2302869 · helix · git.iko.soy

git.iko.soy/helix

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fix: ensure_grapheme_boundary_next_byte needs to index at valid char

2302869Blaž Hrastnik5 years ago

helix-core/src/graphemes.rs+31−1

compare with master

unifiedsplit

@@ -203,7 +203,12 @@ pub fn ensure_grapheme_boundary_next_byte(slice: RopeSlice, byte_idx: usize) ->

203 if byte_idx == 0 {

204 byte_idx

205 } else {

206+ // TODO: optimize so we're not constructing grapheme cursor twice

207+ if is_grapheme_boundary_byte(slice, byte_idx) {

208+ byte_idx

209+ } else {

206− next_grapheme_boundary_byte(slice, byte_idx - 1)

210+ next_grapheme_boundary_byte(slice, byte_idx)

211+ }

207 }

212 }

208}

213}

209

214

@@ -235,6 +240,31 @@ pub fn is_grapheme_boundary(slice: RopeSlice, char_idx: usize) -> bool {

235 }

240 }

236}

241}

237

242

243+/// Returns whether the given byte position is a grapheme boundary.

244+#[must_use]

245+pub fn is_grapheme_boundary_byte(slice: RopeSlice, byte_idx: usize) -> bool {

246+ // Bounds check

247+ debug_assert!(byte_idx <= slice.len_bytes());

248+

249+ // Get the chunk with our byte index in it.

250+ let (chunk, chunk_byte_idx, _, _) = slice.chunk_at_byte(byte_idx);

251+

252+ // Set up the grapheme cursor.

253+ let mut gc = GraphemeCursor::new(byte_idx, slice.len_bytes(), true);

254+

255+ // Determine if the given position is a grapheme cluster boundary.

256+ loop {

257+ match gc.is_boundary(chunk, chunk_byte_idx) {

258+ Ok(n) => return n,

259+ Err(GraphemeIncomplete::PreContext(n)) => {

260+ let (ctx_chunk, ctx_byte_start, _, _) = slice.chunk_at_byte(n - 1);

261+ gc.provide_context(ctx_chunk, ctx_byte_start);

262+ }

263+ Err(_) => unreachable!(),

264+ }

265+ }

266+}

267+

238/// An iterator over the graphemes of a `RopeSlice`.

268/// An iterator over the graphemes of a `RopeSlice`.

239#[derive(Clone)]

269#[derive(Clone)]

240pub struct RopeGraphemes<'a> {

270pub struct RopeGraphemes<'a> {