Typographic substitution while typing (smart quotes + em dash)

CHANGELOG.md

@@ -6,6 +6,12 @@ All notable changes to abstract are documented here. The format follows
 
 ## [Unreleased]
 
+### Added
+- Typographic substitution while typing (smart quotes): `"`/`'` become
+  curly by context, `--` folds into an em dash, and Backspace right after
+  a substitution restores the straight characters. Code and frontmatter
+  stay literal; toggle in Settings → Editor (on by default).
+
 ## [0.1.4] - 2026-10-02
 
 ### Added

src/app.rs

@@ -239,6 +239,9 @@ impl AbstractApp {
     ) -> Self {
         let editor = cx.new(LiveEditor::new);
         editor.update(cx, |ed, cx| ed.set_raw_tables(settings.raw_tables(), cx));
+        editor.update(cx, |ed, cx| {
+            ed.set_smart_quotes(settings.smart_quotes(), cx)
+        });
         let on_change = cx.subscribe(&editor, |this: &mut Self, editor, _: &Changed, cx| {
             let text = editor.read(cx).text();
             this.words = text.split_whitespace().count();

src/app/settings_ui.rs

@@ -352,6 +352,7 @@ impl AbstractApp {
 
         let raw = self.settings.raw_tables();
         let updates = self.settings.updates();
+        let smart_quotes = self.settings.smart_quotes();
         let font_names = cx.text_system().all_font_names();
         let current_font = fonts::resolve(self.settings.font(), &font_names);
         let font_rows =
@@ -430,6 +431,19 @@ impl AbstractApp {
                     cx.listener(move |this, _, window, cx| this.set_raw_tables(!raw, window, cx)),
                 ),
             )
+            .child(
+                toggle(
+                    "smart-quotes",
+                    t(Key::SmartQuotes),
+                    Some(t(Key::SmartQuotesHint)),
+                    smart_quotes,
+                    window,
+                    cx,
+                )
+                .on_click(cx.listener(move |this, _, window, cx| {
+                    this.set_smart_quotes(!smart_quotes, window, cx)
+                })),
+            )
             .child(section(t(Key::General)))
             .child(hover_bg(
                 div()
@@ -647,4 +661,10 @@ impl AbstractApp {
         fonts::apply(&self.settings, cx);
         self.save_settings(window, cx);
     }
+
+    fn set_smart_quotes(&mut self, on: bool, window: &mut Window, cx: &mut Context<Self>) {
+        self.settings.set_smart_quotes(on);
+        self.editor.update(cx, |ed, cx| ed.set_smart_quotes(on, cx));
+        self.save_settings(window, cx);
+    }
 }

src/editor.rs

@@ -216,6 +216,11 @@ pub struct LiveEditor {
     find_current: Option<usize>,
     /// Tables stay Markdown source instead of rendering as a grid.
     raw_tables: bool,
+    /// Typographic `"`/`'`/`--` substitution while typing (the setting).
+    smart_quotes: bool,
+    /// `(inserted range, original)` of the last substitution: a Backspace
+    /// right at its end restores the straight characters.
+    last_subst: Option<(Range<usize>, &'static str)>,
 }
 
 impl EventEmitter<Changed> for LiveEditor {}
@@ -250,6 +255,8 @@ impl LiveEditor {
             finds: Vec::new(),
             find_current: None,
             raw_tables: false,
+            smart_quotes: true,
+            last_subst: None,
         }
     }
 
@@ -314,6 +321,13 @@ impl LiveEditor {
         }
     }
 
+    pub fn set_smart_quotes(&mut self, on: bool, cx: &mut Context<Self>) {
+        if self.smart_quotes != on {
+            self.smart_quotes = on;
+            cx.notify();
+        }
+    }
+
     /// Selects `r` and scrolls it into view.
     pub fn select_range(&mut self, r: Range<usize>, cx: &mut Context<Self>) {
         self.buf.set_sel(r);
@@ -749,6 +763,7 @@ impl LiveEditor {
         self.find_current = None;
         self.scroll_y = 0.;
         self.caret = None;
+        self.last_subst = None;
         self.analysis = self.analyzer.analyze(self.buf.text());
         cx.notify();
     }
@@ -822,10 +837,25 @@ impl LiveEditor {
         self.analysis = self.analyzer.analyze(self.buf.text());
         self.autoscroll = true;
         self.goal_x = None;
+        self.last_subst = None;
         cx.emit(Changed);
         cx.notify();
     }
 
+    /// Backspace right after a substitution restores the straight
+    /// characters (`”` → `"`, `—` → `--`) instead of deleting them.
+    fn backspace(&mut self, cx: &mut Context<Self>) {
+        if self.buf.sel().is_empty()
+            && let Some((r, orig)) = self.last_subst.clone()
+            && r.end == self.buf.cursor()
+        {
+            self.edit(r, orig, None, cx);
+            return;
+        }
+        self.buf.backspace();
+        self.changed(cx);
+    }
+
     fn insert(&mut self, s: &str, cx: &mut Context<Self>) {
         self.buf.insert(s);
         self.changed(cx);
@@ -885,6 +915,7 @@ impl LiveEditor {
     fn after_move(&mut self, cx: &mut Context<Self>) {
         self.autoscroll = true;
         self.goal_x = None;
+        self.last_subst = None;
         cx.notify();
     }
 
