tui: add Vim cw and cc change commands

packages/tui/src/editor.ts

@@ -201,6 +201,7 @@ export function decodeKeys(data: string): EditorKey[] {
 
 const segmenter = new Intl.Segmenter(undefined, { granularity: "grapheme" });
 const wordCharacter = /[\p{L}\p{N}_]/u;
+const blankCharacter = /\s/u;
 
 function boundaries(value: string): number[] {
   const result = [0];
@@ -312,6 +313,30 @@ export class LineEditor {
     }
   }
 
+  /**
+   * Vim `cw`: delete to the end of the current word but keep the separator.
+   * Unlike `dw`, `cw` does not consume the whitespace after the word; on
+   * whitespace (or at the end of the buffer) Vim falls back to `dw`.
+   */
+  changeWordForward(): void {
+    const at = this.cursor < this.buffer.length ? graphemeAt(this.buffer, this.cursor) : "";
+    // On whitespace (or at the end of the buffer) Vim's `cw` falls back to `dw`.
+    if (!at || blankCharacter.test(at)) {
+      this.deleteWordForward();
+      return;
+    }
+    // Otherwise `cw` is `ce`: change to the end of the current word, where a run
+    // of non-blank punctuation counts as a word of its own.
+    const inWord = wordCharacter.test(at);
+    const sameClass = (char: string): boolean =>
+      inWord ? wordCharacter.test(char) : !wordCharacter.test(char) && !blankCharacter.test(char);
+    let to = this.cursor;
+    while (to < this.buffer.length && sameClass(graphemeAt(this.buffer, to))) {
+      to = nextBoundary(this.buffer, to);
+    }
+    this.kill(this.cursor, to);
+  }
+
   deleteWordForward(): void {
     let to = this.wordRight();
     while (to < this.buffer.length && !wordCharacter.test(graphemeAt(this.buffer, to))) {
@@ -327,6 +352,13 @@ export class LineEditor {
     else this.kill(0, lineEnd);
   }
 
+  /** Remove the current line's text, keep the line itself, and put the cursor at its start. */
+  clearCurrentLine(): void {
+    const { lineStart, lineEnd } = this.position();
+    if (lineStart === lineEnd) return;
+    this.kill(lineStart, lineEnd);
+  }
+
   openLine(direction: "above" | "below"): void {
     const { lineStart, lineEnd } = this.position();
     this.snapshot();

packages/tui/src/vim-mode.ts

@@ -32,12 +32,23 @@ export class VimModeController {
       this.pending = "";
       return true;
     }
-    if (key.kind === "enter" || key.kind === "follow-up" || key.kind === "tab") return false;
+    if (key.kind === "enter" || key.kind === "follow-up" || key.kind === "tab") {
+      // Any other key cancels a pending operator, including keys the editor
+      // handles itself.
+      this.pending = "";
+      return false;
+    }
     if (key.kind === "ctrl" && key.char === "r") {
+      this.pending = "";
       editor.apply({ kind: "redo" });
       return true;
     }
-    if (key.kind !== "char") return this.handleNavigation(key, editor);
+    if (key.kind !== "char") {
+      // Navigation cancels a pending operator: `c`, Left, `w` must move by a
+      // word rather than change one.
+      this.pending = "";
+      return this.handleNavigation(key, editor);
+    }
 
     const char = key.char;
     if (this.pending === "f") {
@@ -51,7 +62,18 @@ export class VimModeController {
       else if (char === "w") editor.deleteWordForward();
       return true;
     }
-    if (char === "d" || char === "f") {
+    if (this.pending === "c") {
+      this.pending = "";
+      if (char === "w") {
+        editor.changeWordForward();
+        this.current = "insert";
+      } else if (char === "c") {
+        editor.clearCurrentLine();
+        this.current = "insert";
+      }
+      return true;
+    }
+    if (char === "d" || char === "f" || char === "c") {
       this.pending = char;
       return true;
     }

packages/tui/test/productivity.test.ts

@@ -54,6 +54,113 @@ test("Vim mode edits through the standard grapheme-safe editor", () => {
   assert.equal(editor.render(40).cursorColumn, 3);
 });
 
