feat: add opt-in trailing whitespace highlighting

2026-10-13 22:42:30 +02:00
parent b58fb085a3
commit e2f33519d1
8 changed files with 179 additions and 4 deletions
@@ -1763,6 +1763,7 @@ pub struct Editor {
    popup: PopupConfig,
    labels: BTreeMap<String, String>,
    scroll_distance: Option<usize>,
+    highlight_trailing_whitespace: bool,
    battery_charge: Option<u8>,
    battery_label: String,
    git_blame: bool,
@@ -1865,6 +1866,7 @@ impl Editor {
            popup: PopupConfig::default(),
            labels: BTreeMap::new(),
            scroll_distance: Some(0),
+            highlight_trailing_whitespace: false,
            battery_charge: None,
            battery_label: String::new(),
            git_blame: true,
@@ -2611,6 +2613,14 @@ impl Editor {
        self.scroll_distance = distance;
    }

+    pub(crate) fn highlight_trailing_whitespace(&self) -> bool {
+        self.highlight_trailing_whitespace
+    }
+
+    pub(crate) fn set_highlight_trailing_whitespace(&mut self, enabled: bool) {
+        self.highlight_trailing_whitespace = enabled;
+    }
+
    pub(crate) fn set_diff_context_options(&mut self, context_lines: usize, expand_lines: usize) {
        self.diff_context_options = (context_lines, expand_lines);
        if let Some(diff) = &mut self.diff {
@@ -45,6 +45,7 @@ pub struct Config {
    pub popup: PopupConfig,
    pub labels: BTreeMap<String, String>,
    pub scroll_distance: Option<usize>,
+    pub highlight_trailing_whitespace: bool,
    pub diff_context_lines: usize,
    pub diff_expand_lines: usize,
    pub diff_view_mode: crate::diff::ViewMode,
@@ -91,6 +92,7 @@ impl Default for Config {
            popup: PopupConfig::default(),
            labels: BTreeMap::new(),
            scroll_distance: Some(0),
+            highlight_trailing_whitespace: false,
            diff_context_lines: 10,
            diff_expand_lines: 15,
            diff_view_mode: crate::diff::ViewMode::Split,
@@ -124,6 +126,7 @@ pub fn load_config(path: &Path) -> Result<Config, String> {
                popup,
                labels,
                scroll_distance,
+                highlight_trailing_whitespace,
                diff_context_lines,
                diff_expand_lines,
                diff_view_mode,
@@ -158,6 +161,7 @@ pub fn load_config(path: &Path) -> Result<Config, String> {
            config.popup = popup;
            config.labels = labels;
            config.scroll_distance = scroll_distance;
+            config.highlight_trailing_whitespace = highlight_trailing_whitespace;
            config.diff_context_lines = diff_context_lines;
            config.diff_expand_lines = diff_expand_lines;
            config.diff_view_mode = diff_view_mode;
@@ -491,6 +495,7 @@ struct ConfigFrame {
    labels: BTreeMap<String, String>,
    #[serde(deserialize_with = "scroll_distance")]
    scroll_distance: Option<usize>,
+    highlight_trailing_whitespace: bool,
    #[serde(deserialize_with = "diff_context_lines")]
    diff_context_lines: usize,
    #[serde(deserialize_with = "diff_expand_lines")]
@@ -1234,9 +1239,9 @@ end
            assert!(load_config(&path).unwrap_err().contains(error), "{value}");
        }
        for frame in [
-            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
-            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":null,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
-            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":7,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
+            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"highlight_trailing_whitespace":false,"top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
+            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":null,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"highlight_trailing_whitespace":false,"top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
+            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":7,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","scroll_distance":0,"highlight_trailing_whitespace":false,"top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
        ] {
            assert!(serde_json::from_str::<Response>(frame).is_err(), "{frame}");
        }
@@ -1313,6 +1318,7 @@ end
            "file_explorer_view": "tree", "clipboard_mode": "system", "git_blame": true,
            "git_gutter": "bar",
            "scroll_distance": 0,
+            "highlight_trailing_whitespace": false,
            "top_bar": {}, "bottom_bar": {}, "popup": {"command": {}, "search": {}},
            "labels": {}, "diff_context_lines": 10, "diff_expand_lines": 15,
            "diff_view_mode": "split", "diff_split_orientation": "vertical",
@@ -1331,6 +1337,22 @@ end
        assert!(serde_json::from_value::<Response>(frame).is_err());
    }

