => on_exit_label_text(context),
+        Name::LineEnding => on_exit_line_ending(context),
+        Name::ListOrdered | Name::ListUnordered => on_exit_list(context),
+        Name::ListItem => on_exit_list_item(context),
+        Name::ListItemValue => on_exit_list_item_value(context),
+        Name::Paragraph => on_exit_paragraph(context),
+        Name::ReferenceString => on_exit_reference_string(context),
+        Name::ResourceDestinationString => on_exit_resource_destination_string(context),
+        Name::ResourceTitleString => on_exit_resource_title_string(context),
+        Name::Strong => on_exit_strong(context),
+        Name::ThematicBreak => on_exit_thematic_break(context),
+        _ => {}
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:`*`.
+///
+/// Buffers data.
+fn on_enter_buffer(context: &mut CompileContext) {
+    context.buffer();
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`BlockQuote`][Name::BlockQuote].
+fn on_enter_block_quote(context: &mut CompileContext) {
+    context.tight_stack.push(false);
+    context.line_ending_if_needed();
+    context.push("<blockquote>");
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`CodeIndented`][Name::CodeIndented].
+fn on_enter_code_indented(context: &mut CompileContext) {
+    context.raw_flow_seen_data = Some(false);
+    context.line_ending_if_needed();
+    context.push("<pre><code>");
+}
+
+/// Handle [`Enter`][Kind::Enter]:{[`CodeFenced`][Name::CodeFenced],[`MathFlow`][Name::MathFlow]}.
+fn on_enter_raw_flow(context: &mut CompileContext) {
+    context.raw_flow_seen_data = Some(false);
+    context.line_ending_if_needed();
+    // Note that no `>` is used, which is added later (due to info)
+    context.push("<pre><code");
+    context.raw_flow_fences_count = Some(0);
+
+    if context.events[context.index].name == Name::MathFlow {
+        context.push(" class=\"language-math math-display\"");
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:{[`CodeText`][Name::CodeText],[`MathText`][Name::MathText]}.
+fn on_enter_raw_text(context: &mut CompileContext) {
+    context.raw_text_inside = true;
+    if !context.image_alt_inside {
+        context.push("<code");
+        if context.events[context.index].name == Name::MathText {
+            context.push(" class=\"language-math math-inline\"");
+        }
+        context.push(">");
+    }
+    context.buffer();
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Definition`][Name::Definition].
+fn on_enter_definition(context: &mut CompileContext) {
+    context.buffer();
+    context.media_stack.push(Media {
+        image: false,
+        label: None,
+        label_id: None,
+        reference_id: None,
+        destination: None,
+        title: None,
+    });
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`DefinitionDestinationString`][Name::DefinitionDestinationString].
+fn on_enter_definition_destination_string(context: &mut CompileContext) {
+    context.buffer();
+    context.encode_html = false;
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Emphasis`][Name::Emphasis].
+fn on_enter_emphasis(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("<em>");
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Frontmatter`][Name::Frontmatter].
+fn on_enter_frontmatter(context: &mut CompileContext) {
+    context.buffer();
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmFootnoteDefinition`][Name::GfmFootnoteDefinition].
+fn on_enter_gfm_footnote_definition(context: &mut CompileContext) {
+    context.tight_stack.push(false);
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmFootnoteCall`][Name::GfmFootnoteCall].
+fn on_enter_gfm_footnote_call(context: &mut CompileContext) {
+    context.media_stack.push(Media {
+        image: false,
+        label_id: None,
+        label: None,
+        reference_id: None,
+        destination: None,
+        title: None,
+    });
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmStrikethrough`][Name::GfmStrikethrough].
+fn on_enter_gfm_strikethrough(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("<del>");
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmTable`][Name::GfmTable].
+fn on_enter_gfm_table(context: &mut CompileContext) {
+    // Find the alignment.
+    let mut index = context.index;
+    let mut in_delimiter_row = false;
+    let mut align = vec![];
+
+    while index < context.events.len() {
+        let event = &context.events[index];
+
+        if in_delimiter_row {
+            if event.kind == Kind::Enter {
+                // Start of alignment value: set a new column.
+                if event.name == Name::GfmTableDelimiterCellValue {
+                    align.push(
+                        if context.events[index + 1].name == Name::GfmTableDelimiterMarker {
+                            GfmTableAlign::Left
+                        } else {
+                            GfmTableAlign::None
+                        },
+                    );
+                }
+            } else {
+                // End of alignment value: change the column.
+                if event.name == Name::GfmTableDelimiterCellValue {
+                    if context.events[index - 1].name == Name::GfmTableDelimiterMarker {
+                        let align_index = align.len() - 1;
+                        align[align_index] = if align[align_index] == GfmTableAlign::Left {
+                            GfmTableAlign::Center
+                        } else {
+                            GfmTableAlign::Right
+                        }
+                    }
+                }
+                // Done!
+                else if event.name == Name::GfmTableDelimiterRow {
+                    break;
+                }
+            }
+        } else if event.kind == Kind::Enter && event.name == Name::GfmTableDelimiterRow {
+            in_delimiter_row = true;
+        }
+
+        index += 1;
+    }
+
+    // Generate.
+    context.gfm_table_align = Some(align);
+    context.line_ending_if_needed();
+    context.push("<table>");
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmTableBody`][Name::GfmTableBody].
+fn on_enter_gfm_table_body(context: &mut CompileContext) {
+    context.push("<tbody>");
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmTableCell`][Name::GfmTableCell].
