//! Label occurs in [definition][] and [label end][label_end].
//!
//! ## Grammar
//!
//! Label forms with the following BNF
//! (<small>see [construct][crate::construct] for character groups</small>):
//!
//! ```bnf
//! ; Restriction: maximum `999` codes allowed between brackets.
//! ; Restriction: no blank lines.
//! ; Restriction: at least 1 `text` byte must exist.
//! label ::= '[' *(label_byte | label_escape) ']'
//! label_byte ::= code - '[' - '\\' - ']'
//! label_escape ::= '\\' ['[' | '\\' | ']']
//! ```
//!
//! The maximum allowed size of the label, without the brackets, is `999`
//! (inclusive), which is defined in
//! [`LINK_REFERENCE_SIZE_MAX`][link_reference_size_max].
//!
//! Labels can contain line endings and whitespace, but they are not allowed to
//! contain blank lines, and they must not be blank themselves.
//!
//! The label is interpreted as the [string][] content type.
//! That means that [character escapes][character_escape] and
//! [character references][character_reference] are allowed.
//!
//! > 👉 **Note**: this label relates to, but is not, the initial “label” of
//! > what is know as a reference in markdown:
//! >
//! > | Kind | Link | Image |
//! > | --------- | -------- | --------- |
//! > | Shortcut | `[x]` | `![x]` |
//! > | Collapsed | `[x][]` | `![x][]` |
//! > | Full | `[x][y]` | `![x][y]` |
//! >
//! > The 6 above things are references, in the three kinds they come in, as
//! > links and images.
//! > The label that this module focusses on is only the thing that contains
//! > `y`.
//! >
//! > The thing that contains `x` is not a single thing when parsing markdown,
//! > but instead constists of an opening
//! > ([label start (image)][label_start_image] or
//! > [label start (link)][label_start_link]) and a closing
//! > ([label end][label_end]), so as to allow further phrasing such as
//! > [code (text)][code_text] or [attention][].
//!
//! ## References
//!
//! * [`micromark-factory-label/index.js` in `micromark`](https://github.com/micromark/micromark/blob/main/packages/micromark-factory-label/dev/index.js)
//!
//! [definition]: crate::construct::definition
//! [string]: crate::construct::string
//! [attention]: crate::construct::attention
//! [character_escape]: crate::construct::character_escape
//! [character_reference]: crate::construct::character_reference
//! [label_start_image]: crate::construct::label_start_image
//! [label_start_link]: crate::construct::label_start_link
//! [label_end]: crate::construct::label_end
//! [code_text]: crate::construct::code_text
//! [link_reference_size_max]: crate::util::constant::LINK_REFERENCE_SIZE_MAX
use crate::construct::partial_space_or_tab_eol::{space_or_tab_eol_with_options, Options};
use crate::event::{Content, Link, Name};
use crate::state::{Name as StateName, State};
use crate::subtokenize::link;
use crate::tokenizer::Tokenizer;
use crate::util::constant::LINK_REFERENCE_SIZE_MAX;
/// Start of label.
///
/// ```markdown
/// > | [a]
/// ^
/// ```
pub fn start(tokenizer: &mut Tokenizer) -> State {
match tokenizer.current {
Some(b'[') => {
tokenizer.enter(tokenizer.tokenize_state.token_1.clone());
tokenizer.enter(tokenizer.tokenize_state.token_2.clone());
tokenizer.consume();
tokenizer.exit(tokenizer.tokenize_state.token_2.clone());
State::Next(StateName::LabelAtMarker)
}
_ => State::Nok,
}
}
/// At an optional extra marker.
///
/// Used for footnotes.
///
/// ```markdown
/// > | [^a]
/// ^
/// ```
pub fn at_marker(tokenizer: &mut Tokenizer) -> State {
// For footnotes (and potentially other custom things in the future),
// We need to make sure there is a certain marker after `[`.
if tokenizer.tokenize_state.marker == 0 {
tokenizer.enter(tokenizer.tokenize_state.token_3.clone());
State::Retry(StateName::LabelAtBreak)
} else if tokenizer.current == Some(tokenizer.tokenize_state.marker) {
tokenizer.enter(tokenizer.tokenize_state.token_4.clone());
tokenizer.consume();
tokenizer.exit(tokenizer.tokenize_state.token_4.clone());
tokenizer.enter(tokenizer.tokenize_state.token_3.clone());
State::Next(StateName::LabelAtBreak)
} else {
State::Nok
}
}
/// In label, at something, before something else.