+    #[test]
+    fn trailing_whitespace_configuration_rejects_non_booleans() {
+        let fixture = Fixture::new();
+        for value in ["nil", "0", "\"true\"", "[]", "{}"] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |c| c.highlight_trailing_whitespace = {value} }}"),
+            );
+            assert!(
+                load_config(&path)
+                    .unwrap_err()
+                    .contains("highlight_trailing_whitespace must be true or false")
+            );
+        }
+    }
+
    #[test]
    fn working_diff_tracking_rejects_non_boolean_configuration() {
        let fixture = Fixture::new();
@@ -1564,6 +1586,7 @@ end
            "file_picker_view": "tree", "file_explorer_view": "tree",
            "top_bar": {}, "bottom_bar": {}, "labels": {},
            "scroll_distance": 0,
+            "highlight_trailing_whitespace": false,
            "popup": {"command": {}, "search": {}},
            "clipboard_mode": "system", "diff_context_lines": 0, "diff_expand_lines": 7,
            "diff_view_mode": "split", "diff_split_orientation": "vertical",
@@ -1612,6 +1635,7 @@ end
            "bindings": [], "leader": "space", "file_explorer_side": "right",
            "file_picker_view": "tree", "file_explorer_view": "tree",
            "clipboard_mode": "system", "git_blame": true, "git_gutter": "bar",
+            "highlight_trailing_whitespace": false,
            "top_bar": {}, "bottom_bar": {}, "labels": {},
            "popup": {"command": {}, "search": {}},
            "diff_context_lines": 10, "diff_expand_lines": 15,
@@ -2040,6 +2064,7 @@ end"#,
            "git_blame": true,
            "git_gutter": "bar",
            "scroll_distance": 0,
+            "highlight_trailing_whitespace": false,
            "top_bar": {}, "bottom_bar": {}, "labels": {},
            "popup": {"command": {}, "search": {}},
            "clipboard_mode": "system", "diff_context_lines": 10, "diff_expand_lines": 15,
@@ -142,6 +142,7 @@ module Vamp
      @popup = PopupConfig.new
      @labels = {}
      @scroll_distance = 0
+      @highlight_trailing_whitespace = false
      @diff_context_lines = 10
      @diff_expand_lines = 15
      @diff_view_mode = "split"
@@ -221,6 +222,14 @@ module Vamp
      @scroll_distance = distance.nil? ? nil : diff_line_count!(distance, "scroll_distance", 0)
    end

+    # @param enabled [Boolean]
+    # @return [Boolean]
+    def highlight_trailing_whitespace=(enabled)
+      raise TypeError, "highlight_trailing_whitespace must be true or false" unless [true, false].include?(enabled)
+
+      @highlight_trailing_whitespace = enabled
+    end
+
    # @param lines [Integer] nonnegative context lines around each diff change
    # @return [Integer]
    def diff_context_lines=(lines)
@@ -293,6 +302,7 @@ module Vamp
        "git_blame" => @git_blame,
        "git_gutter" => @git_gutter,
        "scroll_distance" => @scroll_distance,
+        "highlight_trailing_whitespace" => @highlight_trailing_whitespace,
        "top_bar" => @bar.top, "bottom_bar" => @bar.bottom, "labels" => @labels,
        "popup" => { "command" => @popup.command, "search" => @popup.search },
        "diff_context_lines" => @diff_context_lines, "diff_expand_lines" => @diff_expand_lines,
@@ -257,6 +257,7 @@ impl EditorSession {
        editor.set_git_blame(config.git_blame);
        editor.set_gutter_style(config.git_gutter);
        editor.set_scroll_distance(config.scroll_distance);
+        editor.set_highlight_trailing_whitespace(config.highlight_trailing_whitespace);
        editor.set_diff_context_options(config.diff_context_lines, config.diff_expand_lines);
        editor.set_diff_display_options(config.diff_view_mode, config.diff_split_orientation);
        if let Err(error) =
@@ -1865,6 +1865,9 @@ fn draw_document(
                area,
                segment.start,
            );
+            if editor.highlight_trailing_whitespace() {
+                paint_trailing_whitespace(frame, line, area, segment.start);
+            }
            paint_editor_line(
                frame,
                editor,
@@ -2212,6 +2215,21 @@ fn paint_cells(frame: &mut Frame, area: Rect, left: usize, start: usize, end: us
    }
 }

+fn paint_trailing_whitespace(frame: &mut Frame, line: &str, area: Rect, left: usize) {
+    let prefix = line.trim_end_matches(char::is_whitespace);
+    if prefix.len() == line.len() {
+        return;
+    }
+    paint_cells(
+        frame,
+        area,
+        left,
+        display_column(prefix, usize::MAX),
+        display_column(line, usize::MAX),
+        Style::default().bg(Color::Red),
+    );
+}
+
 fn paint_grapheme_range(
    frame: &mut Frame,
    area: Rect,
@@ -2919,6 +2937,7 @@ fn draw_diff(
                    ),
                    wrapped,
                    panels.diff_colors,
+                    editor.is_some_and(Editor::highlight_trailing_whitespace),
                );
                text_widths[0] = text_area.width;
                if let Some(editor) =
@@ -2955,6 +2974,7 @@ fn draw_diff(
                    ),
                    wrapped,
                    panels.diff_colors,
+                    editor.is_some_and(Editor::highlight_trailing_whitespace),
                );
                text_widths[1] = text_area.width;
                if let Some(editor) =
@@ -3109,6 +3129,7 @@ fn draw_diff_pane(
    viewport: (usize, &mut usize, Option<u16>),
    wrapped: Option<&[WrappedDiffRow]>,
    colors: DiffColors,
+    highlight_trailing_whitespace: bool,
 ) -> Rect {
    if area.width == 0 || area.height == 0 {
        return area;
@@ -3281,6 +3302,9 @@ fn draw_diff_pane(
                }
            }
        }
+        if highlight_trailing_whitespace {
+            paint_trailing_whitespace(frame, &text, text_area, left);
+        }
    }
    Rect::new(
        content.x + gutter as u16,
@@ -4859,6 +4883,107 @@ mod tests {
        }
    }

