got undo working properly for different transforms!

lib/components/content.js

@@ -111,7 +111,7 @@ class Content extends React.Component {
     }
 
     state = transform
-      .insert(data)
+      .insertText(data)
       .apply()
 
     this.onChange(state)

lib/models/document.js

@@ -224,14 +224,14 @@ class Document extends Record(DEFAULT_PROPERTIES) {
   }
 
   /**
-   * Insert `data` at a `range`.
+   * Insert `text` at a `range`.
    *
    * @param {Selection} range
-   * @param {String or Node or OrderedMap} data
+   * @param {String} text
    * @return {Document} document
    */
 
-  insertAtRange(range, data) {
+  insertTextAtRange(range, text) {
     let document = this
 
     // When still expanded, remove the current range first.
@@ -240,33 +240,30 @@ class Document extends Record(DEFAULT_PROPERTIES) {
       range = range.moveToStart()
     }
 
-    // When the data is a string of characters...
-    if (typeof data == 'string') {
-      let { startNode, startOffset } = document
-      let { characters } = startNode
+    let { startKey, startOffset } = range
+    let startNode = document.getNode(startKey)
+    let { characters } = startNode
 
-      // Create a list of the new characters, with the right marks.
-      const marks = characters.has(startOffset)
-        ? characters.get(startOffset).marks
-        : null
+    // Create a list of the new characters, with the right marks.
+    const marks = characters.has(startOffset)
+      ? characters.get(startOffset).marks
+      : null
 
-      const newCharacters = data.split('').reduce((list, char) => {
-        const obj = { text: char }
-        if (marks) obj.marks = marks
-        return list.push(Character.create(obj))
-      }, Character.createList())
+    const newCharacters = text.split('').reduce((list, char) => {
+      const obj = { text }
+      if (marks) obj.marks = marks
+      return list.push(Character.create(obj))
+    }, Character.createList())
 
-      // Splice in the new characters.
-      const resumeOffset = startOffset + data.length - 1
-      characters = characters.slice(0, startOffset)
-        .concat(newCharacters)
-        .concat(characters.slice(resumeOffset, Infinity))
+    // Splice in the new characters.
+    const resumeOffset = startOffset + text.length - 1
+    characters = characters.slice(0, startOffset)
+      .concat(newCharacters)
+      .concat(characters.slice(resumeOffset, Infinity))
 
-      // Update the existing text node.
-      startNode = startNode.merge({ characters })
-      document = document.updateNode(startNode)
-      return document
-    }
+    // Update the existing text node.
+    startNode = startNode.merge({ characters })
+    document = document.updateNode(startNode)
 
     // Normalize the document.
     return document.normalize()

lib/models/state.js

@@ -146,23 +146,17 @@ class State extends Record(DEFAULT_PROPERTIES) {
   /**
    * Insert a `text` string at the current cursor position.
    *
-   * @param {String or Node or OrderedMap} data
+   * @param {String} text
    * @return {State} state
    */
 
-  insert(data) {
+  insertText(text) {
     let state = this
     let { document, selection } = state
-    let after
 
-    // Determine what the selection should be after inserting.
-    if (typeof data == 'string') {
-      after = selection.moveForward(data.length)
-    }
-
-    // Insert the data and update the selection.
-    document = document.insertAtRange(selection, data)
-    selection = after
+    // Insert the text and update the selection.
+    document = document.insertTextAtRange(selection, text)
+    selection = selection.moveForward(text.length)
     state = state.merge({ document, selection })
     return state
   }

lib/models/transform.js

@@ -1,4 +1,6 @@
 
+import uniq from 'lodash/uniq'
+import xor from 'lodash/xor'
 import { List, Record } from 'immutable'
 
 /**
@@ -7,7 +9,8 @@ import { List, Record } from 'immutable'
 
 const Snapshot = Record({
   document: null,
-  selection: null
+  selection: null,
+  steps: new List()
 })
 
 /**
@@ -39,8 +42,8 @@ const TRANSFORM_TYPES = [
   'deleteBackwardAtRange',
   'deleteForward',
   'deleteForwardAtRange',
-  'insert',
-  'insertAtRange',
+  'insertText',
+  'insertTextAtRange',
   'split',
   'splitAtRange'
 ]
@@ -58,9 +61,9 @@ class Transform extends Record(DEFAULT_PROPERTIES) {
    */
 
   snapshot() {
-    let { state } = this
+    let { state, steps } = this
     let { document, selection } = state
-    return new Snapshot({ document, selection })
+    return new Snapshot({ document, selection, steps })
   }
 
   /**
@@ -70,17 +73,44 @@ class Transform extends Record(DEFAULT_PROPERTIES) {
    */
 
   apply() {
-    let transform = this
+    const transform = this
     let { state, steps } = transform
     let { history } = state
     let { undos, redos } = history
 
-    // Save the current state into the history before transforming.
-    let snapshot = transform.snapshot()
-    undos = undos.unshift(snapshot)
-    redos = redos.clear()
-    history = history.merge({ undos, redos })
-    state = state.merge({ history })
+    // Determine whether we need to create a new snapshot.
+    let shouldSnapshot = false
+    const previous = undos.peek()
+
+    // If there isn't a previous state, snapshot.
+    if (!previous) shouldSnapshot = true
+
+    // If there is a previous state but the steps are different, snapshot.
+    if (!shouldSnapshot && previous) {
+      const types = steps.map(step => step.type)
+      const prevTypes = previous.steps.map(step => step.type)
+      const diff = xor(types.toArray(), prevTypes.toArray())
+      if (diff.length) shouldSnapshot = true
+    }
+
+    // If the current steps aren't one of the "combinale" types, snapshot.
+    if (!shouldSnapshot) {
+      const allCombinable = (
+        steps.every(step => step.type == 'insertText') ||
+        steps.every(step => step.type == 'deleteForward') ||
+        steps.every(step => step.type == 'deleteBackward')
+      )
+      if (!allCombinable) shouldSnapshot = true
+    }
+
+    // If we should, save a snapshot into the history before transforming.
+    if (shouldSnapshot) {
+      const snapshot = transform.snapshot()
+      undos = undos.unshift(snapshot)
+      redos = redos.clear()
+      history = history.merge({ undos, redos })
+      state = state.merge({ history })
+    }
 
     // Apply each of the steps in the transform, arriving at a new state.
     state = steps.reduce((state, step) => {
@@ -91,7 +121,6 @@ class Transform extends Record(DEFAULT_PROPERTIES) {
     return state
   }
 
-
   /**
    * Undo to the previous state in the history.
    *
@@ -99,7 +128,7 @@ class Transform extends Record(DEFAULT_PROPERTIES) {
    */
 
   undo() {
-    let transform = this
+    const transform = this
     let { state } = transform
     let { history } = state
     let { undos, redos } = history
@@ -129,7 +158,7 @@ class Transform extends Record(DEFAULT_PROPERTIES) {
    */
 
   redo() {
-    let transform = this
+    const transform = this
     let { state } = transform
     let { history } = state
     let { undos, redos } = history