Add configuration for min width of line-numbers gutter

book/src/configuration.md

@@ -255,3 +255,55 @@ render = true
 character = "╎" # Some characters that work well: "▏", "┆", "┊", "⸽"
 skip-levels = 1
 ```
+
+### `[editor.gutters]` Section
+
+For simplicity, `editor.gutters` accepts an array of gutter types, which will
+use default settings for all gutter components.
+
+```toml
+[editor]
+gutters = ["diff", "diagnostics", "line-numbers", "spacer"]
+```
+
+To customize the behavior of gutters, the `[editor.gutters]` section must
+be used. This section contains top level settings, as well as settings for
+specific gutter components as sub-sections.
+
+| Key      | Description                    | Default                                                       |
+| ---      | ---                            | ---                                                           |
+| `layout` | A vector of gutters to display | `["diagnostics", "spacer", "line-numbers", "spacer", "diff"]` |
+
+Example:
+
+```toml
+[editor.gutters]
+layout = ["diff", "diagnostics", "line-numbers", "spacer"]
+```
+
+#### `[editor.gutters.line-numbers]` Section
+
+Options for the line number gutter
+
+| Key         | Description                             | Default |
+| ---         | ---                                     | ---     |
+| `min-width` | The minimum number of characters to use | `3`     |
+
+Example:
+
+```toml
+[editor.gutters.line-numbers]
+min-width = 1
+```
+
+#### `[editor.gutters.diagnotics]` Section
+
+Currently unused
+
+#### `[editor.gutters.diff]` Section
+
+Currently unused
+
+#### `[editor.gutters.spacer]` Section
+
+Currently unused

helix-view/src/editor.rs

@@ -20,6 +20,7 @@ use std::{
     borrow::Cow,
     collections::{BTreeMap, HashMap},
     io::stdin,
+    marker::PhantomData,
     num::NonZeroUsize,
     path::{Path, PathBuf},
     pin::Pin,
@@ -71,6 +72,105 @@ where
     )
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
+pub struct GutterConfig {
+    /// Gutter Layout
+    pub layout: Vec<GutterType>,
+    /// Options specific to the "line-numbers" gutter
+    pub line_numbers: GutterLineNumbersConfig,
+}
+
+impl Default for GutterConfig {
+    fn default() -> Self {
+        Self {
+            layout: vec![
+                GutterType::Diagnostics,
+                GutterType::Spacer,
+                GutterType::LineNumbers,
+                GutterType::Spacer,
+                GutterType::Diff,
+            ],
+            line_numbers: GutterLineNumbersConfig::default(),
+        }
+    }
+}
+
+impl From<Vec<GutterType>> for GutterConfig {
+    fn from(x: Vec<GutterType>) -> Self {
+        GutterConfig {
+            layout: x,
+            ..Default::default()
+        }
+    }
+}
+
+fn deserialize_gutter_seq_or_struct<'de, T, D>(deserializer: D) -> Result<T, D::Error>
+where
+    T: Deserialize<'de> + From<Vec<GutterType>>,
+    D: Deserializer<'de>,
+{
+    // This is a Visitor that forwards string types to T's `FromStr` impl and
+    // forwards map types to T's `Deserialize` impl. The `PhantomData` is to
+    // keep the compiler from complaining about T being an unused generic type
+    // parameter. We need T in order to know the Value type for the Visitor
+    // impl.
