Unnamed repository; edit this file 'description' to name the repository.
| -rw-r--r-- | helix-stdx/src/rope.rs | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/helix-stdx/src/rope.rs b/helix-stdx/src/rope.rs index df7a2873..996fee31 100644 --- a/helix-stdx/src/rope.rs +++ b/helix-stdx/src/rope.rs @@ -169,6 +169,28 @@ pub trait RopeSliceExt<'a>: Sized { /// assert_eq!(graphemes.as_slice(), &["🏴☠️", "😶🌫️"]); /// ``` fn graphemes_at(self, byte_idx: usize) -> RopeGraphemes<'a>; + /// Returns an iterator over the grapheme clusters in a rope and the byte index where each + /// grapheme cluster starts. + /// + /// # Example + /// + /// ``` + /// # use ropey::Rope; + /// # use helix_stdx::rope::RopeSliceExt; + /// let text = Rope::from_str("😶🌫️🏴☠️🖼️"); + /// let slice = text.slice(..); + /// let graphemes: Vec<_> = slice.grapheme_indices_at(0).collect(); + /// assert_eq!( + /// graphemes.as_slice(), + /// &[(0, "😶🌫️".into()), (14, "🏴☠️".into()), (27, "🖼️".into())] + /// ); + /// let graphemes: Vec<_> = slice.grapheme_indices_at(slice.len_bytes()).reversed().collect(); + /// assert_eq!( + /// graphemes.as_slice(), + /// &[(27, "🖼️".into()), (14, "🏴☠️".into()), (0, "😶🌫️".into())] + /// ); + /// ``` + fn grapheme_indices_at(self, byte_idx: usize) -> RopeGraphemeIndices<'a>; /// Finds the byte index of the next grapheme boundary after `byte_idx`. /// /// If the byte index lies on the last grapheme cluster in the slice then this function @@ -456,6 +478,16 @@ impl<'a> RopeSliceExt<'a> for RopeSlice<'a> { } } + fn grapheme_indices_at(self, byte_idx: usize) -> RopeGraphemeIndices<'a> { + // Bounds check + assert!(byte_idx <= self.len_bytes()); + RopeGraphemeIndices { + front_offset: byte_idx, + iter: self.graphemes_at(byte_idx), + is_reversed: false, + } + } + fn nth_next_grapheme_boundary(self, mut byte_idx: usize, n: usize) -> usize { // Bounds check assert!(byte_idx <= self.len_bytes()); @@ -673,6 +705,68 @@ impl<'a> Iterator for RopeGraphemes<'a> { } } +/// An iterator over the grapheme clusters in a rope and the byte indices where each grapheme +/// cluster starts. +/// +/// This iterator wraps `RopeGraphemes` and is also cursor-like. Use `reverse` or `reversed` to +/// toggle the direction of the iterator. See [RopeGraphemes]. +#[derive(Debug, Clone)] +pub struct RopeGraphemeIndices<'a> { + front_offset: usize, + iter: RopeGraphemes<'a>, + is_reversed: bool, +} + +impl<'a> RopeGraphemeIndices<'a> { + #[allow(clippy::should_implement_trait)] + pub fn next(&mut self) -> Option<(usize, RopeSlice<'a>)> { + if self.is_reversed { + self.prev_impl() + } else { + self.next_impl() + } + } + + pub fn prev(&mut self) -> Option<(usize, RopeSlice<'a>)> { + if self.is_reversed { + self.next_impl() + } else { + self.prev_impl() + } + } + + pub fn reverse(&mut self) { + self.is_reversed = !self.is_reversed; + } + + #[must_use] + pub fn reversed(mut self) -> Self { + self.reverse(); + self + } + + fn next_impl(&mut self) -> Option<(usize, RopeSlice<'a>)> { + let slice = self.iter.next()?; + let idx = self.front_offset; + self.front_offset += slice.len_bytes(); + Some((idx, slice)) + } + + fn prev_impl(&mut self) -> Option<(usize, RopeSlice<'a>)> { + let slice = self.iter.prev()?; + self.front_offset -= slice.len_bytes(); + Some((self.front_offset, slice)) + } +} + +impl<'a> Iterator for RopeGraphemeIndices<'a> { + type Item = (usize, RopeSlice<'a>); + + fn next(&mut self) -> Option<Self::Item> { + RopeGraphemeIndices::next(self) + } +} + #[cfg(test)] mod tests { use ropey::RopeSlice; |