Add narrow no-break space support (#9604)

4 files changed, 42 insertions, 3 deletions

diff --git a/book/src/configuration.md b/book/src/configuration.md
index c55426c0..83ab3f6b 100644
--- a/book/src/configuration.md
+++ b/book/src/configuration.md
@@ -255,8 +255,8 @@ Options for rendering whitespace with visible characters. Use `:set whitespace.r
 
 | Key | Description | Default |
 |-----|-------------|---------|
-| `render` | Whether to render whitespace. May either be `"all"` or `"none"`, or a table with sub-keys `space`, `nbsp`, `tab`, and `newline` | `"none"` |
-| `characters` | Literal characters to use when rendering whitespace. Sub-keys may be any of `tab`, `space`, `nbsp`, `newline` or `tabpad` | See example below |
+| `render` | Whether to render whitespace. May either be `"all"` or `"none"`, or a table with sub-keys `space`, `nbsp`, `nnbsp`, `tab`, and `newline` | `"none"` |
+| `characters` | Literal characters to use when rendering whitespace. Sub-keys may be any of `tab`, `space`, `nbsp`, `nnbsp`, `newline` or `tabpad` | See example below |
 
 Example
 
@@ -267,11 +267,14 @@ render = "all"
 [editor.whitespace.render]
 space = "all"
 tab = "all"
+nbsp = "none"
+nnbsp = "none"
 newline = "none"
 
 [editor.whitespace.characters]
 space = "·"
 nbsp = "⍽"
+nnbsp = "␣"
 tab = "→"
 newline = "⏎"
 tabpad = "·" # Tabs will look like "→···" (depending on tab width)
diff --git a/helix-term/src/ui/document.rs b/helix-term/src/ui/document.rs
index dc61ca2e..b571b83c 100644
--- a/helix-term/src/ui/document.rs
+++ b/helix-term/src/ui/document.rs
@@ -341,6 +341,7 @@ pub struct TextRenderer<'a> {
     pub indent_guide_style: Style,
     pub newline: String,
     pub nbsp: String,
+    pub nnbsp: String,
     pub space: String,
     pub tab: String,
     pub virtual_tab: String,
@@ -395,6 +396,11 @@ impl<'a> TextRenderer<'a> {
         } else {
             " ".to_owned()
         };
+        let nnbsp = if ws_render.nnbsp() == WhitespaceRenderValue::All {
+            ws_chars.nnbsp.into()
+        } else {
+            " ".to_owned()
+        };
 
         let text_style = theme.get("ui.text");
 
@@ -405,6 +411,7 @@ impl<'a> TextRenderer<'a> {
             indent_guide_char: editor_config.indent_guides.character.into(),
             newline,
             nbsp,
+            nnbsp,
             space,
             tab,
             virtual_tab,
@@ -448,6 +455,7 @@ impl<'a> TextRenderer<'a> {
         let width = grapheme.width();
         let space = if is_virtual { " " } else { &self.space };
         let nbsp = if is_virtual { " " } else { &self.nbsp };
+        let nnbsp = if is_virtual { " " } else { &self.nnbsp };
         let tab = if is_virtual {
             &self.virtual_tab
         } else {
@@ -461,6 +469,7 @@ impl<'a> TextRenderer<'a> {
             // TODO special rendering for other whitespaces?
             Grapheme::Other { ref g } if g == " " => space,
             Grapheme::Other { ref g } if g == "\u{00A0}" => nbsp,
+            Grapheme::Other { ref g } if g == "\u{202F}" => nnbsp,
             Grapheme::Other { ref g } => g,
             Grapheme::Newline => &self.newline,
         };
diff --git a/helix-tui/src/widgets/reflow.rs b/helix-tui/src/widgets/reflow.rs
index c30aa6e0..67c4db44 100644
--- a/helix-tui/src/widgets/reflow.rs
+++ b/helix-tui/src/widgets/reflow.rs
@@ -4,6 +4,7 @@ use helix_core::unicode::width::UnicodeWidthStr;
 use unicode_segmentation::UnicodeSegmentation;
 
 const NBSP: &str = "\u{00a0}";
+const NNBSP: &str = "\u{202f}";
 
 /// A state machine to pack styled symbols into lines.
 /// Cannot implement it as Iterator since it yields slices of the internal buffer (need streaming
@@ -58,7 +59,8 @@ impl<'a, 'b> LineComposer<'a> for WordWrapper<'a, 'b> {
         let mut symbols_exhausted = true;
         for StyledGrapheme { symbol, style } in &mut self.symbols {
             symbols_exhausted = false;
-            let symbol_whitespace = symbol.chars().all(&char::is_whitespace) && symbol != NBSP;
+            let symbol_whitespace =
+                symbol.chars().all(&char::is_whitespace) && symbol != NBSP && symbol != NNBSP;
 
             // Ignore characters wider that the total max width.
             if symbol.width() as u16 > self.max_line_width
@@ -497,6 +499,20 @@ mod test {
     }
 
     #[test]
+    fn line_composer_word_wrapper_nnbsp() {
+        let width = 20;
+        let text = "AAAAAAAAAAAAAAA AAAA\u{202f}AAA";
+        let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width);
+        assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAA", "AAAA\u{202f}AAA",]);
+
+        // Ensure that if the character was a regular space, it would be wrapped differently.
+        let text_space = text.replace('\u{202f}', " ");
+        let (word_wrapper_space, _) =
+            run_composer(Composer::WordWrapper { trim: true }, &text_space, width);
+        assert_eq!(word_wrapper_space, vec!["AAAAAAAAAAAAAAA AAAA", "AAA",]);
+    }
+
+    #[test]
     fn line_composer_word_wrapper_preserve_indentation() {
         let width = 20;
         let text = "AAAAAAAAAAAAAAAAAAAA    AAA";
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index 3c530c4e..dd360a78 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -702,6 +702,7 @@ pub enum WhitespaceRender {
         default: Option<WhitespaceRenderValue>,
         space: Option<WhitespaceRenderValue>,
         nbsp: Option<WhitespaceRenderValue>,
+        nnbsp: Option<WhitespaceRenderValue>,
         tab: Option<WhitespaceRenderValue>,
         newline: Option<WhitespaceRenderValue>,
     },
@@ -733,6 +734,14 @@ impl WhitespaceRender {
             }
         }
     }
+    pub fn nnbsp(&self) -> WhitespaceRenderValue {
+        match *self {
+            Self::Basic(val) => val,
+            Self::Specific { default, nnbsp, .. } => {
+                nnbsp.or(default).unwrap_or(WhitespaceRenderValue::None)
+            }
+        }
+    }
     pub fn tab(&self) -> WhitespaceRenderValue {
         match *self {
             Self::Basic(val) => val,
@@ -756,6 +765,7 @@ impl WhitespaceRender {
 pub struct WhitespaceCharacters {
     pub space: char,
     pub nbsp: char,
+    pub nnbsp: char,
     pub tab: char,
     pub tabpad: char,
     pub newline: char,
@@ -766,6 +776,7 @@ impl Default for WhitespaceCharacters {
         Self {
             space: '·',   // U+00B7
             nbsp: '⍽',    // U+237D
+            nnbsp: '␣',   // U+2423
             tab: '→',     // U+2192
             newline: '⏎', // U+23CE
             tabpad: ' ',