+fn on_enter_gfm_table_cell(context: &mut CompileContext) {
+    let column = context.gfm_table_column;
+    let align = context.gfm_table_align.as_ref().unwrap();
+
+    if column >= align.len() {
+        // Capture cell to ignore it.
+        context.buffer();
+    } else {
+        let value = align[column];
+        context.line_ending_if_needed();
+
+        if context.gfm_table_in_head {
+            context.push("<th");
+        } else {
+            context.push("<td");
+        }
+
+        match value {
+            GfmTableAlign::Left => context.push(" align=\"left\""),
+            GfmTableAlign::Right => context.push(" align=\"right\""),
+            GfmTableAlign::Center => context.push(" align=\"center\""),
+            GfmTableAlign::None => {}
+        }
+
+        context.push(">");
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmTableHead`][Name::GfmTableHead].
+fn on_enter_gfm_table_head(context: &mut CompileContext) {
+    context.line_ending_if_needed();
+    context.push("<thead>");
+    context.gfm_table_in_head = true;
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmTableRow`][Name::GfmTableRow].
+fn on_enter_gfm_table_row(context: &mut CompileContext) {
+    context.line_ending_if_needed();
+    context.push("<tr>");
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`GfmTaskListItemCheck`][Name::GfmTaskListItemCheck].
+fn on_enter_gfm_task_list_item_check(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("<input type=\"checkbox\" disabled=\"\" ");
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`HtmlFlow`][Name::HtmlFlow].
+fn on_enter_html_flow(context: &mut CompileContext) {
+    context.line_ending_if_needed();
+    if context.options.allow_dangerous_html {
+        context.encode_html = false;
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`HtmlText`][Name::HtmlText].
+fn on_enter_html_text(context: &mut CompileContext) {
+    if context.options.allow_dangerous_html {
+        context.encode_html = false;
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Image`][Name::Image].
+fn on_enter_image(context: &mut CompileContext) {
+    context.media_stack.push(Media {
+        image: true,
+        label_id: None,
+        label: None,
+        reference_id: None,
+        destination: None,
+        title: None,
+    });
+    context.image_alt_inside = true; // Disallow tags.
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Link`][Name::Link].
+fn on_enter_link(context: &mut CompileContext) {
+    context.media_stack.push(Media {
+        image: false,
+        label_id: None,
+        label: None,
+        reference_id: None,
+        destination: None,
+        title: None,
+    });
+}
+
+/// Handle [`Enter`][Kind::Enter]:{[`ListOrdered`][Name::ListOrdered],[`ListUnordered`][Name::ListUnordered]}.
+fn on_enter_list(context: &mut CompileContext) {
+    let events = &context.events;
+    let mut index = context.index;
+    let mut balance = 0;
+    let mut loose = false;
+    let name = &events[index].name;
+
+    while index < events.len() {
+        let event = &events[index];
+
+        if event.kind == Kind::Enter {
+            balance += 1;
+        } else {
+            balance -= 1;
+
+            if balance < 3 && event.name == Name::BlankLineEnding {
+                // Blank line directly after a prefix:
+                //
+                // ```markdown
+                // > | -␊
+                //      ^
+                //   |   a
+                // ```
+                let mut at_prefix = false;
+                // Blank line directly after item, which is just a prefix.
+                //
+                // ```markdown
+                // > | -␊
+                //      ^
+                //   | - a
+                // ```
+                let mut at_empty_list_item = false;
+                // Blank line at block quote prefix:
+                //
+                // ```markdown
+                // > | * >␊
+                //        ^
+                //   | * a
+                // ```
+                let mut at_empty_block_quote = false;
+
+                if balance == 1 {
+                    let mut before = index - 2;
+
+                    if events[before].name == Name::ListItem {
+                        before -= 1;
+
+                        if events[before].name == Name::SpaceOrTab {
+                            before -= 2;
+                        }
+
+                        if events[before].name == Name::BlockQuote
+                            && events[before - 1].name == Name::BlockQuotePrefix
+                        {
+                            at_empty_block_quote = true;
+                        } else if events[before].name == Name::ListItemPrefix {
+                            at_empty_list_item = true;
+                        }
+                    }
+                } else {
+                    let mut before = index - 2;
+
+                    if events[before].name == Name::SpaceOrTab {
+                        before -= 2;
+                    }
+
+                    if events[before].name == Name::ListItemPrefix {
+                        at_prefix = true;
+                    }
+                }
+
+                if !at_prefix && !at_empty_list_item && !at_empty_block_quote {
+                    loose = true;
+                    break;
+                }
+            }
+
+            // Done.
+            if balance == 0 && event.name == *name {
+                break;
+            }
+        }
+
+        index += 1;
+    }
+
+    context.tight_stack.push(!loose);
+    context.line_ending_if_needed();
+    // Note: no `>`.
+    context.push(if *name == Name::ListOrdered {
+        "<ol"
+    } else {
+        "<ul"
+    });
+    context.list_expect_first_marker = Some(true);
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`ListItemMarker`][Name::ListItemMarker].
+fn on_enter_list_item_marker(context: &mut CompileContext) {
+    if context.list_expect_first_marker.take().unwrap() {
+        context.push(">");
+    }
+
+    context.line_ending_if_needed();
+
+    context.push("<li>");
+    context.list_expect_first_marker = Some(false);
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Paragraph`][Name::Paragraph].
