Dynamically resize line number gutter width (#3469)

* dynamically resize line number gutter width

* removing digits lower-bound, permitting spacer

* removing max line num char limit; adding notes; qualified successors; notes

* updating tests to use new line number width when testing views

* linenr width based on document line count

* using min width of 2 so line numbers relative is useful

* lint rolling; removing unnecessary type parameter lifetime

* merge change resolution

* reformat code

* rename row_styler to style; add int_log resource

* adding spacer to gutters default; updating book config entry

* adding view.inner_height(), swap for loop for iterator

* reverting change of current! to view! now that doc is not needed

5 files changed, 125 insertions, 92 deletions

diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index bcd8dedb..db97cbb1 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -456,6 +456,7 @@ impl std::str::FromStr for GutterType {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match s.to_lowercase().as_str() {
             "diagnostics" => Ok(Self::Diagnostics),
+            "spacer" => Ok(Self::Spacer),
             "line-numbers" => Ok(Self::LineNumbers),
             _ => anyhow::bail!("Gutter type can only be `diagnostics` or `line-numbers`."),
         }
@@ -589,7 +590,11 @@ impl Default for Config {
             line_number: LineNumber::Absolute,
             cursorline: false,
             cursorcolumn: false,
-            gutters: vec![GutterType::Diagnostics, GutterType::LineNumbers],
+            gutters: vec![
+                GutterType::Diagnostics,
+                GutterType::Spacer,
+                GutterType::LineNumbers,
+            ],
             middle_click_paste: true,
             auto_pairs: AutoPairConfig::default(),
             auto_completion: true,
@@ -1308,7 +1313,7 @@ impl Editor {
             .primary()
             .cursor(doc.text().slice(..));
         if let Some(mut pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
-            let inner = view.inner_area();
+            let inner = view.inner_area(doc);
             pos.col += inner.x as usize;
             pos.row += inner.y as usize;
             let cursorkind = config.cursor_shape.from_mode(self.mode);
diff --git a/helix-view/src/gutter.rs b/helix-view/src/gutter.rs
index 2c207d27..61a17791 100644
--- a/helix-view/src/gutter.rs
+++ b/helix-view/src/gutter.rs
@@ -1,21 +1,54 @@
 use std::fmt::Write;
 
 use crate::{
+    editor::GutterType,
     graphics::{Color, Style, UnderlineStyle},
     Document, Editor, Theme, View,
 };
 
+fn count_digits(n: usize) -> usize {
+    // NOTE: if int_log gets standardized in stdlib, can use checked_log10
+    // (https://github.com/rust-lang/rust/issues/70887#issue)
+    std::iter::successors(Some(n), |&n| (n >= 10).then(|| n / 10)).count()
+}
+
 pub type GutterFn<'doc> = Box<dyn Fn(usize, bool, &mut String) -> Option<Style> + 'doc>;
 pub type Gutter =
     for<'doc> fn(&'doc Editor, &'doc Document, &View, &Theme, bool, usize) -> GutterFn<'doc>;
 
+impl GutterType {
+    pub fn style<'doc>(
+        self,
+        editor: &'doc Editor,
+        doc: &'doc Document,
+        view: &View,
+        theme: &Theme,
+        is_focused: bool,
+    ) -> GutterFn<'doc> {
+        match self {
+            GutterType::Diagnostics => {
+                diagnostics_or_breakpoints(editor, doc, view, theme, is_focused)
+            }
+            GutterType::LineNumbers => line_numbers(editor, doc, view, theme, is_focused),
+            GutterType::Spacer => padding(editor, doc, view, theme, is_focused),
+        }
+    }
+
+    pub fn width(self, _view: &View, doc: &Document) -> usize {
+        match self {
+            GutterType::Diagnostics => 1,
+            GutterType::LineNumbers => line_numbers_width(_view, doc),
+            GutterType::Spacer => 1,
+        }
+    }
+}
+
 pub fn diagnostic<'doc>(
     _editor: &'doc Editor,
     doc: &'doc Document,
     _view: &View,
     theme: &Theme,
     _is_focused: bool,
-    _width: usize,
 ) -> GutterFn<'doc> {
     let warning = theme.get("warning");
     let error = theme.get("error");
@@ -56,10 +89,11 @@ pub fn line_numbers<'doc>(
     view: &View,
     theme: &Theme,
     is_focused: bool,
-    width: usize,
 ) -> GutterFn<'doc> {
     let text = doc.text().slice(..);
     let last_line = view.last_line(doc);
+    let width = GutterType::LineNumbers.width(view, 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();
@@ -91,24 +125,35 @@ pub fn line_numbers<'doc>(
             } else {
                 line + 1
             };
+
             let style = if selected && is_focused {
                 linenr_select
             } else {
                 linenr
             };
+
             write!(out, "{:>1$}", display_num, width).unwrap();
             Some(style)
         }
     })
 }
 
