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use super::*;
pub(super) struct Quantifier {
minimum: u32,
maximum: Option<u32>,
greedy: bool,
}
impl Parser<'_> {
/// Apply a trailing quantifier to `atom` when one follows; a
/// second quantifier after the first is E871 (multi follow multi).
pub(super) fn parse_quantifier(&mut self, atom: Node) -> Result<Node, QueryError> {
let Some(Quantifier {
minimum: min,
maximum: max,
greedy,
}) = self.quant_at()?
else {
return Ok(atom);
};
let after_first = self.at;
if self.quant_at()?.is_some() {
// vim's E871: a multi cannot follow a multi
return Err(QueryError::BadRepeat { at: after_first });
}
if matches!(
atom,
Node::LineStart
| Node::LineEnd
| Node::BufStart
| Node::BufEnd
| Node::WordStart
| Node::WordEnd
| Node::SetStart
| Node::SetEnd
) {
// a quantifier on a zero-width assertion is vim's E871 too
return Err(QueryError::BadRepeat { at: self.at });
}
Ok(Node::Rep {
node: Box::new(atom),
min,
max,
greedy,
})
}
/// Consume a quantifier if one starts here; Ok(None) = none.
pub(super) fn quant_at(&mut self) -> Result<Option<Quantifier>, QueryError> {
match self.mode {
Magic::Magic => {
if self.peek() == Some(b'*') {
self.at += 1;
return Ok(Some(Quantifier {
minimum: 0,
maximum: None,
greedy: true,
}));
}
if self.starts_with(b"\\+") {
self.at += 2;
return Ok(Some(Quantifier {
minimum: 1,
maximum: None,
greedy: true,
}));
}
if self.starts_with(b"\\=") || self.starts_with(b"\\?") {
self.at += 2;
return Ok(Some(Quantifier {
minimum: 0,
maximum: Some(1),
greedy: true,
}));
}
if self.starts_with(b"\\{") {
return self.parse_braces().map(Some);
}
}
Magic::VeryMagic => {
if self.peek() == Some(b'*') {
self.at += 1;
return Ok(Some(Quantifier {
minimum: 0,
maximum: None,
greedy: true,
}));
}
if self.peek() == Some(b'+') {
self.at += 1;
return Ok(Some(Quantifier {
minimum: 1,
maximum: None,
greedy: true,
}));
}
if self.peek() == Some(b'=') || self.peek() == Some(b'?') {
self.at += 1;
return Ok(Some(Quantifier {
minimum: 0,
maximum: Some(1),
greedy: true,
}));
}
if self.peek() == Some(b'{') {
return self.parse_braces().map(Some);
}
}
}
Ok(None)
}
/// `\{n,m}` (magic) / `{n,m}` (very magic); a `-` right after the
/// brace marks lazy (`\{-1,3}`, `\va{-}`). Reversed ranges swap
/// (vim: `a\{2,1}b` matches "ab" — corpus-pinned).
pub(super) fn parse_braces(&mut self) -> Result<Quantifier, QueryError> {
let start = self.at;
self.at += if self.mode == Magic::Magic { 2 } else { 1 };
let greedy = if self.peek() == Some(b'-') {
self.at += 1;
false
} else {
true
};
let mut min: Option<u32> = None;
let mut cur = String::new();
let mut stage = 0; // 0 = min, 1 = max
loop {
let Some(c) = self.peek() else {
return Err(QueryError::BadRepeat { at: start });
};
self.at += 1;
match c {
b'0'..=b'9' => cur.push(c as char),
b',' if stage == 0 => {
min = Some(if cur.is_empty() {
0
} else {
self.num(&cur, start)?
});
cur.clear();
stage = 1;
}
b'}' => break,
b'\\' if self.mode == Magic::Magic && self.peek() == Some(b'}') => {
self.at += 1; // tolerated escaped close
break;
}
_ => return Err(QueryError::BadRepeat { at: start }),
}
}
let (min, max) = match stage {
0 => {
if cur.is_empty() {
// `\{}` / `{}` — same as star
(0, None)
} else {
let n = self.num(&cur, start)?;
(n, Some(n))
}
}
_ => {
let hi = if cur.is_empty() {
None // `\{2,}` unbounded
} else {
Some(self.num(&cur, start)?)
};
(min.unwrap_or(0), hi) // `\{,3}` — min omitted
}
};
// vim swaps reversed ranges rather than erroring
let (min, max) = match max {
Some(hi) if hi < min => (hi, Some(min)),
_ => (min, max),
};
Ok(Quantifier {
minimum: min,
maximum: max,
greedy,
})
}
pub(super) fn num(&self, s: &str, at: usize) -> Result<u32, QueryError> {
s.parse::<u32>()
.ok()
.filter(|n| *n <= MAX_REPEAT)
.ok_or(QueryError::BadRepeat { at })
}
}