+fn on_enter_paragraph(context: &mut CompileContext) {
+    let tight = context.tight_stack.last().unwrap_or(&false);
+
+    if !tight {
+        context.line_ending_if_needed();
+        context.push("<p>");
+    }
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Resource`][Name::Resource].
+fn on_enter_resource(context: &mut CompileContext) {
+    context.buffer(); // We can have line endings in the resource, ignore them.
+    context.media_stack.last_mut().unwrap().destination = Some("".to_string());
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`ResourceDestinationString`][Name::ResourceDestinationString].
+fn on_enter_resource_destination_string(context: &mut CompileContext) {
+    context.buffer();
+    // Ignore encoding the result, as we’ll first percent encode the url and
+    // encode manually after.
+    context.encode_html = false;
+}
+
+/// Handle [`Enter`][Kind::Enter]:[`Strong`][Name::Strong].
+fn on_enter_strong(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("<strong>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`AutolinkEmail`][Name::AutolinkEmail].
+fn on_exit_autolink_email(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        Some("mailto:"),
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        false,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`AutolinkProtocol`][Name::AutolinkProtocol].
+fn on_exit_autolink_protocol(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        None,
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        false,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`HardBreakEscape`][Name::HardBreakEscape],[`HardBreakTrailing`][Name::HardBreakTrailing]}.
+fn on_exit_break(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("<br />");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`BlankLineEnding`][Name::BlankLineEnding].
+fn on_exit_blank_line_ending(context: &mut CompileContext) {
+    if context.index == context.events.len() - 1 {
+        context.line_ending_if_needed();
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`BlockQuote`][Name::BlockQuote].
+fn on_exit_block_quote(context: &mut CompileContext) {
+    context.tight_stack.pop();
+    context.line_ending_if_needed();
+    context.slurp_one_line_ending = false;
+    context.push("</blockquote>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceMarker`][Name::CharacterReferenceMarker].
+fn on_exit_character_reference_marker(context: &mut CompileContext) {
+    context.character_reference_marker = Some(b'&');
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceMarkerHexadecimal`][Name::CharacterReferenceMarkerHexadecimal].
+fn on_exit_character_reference_marker_hexadecimal(context: &mut CompileContext) {
+    context.character_reference_marker = Some(b'x');
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceMarkerNumeric`][Name::CharacterReferenceMarkerNumeric].
+fn on_exit_character_reference_marker_numeric(context: &mut CompileContext) {
+    context.character_reference_marker = Some(b'#');
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`CharacterReferenceValue`][Name::CharacterReferenceValue].
+fn on_exit_character_reference_value(context: &mut CompileContext) {
+    let marker = context
+        .character_reference_marker
+        .take()
+        .expect("expected `character_reference_kind` to be set");
+    let slice = Slice::from_position(
+        context.bytes,
+        &Position::from_exit_event(context.events, context.index),
+    );
+    let value = slice.as_str();
+
+    let value = match marker {
+        b'#' => decode_numeric(value, 10),
+        b'x' => decode_numeric(value, 16),
+        b'&' => decode_named(value),
+        _ => panic!("impossible"),
+    };
+
+    context.push(&encode(&value, context.encode_html));
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`CodeFlowChunk`][Name::CodeFlowChunk],[`MathFlowChunk`][Name::MathFlowChunk]}.
+fn on_exit_raw_flow_chunk(context: &mut CompileContext) {
+    context.raw_flow_seen_data = Some(true);
+    context.push(&encode(
+        &Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        // Must serialize to get virtual spaces.
+        .serialize(),
+        context.encode_html,
+    ));
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`CodeFencedFence`][Name::CodeFencedFence],[`MathFlowFence`][Name::MathFlowFence]}.
+fn on_exit_raw_flow_fence(context: &mut CompileContext) {
+    let count = if let Some(count) = context.raw_flow_fences_count {
+        count
+    } else {
+        0
+    };
+
+    if count == 0 {
+        context.push(">");
+        context.slurp_one_line_ending = true;
+    }
+
+    context.raw_flow_fences_count = Some(count + 1);
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`CodeFencedFenceInfo`][Name::CodeFencedFenceInfo].
+///
+/// Note: math (flow) does not support `info`.
+fn on_exit_raw_flow_fence_info(context: &mut CompileContext) {
+    let value = context.resume();
+    context.push(" class=\"language-");
+    context.push(&value);
+    context.push("\"");
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`CodeFenced`][Name::CodeFenced],[`CodeIndented`][Name::CodeIndented],[`MathFlow`][Name::MathFlow]}.
+fn on_exit_raw_flow(context: &mut CompileContext) {
+    // One special case is if we are inside a container, and the raw (flow) was
+    // not closed (meaning it runs to the end).
+    // In that case, the following line ending, is considered *outside* the
+    // fenced code and block quote by micromark, but CM wants to treat that
+    // ending as part of the code.
+    if let Some(count) = context.raw_flow_fences_count {
+        // No closing fence.
+        if count == 1
+            // In a container.
+            && !context.tight_stack.is_empty()
+            // Empty (as the closing is right at the opening fence)
+            && !matches!(context.events[context.index - 1].name, Name::CodeFencedFence | Name::MathFlowFence)
+        {
+            context.line_ending();
+        }
+    }
+
+    // But in most cases, it’s simpler: when we’ve seen some data, emit an extra
+    // line ending when needed.
