feat: implement :change ex-command

src/actions/commands/commandLine.ts

@@ -1,6 +1,7 @@
 import * as vscode from 'vscode';
 
 import { CommandLine, ExCommandLine, SearchCommandLine } from '../../cmd_line/commandLine';
+import { ChangeCommand } from '../../cmd_line/commands/change';
 import { ErrorCode, VimError } from '../../error';
 import { Mode } from '../../mode/mode';
 import { Register, RegisterMode } from '../../register/register';
@@ -152,6 +153,11 @@ class ExCommandLineEnter extends CommandLineAction {
 
   protected override async run(vimState: VimState, commandLine: CommandLine): Promise<void> {
     await commandLine.run(vimState);
+
+    if (commandLine instanceof ExCommandLine && commandLine.getCommand() instanceof ChangeCommand) {
+      return;
+    }
+
     await vimState.setCurrentMode(Mode.Normal);
   }
 }

src/cmd_line/commandLine.ts

@@ -243,6 +243,10 @@ export class ExCommandLine extends CommandLine {
     return undefined;
   }
 
+  public getCommand(): ExCommand | undefined {
+    return this.command;
+  }
+
   public getDecorations(vimState: VimState): SearchDecorations | undefined {
     return this.command instanceof SubstituteCommand &&
       vimState.currentMode === Mode.CommandlineInProgress

src/cmd_line/commands/change.ts

@@ -0,0 +1,103 @@
+import * as vscode from 'vscode';
+// eslint-disable-next-line id-denylist
+import { Parser, alt, any, optWhitespace, seq, whitespace } from 'parsimmon';
+import { Position } from 'vscode';
+import { Mode } from '../../mode/mode';
+import { Register, RegisterMode } from '../../register/register';
+import { VimState } from '../../state/vimState';
+import { ExCommand } from '../../vimscript/exCommand';
+import { LineRange } from '../../vimscript/lineRange';
+import { numberParser } from '../../vimscript/parserUtils';
+
+export interface IChangeCommandArguments {
+  register?: string;
+  count?: number;
+}
+
+export class ChangeCommand extends ExCommand {
+  public static readonly argParser: Parser<ChangeCommand> = optWhitespace.then(
+    alt(
+      numberParser.map((count) => {
+        return { register: undefined, count };
+      }),
+      // eslint-disable-next-line id-denylist
+      seq(any.fallback(undefined), whitespace.then(numberParser).fallback(undefined)).map(
+        ([register, count]) => {
+          return { register, count };
+        },
+      ),
+    ).map(
+      ({ register, count }) =>
+        new ChangeCommand({
+          register,
+          count,
+        }),
+    ),
+  );
+
+  private readonly arguments: IChangeCommandArguments;
+  constructor(args: IChangeCommandArguments) {
+    super();
+    this.arguments = args;
+  }
+
+  public override neovimCapable(): boolean {
+    return true;
+  }
+
+  /**
+   * Deletes text between `startLine` and `endLine`, inclusive.
+   * Puts the cursor at the start of the line where the deleted range was
+   * Then enters insert mode
+   */
+  private changeRange(startLine: number, endLine: number, vimState: VimState): void {
+    const start = new Position(startLine, 0);
+    const end = new Position(endLine + 1, 0);
+
+    const range = new vscode.Range(start, end);
+    const text = vimState.document.getText(range);
+
+    vimState.recordedState.transformer.addTransformation({
+      type: 'replaceText',
+      text: '\n',
+      range,
+      manuallySetCursorPositions: true,
+    });
+    vimState.cursorStopPosition = start;
+
+    if (this.arguments.register) {
+      vimState.recordedState.registerName = this.arguments.register;
+    }
+    vimState.currentRegisterMode = RegisterMode.LineWise;
+    Register.put(vimState, text, 0, true);
+  }
+
+  async execute(vimState: VimState): Promise<void> {
+    const linesToRemove = this.arguments.count ?? 1;
+    // :c[hange][cnt] changes [cnt] lines
+    const startLine = vimState.cursorStartPosition.line;
+    const endLine = startLine + (linesToRemove - 1);
+    this.changeRange(startLine, endLine, vimState);
+
+    // Enter insert mode
+    await vimState.setCurrentMode(Mode.Insert);
+  }
+
+  override async executeWithRange(vimState: VimState, range: LineRange): Promise<void> {
+    /**
+     * If a [cnt] and [range] is specified (e.g. :.+2c3), :change
+     * the end of the [range].
+     * Ex. if two lines are VisualLine hightlighted, :<,>c3 will :c3
+     * from the end of the selected lines
+     */
+    const { start, end } = range.resolve(vimState);
+    if (this.arguments.count) {
+      vimState.cursorStartPosition = new Position(end, 0);
+      await this.execute(vimState);
+      return;
+    }
+    this.changeRange(start, end, vimState);
+    // Enter insert mode
+    await vimState.setCurrentMode(Mode.Insert);
+  }
+}

src/vimscript/exCommandParser.ts

@@ -4,6 +4,7 @@ import { AsciiCommand } from '../cmd_line/commands/ascii';
 import { BangCommand } from '../cmd_line/commands/bang';
 import { Breakpoints } from '../cmd_line/commands/breakpoints';
 import { BufferDeleteCommand } from '../cmd_line/commands/bufferDelete';
+import { ChangeCommand } from '../cmd_line/commands/change';
 import { CloseCommand } from '../cmd_line/commands/close';
 import { CopyCommand } from '../cmd_line/commands/copy';
 import { DeleteCommand } from '../cmd_line/commands/delete';
@@ -120,7 +121,7 @@ export const builtinExCommands: ReadonlyArray<[[string, string], ArgParser | und
   [['buffers', ''], undefined],
   [['bun', 'load'], undefined],
   [['bw', 'ipeout'], undefined],
-  [['c', 'hange'], undefined],
+  [['c', 'hange'], ChangeCommand.argParser],
   [['cN', 'ext'], undefined],
   [['cNf', 'ile'], undefined],
   [['ca', 'bbrev'], undefined],

test/cmd_line/change.test.ts

@@ -0,0 +1,43 @@
+import { Mode } from '../../src/mode/mode';
+import { newTest } from '../testSimplifier';
+import { cleanUpWorkspace, setupWorkspace } from '../testUtils';
+
+suite('cmd_line change', () => {
+  setup(async () => {
+    await setupWorkspace();
+  });
+
+  teardown(cleanUpWorkspace);
+
+  newTest({
+    title: 'c deletes current line and enters insert mode',
+    start: ['first line', 'sec|ond line', 'third line'],
+    keysPressed: ':c\n',
+    end: ['first line', '|', 'third line'],
+    endMode: Mode.Insert,
+  });
+
+  newTest({
+    title: 'c with count deletes multiple lines and enters insert mode',
+    start: ['first line', 'sec|ond line', 'third line', 'fourth line'],
+    keysPressed: ':c2\n',
+    end: ['first line', '|', 'fourth line'],
+    endMode: Mode.Insert,
+  });
+
+  newTest({
+    title: 'c with range deletes specified lines and enters insert mode',
+    start: ['first line', 'sec|ond line', 'third line', 'fourth line'],
+    keysPressed: ':2, 3c\n',
+    end: ['first line', '|', 'fourth line'],
+    endMode: Mode.Insert,
+  });
+
+  newTest({
+    title: 'c with range and visual selection',
+    start: ['first line', 'sec|ond line', 'third line', 'fourth line'],
+    keysPressed: 'V:c\n',
+    end: ['first line', '|', 'third line', 'fourth line'],
+    endMode: Mode.Insert,
+  });
+});