Fixed primary cursor position calculation to use 1-width semantics.

This had a bunch of knock-on effects that were buggy, such as bracket
match highlighting.

6 files changed, 58 insertions, 29 deletions

diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs
index 21a6c108..7d2526b0 100644
--- a/helix-core/src/selection.rs
+++ b/helix-core/src/selection.rs
@@ -267,8 +267,15 @@ impl Selection {
     }
 
     #[must_use]
-    pub fn cursor(&self) -> usize {
-        self.primary().head
+    pub fn cursor(&self, text: RopeSlice) -> usize {
+        let range = self.primary();
+
+        // For 1-width cursor semantics.
+        if range.anchor < range.head {
+            prev_grapheme_boundary(text, range.head)
+        } else {
+            range.head
+        }
     }
 
     /// Ensure selection containing only the primary selection.
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index cea5a24e..add83b41 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -121,7 +121,7 @@ enum Align {
 }
 
 fn align_view(doc: &Document, view: &mut View, align: Align) {
-    let pos = doc.selection(view.id).cursor();
+    let pos = doc.selection(view.id).cursor(doc.text().slice(..));
     let line = doc.text().char_to_line(pos);
 
     let relative = match align {
@@ -868,7 +868,10 @@ fn switch_to_lowercase(cx: &mut Context) {
 fn scroll(cx: &mut Context, offset: usize, direction: Direction) {
     use Direction::*;
     let (view, doc) = current!(cx.editor);
-    let cursor = coords_at_pos(doc.text().slice(..), doc.selection(view.id).cursor());
+    let cursor = coords_at_pos(
+        doc.text().slice(..),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
+    );
     let doc_last_line = doc.text().len_lines() - 1;
 
     let last_line = view.last_line(doc);
@@ -1038,7 +1041,7 @@ fn split_selection_on_newline(cx: &mut Context) {
 fn search_impl(doc: &mut Document, view: &mut View, contents: &str, regex: &Regex, extend: bool) {
     let text = doc.text();
     let selection = doc.selection(view.id);
-    let start = text.char_to_byte(selection.cursor());
+    let start = text.char_to_byte(selection.cursor(text.slice(..)));
 
     // use find_at to find the next match after the cursor, loop around the end
     // Careful, `Regex` uses `bytes` as offsets, not character indices!
@@ -2446,7 +2449,11 @@ fn goto_definition(cx: &mut Context) {
 
     let offset_encoding = language_server.offset_encoding();
 
-    let pos = pos_to_lsp_pos(doc.text(), doc.selection(view.id).cursor(), offset_encoding);
+    let pos = pos_to_lsp_pos(
+        doc.text(),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
+        offset_encoding,
+    );
 
     // TODO: handle fails
     let future = language_server.goto_definition(doc.identifier(), pos, None);
@@ -2483,7 +2490,11 @@ fn goto_type_definition(cx: &mut Context) {
 
     let offset_encoding = language_server.offset_encoding();
 
-    let pos = pos_to_lsp_pos(doc.text(), doc.selection(view.id).cursor(), offset_encoding);
+    let pos = pos_to_lsp_pos(
+        doc.text(),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
+        offset_encoding,
+    );
 
     // TODO: handle fails
     let future = language_server.goto_type_definition(doc.identifier(), pos, None);
@@ -2520,7 +2531,11 @@ fn goto_implementation(cx: &mut Context) {
 
     let offset_encoding = language_server.offset_encoding();
 
-    let pos = pos_to_lsp_pos(doc.text(), doc.selection(view.id).cursor(), offset_encoding);
+    let pos = pos_to_lsp_pos(
+        doc.text(),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
+        offset_encoding,
+    );
 
     // TODO: handle fails
     let future = language_server.goto_implementation(doc.identifier(), pos, None);
@@ -2557,7 +2572,11 @@ fn goto_reference(cx: &mut Context) {
 
     let offset_encoding = language_server.offset_encoding();
 