+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)
+}
+
 pub fn padding<'doc>(
     _editor: &'doc Editor,
     _doc: &'doc Document,
     _view: &View,
     _theme: &Theme,
     _is_focused: bool,
-    _width: usize,
 ) -> GutterFn<'doc> {
     Box::new(|_line: usize, _selected: bool, _out: &mut String| None)
 }
@@ -128,7 +173,6 @@ pub fn breakpoints<'doc>(
     _view: &View,
     theme: &Theme,
     _is_focused: bool,
-    _width: usize,
 ) -> GutterFn<'doc> {
     let warning = theme.get("warning");
     let error = theme.get("error");
@@ -181,10 +225,9 @@ pub fn diagnostics_or_breakpoints<'doc>(
     view: &View,
     theme: &Theme,
     is_focused: bool,
-    width: usize,
 ) -> GutterFn<'doc> {
-    let diagnostics = diagnostic(editor, doc, view, theme, is_focused, width);
-    let breakpoints = breakpoints(editor, doc, view, theme, is_focused, width);
+    let diagnostics = diagnostic(editor, doc, view, theme, is_focused);
+    let breakpoints = breakpoints(editor, doc, view, theme, is_focused);
 
     Box::new(move |line, selected, out| {
         breakpoints(line, selected, out).or_else(|| diagnostics(line, selected, out))
diff --git a/helix-view/src/lib.rs b/helix-view/src/lib.rs
index 52044ac7..4c32b356 100644
--- a/helix-view/src/lib.rs
+++ b/helix-view/src/lib.rs
@@ -55,7 +55,7 @@ pub fn align_view(doc: &Document, view: &mut View, align: Align) {
         .cursor(doc.text().slice(..));
     let line = doc.text().char_to_line(pos);
 
-    let last_line_height = view.inner_area().height.saturating_sub(1) as usize;
+    let last_line_height = view.inner_height().saturating_sub(1);
 
     let relative = match align {
         Align::Center => last_line_height / 2,
diff --git a/helix-view/src/tree.rs b/helix-view/src/tree.rs
index a1977764..6174021c 100644
--- a/helix-view/src/tree.rs
+++ b/helix-view/src/tree.rs
@@ -499,7 +499,7 @@ impl Tree {
                     // in a vertical container (and already correct based on previous search)
                     child_id = *container.children.iter().min_by_key(|id| {
                         let x = match &self.nodes[**id].content {
-                            Content::View(view) => view.inner_area().left(),
+                            Content::View(view) => view.area.left(),
                             Content::Container(container) => container.area.left(),
                         };
                         (current_x as i16 - x as i16).abs()
@@ -510,7 +510,7 @@ impl Tree {
                     // in a horizontal container (and already correct based on previous search)
                     child_id = *container.children.iter().min_by_key(|id| {
                         let y = match &self.nodes[**id].content {
-                            Content::View(view) => view.inner_area().top(),
+                            Content::View(view) => view.area.top(),
                             Content::Container(container) => container.area.top(),
                         };
                         (current_y as i16 - y as i16).abs()
diff --git a/helix-view/src/view.rs b/helix-view/src/view.rs
index 62984b88..6da4df1f 100644
--- a/helix-view/src/view.rs
+++ b/helix-view/src/view.rs
@@ -1,8 +1,4 @@
-use crate::{
-    graphics::Rect,
-    gutter::{self, Gutter},
-    Document, DocumentId, ViewId,
-};
+use crate::{editor::GutterType, graphics::Rect, Document, DocumentId, ViewId};
 use helix_core::{
     pos_at_visual_coords, visual_coords_at_pos, Position, RopeSlice, Selection, Transaction,
 };
@@ -98,11 +94,8 @@ pub struct View {
     pub last_modified_docs: [Option<DocumentId>; 2],
     /// used to store previous selections of tree-sitter objects
     pub object_selections: Vec<Selection>,
-    /// Gutter (constructor) and width of gutter, used to calculate
-    /// `gutter_offset`
-    gutters: Vec<(Gutter, usize)>,
-    /// cached total width of gutter
-    gutter_offset: u16,
+    /// GutterTypes used to fetch Gutter (constructor) and width for rendering
+    gutters: Vec<GutterType>,
 }
 