+    if context
+        .raw_flow_seen_data
+        .take()
+        .expect("`raw_flow_seen_data` must be defined")
+    {
+        context.line_ending_if_needed();
+    }
+
+    context.push("</code></pre>");
+
+    if let Some(count) = context.raw_flow_fences_count.take() {
+        if count < 2 {
+            context.line_ending_if_needed();
+        }
+    }
+
+    context.slurp_one_line_ending = false;
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`CodeText`][Name::CodeText],[`MathText`][Name::MathText]}.
+fn on_exit_raw_text(context: &mut CompileContext) {
+    let result = context.resume();
+    let mut bytes = result.as_bytes().to_vec();
+
+    // If we are in a GFM table, we need to decode escaped pipes.
+    // This is a rather weird GFM feature.
+    if context.gfm_table_align.is_some() {
+        let mut index = 0;
+        let mut len = bytes.len();
+
+        while index < len {
+            if index + 1 < len && bytes[index] == b'\\' && bytes[index + 1] == b'|' {
+                bytes.remove(index);
+                len -= 1;
+            }
+
+            index += 1;
+        }
+    }
+
+    let mut trim = false;
+    let mut index = 0;
+    let mut end = bytes.len();
+
+    if end > 2 && bytes[index] == b' ' && bytes[end - 1] == b' ' {
+        index += 1;
+        end -= 1;
+        while index < end && !trim {
+            if bytes[index] != b' ' {
+                trim = true;
+                break;
+            }
+            index += 1;
+        }
+    }
+
+    if trim {
+        bytes.remove(0);
+        bytes.pop();
+    }
+
+    context.raw_text_inside = false;
+    context.push(str::from_utf8(&bytes).unwrap());
+
+    if !context.image_alt_inside {
+        context.push("</code>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:*.
+///
+/// Resumes, and ignores what was resumed.
+fn on_exit_drop(context: &mut CompileContext) {
+    context.resume();
+}
+
+/// Handle [`Exit`][Kind::Exit]:*.
+///
+/// Resumes, ignores what was resumed, and slurps the following line ending.
+fn on_exit_drop_slurp(context: &mut CompileContext) {
+    context.resume();
+    context.slurp_one_line_ending = true;
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`CodeTextData`][Name::CodeTextData],[`Data`][Name::Data],[`CharacterEscapeValue`][Name::CharacterEscapeValue]}.
+fn on_exit_data(context: &mut CompileContext) {
+    context.push(&encode(
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        context.encode_html,
+    ));
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`Definition`][Name::Definition].
+fn on_exit_definition(context: &mut CompileContext) {
+    context.resume();
+    let media = context.media_stack.pop().unwrap();
+    let indices = media.reference_id.unwrap();
+    let id =
+        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str());
+
+    context.definitions.push(Definition {
+        id,
+        destination: media.destination,
+        title: media.title,
+    });
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`DefinitionDestinationString`][Name::DefinitionDestinationString].
+fn on_exit_definition_destination_string(context: &mut CompileContext) {
+    let buf = context.resume();
+    context.media_stack.last_mut().unwrap().destination = Some(buf);
+    context.encode_html = true;
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`DefinitionLabelString`][Name::DefinitionLabelString].
+fn on_exit_definition_label_string(context: &mut CompileContext) {
+    // Discard label, use the source content instead.
+    context.resume();
+    context.media_stack.last_mut().unwrap().reference_id =
+        Some(Position::from_exit_event(context.events, context.index).to_indices());
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`DefinitionTitleString`][Name::DefinitionTitleString].
+fn on_exit_definition_title_string(context: &mut CompileContext) {
+    let buf = context.resume();
+    context.media_stack.last_mut().unwrap().title = Some(buf);
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`Emphasis`][Name::Emphasis].
+fn on_exit_emphasis(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("</em>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`Frontmatter`][Name::Frontmatter].
+fn on_exit_frontmatter(context: &mut CompileContext) {
+    context.resume();
+    context.slurp_one_line_ending = true;
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralEmail`][Name::GfmAutolinkLiteralEmail].
+fn on_exit_gfm_autolink_literal_email(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        Some("mailto:"),
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        true,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralMailto`][Name::GfmAutolinkLiteralMailto].
+fn on_exit_gfm_autolink_literal_mailto(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        None,
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        true,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralProtocol`][Name::GfmAutolinkLiteralProtocol].
+fn on_exit_gfm_autolink_literal_protocol(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        None,
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        true,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralWww`][Name::GfmAutolinkLiteralWww].
+fn on_exit_gfm_autolink_literal_www(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        Some("http://"),
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        true,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmAutolinkLiteralXmpp`][Name::GfmAutolinkLiteralXmpp].
+fn on_exit_gfm_autolink_literal_xmpp(context: &mut CompileContext) {
+    generate_autolink(
+        context,
+        None,
+        Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .as_str(),
+        true,
+    );
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteCall`][Name::GfmFootnoteCall].
+fn on_exit_gfm_footnote_call(context: &mut CompileContext) {
+    let indices = context.media_stack.pop().unwrap().label_id.unwrap();
+    let id =
+        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str());
+    let safe_id = sanitize(&id.to_lowercase());
+    let mut call_index = 0;
+
+    // See if this has been called before.
+    while call_index < context.gfm_footnote_definition_calls.len() {
+        if context.gfm_footnote_definition_calls[call_index].0 == id {
+            break;
+        }
+        call_index += 1;
+    }
+
+    // New.