-    let pos = pos_to_lsp_pos(doc.text(), doc.selection(view.id).cursor(), offset_encoding);
+    let pos = pos_to_lsp_pos(
+        doc.text(),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
+        offset_encoding,
+    );
 
     // TODO: handle fails
     let future = language_server.goto_reference(doc.identifier(), pos, None);
@@ -2616,7 +2635,7 @@ fn goto_next_diag(cx: &mut Context) {
     let editor = &mut cx.editor;
     let (view, doc) = current!(editor);
 
-    let cursor_pos = doc.selection(view.id).cursor();
+    let cursor_pos = doc.selection(view.id).cursor(doc.text().slice(..));
     let diag = if let Some(diag) = doc
         .diagnostics()
         .iter()
@@ -2637,7 +2656,7 @@ fn goto_prev_diag(cx: &mut Context) {
     let editor = &mut cx.editor;
     let (view, doc) = current!(editor);
 
-    let cursor_pos = doc.selection(view.id).cursor();
+    let cursor_pos = doc.selection(view.id).cursor(doc.text().slice(..));
     let diag = if let Some(diag) = doc
         .diagnostics()
         .iter()
@@ -2665,7 +2684,7 @@ fn signature_help(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
         language_server.offset_encoding(),
     );
 
@@ -3403,13 +3422,14 @@ fn completion(cx: &mut Context) {
     };
 
     let offset_encoding = language_server.offset_encoding();
+    let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
 
-    let pos = pos_to_lsp_pos(doc.text(), doc.selection(view.id).cursor(), offset_encoding);
+    let pos = pos_to_lsp_pos(doc.text(), cursor, offset_encoding);
 
     // TODO: handle fails
     let future = language_server.completion(doc.identifier(), pos, None);
 
-    let trigger_offset = doc.selection(view.id).cursor();
+    let trigger_offset = cursor;
 
     cx.callback(
         future,
@@ -3459,7 +3479,7 @@ fn hover(cx: &mut Context) {
 
     let pos = pos_to_lsp_pos(
         doc.text(),
-        doc.selection(view.id).cursor(),
+        doc.selection(view.id).cursor(doc.text().slice(..)),
         language_server.offset_encoding(),
     );
 
@@ -3525,7 +3545,7 @@ fn match_brackets(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
 
     if let Some(syntax) = doc.syntax() {
-        let pos = doc.selection(view.id).cursor();
+        let pos = doc.selection(view.id).cursor(doc.text().slice(..));
         if let Some(pos) = match_brackets::find(syntax, doc.text(), pos) {
             let selection = Selection::point(pos);
             doc.set_selection(view.id, selection);
@@ -3629,7 +3649,7 @@ fn align_view_bottom(cx: &mut Context) {
 
 fn align_view_middle(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
-    let pos = doc.selection(view.id).cursor();
+    let pos = doc.selection(view.id).cursor(doc.text().slice(..));
     let pos = coords_at_pos(doc.text().slice(..), pos);
 
     const OFFSET: usize = 7; // gutters
diff --git a/helix-term/src/ui/completion.rs b/helix-term/src/ui/completion.rs
index be6db42c..942a2483 100644
--- a/helix-term/src/ui/completion.rs
+++ b/helix-term/src/ui/completion.rs
@@ -86,7 +86,7 @@ impl Completion {
                     let item = item.unwrap();
 
                     // if more text was entered, remove it
-                    let cursor = doc.selection(view.id).cursor();
+                    let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
                     if trigger_offset < cursor {
                         let remove = Transaction::change(
                             doc.text(),
@@ -109,7 +109,7 @@ impl Completion {
                         )
                     } else {
                         let text = item.insert_text.as_ref().unwrap_or(&item.label);
-                        let cursor = doc.selection(view.id).cursor();
+                        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
                         Transaction::change(
                             doc.text(),
                             vec![(cursor, cursor, Some(text.as_str().into()))].into_iter(),
@@ -155,7 +155,7 @@ impl Completion {
         // TODO: hooks should get processed immediately so maybe do it after select!(), before
         // looping?
 