+    #[test]
+    fn trailing_whitespace_is_opt_in_and_preserves_wrapping_and_selection() {
+        let directory = Directory::new();
+        let source = "a b\t \u{3000}\n \t\n\nabcdefg  ";
+        let path = directory.file("whitespace.txt", source);
+        let config = directory.file(
+            "config.rb",
+            "Vamp.configure { |c| c.highlight_trailing_whitespace = true; c.git_gutter = 'none' }",
+        );
+        let mut session = EditorSession::open(Some(path), vec![], Some(&config)).unwrap();
+        session.execute("word_wrap.toggle");
+        let mut terminal = Terminal::new(ratatui::backend::TestBackend::new(10, 10)).unwrap();
+        let mut views = BufferViewports::default();
+        terminal
+            .draw(|frame| views.draw(frame, session.editor_mut()))
+            .unwrap();
+        let buffer = terminal.backend().buffer();
+        for (y, range) in [(0, 5..9), (1, 2..6), (3, 9..10), (4, 2..3)] {
+            for x in 2..10 {
+                // The backend skips the covered cell of a wide grapheme.
+                if (x, y) == (8, 0) {
+                    continue;
+                }
+                assert_eq!(
+                    buffer[(x, y)].bg == Color::Red,
+                    range.contains(&x),
+                    "({x}, {y})"
+                );
+            }
+        }
+        assert_eq!(buffer[(2, 2)].bg, Color::Reset);
+        session.handle(Input::End);
+        session.handle(Input::Char('v'));
+        session.handle(Input::Left);
+        terminal
+            .draw(|frame| views.draw(frame, session.editor_mut()))
+            .unwrap();
+        assert_eq!(terminal.backend().buffer()[(6, 0)].bg, Color::Blue);
+        assert_eq!(session.editor().lines().join("\n"), source);
+        assert!(!session.editor().dirty());
+
+        let mut editor = Editor::open(None, vec![]).unwrap();
+        editor
+            .apply(vec![crate::editor::Effect::Replace("x \t".into())])
+            .unwrap();
+        terminal
+            .draw(|frame| views.draw(frame, &mut editor))
+            .unwrap();
+        assert_ne!(terminal.backend().buffer()[(7, 0)].bg, Color::Red);
+    }
+
+    #[test]
+    fn trailing_whitespace_covers_both_diff_sides_and_unified_rows() {
+        for mode in [ViewMode::Split, ViewMode::Unified] {
+            for wrapped in [false, true] {
+                let mut editor = Editor::open(None, vec![]).unwrap();
+                editor.set_diff_display_options(mode, crate::panes::SplitAxis::Vertical);
+                install_readonly_diff(
+                    &mut editor,
+                    syntax_diff_file("whitespace.txt", "old \t", "new \t"),
+                );
+                editor.set_highlight_trailing_whitespace(true);
+                if wrapped {
+                    editor.execute("word_wrap.toggle");
+                }
+                let mut terminal =
+                    Terminal::new(ratatui::backend::TestBackend::new(80, 15)).unwrap();
+                let mut views = BufferViewports::default();
+                render_native_diff(&mut terminal, &mut views, &mut editor);
+                let buffer = terminal.backend().buffer();
+                for word in ["old", "new"] {
+                    let start = buffer
+                        .content
+                        .iter()
+                        .enumerate()
+                        .find_map(|(index, cell)| {
+                            (cell.symbol() == &word[..1]
+                                && buffer
+                                    .content
+                                    .get(index + 1)
+                                    .is_some_and(|cell| cell.symbol() == &word[1..2])
+                                && buffer
+                                    .content
+                                    .get(index + 2)
+                                    .is_some_and(|cell| cell.symbol() == &word[2..3]))
+                            .then_some(index)
+                        })
+                        .unwrap();
+                    for offset in 3..8 {
+                        assert_eq!(
+                            buffer.content[start + offset].bg,
+                            Color::Red,
+                            "{mode:?} {wrapped} {word}"
+                        );
+                    }
+                    assert_ne!(buffer.content[start + 8].bg, Color::Red);
+                }
+            }
+        }
+    }
+
    #[test]
    fn scroll_distance_follows_document_and_diff_visual_rows_and_columns() {
        let directory = Directory::new();