Fix GFM task list checkboxes followed by eol

Closes GH-24.

3 files changed, 114 insertions, 46 deletions

diff --git a/src/to_mdast.rs b/src/to_mdast.rs
index f00a4d6..4d2ca76 100644
--- a/src/to_mdast.rs
+++ b/src/to_mdast.rs
@@ -90,7 +90,6 @@ struct CompileContext<'a> {
     // compile markdown.
     character_reference_marker: u8,
     gfm_table_inside: bool,
-    gfm_task_list_item_check_after: bool,
     hard_break_after: bool,
     heading_setext_text_after: bool,
     jsx_tag_stack: Vec<JsxTag>,
@@ -128,7 +127,6 @@ impl<'a> CompileContext<'a> {
             bytes,
             character_reference_marker: 0,
             gfm_table_inside: false,
-            gfm_task_list_item_check_after: false,
             hard_break_after: false,
             heading_setext_text_after: false,
             jsx_tag_stack: vec![],
@@ -347,7 +345,6 @@ fn exit(context: &mut CompileContext) -> Result<(), String> {
         | Name::GfmTableRow
         | Name::GfmTableCell
         | Name::HeadingAtx
-        | Name::ListItem
         | Name::ListOrdered
         | Name::ListUnordered
         | Name::Paragraph
@@ -358,6 +355,7 @@ fn exit(context: &mut CompileContext) -> Result<(), String> {
         Name::CharacterEscapeValue
         | Name::CodeFlowChunk
         | Name::CodeTextData
+        | Name::Data
         | Name::FrontmatterChunk
         | Name::HtmlFlowData
         | Name::HtmlTextData
@@ -385,7 +383,6 @@ fn exit(context: &mut CompileContext) -> Result<(), String> {
         Name::CodeFenced | Name::MathFlow => on_exit_raw_flow(context)?,
         Name::CodeIndented => on_exit_code_indented(context)?,
         Name::CodeText | Name::MathText => on_exit_raw_text(context)?,
-        Name::Data => on_exit_data_actual(context)?,
         Name::DefinitionDestinationString => on_exit_definition_destination_string(context),
         Name::DefinitionLabelString | Name::GfmFootnoteDefinitionLabelString => {
             on_exit_definition_id(context);
@@ -399,7 +396,6 @@ fn exit(context: &mut CompileContext) -> Result<(), String> {
         | Name::GfmAutolinkLiteralXmpp => on_exit_gfm_autolink_literal(context)?,
         Name::GfmFootnoteCall | Name::Image | Name::Link => on_exit_media(context)?,
         Name::GfmTable => on_exit_gfm_table(context)?,
-        Name::GfmTaskListItemCheck => on_exit_gfm_task_list_item_check(context),
         Name::GfmTaskListItemValueUnchecked | Name::GfmTaskListItemValueChecked => {
             on_exit_gfm_task_list_item_value(context);
         }
@@ -411,6 +407,7 @@ fn exit(context: &mut CompileContext) -> Result<(), String> {
         Name::HtmlFlow | Name::HtmlText => on_exit_html(context)?,
         Name::LabelText => on_exit_label_text(context),
         Name::LineEnding => on_exit_line_ending(context)?,
+        Name::ListItem => on_exit_list_item(context)?,
         Name::ListItemValue => on_exit_list_item_value(context),
         Name::MdxEsm | Name::MdxFlowExpression | Name::MdxTextExpression => {
             on_exit_mdx_esm_or_expression(context)?;
@@ -1089,29 +1086,6 @@ fn on_exit_data(context: &mut CompileContext) -> Result<(), String> {
     Ok(())
 }
 
