markdown/construct/
gfm_task_list_item_check.rs

1//! GFM: Task list item check occurs in the [text][] content type.
2//!
3//! ## Grammar
4//!
5//! Checks form with the following BNF
6//! (<small>see [construct][crate::construct] for character groups</small>):
7//!
8//! ```bnf
9//! gfm_task_list_item_check ::= '[' (0x09 | ' ' | 'X' | 'x') ']'
10//! ```
11//!
12//! The check is only allowed at the start of the first paragraph, optionally
13//! following zero or more definitions or a blank line, in a list item.
14//! The check must be followed by whitespace, which is in turn followed by
15//! non-whitespace.
16//!
17//! ## HTML
18//!
19//! Checks relate to the `<input>` element, in the checkbox state
20//! (`type=checkbox`), in HTML.
21//! See [*§ 4.10.5.1.15 Checkbox state (`type=checkbox`)*][html-input-checkbox]
22//! in the HTML spec for more info.
23//!
24//! ## Recommendation
25//!
26//! It is recommended to use lowercase `x` (instead of uppercase `X`), because
27//! in markdown, it is more common to use lowercase in places where casing does
28//! not matter.
29//! It is also recommended to use a space (instead of a tab), as there is no
30//! benefit of using tabs in this case.
31//!
32//! ## Tokens
33//!
34//! * [`GfmTaskListItemCheck`][Name::GfmTaskListItemCheck]
35//! * [`GfmTaskListItemMarker`][Name::GfmTaskListItemMarker]
36//! * [`GfmTaskListItemValueChecked`][Name::GfmTaskListItemValueChecked]
37//! * [`GfmTaskListItemValueUnchecked`][Name::GfmTaskListItemValueUnchecked]
38//!
39//! ## References
40//!
41//! * [`micromark-extension-gfm-task-list-item`](https://github.com/micromark/micromark-extension-gfm-task-list-item)
42//! * [*§ 5.3 Task list items (extension)* in `GFM`](https://github.github.com/gfm/#task-list-items-extension-)
43//!
44//! [text]: crate::construct::text
45//! [html-input-checkbox]: https://html.spec.whatwg.org/multipage/input.html#checkbox-state-(type=checkbox)
46
47use crate::construct::partial_space_or_tab::space_or_tab;
48use crate::event::Name;
49use crate::state::{Name as StateName, State};
50use crate::tokenizer::Tokenizer;
51
52/// At start of task list item check.
53///
54/// ```markdown
55/// > | * [x] y.
56///       ^
57/// ```
58pub fn start(tokenizer: &mut Tokenizer) -> State {
59    if tokenizer.parse_state.options.constructs.gfm_task_list_item
60        && tokenizer
61            .tokenize_state
62            .document_at_first_paragraph_of_list_item
63        && tokenizer.current == Some(b'[')
64        && tokenizer.previous.is_none()
65    {
66        tokenizer.enter(Name::GfmTaskListItemCheck);
67        tokenizer.enter(Name::GfmTaskListItemMarker);
68        tokenizer.consume();
69        tokenizer.exit(Name::GfmTaskListItemMarker);
70        State::Next(StateName::GfmTaskListItemCheckInside)
71    } else {
72        State::Nok
73    }
74}
75
76/// In task list item check.
77///
78/// ```markdown
79/// > | * [x] y.
80///        ^
81/// ```
82pub fn inside(tokenizer: &mut Tokenizer) -> State {
83    match tokenizer.current {
84        Some(b'\t' | b'\n' | b' ') => {
85            tokenizer.enter(Name::GfmTaskListItemValueUnchecked);
86            tokenizer.consume();
87            tokenizer.exit(Name::GfmTaskListItemValueUnchecked);
88            State::Next(StateName::GfmTaskListItemCheckClose)
89        }
90        Some(b'X' | b'x') => {
91            tokenizer.enter(Name::GfmTaskListItemValueChecked);
92            tokenizer.consume();
93            tokenizer.exit(Name::GfmTaskListItemValueChecked);
94            State::Next(StateName::GfmTaskListItemCheckClose)
95        }
96        _ => State::Nok,
97    }
98}
99
100/// At close of task list item check.
101///
102/// ```markdown
103/// > | * [x] y.
104///         ^
105/// ```
106pub fn close(tokenizer: &mut Tokenizer) -> State {
107    match tokenizer.current {
108        Some(b']') => {
109            tokenizer.enter(Name::GfmTaskListItemMarker);
110            tokenizer.consume();
111            tokenizer.exit(Name::GfmTaskListItemMarker);
112            tokenizer.exit(Name::GfmTaskListItemCheck);
113            State::Next(StateName::GfmTaskListItemCheckAfter)
114        }
115        _ => State::Nok,
116    }
117}
118
119/// After task list item check.
120///
121/// ```markdown
122/// > | * [x] y.
123///          ^
124/// ```
125pub fn after(tokenizer: &mut Tokenizer) -> State {
126    match tokenizer.current {
127        // EOL in paragraph means there must be something else after it.
128        Some(b'\n') => State::Ok,
129        // Space or tab?
130        // Check what comes after.
131        Some(b'\t' | b' ') => {
132            tokenizer.check(State::Ok, State::Nok);
133            tokenizer.attempt(
134                State::Next(StateName::GfmTaskListItemCheckAfterSpaceOrTab),
135                State::Nok,
136            );
137            State::Retry(space_or_tab(tokenizer))
138        }
139        // EOF, or non-whitespace, both wrong.
140        _ => State::Nok,
141    }
142}
143
144/// After whitespace, after task list item check.
145///
146/// ```markdown
147/// > | * [x] y.
148///           ^
149/// ```
150pub fn after_space_or_tab(tokenizer: &mut Tokenizer) -> State {
151    // End of paragraph, after whitespace, after check, is not okay.
152    if tokenizer.current.is_none() {
153        State::Nok
154    } else {
155        State::Ok
156    }
157}
markdown/construct/gfm_task_list_item_check.rs

markdown/construct/
gfm_task_list_item_check.rs
