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|
use crate::regex::CharacterClass;
use super::{Match, Pattern, RegexEngine};
fn empty_match() -> Option<Match> {
Some(Match {
submatches: [].into(),
})
}
pub struct Anything;
#[derive(Debug, Clone)]
pub struct NotASimpleWildcard;
impl RegexEngine for Anything {
type CompileError = NotASimpleWildcard;
fn compile(pat: Pattern) -> Result<Self, Self::CompileError> {
if let Pattern::Rep(pat, 0, None, _) = pat
&& let Pattern::CharacterClass(CharacterClass::Everything) = *pat
{
Ok(Anything)
} else {
Err(NotASimpleWildcard)
}
}
fn run(&self, _input: &[u8]) -> Option<Match> {
empty_match()
}
}
pub struct Nothing;
#[derive(Debug, Clone)]
pub struct NotASimpleNothing;
impl RegexEngine for Nothing {
type CompileError = NotASimpleNothing;
fn compile(pat: Pattern) -> Result<Self, Self::CompileError> {
match pat {
Pattern::Range(a, b) if a > b => Ok(Nothing),
Pattern::CharacterClass(CharacterClass::Nothing) => Ok(Nothing),
Pattern::Alt(pats) => {
let all_impossible = pats.into_iter().map(Self::compile).all(|p| p.is_ok());
if all_impossible {
Ok(Nothing)
} else {
Err(NotASimpleNothing)
}
}
Pattern::Concat(pats) => {
if let Some(pat) = pats.into_iter().next() {
Self::compile(pat)
} else {
Err(NotASimpleNothing)
}
}
Pattern::Rep(_, x, Some(y), _) if y < x => Ok(Nothing),
Pattern::Rep(_, 0, None, _) => Err(NotASimpleNothing),
Pattern::Rep(pat, _gt_0, _, _) => Self::compile(*pat),
Pattern::Submatch(pat) => Self::compile(*pat),
_ => Err(NotASimpleNothing),
}
}
fn run(&self, _input: &[u8]) -> Option<Match> {
None
}
}
pub struct Exact {
bytes: Vec<u8>,
}
const MEM_LIMIT: usize = 25_000;
#[derive(Debug, Clone)]
pub struct NotSimplyAString;
fn ce(pat: Pattern) -> Option<Vec<u8>> {
match pat {
Pattern::Byte(b) => Some(vec![b]),
Pattern::Concat(patterns) => {
let mut pats = patterns.into_iter().map(ce).collect::<Option<Vec<_>>>()?;
let mut out = Vec::new();
for p in pats.iter_mut() {
out.append(p);
}
Some(out)
}
Pattern::Rep(pat, min, Some(max), _) if min == max => {
if let Some(bytes) = ce(*pat)
&& bytes.len() * (min as usize) < MEM_LIMIT
{
Some(bytes.repeat(min as usize))
} else {
None
}
}
Pattern::Submatch(_) => None, // TODO: submatches could be stored as constant offsets
Pattern::Nothing => Some(Vec::new()),
_ => None,
}
}
impl RegexEngine for Exact {
type CompileError = NotSimplyAString;
fn compile(pat: Pattern) -> Result<Self, Self::CompileError> {
match ce(pat) {
Some(bytes) => Ok(Self { bytes }),
None => Err(NotSimplyAString),
}
}
fn run(&self, input: &[u8]) -> Option<Match> {
if input == self.bytes {
empty_match()
} else {
None
}
}
}
|
