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#![no_std]
extern crate fst;
use fst::Automaton;
#[derive(Clone, Debug)]
pub struct SubseqAsciiCaseless<'a> {
subseq: &'a [u8],
}
impl<'a> SubseqAsciiCaseless<'a> {
pub fn new(subseq: &'a str) -> Self {
assert!(!subseq.bytes().any(|b| b.is_ascii_uppercase()));
Self::new_unchecked(subseq)
}
pub fn new_unchecked(subseq: &'a str) -> Self {
SubseqAsciiCaseless {
subseq: subseq.as_bytes(),
}
}
}
impl<'a> Automaton for SubseqAsciiCaseless<'a> {
type State = usize;
fn start(&self) -> usize {
0
}
fn is_match(&self, state: &usize) -> bool {
*state == self.subseq.len()
}
fn can_match(&self, _: &usize) -> bool {
true
}
fn will_always_match(&self, state: &usize) -> bool {
self.is_match(state)
}
fn accept(&self, state: &usize, byte: u8) -> usize {
if self.is_match(state) {
return *state;
}
state + (byte.to_ascii_lowercase() == self.subseq[*state]) as usize
}
}
#[cfg(test)]
mod tests {
use super::*;
const PATTERN1: &str = "sqaicl";
#[test]
fn test_states() {
let subseq = SubseqAsciiCaseless::new(PATTERN1);
assert_eq!(subseq.start(), 0);
assert_eq!(subseq.accept(&0, b'q'), 0);
assert_eq!(subseq.accept(&0, b'S'), 1);
assert_eq!(subseq.accept(&1, b'x'), 1);
assert_eq!(subseq.accept(&1, b'q'), 2);
assert_eq!(subseq.accept(&2, b'a'), 3);
assert_eq!(subseq.accept(&3, b'I'), 4);
assert_eq!(subseq.accept(&4, b'l'), 4);
assert_eq!(subseq.accept(&4, b'C'), 5);
assert_eq!(subseq.accept(&5, b'L'), 6);
}
#[test]
fn test_is_match() {
let subseq = SubseqAsciiCaseless::new(PATTERN1);
for i in 0..PATTERN1.len() {
assert!(!subseq.is_match(&i));
}
assert!(subseq.is_match(&PATTERN1.len()));
}
#[test]
#[should_panic]
fn test_new_check() {
SubseqAsciiCaseless::new("SqAiCl");
}
}