 impl fmt::Debug for View {
@@ -117,28 +110,6 @@ impl fmt::Debug for View {
 
 impl View {
     pub fn new(doc: DocumentId, gutter_types: Vec<crate::editor::GutterType>) -> Self {
-        let mut gutters: Vec<(Gutter, usize)> = vec![];
-        let mut gutter_offset = 0;
-        use crate::editor::GutterType;
-        for gutter_type in &gutter_types {
-            let width = match gutter_type {
-                GutterType::Diagnostics => 1,
-                GutterType::LineNumbers => 5,
-                GutterType::Spacer => 1,
-            };
-            gutter_offset += width;
-            gutters.push((
-                match gutter_type {
-                    GutterType::Diagnostics => gutter::diagnostics_or_breakpoints,
-                    GutterType::LineNumbers => gutter::line_numbers,
-                    GutterType::Spacer => gutter::padding,
-                },
-                width as usize,
-            ));
-        }
-        if !gutter_types.is_empty() {
-            gutter_offset += 1;
-        }
         Self {
             id: ViewId::default(),
             doc,
@@ -148,8 +119,7 @@ impl View {
             docs_access_history: Vec::new(),
             last_modified_docs: [None, None],
             object_selections: Vec::new(),
-            gutters,
-            gutter_offset,
+            gutters: gutter_types,
         }
     }
 
@@ -160,15 +130,32 @@ impl View {
         self.docs_access_history.push(id);
     }
 
-    pub fn inner_area(&self) -> Rect {
-        // TODO add abilty to not use cached offset for runtime configurable gutter
-        self.area.clip_left(self.gutter_offset).clip_bottom(1) // -1 for statusline
+    pub fn inner_area(&self, doc: &Document) -> Rect {
+        self.area.clip_left(self.gutter_offset(doc)).clip_bottom(1) // -1 for statusline
+    }
+
+    pub fn inner_height(&self) -> usize {
+        self.area.clip_bottom(1).height.into() // -1 for statusline
     }
 
-    pub fn gutters(&self) -> &[(Gutter, usize)] {
+    pub fn gutters(&self) -> &[GutterType] {
         &self.gutters
     }
 
+    pub fn gutter_offset(&self, doc: &Document) -> u16 {
+        let mut offset = self
+            .gutters
+            .iter()
+            .map(|gutter| gutter.width(self, doc) as u16)
+            .sum();
+
+        if offset > 0 {
+            offset += 1
+        }
+
+        offset
+    }
+
     //
     pub fn offset_coords_to_in_view(
         &self,
@@ -183,7 +170,7 @@ impl View {
         let Position { col, row: line } =
             visual_coords_at_pos(doc.text().slice(..), cursor, doc.tab_width());
 
-        let inner_area = self.inner_area();
+        let inner_area = self.inner_area(doc);
         let last_line = (self.offset.row + inner_area.height as usize).saturating_sub(1);
 
         // - 1 so we have at least one gap in the middle.
@@ -233,10 +220,9 @@ impl View {
     /// Calculates the last visible line on screen
     #[inline]
     pub fn last_line(&self, doc: &Document) -> usize {
-        let height = self.inner_area().height;
         std::cmp::min(
             // Saturating subs to make it inclusive zero indexing.
-            (self.offset.row + height as usize).saturating_sub(1),
+            (self.offset.row + self.inner_height()).saturating_sub(1),
             doc.text().len_lines().saturating_sub(1),
         )
     }
@@ -270,12 +256,13 @@ impl View {
 
     pub fn text_pos_at_screen_coords(
         &self,
-        text: &RopeSlice,
+        doc: &Document,
         row: u16,
         column: u16,
         tab_width: usize,
     ) -> Option<usize> {
-        let inner = self.inner_area();
+        let text = doc.text().slice(..);
+        let inner = self.inner_area(doc);
         // 1 for status
         if row < inner.top() || row >= inner.bottom() {
             return None;
@@ -293,7 +280,7 @@ impl View {
         let text_col = (column - inner.x) as usize + self.offset.col;
 
         Some(pos_at_visual_coords(
-            *text,
+            text,
             Position {
                 row: text_row,
                 col: text_col,
@@ -305,7 +292,7 @@ impl View {
     /// Translates a screen position to position in the text document.
     /// Returns a usize typed position in bounds of the text if found in this view, None if out of view.
     pub fn pos_at_screen_coords(&self, doc: &Document, row: u16, column: u16) -> Option<usize> {
-        self.text_pos_at_screen_coords(&doc.text().slice(..), row, column, doc.tab_width())
+        self.text_pos_at_screen_coords(doc, row, column, doc.tab_width())
     }
 