+    if call_index == context.gfm_footnote_definition_calls.len() {
+        context.gfm_footnote_definition_calls.push((id, 0));
+    }
+
+    // Increment.
+    context.gfm_footnote_definition_calls[call_index].1 += 1;
+
+    // No call is output in an image alt, though the definition and
+    // backreferences are generated as if it was the case.
+    if context.image_alt_inside {
+        return;
+    }
+
+    context.push("<sup><a href=\"#");
+    if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
+        context.push(&encode(value, context.encode_html));
+    } else {
+        context.push("user-content-");
+    }
+    context.push("fn-");
+    context.push(&safe_id);
+    context.push("\" id=\"");
+    if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
+        context.push(&encode(value, context.encode_html));
+    } else {
+        context.push("user-content-");
+    }
+    context.push("fnref-");
+    context.push(&safe_id);
+    if context.gfm_footnote_definition_calls[call_index].1 > 1 {
+        context.push("-");
+        context.push(
+            &context.gfm_footnote_definition_calls[call_index]
+                .1
+                .to_string(),
+        );
+    }
+    context.push("\" data-footnote-ref=\"\" aria-describedby=\"footnote-label\">");
+
+    context.push(&(call_index + 1).to_string());
+    context.push("</a></sup>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteDefinitionLabelString`][Name::GfmFootnoteDefinitionLabelString].
+fn on_exit_gfm_footnote_definition_label_string(context: &mut CompileContext) {
+    context
+        .gfm_footnote_definition_stack
+        .push(Position::from_exit_event(context.events, context.index).to_indices());
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteDefinitionPrefix`][Name::GfmFootnoteDefinitionPrefix].
+fn on_exit_gfm_footnote_definition_prefix(context: &mut CompileContext) {
+    // Drop the prefix.
+    context.resume();
+    // Capture everything until end of definition.
+    context.buffer();
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmFootnoteDefinition`][Name::GfmFootnoteDefinition].
+fn on_exit_gfm_footnote_definition(context: &mut CompileContext) {
+    let value = context.resume();
+    let indices = context.gfm_footnote_definition_stack.pop().unwrap();
+    context.tight_stack.pop();
+    context.gfm_footnote_definitions.push((
+        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str()),
+        value,
+    ));
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmStrikethrough`][Name::GfmStrikethrough].
+fn on_exit_gfm_strikethrough(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("</del>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTable`][Name::GfmTable].
+fn on_exit_gfm_table(context: &mut CompileContext) {
+    context.gfm_table_align = None;
+    context.line_ending_if_needed();
+    context.push("</table>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTableBody`][Name::GfmTableBody].
+fn on_exit_gfm_table_body(context: &mut CompileContext) {
+    context.line_ending_if_needed();
+    context.push("</tbody>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTableCell`][Name::GfmTableCell].
+fn on_exit_gfm_table_cell(context: &mut CompileContext) {
+    let align = context.gfm_table_align.as_ref().unwrap();
+
+    if context.gfm_table_column < align.len() {
+        if context.gfm_table_in_head {
+            context.push("</th>");
+        } else {
+            context.push("</td>");
+        }
+    } else {
+        // Stop capturing.
+        context.resume();
+    }
+
+    context.gfm_table_column += 1;
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTableHead`][Name::GfmTableHead].
+fn on_exit_gfm_table_head(context: &mut CompileContext) {
+    context.gfm_table_in_head = false;
+    context.line_ending_if_needed();
+    context.push("</thead>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTableRow`][Name::GfmTableRow].
+fn on_exit_gfm_table_row(context: &mut CompileContext) {
+    let mut column = context.gfm_table_column;
+    let len = context.gfm_table_align.as_ref().unwrap().len();
+
+    // Add “phantom” cells, for body rows that are shorter than the delimiter
+    // row (which is equal to the head row).
+    while column < len {
+        on_enter_gfm_table_cell(context);
+        on_exit_gfm_table_cell(context);
+        column += 1;
+    }
+
+    context.gfm_table_column = 0;
+    context.line_ending_if_needed();
+    context.push("</tr>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTaskListItemCheck`][Name::GfmTaskListItemCheck].
+fn on_exit_gfm_task_list_item_check(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("/>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`GfmTaskListItemValueChecked`][Name::GfmTaskListItemValueChecked].
+fn on_exit_gfm_task_list_item_value_checked(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("checked=\"\" ");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`HeadingAtx`][Name::HeadingAtx].
+fn on_exit_heading_atx(context: &mut CompileContext) {
+    let rank = context
+        .heading_atx_rank
+        .take()
+        .expect("`heading_atx_rank` must be set in headings");
+
+    context.push("</h");
+    context.push(&rank.to_string());
+    context.push(">");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`HeadingAtxSequence`][Name::HeadingAtxSequence].
+fn on_exit_heading_atx_sequence(context: &mut CompileContext) {
+    // First fence we see.
+    if context.heading_atx_rank.is_none() {
+        let rank = Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        )
+        .len();
+        context.line_ending_if_needed();
+        context.heading_atx_rank = Some(rank);
+        context.push("<h");
+        context.push(&rank.to_string());
+        context.push(">");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`HeadingAtxText`][Name::HeadingAtxText].
+fn on_exit_heading_atx_text(context: &mut CompileContext) {
+    let value = context.resume();
+    context.push(&value);
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`HeadingSetextText`][Name::HeadingSetextText].
