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index_before and index_after return Option<usize> instead of just usize

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Eryn Wells 2016-12-22 09:25:10 -08:00
parent 93353f0f9e
commit 2c9b024ac5
1 changed files with 8 additions and 8 deletions
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16
src/characters.rs
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@ -43,30 +43,30 @@ pub fn identifier_subsequents() -> CharSet {
} }
pub trait RelativeIndexable { pub trait RelativeIndexable {
fn index_before(&self, &usize) -> usize; fn index_before(&self, &usize) -> Option<usize>;
fn index_after(&self, &usize) -> usize; fn index_after(&self, &usize) -> Option<usize>;
} }
impl RelativeIndexable for str { impl RelativeIndexable for str {
fn index_before(&self, index: &usize) -> usize { fn index_before(&self, index: &usize) -> Option<usize> {
let mut prev_index = index - 1; let mut prev_index = index - 1;
if prev_index <= 0 { if prev_index <= 0 {
return 0; return None;
} }
while !self.is_char_boundary(prev_index) { while !self.is_char_boundary(prev_index) {
prev_index -= 1; prev_index -= 1;
} }
prev_index Some(prev_index)
} }
fn index_after(&self, index: &usize) -> usize { fn index_after(&self, index: &usize) -> Option<usize> {
let mut next_index = index + 1; let mut next_index = index + 1;
if next_index >= self.len() { if next_index >= self.len() {
return self.len(); return None;
} }
while !self.is_char_boundary(next_index) { while !self.is_char_boundary(next_index) {
next_index += 1; next_index += 1;
} }
next_index Some(next_index)
} }
} }