+    struct GutterSeqOrStruct<T>(PhantomData<fn() -> T>);
+
+    impl<'de, T> serde::de::Visitor<'de> for GutterSeqOrStruct<T>
+    where
+        T: Deserialize<'de> + From<Vec<GutterType>>,
+    {
+        type Value = T;
+
+        fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+            write!(
+                formatter,
+                "an array of gutter names or a detailed gutter configuration"
+            )
+        }
+
+        fn visit_seq<S>(self, mut seq: S) -> Result<Self::Value, S::Error>
+        where
+            S: serde::de::SeqAccess<'de>,
+        {
+            let mut gutters = Vec::new();
+            while let Some(gutter) = seq.next_element::<&str>()? {
+                gutters.push(
+                    gutter
+                        .parse::<GutterType>()
+                        .map_err(serde::de::Error::custom)?,
+                )
+            }
+
+            Ok(gutters.into())
+        }
+
+        fn visit_map<M>(self, map: M) -> Result<Self::Value, M::Error>
+        where
+            M: serde::de::MapAccess<'de>,
+        {
+            let deserializer = serde::de::value::MapAccessDeserializer::new(map);
+            Deserialize::deserialize(deserializer)
+        }
+    }
+
+    deserializer.deserialize_any(GutterSeqOrStruct(PhantomData))
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
+pub struct GutterLineNumbersConfig {
+    /// Minimum number of characters to use for line number gutter. Defaults to 3.
+    pub min_width: usize,
+}
+
+impl Default for GutterLineNumbersConfig {
+    fn default() -> Self {
+        Self { min_width: 3 }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
 pub struct FilePickerConfig {
@@ -132,8 +232,8 @@ pub struct Config {
     pub cursorline: bool,
     /// Highlight the columns cursors are currently on. Defaults to false.
     pub cursorcolumn: bool,
-    /// Gutters. Default ["diagnostics", "line-numbers"]
-    pub gutters: Vec<GutterType>,
+    #[serde(deserialize_with = "deserialize_gutter_seq_or_struct")]
+    pub gutters: GutterConfig,
     /// Middle click paste support. Defaults to true.
     pub middle_click_paste: bool,
     /// Automatic insertion of pairs to parentheses, brackets,
@@ -603,13 +703,7 @@ impl Default for Config {
             line_number: LineNumber::Absolute,
             cursorline: false,
             cursorcolumn: false,
-            gutters: vec![
-                GutterType::Diagnostics,
-                GutterType::Spacer,
-                GutterType::LineNumbers,
-                GutterType::Spacer,
-                GutterType::Diff,
-            ],
+            gutters: GutterConfig::default(),
             middle_click_paste: true,
             auto_pairs: AutoPairConfig::default(),
             auto_completion: true,
@@ -841,6 +935,7 @@ impl Editor {
         let config = self.config();
         self.auto_pairs = (&config.auto_pairs).into();
         self.reset_idle_timer();
+        self._refresh();
     }
 
     pub fn clear_idle_timer(&mut self) {
@@ -981,6 +1076,7 @@ impl Editor {
         for (view, _) in self.tree.views_mut() {
             let doc = doc_mut!(self, &view.doc);
             view.sync_changes(doc);
+            view.gutters = config.gutters.clone();
             view.ensure_cursor_in_view(doc, config.scrolloff)
         }
     }

helix-view/src/gutter.rs

@@ -1,3 +1,4 @@
+use std::cmp::max;
 use std::fmt::Write;
 
 use crate::{
@@ -140,12 +141,18 @@ 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 last_line = text.len_lines().saturating_sub(1);
+    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 last_drawn_line = if draw_last { last_line + 1 } else { last_line };
+
+    // characters used to display last line, and settings for min/max
+    let n_last_line = count_digits(last_drawn_line);
+    let n_min = view.gutters.line_numbers.min_width;
 
     let linenr = theme.get("ui.linenr");
     let linenr_select = theme.get("ui.linenr.selected");
@@ -158,7 +165,8 @@ 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 {
+            let width = max(n_last_line, n_min);
             write!(out, "{:>1$}", '~', width).unwrap();
             Some(linenr)
         } else {
@@ -181,20 +189,26 @@ pub fn line_numbers<'doc>(
                 linenr
             };
 
+            let width = max(n_last_line, n_min);
             write!(out, "{:>1$}", display_num, width).unwrap();
             Some(style)
         }
     })
 }
 
-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.
+pub 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;
+    max(digits, n_min)
 }
 
 pub fn padding<'doc>(
@@ -282,3 +296,82 @@ 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);
+    }
+}