+fn on_exit_heading_setext_text(context: &mut CompileContext) {
+    let buf = context.resume();
+    context.heading_setext_buffer = Some(buf);
+    context.slurp_one_line_ending = true;
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`HeadingSetextUnderlineSequence`][Name::HeadingSetextUnderlineSequence].
+fn on_exit_heading_setext_underline_sequence(context: &mut CompileContext) {
+    let text = context
+        .heading_setext_buffer
+        .take()
+        .expect("`heading_atx_rank` must be set in headings");
+    let head = Slice::from_position(
+        context.bytes,
+        &Position::from_exit_event(context.events, context.index),
+    )
+    .head();
+    let rank = if head == Some(b'-') { "2" } else { "1" };
+
+    context.line_ending_if_needed();
+    context.push("<h");
+    context.push(rank);
+    context.push(">");
+    context.push(&text);
+    context.push("</h");
+    context.push(rank);
+    context.push(">");
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`HtmlFlow`][Name::HtmlFlow],[`HtmlText`][Name::HtmlText]}.
+fn on_exit_html(context: &mut CompileContext) {
+    context.encode_html = true;
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`HtmlFlowData`][Name::HtmlFlowData],[`HtmlTextData`][Name::HtmlTextData]}.
+fn on_exit_html_data(context: &mut CompileContext) {
+    let slice = Slice::from_position(
+        context.bytes,
+        &Position::from_exit_event(context.events, context.index),
+    );
+    let value = slice.as_str();
+
+    let encoded = if context.options.gfm_tagfilter && context.options.allow_dangerous_html {
+        encode(&gfm_tagfilter(value), context.encode_html)
+    } else {
+        encode(value, context.encode_html)
+    };
+
+    context.push(&encoded);
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`Label`][Name::Label].
+fn on_exit_label(context: &mut CompileContext) {
+    let buf = context.resume();
+    context.media_stack.last_mut().unwrap().label = Some(buf);
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`LabelText`][Name::LabelText].
+fn on_exit_label_text(context: &mut CompileContext) {
+    context.media_stack.last_mut().unwrap().label_id =
+        Some(Position::from_exit_event(context.events, context.index).to_indices());
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`LineEnding`][Name::LineEnding].
+fn on_exit_line_ending(context: &mut CompileContext) {
+    if context.raw_text_inside {
+        context.push(" ");
+    } else if context.slurp_one_line_ending
+        // Ignore line endings after definitions.
+        || (context.index > 1
+            && (context.events[context.index - 2].name == Name::Definition
+                || context.events[context.index - 2].name == Name::GfmFootnoteDefinition))
+    {
+        context.slurp_one_line_ending = false;
+    } else {
+        context.push(&encode(
+            Slice::from_position(
+                context.bytes,
+                &Position::from_exit_event(context.events, context.index),
+            )
+            .as_str(),
+            context.encode_html,
+        ));
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`ListOrdered`][Name::ListOrdered],[`ListUnordered`][Name::ListUnordered]}.
+fn on_exit_list(context: &mut CompileContext) {
+    context.tight_stack.pop();
+    context.line_ending();
+    context.push(if context.events[context.index].name == Name::ListOrdered {
+        "</ol>"
+    } else {
+        "</ul>"
+    });
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`ListItem`][Name::ListItem].
+fn on_exit_list_item(context: &mut CompileContext) {
+    let tight = context.tight_stack.last().unwrap_or(&false);
+    let before_item = skip::opt_back(
+        context.events,
+        context.index - 1,
+        &[
+            Name::BlankLineEnding,
+            Name::BlockQuotePrefix,
+            Name::LineEnding,
+            Name::SpaceOrTab,
+            // Also ignore things that don’t contribute to the document.
+            Name::Definition,
+            Name::GfmFootnoteDefinition,
+        ],
+    );
+    let previous = &context.events[before_item];
+    let tight_paragraph = *tight && previous.name == Name::Paragraph;
+    let empty_item = previous.name == Name::ListItemPrefix;
+
+    context.slurp_one_line_ending = false;
+
+    if !tight_paragraph && !empty_item {
+        context.line_ending_if_needed();
+    }
+
+    context.push("</li>");
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`ListItemValue`][Name::ListItemValue].
+fn on_exit_list_item_value(context: &mut CompileContext) {
+    if context.list_expect_first_marker.unwrap() {
+        let slice = Slice::from_position(
+            context.bytes,
+            &Position::from_exit_event(context.events, context.index),
+        );
+        let value = slice.as_str().parse::<u32>().ok().unwrap();
+
+        if value != 1 {
+            context.push(" start=\"");
+            context.push(&value.to_string());
+            context.push("\"");
+        }
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:{[`Image`][Name::Image],[`Link`][Name::Link]}.
+fn on_exit_media(context: &mut CompileContext) {
+    let mut is_in_image = false;
+    let mut index = 0;
+
+    // Skip current.
