Merge pull request #2013 from zed-industries/autocomplete-require-word-start-match

Require first codepoint of autocomplete query to match the first codepoint of some completion's subword

crates/editor/src/editor.rs

@@ -828,6 +828,23 @@ impl CompletionsMenu {
                 })
                 .collect()
         };
+
+        //Remove all candidates where the query's start does not match the start of any word in the candidate
+        if let Some(query) = query {
+            if let Some(query_start) = query.chars().next() {
+                matches.retain(|string_match| {
+                    split_words(&string_match.string).any(|word| {
+                        //Check that the first codepoint of the word as lowercase matches the first
+                        //codepoint of the query as lowercase
+                        word.chars()
+                            .flat_map(|codepoint| codepoint.to_lowercase())
+                            .zip(query_start.to_lowercase())
+                            .all(|(word_cp, query_cp)| word_cp == query_cp)
+                    })
+                });
+            }
+        }
+
         matches.sort_unstable_by_key(|mat| {
             let completion = &self.completions[mat.candidate_id];
             (
@@ -6802,6 +6819,34 @@ pub fn styled_runs_for_code_label<'a>(
         })
 }
 
+pub fn split_words<'a>(text: &'a str) -> impl std::iter::Iterator<Item = &'a str> + 'a {
+    let mut index = 0;
+    let mut codepoints = text.char_indices().peekable();
+
+    std::iter::from_fn(move || {
+        let start_index = index;
+        while let Some((new_index, codepoint)) = codepoints.next() {
+            index = new_index + codepoint.len_utf8();
+            let current_upper = codepoint.is_uppercase();
+            let next_upper = codepoints
+                .peek()
+                .map(|(_, c)| c.is_uppercase())
+                .unwrap_or(false);
+
+            if !current_upper && next_upper {
+                return Some(&text[start_index..index]);
+            }
+        }
+
+        index = text.len();
+        if start_index < text.len() {
+            return Some(&text[start_index..]);
+        }
+        None
+    })
+    .flat_map(|word| word.split_inclusive('_'))
+}
+
 trait RangeExt<T> {
     fn sorted(&self) -> Range<T>;
     fn to_inclusive(&self) -> RangeInclusive<T>;