-        let cursor = doc.selection(view.id).cursor();
+        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
         if self.trigger_offset <= cursor {
             let fragment = doc.text().slice(self.trigger_offset..cursor);
             let text = Cow::from(fragment);
@@ -212,7 +212,7 @@ impl Component for Completion {
                 .language()
                 .and_then(|scope| scope.strip_prefix("source."))
                 .unwrap_or("");
-            let cursor_pos = doc.selection(view.id).cursor();
+            let cursor_pos = doc.selection(view.id).cursor(doc.text().slice(..));
             let cursor_pos = (helix_core::coords_at_pos(doc.text().slice(..), cursor_pos).row
                 - view.first_line) as u16;
 
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 6a588e12..acf60905 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -398,7 +398,7 @@ impl EditorView {
                     // TODO: set cursor position for IME
                     if let Some(syntax) = doc.syntax() {
                         use helix_core::match_brackets;
-                        let pos = doc.selection(view.id).cursor();
+                        let pos = doc.selection(view.id).cursor(doc.text().slice(..));
                         let pos = match_brackets::find(syntax, doc.text(), pos)
                             .and_then(|pos| view.screen_coords_at_pos(doc, text, pos));
 
@@ -443,7 +443,7 @@ impl EditorView {
             widgets::{Paragraph, Widget},
         };
 
-        let cursor = doc.selection(view.id).cursor();
+        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
 
         let diagnostics = doc.diagnostics().iter().filter(|diagnostic| {
             diagnostic.range.start <= cursor && diagnostic.range.end >= cursor
@@ -555,7 +555,10 @@ impl EditorView {
         //     _ => "indent:ERROR",
         // };
         let position_info = {
-            let pos = coords_at_pos(doc.text().slice(..), doc.selection(view.id).cursor());
+            let pos = coords_at_pos(
+                doc.text().slice(..),
+                doc.selection(view.id).cursor(doc.text().slice(..)),
+            );
             format!("{}:{}", pos.row + 1, pos.col + 1) // convert to 1-indexing
         };
 
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index cd9d0a92..1cd0af02 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -141,12 +141,11 @@ impl Editor {
                 let (view, doc) = current!(self);
 
                 // initialize selection for view
-                let selection = doc
-                    .selections
+                doc.selections
                     .entry(view.id)
                     .or_insert_with(|| Selection::point(0));
                 // TODO: reuse align_view
-                let pos = selection.cursor();
+                let pos = doc.selection(view.id).cursor(doc.text().slice(..));
                 let line = doc.text().char_to_line(pos);
                 view.first_line = line.saturating_sub(view.area.height as usize / 2);
 
@@ -296,7 +295,7 @@ impl Editor {
         const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
         let view = view!(self);
         let doc = &self.documents[view.doc];
-        let cursor = doc.selection(view.id).cursor();
+        let cursor = doc.selection(view.id).cursor(doc.text().slice(..));
         if let Some(mut pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
             pos.col += view.area.x as usize + OFFSET as usize;
             pos.row += view.area.y as usize;
diff --git a/helix-view/src/view.rs b/helix-view/src/view.rs
index ccb61646..67585ed3 100644
--- a/helix-view/src/view.rs
+++ b/helix-view/src/view.rs
@@ -84,7 +84,7 @@ impl View {
     }
 
     pub fn ensure_cursor_in_view(&mut self, doc: &Document) {
-        let cursor = doc.selection(self.id).cursor();
+        let cursor = doc.selection(self.id).cursor(doc.text().slice(..));
         let pos = coords_at_pos(doc.text().slice(..), cursor);
         let line = pos.row;
         let col = pos.col;