+test("Vim mode cw changes the word but keeps the separator", () => {
+  const editor = new LineEditor();
+  const vim = new VimModeController();
+  editor.setText("one two");
+
+  assert.equal(vim.handle({ kind: "escape" }, editor), true);
+  vim.handle({ kind: "char", char: "0" }, editor);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  vim.handle({ kind: "char", char: "w" }, editor);
+  // Vim's cw stops at the end of the word; unlike dw it does not eat the space.
+  assert.equal(editor.text, " two");
+  assert.equal(vim.mode, "insert");
+});
+
+test("Vim mode cw mid-word and on whitespace match Vim", () => {
+  const editor = new LineEditor();
+  const vim = new VimModeController();
+  editor.setText("alpha beta gamma");
+
+  vim.handle({ kind: "escape" }, editor);
+  // Mid-word: delete from the cursor to the end of "alpha".
+  vim.handle({ kind: "char", char: "0" }, editor);
+  vim.handle({ kind: "char", char: "l" }, editor);
+  vim.handle({ kind: "char", char: "l" }, editor);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  vim.handle({ kind: "char", char: "w" }, editor);
+  assert.equal(editor.text, "al beta gamma");
+
+  // On whitespace cw falls back to dw, which takes the whitespace run and the
+  // following word with it.
+  const second = new LineEditor();
+  const secondVim = new VimModeController();
+  second.setText("one   two");
+  secondVim.handle({ kind: "escape" }, second);
+  secondVim.handle({ kind: "char", char: "0" }, second);
+  secondVim.handle({ kind: "right" }, second);
+  secondVim.handle({ kind: "right" }, second);
+  secondVim.handle({ kind: "right" }, second);
+  secondVim.handle({ kind: "char", char: "c" }, second);
+  secondVim.handle({ kind: "char", char: "w" }, second);
+  assert.equal(second.text, "one");
+});
+
+test("Vim mode cc clears the current line but keeps it", () => {
+  const editor = new LineEditor();
+  const vim = new VimModeController();
+  editor.setText("hello\nworld");
+
+  assert.equal(vim.handle({ kind: "escape" }, editor), true);
+  vim.handle({ kind: "char", char: "k" }, editor);
+  vim.handle({ kind: "char", char: "0" }, editor);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  assert.equal(editor.text, "\nworld");
+  assert.equal(vim.mode, "insert");
+});
+
+test("Vim mode c followed by another key cancels without editing", () => {
+  const editor = new LineEditor();
+  const vim = new VimModeController();
+  editor.setText("abc");
+
+  assert.equal(vim.handle({ kind: "escape" }, editor), true);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  vim.handle({ kind: "char", char: "x" }, editor);
+  assert.equal(editor.text, "abc");
+  assert.equal(vim.mode, "normal");
+});
+
+test("Vim mode navigation cancels a pending operator", () => {
+  const editor = new LineEditor();
+  const vim = new VimModeController();
+  editor.setText("one two three");
+
+  vim.handle({ kind: "escape" }, editor);
+  vim.handle({ kind: "char", char: "0" }, editor);
+  vim.handle({ kind: "char", char: "w" }, editor);
+  assert.equal(editor.render(40).cursorColumn, 3);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  // The exact sequence from review: `c`, Left, `w`. The Left cancels `c`, so
+  // `w` moves a word instead of changing one.
+  vim.handle({ kind: "left" }, editor);
+  vim.handle({ kind: "char", char: "w" }, editor);
+
+  assert.equal(editor.text, "one two three");
+  assert.equal(vim.mode, "normal");
+  assert.equal(editor.render(40).cursorColumn, 3);
+});
+
+test("Vim mode cw on punctuation changes only the punctuation run", () => {
+  const editor = new LineEditor();
+  const vim = new VimModeController();
+  editor.setText("foo.bar baz");
+
+  vim.handle({ kind: "escape" }, editor);
+  vim.handle({ kind: "char", char: "0" }, editor);
+  vim.handle({ kind: "char", char: "l" }, editor);
+  vim.handle({ kind: "char", char: "l" }, editor);
+  vim.handle({ kind: "char", char: "l" }, editor);
+  vim.handle({ kind: "char", char: "c" }, editor);
+  vim.handle({ kind: "char", char: "w" }, editor);
+
+  // Vim treats the punctuation run as its own word, so `.bar ` is not removed.
+  assert.equal(editor.text, "foobar baz");
+  assert.equal(vim.mode, "insert");
+});
+
 test("vertical movement preserves the preferred visual column", () => {
   const editor = new LineEditor();
   editor.setText("abcdef\nx\nabcdef");