-/// Handle [`Exit`][Kind::Exit]:[`Data`][Name::Data] itself.
-fn on_exit_data_actual(context: &mut CompileContext) -> Result<(), String> {
-    on_exit_data(context)?;
-
-    // This field is set when a check exits.
-    // When that’s the case, there’s always a `data` event right after it.
-    // That data event is the first child (after the check) of the paragraph.
-    // We update the text positional info (from the already fixed paragraph),
-    // and remove the first byte, which is always a space or tab.
-    if context.gfm_task_list_item_check_after {
-        let parent = context.tail_mut();
-        let start = parent.position().unwrap().start.clone();
-        let node = parent.children_mut().unwrap().last_mut().unwrap();
-        node.position_mut().unwrap().start = start;
-        if let Node::Text(node) = node {
-            node.value.remove(0);
-        }
-        context.gfm_task_list_item_check_after = false;
-    }
-
-    Ok(())
-}
-
 /// Handle [`Exit`][Kind::Exit]:[`DefinitionDestinationString`][Name::DefinitionDestinationString].
 fn on_exit_definition_destination_string(context: &mut CompileContext) {
     let value = context.resume().to_string();
@@ -1210,23 +1184,6 @@ fn on_exit_gfm_table(context: &mut CompileContext) -> Result<(), String> {
     Ok(())
 }
 
-/// Handle [`Exit`][Kind::Exit]:[`GfmTaskListItemCheck`][Name::GfmTaskListItemCheck].
-fn on_exit_gfm_task_list_item_check(context: &mut CompileContext) {
-    // This field is set when a check exits.
-    // When that’s the case, there’s always a `data` event right after it.
-    // That data event is the first child (after the check) of the paragraph.
-    // We update the paragraph positional info to start after the check.
-    let mut start = point_from_event(&context.events[context.index]);
-    debug_assert!(
-        matches!(context.bytes[start.offset], b'\t' | b' '),
-        "expected tab or space after check"
-    );
-    start.column += 1;
-    start.offset += 1;
-    context.tail_mut().position_mut().unwrap().start = start;
-    context.gfm_task_list_item_check_after = true;
-}
-
 /// Handle [`Exit`][Kind::Exit]:{[`GfmTaskListItemValueChecked`][Name::GfmTaskListItemValueChecked],[`GfmTaskListItemValueUnchecked`][Name::GfmTaskListItemValueUnchecked]}.
 fn on_exit_gfm_task_list_item_value(context: &mut CompileContext) {
     let checked = context.events[context.index].name == Name::GfmTaskListItemValueChecked;
@@ -1416,6 +1373,51 @@ fn on_exit_media(context: &mut CompileContext) -> Result<(), String> {
     Ok(())
 }
 
+/// Handle [`Exit`][Kind::Exit]:[`ListItem`][Name::ListItem].
+fn on_exit_list_item(context: &mut CompileContext) -> Result<(), String> {
+    if let Node::ListItem(item) = context.tail_mut() {
+        if item.checked.is_some() {
+            if let Some(Node::Paragraph(paragraph)) = item.children.first_mut() {
+                if let Some(Node::Text(text)) = paragraph.children.first_mut() {
+                    let mut point = text.position.as_ref().unwrap().start.clone();
+                    let bytes = text.value.as_bytes();
+                    let mut start = 0;
+
+                    // Move past eol.
+                    if matches!(bytes[0], b'\t' | b' ') {
+                        point.offset += 1;
+                        point.column += 1;
+                        start += 1;
+                    } else if matches!(bytes[0], b'\r' | b'\n') {
+                        point.line += 1;
+                        point.column = 1;
+                        point.offset += 1;
+                        start += 1;
+                        // Move past the LF of CRLF.
+                        if bytes.len() > 1 && bytes[0] == b'\r' && bytes[1] == b'\n' {
+                            point.offset += 1;
+                            start += 1;
+                        }
+                    }
+
+                    // The whole text is whitespace: update the text.
+                    if start == bytes.len() {
+                        paragraph.children.remove(0);
+                    } else {
+                        text.value = str::from_utf8(&bytes[start..]).unwrap().into();
+                        text.position.as_mut().unwrap().start = point.clone();
+                    }
+                    paragraph.position.as_mut().unwrap().start = point;
+                }
+            }
+        }
+    }
+
+    on_exit(context)?;
+
+    Ok(())
+}
+
 /// Handle [`Exit`][Kind::Exit]:[`ListItemValue`][Name::ListItemValue].
 fn on_exit_list_item_value(context: &mut CompileContext) {
     let start = Slice::from_position(
diff --git a/tests/fuzz.rs b/tests/fuzz.rs
index d1a87b7..297e6a9 100644
--- a/tests/fuzz.rs
+++ b/tests/fuzz.rs
@@ -109,5 +109,13 @@ fn fuzz() -> Result<(), String> {
         "10: attention in different links (GH-21)"
     );
 