+    let end = context.media_stack.len() - 1;
+    while index < end {
+        if context.media_stack[index].image {
+            is_in_image = true;
+            break;
+        }
+        index += 1;
+    }
+
+    context.image_alt_inside = is_in_image;
+
+    let media = context.media_stack.pop().unwrap();
+    let label = media.label.unwrap();
+    let id = media.reference_id.or(media.label_id).map(|indices| {
+        normalize_identifier(Slice::from_indices(context.bytes, indices.0, indices.1).as_str())
+    });
+
+    let definition_index = if media.destination.is_none() {
+        id.and_then(|id| {
+            let mut index = 0;
+
+            while index < context.definitions.len() {
+                if context.definitions[index].id == id {
+                    return Some(index);
+                }
+
+                index += 1;
+            }
+
+            None
+        })
+    } else {
+        None
+    };
+
+    if !is_in_image {
+        if media.image {
+            context.push("<img src=\"");
+        } else {
+            context.push("<a href=\"");
+        };
+
+        let destination = if let Some(index) = definition_index {
+            context.definitions[index].destination.as_ref()
+        } else {
+            media.destination.as_ref()
+        };
+
+        if let Some(destination) = destination {
+            let url = if context.options.allow_dangerous_protocol {
+                sanitize(destination)
+            } else {
+                sanitize_with_protocols(
+                    destination,
+                    if media.image {
+                        &SAFE_PROTOCOL_SRC
+                    } else {
+                        &SAFE_PROTOCOL_HREF
+                    },
+                )
+            };
+            context.push(&url);
+        }
+
+        if media.image {
+            context.push("\" alt=\"");
+        };
+    }
+
+    if media.image {
+        context.push(&label);
+    }
+
+    if !is_in_image {
+        context.push("\"");
+
+        let title = if let Some(index) = definition_index {
+            context.definitions[index].title.clone()
+        } else {
+            media.title
+        };
+
+        if let Some(title) = title {
+            context.push(" title=\"");
+            context.push(&title);
+            context.push("\"");
+        };
+
+        if media.image {
+            context.push(" /");
+        }
+
+        context.push(">");
+    }
+
+    if !media.image {
+        context.push(&label);
+
+        if !is_in_image {
+            context.push("</a>");
+        }
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`Paragraph`][Name::Paragraph].
+fn on_exit_paragraph(context: &mut CompileContext) {
+    let tight = context.tight_stack.last().unwrap_or(&false);
+
+    if *tight {
+        context.slurp_one_line_ending = true;
+    } else {
+        context.push("</p>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`ReferenceString`][Name::ReferenceString].
+fn on_exit_reference_string(context: &mut CompileContext) {
+    // Drop stuff.
+    context.resume();
+
+    context.media_stack.last_mut().unwrap().reference_id =
+        Some(Position::from_exit_event(context.events, context.index).to_indices());
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`ResourceDestinationString`][Name::ResourceDestinationString].
+fn on_exit_resource_destination_string(context: &mut CompileContext) {
+    let buf = context.resume();
+    context.media_stack.last_mut().unwrap().destination = Some(buf);
+    context.encode_html = true;
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`ResourceTitleString`][Name::ResourceTitleString].
+fn on_exit_resource_title_string(context: &mut CompileContext) {
+    let buf = context.resume();
+    context.media_stack.last_mut().unwrap().title = Some(buf);
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`Strong`][Name::Strong].
+fn on_exit_strong(context: &mut CompileContext) {
+    if !context.image_alt_inside {
+        context.push("</strong>");
+    }
+}
+
+/// Handle [`Exit`][Kind::Exit]:[`ThematicBreak`][Name::ThematicBreak].
+fn on_exit_thematic_break(context: &mut CompileContext) {
+    context.line_ending_if_needed();
+    context.push("<hr />");
+}
+
+/// Generate a footnote section.
+fn generate_footnote_section(context: &mut CompileContext) {
+    context.line_ending_if_needed();
+    context.push("<section data-footnotes=\"\" class=\"footnotes\"><");
+    if let Some(ref value) = context.options.gfm_footnote_label_tag_name {
+        context.push(&encode(value, context.encode_html));
+    } else {
+        context.push("h2");
+    }
+    context.push(" id=\"footnote-label\" ");
+    if let Some(ref value) = context.options.gfm_footnote_label_attributes {
+        context.push(value);
+    } else {
+        context.push("class=\"sr-only\"");
+    }
+    context.push(">");
+    if let Some(ref value) = context.options.gfm_footnote_label {
+        context.push(&encode(value, context.encode_html));
+    } else {
+        context.push("Footnotes");
+    }
+    context.push("</");
+    if let Some(ref value) = context.options.gfm_footnote_label_tag_name {
+        context.push(&encode(value, context.encode_html));
+    } else {
+        context.push("h2");
+    }
+    context.push(">");
+    context.line_ending();
+    context.push("<ol>");
+
+    let mut index = 0;
+    while index < context.gfm_footnote_definition_calls.len() {
+        generate_footnote_item(context, index);
+        index += 1;
+    }
+
+    context.line_ending();
+    context.push("</ol>");
+    context.line_ending();
+    context.push("</section>");
+    context.line_ending();
+}
+
+/// Generate a footnote item from a call.
+fn generate_footnote_item(context: &mut CompileContext, index: usize) {
+    let id = &context.gfm_footnote_definition_calls[index].0;
+    let safe_id = sanitize(&id.to_lowercase());
+
+    // Find definition: we’ll always find it.
+    let mut definition_index = 0;
+    while definition_index < context.gfm_footnote_definitions.len() {
+        if &context.gfm_footnote_definitions[definition_index].0 == id {
+            break;
+        }
+        definition_index += 1;
+    }
+
+    debug_assert_ne!(
+        definition_index,
+        context.gfm_footnote_definitions.len(),
+        "expected definition"
+    );
+
+    context.line_ending();
+    context.push("<li id=\"");
+    if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
+        context.push(&encode(value, context.encode_html));
+    } else {
+        context.push("user-content-");
+    }
+    context.push("fn-");
+    context.push(&safe_id);
+    context.push("\">");
+    context.line_ending();
+
+    // Create one or more backreferences.
