1 files changed, 95 insertions, 10 deletions

diff --git a/helix-view/src/gutter.rs b/helix-view/src/gutter.rs
index 377518fb..c1b5e2b1 100644
--- a/helix-view/src/gutter.rs
+++ b/helix-view/src/gutter.rs
@@ -35,10 +35,10 @@ impl GutterType {
         }
     }
 
-    pub fn width(self, _view: &View, doc: &Document) -> usize {
+    pub fn width(self, view: &View, doc: &Document) -> usize {
         match self {
             GutterType::Diagnostics => 1,
-            GutterType::LineNumbers => line_numbers_width(_view, doc),
+            GutterType::LineNumbers => line_numbers_width(view, doc),
             GutterType::Spacer => 1,
             GutterType::Diff => 1,
         }
@@ -140,12 +140,13 @@ pub fn line_numbers<'doc>(
     is_focused: bool,
 ) -> GutterFn<'doc> {
     let text = doc.text().slice(..);
-    let last_line = view.last_line(doc);
-    let width = GutterType::LineNumbers.width(view, doc);
+    let width = line_numbers_width(view, doc);
+
+    let last_line_in_view = view.last_line(doc);
 
     // Whether to draw the line number for the last line of the
     // document or not.  We only draw it if it's not an empty line.
-    let draw_last = text.line_to_byte(last_line) < text.len_bytes();
+    let draw_last = text.line_to_byte(last_line_in_view) < text.len_bytes();
 
     let linenr = theme.get("ui.linenr");
     let linenr_select = theme.get("ui.linenr.selected");
@@ -158,7 +159,7 @@ pub fn line_numbers<'doc>(
     let mode = editor.mode;
 
     Box::new(move |line: usize, selected: bool, out: &mut String| {
-        if line == last_line && !draw_last {
+        if line == last_line_in_view && !draw_last {
             write!(out, "{:>1$}", '~', width).unwrap();
             Some(linenr)
         } else {
@@ -187,14 +188,19 @@ pub fn line_numbers<'doc>(
     })
 }
 
-pub fn line_numbers_width(_view: &View, doc: &Document) -> usize {
+/// The width of a "line-numbers" gutter
+///
+/// The width of the gutter depends on the number of lines in the document,
+/// whether there is content on the last line (the `~` line), and the
+/// `editor.gutters.line-numbers.min-width` settings.
+fn line_numbers_width(view: &View, doc: &Document) -> usize {
     let text = doc.text();
     let last_line = text.len_lines().saturating_sub(1);
     let draw_last = text.line_to_byte(last_line) < text.len_bytes();
     let last_drawn = if draw_last { last_line + 1 } else { last_line };
-
-    // set a lower bound to 2-chars to minimize ambiguous relative line numbers
-    std::cmp::max(count_digits(last_drawn), 2)
+    let digits = count_digits(last_drawn);
+    let n_min = view.gutters.line_numbers.min_width;
+    digits.max(n_min)
 }
 
 pub fn padding<'doc>(
@@ -282,3 +288,82 @@ pub fn diagnostics_or_breakpoints<'doc>(
         breakpoints(line, selected, out).or_else(|| diagnostics(line, selected, out))
     })
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::document::Document;
+    use crate::editor::{GutterConfig, GutterLineNumbersConfig};
+    use crate::graphics::Rect;
+    use crate::DocumentId;
+    use helix_core::Rope;
+
+    #[test]
+    fn test_default_gutter_widths() {
+        let mut view = View::new(DocumentId::default(), GutterConfig::default());
+        view.area = Rect::new(40, 40, 40, 40);
+
+        let rope = Rope::from_str("abc\n\tdef");
+        let doc = Document::from(rope, None);
+
+        assert_eq!(view.gutters.layout.len(), 5);
+        assert_eq!(view.gutters.layout[0].width(&view, &doc), 1);
+        assert_eq!(view.gutters.layout[1].width(&view, &doc), 1);
+        assert_eq!(view.gutters.layout[2].width(&view, &doc), 3);
+        assert_eq!(view.gutters.layout[3].width(&view, &doc), 1);
+        assert_eq!(view.gutters.layout[4].width(&view, &doc), 1);
+    }
+
+    #[test]
+    fn test_configured_gutter_widths() {
+        let gutters = GutterConfig {
+            layout: vec![GutterType::Diagnostics],
+            ..Default::default()
+        };
+
+        let mut view = View::new(DocumentId::default(), gutters);
+        view.area = Rect::new(40, 40, 40, 40);
+
+        let rope = Rope::from_str("abc\n\tdef");
+        let doc = Document::from(rope, None);
+
+        assert_eq!(view.gutters.layout.len(), 1);
+        assert_eq!(view.gutters.layout[0].width(&view, &doc), 1);
+
+        let gutters = GutterConfig {
+            layout: vec![GutterType::Diagnostics, GutterType::LineNumbers],
+            line_numbers: GutterLineNumbersConfig { min_width: 10 },
+        };
+
+        let mut view = View::new(DocumentId::default(), gutters);
+        view.area = Rect::new(40, 40, 40, 40);
+
+        let rope = Rope::from_str("abc\n\tdef");
+        let doc = Document::from(rope, None);
+
+        assert_eq!(view.gutters.layout.len(), 2);
+        assert_eq!(view.gutters.layout[0].width(&view, &doc), 1);
+        assert_eq!(view.gutters.layout[1].width(&view, &doc), 10);
+    }
+
+    #[test]
+    fn test_line_numbers_gutter_width_resizes() {
+        let gutters = GutterConfig {
+            layout: vec![GutterType::Diagnostics, GutterType::LineNumbers],
+            line_numbers: GutterLineNumbersConfig { min_width: 1 },
+        };
+
+        let mut view = View::new(DocumentId::default(), gutters);
+        view.area = Rect::new(40, 40, 40, 40);
+
+        let rope = Rope::from_str("a\nb");
+        let doc_short = Document::from(rope, None);
+
+        let rope = Rope::from_str("a\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk\nl\nm\nn\no\np");
+        let doc_long = Document::from(rope, None);
+
+        assert_eq!(view.gutters.layout.len(), 2);
+        assert_eq!(view.gutters.layout[1].width(&view, &doc_short), 1);
+        assert_eq!(view.gutters.layout[1].width(&view, &doc_long), 2);
+    }
+}