@@ -1098,11 +1129,40 @@ impl EntityInputHandler for LiveEditor {
         _: &mut Window,
         cx: &mut Context<Self>,
     ) {
-        let r = range
+        let mut r = range
             .map(|r| self.buf.range_from_utf16(&r))
             .or(self.buf.marked())
             .unwrap_or(self.buf.sel());
+        // Typographic substitution on typed text only (paste goes through
+        // `insert`, untouched): a lone `"`, `'` or `-` may become a curly
+        // quote or fold into `—`.
+        let mut sub = None;
+        let mut new = new;
+        if self.smart_quotes && new.chars().count() == 1 {
+            let text = self.buf.text();
+            let line = self.line_range(r.start);
+            let before = &text[line.start..r.start];
+            if let Some(s) = crate::smart::substitute(
+                &text[line.clone()],
+                before,
+                new.chars().next().unwrap_or_default(),
+                true,
+                crate::smart::literal_at(&self.analysis, r.start, before),
+            ) {
+                // `back` chars before the caret fold into the substitution
+                // (`--`: the first `-` goes into the `—`).
+                for _ in 0..s.back {
+                    r.start = self.buf.prev_boundary(r.start);
+                }
+                new = s.text;
+                sub = Some(s);
+            }
+        }
+        let at = r.start;
         self.edit(r, new, None, cx);
+        if let Some(s) = sub {
+            self.last_subst = Some((at..at + s.text.len(), s.orig));
+        }
     }
 
     fn replace_and_mark_text_in_range(
@@ -1177,10 +1237,7 @@ impl Render for LiveEditor {
             .aria_label(crate::i18n::t(crate::i18n::Key::EditorAria))
             .size_full()
             .cursor_text()
-            .on_action(cx.listener(|this, _: &Backspace, _, cx| {
-                this.buf.backspace();
-                this.changed(cx);
-            }))
+            .on_action(cx.listener(|this, _: &Backspace, _, cx| this.backspace(cx)))
             .on_action(cx.listener(|this, _: &Delete, _, cx| {
                 this.buf.delete();
                 this.changed(cx);

src/i18n.rs

@@ -264,6 +264,9 @@ pub enum Key {
     TableInsertColumnRight,
     TableDeleteRow,
     TableDeleteColumn,
+    // Typographic substitution
+    SmartQuotes,
+    SmartQuotesHint,
 }
 
 impl Key {
@@ -446,6 +449,8 @@ impl Key {
         Key::TableInsertColumnRight,
         Key::TableDeleteRow,
         Key::TableDeleteColumn,
+        Key::SmartQuotes,
+        Key::SmartQuotesHint,
     ];
 }
 
@@ -644,6 +649,8 @@ fn en(k: Key) -> &'static str {
         Key::TableInsertColumnRight => "Insert column to the right",
         Key::TableDeleteRow => "Delete row",
         Key::TableDeleteColumn => "Delete column",
+        Key::SmartQuotes => "Smart quotes",
+        Key::SmartQuotesHint => "Typographic “quotes” and — dashes while you type.",
     }
 }
 
@@ -846,6 +853,8 @@ fn pt(k: Key) -> &'static str {
         Key::TableInsertColumnRight => "Inserir coluna à direita",
         Key::TableDeleteRow => "Apagar linha",
         Key::TableDeleteColumn => "Apagar coluna",
+        Key::SmartQuotes => "Aspas tipográficas",
+        Key::SmartQuotesHint => "Aspas “curvas” e travessões — ao digitar.",
     }
 }
 

src/main.rs

@@ -20,6 +20,7 @@ mod md;
 #[cfg(test)]
 mod perf;
 mod search;
+mod smart;
 mod spaces;
 mod store;
 mod table;

src/md.rs

@@ -192,6 +192,8 @@ pub struct Analysis {
     /// `==…==` marks, in buffer order; `tint` comes from an optional `{color}`
     /// prefix right after the opener.
     pub marks: Vec<MarkSpan>,
+    /// YAML (`---`) / TOML (`+++`) frontmatter ranges, in buffer order.
+    pub metadata: Vec<Range<usize>>,
 }
 
 pub struct Analyzer {
@@ -236,6 +238,7 @@ impl Analyzer {
             callouts: Vec::new(),
             tables: Vec::new(),
             marks: Vec::new(),
+            metadata: Vec::new(),
         };
         if len == 0 {
             return out;
@@ -442,11 +445,12 @@ impl Analyzer {
                     out.tables.push(first..last + 1);
                     true
                 }
-                "html_block"
-                | "minus_metadata"
-                | "plus_metadata"
-                | "link_reference_definition"
-                | "pipe_table_delimiter_row" => {
+                "minus_metadata" | "plus_metadata" => {
+                    out.metadata.push(range.clone());
+                    out.mark(range, MUTED);
+                    false
+                }
+                "html_block" | "link_reference_definition" | "pipe_table_delimiter_row" => {
                     out.mark(range, MUTED);
                     false
                 }