+    let mut reference_index = 0;
+    let mut backreferences = String::new();
+    while reference_index < context.gfm_footnote_definition_calls[index].1 {
+        if reference_index != 0 {
+            backreferences.push(' ');
+        }
+        backreferences.push_str("<a href=\"#");
+        if let Some(ref value) = context.options.gfm_footnote_clobber_prefix {
+            backreferences.push_str(&encode(value, context.encode_html));
+        } else {
+            backreferences.push_str("user-content-");
+        }
+        backreferences.push_str("fnref-");
+        backreferences.push_str(&safe_id);
+        if reference_index != 0 {
+            backreferences.push('-');
+            backreferences.push_str(&(reference_index + 1).to_string());
+        }
+        backreferences.push_str("\" data-footnote-backref=\"\" aria-label=\"");
+        if let Some(ref value) = context.options.gfm_footnote_back_label {
+            backreferences.push_str(&encode(value, context.encode_html));
+        } else {
+            backreferences.push_str("Back to content");
+        }
+        backreferences.push_str("\" class=\"data-footnote-backref\">↩");
+        if reference_index != 0 {
+            backreferences.push_str("<sup>");
+            backreferences.push_str(&(reference_index + 1).to_string());
+            backreferences.push_str("</sup>");
+        }
+        backreferences.push_str("</a>");
+
+        reference_index += 1;
+    }
+
+    let value = context.gfm_footnote_definitions[definition_index].1.clone();
+    let bytes = value.as_bytes();
+    let mut byte_index = bytes.len();
+    // Move back past EOL.
+    while byte_index > 0 && matches!(bytes[byte_index - 1], b'\n' | b'\r') {
+        byte_index -= 1;
+    }
+    // Check if it ends in `</p>`.
+    // This is a bit funky if someone wrote a safe paragraph by hand in
+    // there.
+    // But in all other cases, `<` and `>` would be encoded, so we can be
+    // sure that this is generated by our compiler.
+    if byte_index > 3
+        && bytes[byte_index - 4] == b'<'
+        && bytes[byte_index - 3] == b'/'
+        && bytes[byte_index - 2] == b'p'
+        && bytes[byte_index - 1] == b'>'
+    {
+        let (before, after) = bytes.split_at(byte_index - 4);
+        let mut result = String::new();
+        result.push_str(str::from_utf8(before).unwrap());
+        result.push(' ');
+        result.push_str(&backreferences);
+        result.push_str(str::from_utf8(after).unwrap());
+        context.push(&result);
+    } else {
+        context.push(&value);
+        context.line_ending_if_needed();
+        context.push(&backreferences);
+    }
+    context.line_ending_if_needed();
+    context.push("</li>");
+}
+
+/// Generate an autolink (used by unicode autolinks and GFM autolink literals).
+fn generate_autolink(
+    context: &mut CompileContext,
+    protocol: Option<&str>,
+    value: &str,
+    is_gfm_literal: bool,
+) {
+    let mut is_in_link = false;
+    let mut index = 0;
+
+    while index < context.media_stack.len() {
+        if !context.media_stack[index].image {
+            is_in_link = true;
+            break;
+        }
+        index += 1;
+    }
+
+    if !context.image_alt_inside && (!is_in_link || !is_gfm_literal) {
+        context.push("<a href=\"");
+        let url = if let Some(protocol) = protocol {
+            format!("{}{}", protocol, value)
+        } else {
+            value.to_string()
+        };
+
+        let url = if context.options.allow_dangerous_protocol {
+            sanitize(&url)
+        } else {
+            sanitize_with_protocols(&url, &SAFE_PROTOCOL_HREF)
+        };
+
+        context.push(&url);
+        context.push("\">");
+    }
+
+    context.push(&encode(value, context.encode_html));
+
+    if !context.image_alt_inside && (!is_in_link || !is_gfm_literal) {
+        context.push("</a>");
+    }
+}
diff --git a/src/to_mdast.rs b/src/to_mdast.rs
new file mode 100644
index 0000000..d56134a
--- /dev/null
+++ b/src/to_mdast.rs
@@ -0,0 +1,40 @@
+//! Turn events into a syntax tree.
+
+// To do: example.
+
+use crate::event::Event;
+use crate::mdast;
+use crate::Options;
+use alloc::vec;
+
+/// Turn events and bytes into a syntax tree.
+pub fn compile(events: &[Event], _bytes: &[u8], _options: &Options) -> mdast::Root {
+    mdast::Root {
+        kind: mdast::Kind::Root,
+        children: vec![],
+        position: Some(mdast::Position {
+            start: if events.is_empty() {
+                create_point(1, 1, 0)
+            } else {
+                point_from_event(&events[0])
+            },
+            end: if events.is_empty() {
+                create_point(1, 1, 0)
+            } else {
+                point_from_event(&events[events.len() - 1])
+            },
+        }),
+    }
+}
+
+fn point_from_event(event: &Event) -> mdast::Point {
+    create_point(event.point.line, event.point.column, event.point.index)
+}
+
+fn create_point(line: usize, column: usize, offset: usize) -> mdast::Point {
+    mdast::Point {
+        line,
+        column,
+        offset,
+    }
+}
-- 
cgit