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//! Several helpers to parse whitespace (`space_or_tab`).
//!
//! ## References
//!
//! * [`micromark-factory-space/index.js` in `micromark`](https://github.com/micromark/micromark/blob/main/packages/micromark-factory-space/dev/index.js)
use crate::tokenizer::{Code, State, StateFn, StateFnResult, TokenType, Tokenizer};
/// Options to parse whitespace.
#[derive(Debug)]
struct Info {
/// Current size.
size: usize,
/// Minimum allowed characters (inclusive).
min: usize,
/// Maximum allowed characters (inclusive).
max: usize,
/// Token type to use for whitespace events.
kind: TokenType,
}
/// Optional `space_or_tab`
///
/// ```bnf
/// space_or_tab_opt ::= *( ' ' '\t' )
/// ```
pub fn space_or_tab_opt() -> Box<StateFn> {
space_or_tab_min_max(0, usize::MAX)
}
/// Between `x` and `y` `space_or_tab`
///
/// ```bnf
/// space_or_tab_min_max ::= x*y( ' ' '\t' )
/// ```
pub fn space_or_tab_min_max(min: usize, max: usize) -> Box<StateFn> {
space_or_tab(TokenType::Whitespace, min, max)
}
/// Between `x` and `y` `space_or_tab`, with the given token type.
///
/// ```bnf
/// space_or_tab ::= x*y( ' ' '\t' )
/// ```
pub fn space_or_tab(kind: TokenType, min: usize, max: usize) -> Box<StateFn> {
let info = Info {
size: 0,
min,
max,
kind,
};
Box::new(|t, c| start(t, c, info))
}
/// Before whitespace.
///
/// ```markdown
/// alpha| bravo
/// ```
fn start(tokenizer: &mut Tokenizer, code: Code, mut info: Info) -> StateFnResult {
match code {
Code::VirtualSpace | Code::Char('\t' | ' ') if info.max > 0 => {
tokenizer.enter(info.kind.clone());
tokenizer.consume(code);
info.size += 1;
(State::Fn(Box::new(|t, c| inside(t, c, info))), None)
}
_ => (
if info.min == 0 { State::Ok } else { State::Nok },
Some(vec![code]),
),
}
}
/// In whitespace.
///
/// ```markdown
/// alpha |bravo
/// alpha | bravo
/// ```
fn inside(tokenizer: &mut Tokenizer, code: Code, mut info: Info) -> StateFnResult {
match code {
Code::VirtualSpace | Code::Char('\t' | ' ') if info.size < info.max => {
tokenizer.consume(code);
info.size += 1;
(State::Fn(Box::new(|t, c| inside(t, c, info))), None)
}
_ => {
tokenizer.exit(info.kind.clone());
(
if info.size >= info.min {
State::Ok
} else {
State::Nok
},
Some(vec![code]),
)
}
}
}
|