///
/// ```markdown
/// > | [a]
/// ^
/// ```
pub fn at_break(tokenizer: &mut Tokenizer) -> State {
if tokenizer.tokenize_state.size > LINK_REFERENCE_SIZE_MAX
|| matches!(tokenizer.current, None | Some(b'['))
|| (matches!(tokenizer.current, Some(b']')) && !tokenizer.tokenize_state.seen)
{
tokenizer.tokenize_state.connect = false;
tokenizer.tokenize_state.seen = false;
tokenizer.tokenize_state.size = 0;
State::Nok
} else {
match tokenizer.current {
Some(b'\n') => {
tokenizer.attempt(
State::Next(StateName::LabelEolAfter),
State::Next(StateName::LabelAtBlankLine),
);
State::Retry(space_or_tab_eol_with_options(
tokenizer,
Options {
content: Some(Content::String),
connect: tokenizer.tokenize_state.connect,
},
))
}
Some(b']') => {
tokenizer.exit(tokenizer.tokenize_state.token_3.clone());
tokenizer.enter(tokenizer.tokenize_state.token_2.clone());
tokenizer.consume();
tokenizer.exit(tokenizer.tokenize_state.token_2.clone());
tokenizer.exit(tokenizer.tokenize_state.token_1.clone());
tokenizer.tokenize_state.connect = false;
tokenizer.tokenize_state.seen = false;
tokenizer.tokenize_state.size = 0;
State::Ok
}
_ => {
tokenizer.enter_link(
Name::Data,
Link {
previous: None,
next: None,
content: Content::String,
},
);
if tokenizer.tokenize_state.connect {
let index = tokenizer.events.len() - 1;
link(&mut tokenizer.events, index);
} else {
tokenizer.tokenize_state.connect = true;
}
State::Retry(StateName::LabelInside)
}
}
}
}
/// In label, after whitespace.
///
/// ```markdown
/// | [a␊
/// > | b]
/// ^
/// ```
pub fn eol_after(tokenizer: &mut Tokenizer) -> State {
tokenizer.tokenize_state.connect = true;
State::Retry(StateName::LabelAtBreak)
}
/// In label, at blank line.
///
/// ```markdown
/// | [a␊
/// > | ␊
/// ^
/// | b]
/// ```
pub fn at_blank_line(tokenizer: &mut Tokenizer) -> State {
tokenizer.tokenize_state.marker = 0;
tokenizer.tokenize_state.connect = false;
State::Nok
}
/// In label, in text.
///
/// ```markdown
/// > | [a]
/// ^
/// ```
pub fn inside(tokenizer: &mut Tokenizer) -> State {
match tokenizer.current {
None | Some(b'\n' | b'[' | b']') => {
tokenizer.exit(Name::Data);
State::Retry(StateName::LabelAtBreak)
}
Some(byte) => {
if tokenizer.tokenize_state.size > LINK_REFERENCE_SIZE_MAX {
tokenizer.exit(Name::Data);
State::Retry(StateName::LabelAtBreak)
} else {
tokenizer.consume();
tokenizer.tokenize_state.size += 1;
if !tokenizer.tokenize_state.seen && !matches!(byte, b'\t' | b' ') {
tokenizer.tokenize_state.seen = true;
}
State::Next(if matches!(byte, b'\\') {
StateName::LabelEscape
} else {
StateName::LabelInside
})
}
}
}
}
/// After `\`, at a special character.
///
/// ```markdown
/// > | [a\*a]
/// ^
/// ```
pub fn escape(tokenizer: &mut Tokenizer) -> State {
match tokenizer.current {
Some(b'[' | b'\\' | b']') => {
tokenizer.consume();
tokenizer.tokenize_state.size += 1;
State::Next(StateName::LabelInside)
}
_ => State::Retry(StateName::LabelInside),
}
}
