added undo/redo support

lib/models/state.js

@@ -4,7 +4,7 @@ import Node from './node'
 import Text from './text'
 import convertRangesToCharacters from '../utils/convert-ranges-to-characters'
 import toCamel from 'to-camel-case'
-import { OrderedMap, Record } from 'immutable'
+import { OrderedMap, Record, Stack } from 'immutable'
 
 /**
  * Record.
@@ -12,7 +12,9 @@ import { OrderedMap, Record } from 'immutable'
 
 const StateRecord = new Record({
   nodes: new OrderedMap(),
-  selection: new Selection()
+  selection: new Selection(),
+  undoStack: new Stack(),
+  redoStack: new Stack()
 })
 
 /**
@@ -58,8 +60,9 @@ const SELECTION_LIKE_METHODS = [
 class State extends StateRecord {
 
   /**
-   * Create a new `State` from `attrs`.
+   * Create a new `State` from a Javascript `object`.
    *
+   * @param {Objetc} object
    * @return {State} state
    */
 
@@ -554,6 +557,80 @@ class State extends StateRecord {
     return state
   }
 
+  /**
+   * Save the current state into the history.
+   *
+   * @return {State} state
+   */
+
+  save() {
+    let state = this
+    let { undoStack, redoStack } = state
+
+    undoStack = undoStack.unshift(state)
+    redoStack = redoStack.clear()
+    state = state.merge({
+      undoStack,
+      redoStack
+    })
+
+    return state
+  }
+
+  /**
+   * Undo.
+   *
+   * @return {State} state
+   */
+
+  undo() {
+    let state = this
+    let { undoStack, redoStack } = state
+
+    // If there's no previous state, do nothing.
+    let previous = undoStack.peek()
+    if (!previous) return state
+
+    // Remove the previous state from the undo stack.
+    undoStack = undoStack.shift()
+
+    // Move the current state into the redo stack.
+    redoStack = redoStack.unshift(state)
+
+    // Return the previous state, with the new history.
+    return previous.merge({
+      undoStack,
+      redoStack
+    })
+  }
+
+  /**
+   * Redo.
+   *
+   * @return {State} state
+   */
+
+  redo() {
+    let state = this
+    let { undoStack, redoStack } = state
+
+    // If there's no next state, do nothing.
+    let next = redoStack.peek()
+    if (!next) return state
+
+    // Remove the next state from the redo stack.
+    redoStack = redoStack.shift()
+
+    // Move the current state into the undo stack.
+    undoStack = undoStack.unshift(state)
+
+    // Return the next state, with the new history.
+    return next.merge({
+      undoStack,
+      redoStack
+    })
+  }
+
 }
 
 /**

lib/plugins/core.js

@@ -31,8 +31,8 @@ const CORE_PLUGIN = {
         if (IS_WINDOWS && e.shiftKey) return
         e.preventDefault()
         return isWord(e)
-          ? state.backspaceWord()
-          : state.deleteBackward()
+          ? state.save().backspaceWord()
+          : state.save().deleteBackward()
       }
 
       case 'delete': {
@@ -40,8 +40,8 @@ const CORE_PLUGIN = {
         if (IS_WINDOWS && e.shiftKey) return
         e.preventDefault()
         return isWord(e)
-          ? state.deleteWord()
-          : state.deleteForward()
+          ? state.save().deleteWord()
+          : state.save().deleteForward()
       }
 
       case 'y': {