     /// Translates screen coordinates into coordinates on the gutter of the view.
@@ -366,9 +353,10 @@ impl View {
 mod tests {
     use super::*;
     use helix_core::Rope;
-    const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
+    const OFFSET: u16 = 4; // 1 diagnostic + 2 linenr (< 100 lines) + 1 gutter
     const OFFSET_WITHOUT_LINE_NUMBERS: u16 = 2; // 1 diagnostic + 1 gutter
                                                 // const OFFSET: u16 = GUTTERS.iter().map(|(_, width)| *width as u16).sum();
+    use crate::document::Document;
     use crate::editor::GutterType;
 
     #[test]
@@ -379,45 +367,45 @@ mod tests {
         );
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("abc\n\tdef");
-        let text = rope.slice(..);
+        let doc = Document::from(rope, None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 40, 2, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 40, 2, 4), None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 40, 41, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 40, 41, 4), None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 0, 2, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 0, 2, 4), None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 0, 49, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 0, 49, 4), None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 0, 41, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 0, 41, 4), None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 40, 81, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 40, 81, 4), None);
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 78, 41, 4), None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 78, 41, 4), None);
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 3, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 3, 4),
             Some(3)
         );
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 40, 80, 4), Some(3));
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 40, 80, 4), Some(3));
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 41, 40 + OFFSET + 1, 4),
+            view.text_pos_at_screen_coords(&doc, 41, 40 + OFFSET + 1, 4),
             Some(4)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 41, 40 + OFFSET + 4, 4),
+            view.text_pos_at_screen_coords(&doc, 41, 40 + OFFSET + 4, 4),
             Some(5)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 41, 40 + OFFSET + 7, 4),
+            view.text_pos_at_screen_coords(&doc, 41, 40 + OFFSET + 7, 4),
             Some(8)
         );
 
-        assert_eq!(view.text_pos_at_screen_coords(&text, 41, 80, 4), Some(8));
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 41, 80, 4), Some(8));
     }
 
     #[test]
@@ -425,9 +413,9 @@ mod tests {
         let mut view = View::new(DocumentId::default(), vec![GutterType::Diagnostics]);
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("abc\n\tdef");
-        let text = rope.slice(..);
+        let doc = Document::from(rope, None);
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 41, 40 + OFFSET_WITHOUT_LINE_NUMBERS + 1, 4),
+            view.text_pos_at_screen_coords(&doc, 41, 40 + OFFSET_WITHOUT_LINE_NUMBERS + 1, 4),
             Some(4)
         );
     }
@@ -437,11 +425,8 @@ mod tests {
         let mut view = View::new(DocumentId::default(), vec![]);
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("abc\n\tdef");
-        let text = rope.slice(..);
-        assert_eq!(
-            view.text_pos_at_screen_coords(&text, 41, 40 + 1, 4),
-            Some(4)
-        );
+        let doc = Document::from(rope, None);
+        assert_eq!(view.text_pos_at_screen_coords(&doc, 41, 40 + 1, 4), Some(4));
     }
 
     #[test]
@@ -452,34 +437,34 @@ mod tests {
         );
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("Hi! こんにちは皆さん");
-        let text = rope.slice(..);
+        let doc = Document::from(rope, None);
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET, 4),
             Some(0)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 4, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 4, 4),
             Some(4)
         );
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 5, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 5, 4),
             Some(4)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 6, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 6, 4),
             Some(5)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 7, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 7, 4),
             Some(5)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 8, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 8, 4),
             Some(6)
         );
     }
@@ -492,30 +477,30 @@ mod tests {
         );
         view.area = Rect::new(40, 40, 40, 40);
         let rope = Rope::from_str("Hèl̀l̀ò world!");
-        let text = rope.slice(..);
+        let doc = Document::from(rope, None);
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET, 4),
             Some(0)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 1, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 1, 4),
             Some(1)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 2, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 2, 4),
             Some(3)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 3, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 3, 4),
             Some(5)
         );
 
         assert_eq!(
-            view.text_pos_at_screen_coords(&text, 40, 40 + OFFSET + 4, 4),
+            view.text_pos_at_screen_coords(&doc, 40, 40 + OFFSET + 4, 4),
             Some(7)
         );
     }