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@monbolc/lowcode-plugin-command (L2)

Version: 2.0.2 · React-free · Pure logic · 20 tests

Purpose

The command pattern + undo/redo + shortcut parsing. Pure logic, no React, no UI. Every L3+ command (in designer) implements ICommand and registers with a CommandManager.

Public exports

Types

  • CommandArgs, CommandResult
  • CommandManagerEvents — registered, unregistered, executed, undone, redone, cleared
  • ICommand<TArgs, TReturn> — name, label, group, shortcut, execute, optional undo, optional mergeable/mergeWindowMs
  • ICommandManager
  • CommandManagerOptions — historyLimit, autoMerge
  • ParsedShortcut, ShortcutBinder, ShortcutBinderOptions, ShortcutToken

Functions

  • parseShortcut(input) — supports Mod (Meta on macOS, Ctrl elsewhere), Ctrl, Meta, Shift, Alt. Mod+Z style.
  • bindShortcuts(manager, options) — adds a global keydown listener; SSR-safe (no-op if window is undefined)
  • isMacOS()

Classes

  • CommandManager (implements ICommandManager)

Key types

interface ICommand<TArgs = unknown, TReturn = unknown> {
  name: string;
  label?: string;
  group?: string;
  shortcut?: string;
  execute(args: TArgs): TReturn | Promise<TReturn>;
  undo?(args: TArgs, returnValue: TReturn): void | Promise<void>;
  // Optional auto-merge for slider-style operations
  mergeable?: boolean;
  mergeWindowMs?: number;  // default 500
}

Implementation patterns

  • Uses @monbolc/lowcode-utils's Emitter for events
  • CommandManager keeps two stacks (undoStack, redoStack); a new execute clears the redo stack
  • Auto-merge: when a command has mergeable: true and the top of the undo stack is the same name within mergeWindowMs (default 500ms), update the top's args in place (keeping the original returnValue so undo restores the pre-window state). Critical for SetPropCommand (slider drag).
  • On undo/redo failure, the entry is restored to its original stack so the user can retry
  • unregister also prunes in-flight history entries for that command name

Test coverage

  • 2 test files, 20 tests
  • manager.test.ts (14): registration, undo, redo, merge windows, history limit, events, prune-on-unregister
  • shortcut.test.ts (6): parseShortcut coverage

External deps

  • @monbolc/lowcode-types (workspace)
  • @monbolc/lowcode-utils (workspace)

See also