+    assert!(
+        matches!(
+            to_mdast("* [ ]\na", &Default::default()),
+            Ok(mdast::Node::Root(_))
+        ),
+        "11: gfm task list items followed by eols (GH-24)"
+    );
+
     Ok(())
 }
diff --git a/tests/gfm_task_list_item.rs b/tests/gfm_task_list_item.rs
index 638206f..8b3f066 100644
--- a/tests/gfm_task_list_item.rs
+++ b/tests/gfm_task_list_item.rs
@@ -1,5 +1,5 @@
 use markdown::{
-    mdast::{List, ListItem, Node, Paragraph, Root, Text},
+    mdast::{Emphasis, List, ListItem, Node, Paragraph, Root, Text},
     to_html, to_html_with_options, to_mdast,
     unist::Position,
     Options, ParseOptions,
@@ -291,5 +291,63 @@ Text.</li>
         "should support task list items as `checked` fields on `ListItem`s in mdast"
     );
 
+    assert_eq!(
+        to_mdast(
+            "* [x]\r\n  a\n* [ ]   b\n* [x]\t \r*c*",
+            &ParseOptions::gfm()
+        )?,
+        Node::Root(Root {
+            children: vec![Node::List(List {
+                ordered: false,
+                spread: false,
+                start: None,
+                children: vec![
+                    Node::ListItem(ListItem {
+                        checked: Some(true),
+                        spread: false,
+                        children: vec![Node::Paragraph(Paragraph {
+                            children: vec![Node::Text(Text {
+                                value: "a".into(),
+                                position: Some(Position::new(2, 1, 7, 2, 4, 10))
+                            }),],
+                            position: Some(Position::new(2, 1, 7, 2, 4, 10))
+                        })],
+                        position: Some(Position::new(1, 1, 0, 2, 4, 10))
+                    }),
+                    Node::ListItem(ListItem {
+                        checked: Some(false),
+                        spread: false,
+                        children: vec![Node::Paragraph(Paragraph {
+                            children: vec![Node::Text(Text {
+                                value: "  b".into(),
+                                position: Some(Position::new(3, 7, 17, 3, 10, 20))
+                            }),],
+                            position: Some(Position::new(3, 7, 17, 3, 10, 20))
+                        })],
+                        position: Some(Position::new(3, 1, 11, 3, 10, 20))
+                    }),
+                    Node::ListItem(ListItem {
+                        checked: Some(true),
+                        spread: false,
+                        children: vec![Node::Paragraph(Paragraph {
+                            children: vec![Node::Emphasis(Emphasis {
+                                children: vec![Node::Text(Text {
+                                    value: "c".into(),
+                                    position: Some(Position::new(5, 2, 30, 5, 3, 31))
+                                }),],
+                                position: Some(Position::new(5, 1, 29, 5, 4, 32))
+                            })],
+                            position: Some(Position::new(5, 1, 29, 5, 4, 32))
+                        })],
+                        position: Some(Position::new(4, 1, 21, 5, 4, 32))
+                    }),
+                ],
+                position: Some(Position::new(1, 1, 0, 5, 4, 32))
+            })],
+            position: Some(Position::new(1, 1, 0, 5, 4, 32))
+        }),
+        "should handle lots of whitespace after checkbox, and non-text"
+    );
+
     Ok(())
 }