refactor operations

lib/models/transform.js

@@ -1,4 +1,5 @@
 
+import Operations from '../transforms/operations'
 import Transforms from '../transforms'
 import includes from 'lodash/includes'
 import xor from 'lodash/xor'
@@ -70,13 +71,19 @@ class Transform {
   /**
    * Add an `operation` to the transform that resulted in `state`.
    *
-   * @param {State} state
    * @param {Object} operation
    * @return {Transform}
    */
 
-  add(state, operation) {
+  operate(operation) {
-    this.state = state
+    const { type } = operation
+    const fn = Operations[type]
+
+    if (!fn) {
+      throw new Error(`Unknown operation type: "${type}".`)
+    }
+
+    this.state = fn(this.state, operation)
     this.operations.push(operation)
     return this
   }

lib/transforms/at-current-range.js

@@ -18,7 +18,7 @@ export function addMark(transform, mark) {
   if (selection.isCollapsed) {
     const marks = document.getMarksAtRange(selection).add(mark)
     const sel = selection.merge({ marks })
-    return transform.updateSelection(sel)
+    return transform.setSelection(sel)
   }
 
   return transform.addMarkAtRange(selection, mark)
@@ -73,7 +73,7 @@ export function _delete(transform) {
 
   return transform
     .deleteAtRange(selection)
-    .updateSelection(after)
+    .setSelection(after)
 }
 
 /**
@@ -147,7 +147,7 @@ export function deleteBackward(transform, n = 1) {
 
   return transform
     .deleteBackwardAtRange(selection, n)
-    .updateSelection(after)
+    .setSelection(after)
 }
 
 /**
@@ -206,7 +206,7 @@ export function deleteForward(transform, n = 1) {
 
   return transform
     .deleteForwardAtRange(selection, n)
-    .updateSelection(after)
+    .setSelection(after)
 }
 
 /**
@@ -229,7 +229,7 @@ export function insertBlock(transform, block) {
   const text = document.getTexts().find(n => !keys.includes(n.key))
   const after = selection.collapseToEndOf(text)
 
-  return transform.updateSelection(after)
+  return transform.setSelection(after)
 }
 
 /**
@@ -279,7 +279,7 @@ export function insertFragment(transform, fragment) {
       .moveForward(lastText.length)
   }
 
-  return transform.updateSelection(after)
+  return transform.setSelection(after)
 }
 
 /**
@@ -311,7 +311,7 @@ export function insertInline(transform, inline) {
     after = selection.collapseToEndOf(text)
   }
 
-  return transform.updateSelection(after)
+  return transform.setSelection(after)
 }
 
 /**
@@ -346,7 +346,7 @@ export function insertText(transform, text, marks) {
 
   return transform
     .insertTextAtRange(selection, text, marks)
-    .updateSelection(after)
+    .setSelection(after)
 }
 
 /**
@@ -399,7 +399,7 @@ export function splitBlock(transform, depth = 1) {
   const nextNode = document.getNextText(startNode)
   const after = selection.collapseToStartOf(nextNode)
 
-  return transform.updateSelection(after)
+  return transform.setSelection(after)
 }
 
 /**
@@ -428,7 +428,7 @@ export function splitInline(transform, depth = Infinity) {
     after = selection.collapseToStartOf(nextNode)
   }
 
-  return transform.updateSelection(after)
+  return transform.setSelection(after)
 }
 
 /**
@@ -448,7 +448,7 @@ export function removeMark(transform, mark) {
   if (selection.isCollapsed) {
     const marks = document.getMarksAtRange(selection).remove(mark)
     const sel = selection.merge({ marks })
-    return transform.updateSelection(sel)
+    return transform.setSelection(sel)
   }
 
   return transform.removeMarkAtRange(selection, mark)
@@ -566,7 +566,7 @@ export function wrapInline(transform, properties) {
   }
 
   after = after.normalize(document)
-  return transform.updateSelection(after)
+  return transform.setSelection(after)
 }
 
 /**
@@ -597,5 +597,5 @@ export function wrapText(transform, prefix, suffix = prefix) {
 
   return transform
     .wrapTextAtRange(selection, prefix, suffix)
-    .updateSelection(after)
+    .setSelection(after)
 }

lib/transforms/at-range.js

@@ -323,7 +323,7 @@ export function insertFragmentAtRange(transform, range, fragment) {
     const lastIndex = lastBlock.nodes.size
 
     nextNodes.forEach((node, i) => {
-      const newIndex = lastIndex + i + 1
+      const newIndex = lastIndex + i
       transform.moveNodeByKey(node.key, lastBlock.key, newIndex)
     })
   }
@@ -737,7 +737,7 @@ export function wrapBlockAtRange(transform, range, block) {
   const parent = document.getParent(first)
   const index = parent.nodes.indexOf(first)
 
-  transform.insertNodeByKey(parent.key, index + 1, block)
+  transform.insertNodeByKey(parent.key, index, block)
 
   siblings.forEach((node, i) => {
     transform.moveNodeByKey(node.key, block.key, i)
@@ -818,8 +818,8 @@ export function wrapInlineAtRange(transform, range, inline) {
     const startNode = inline.merge({ key: uid() })
     const endNode = inline.merge({ key: uid() })
 
-    transform.insertNodeByKey(startBlock.key, startIndex + 1, startNode)
+    transform.insertNodeByKey(startBlock.key, startIndex - 1, startNode)
-    transform.insertNodeByKey(endBlock.key, endIndex + 1, endNode)
+    transform.insertNodeByKey(endBlock.key, endIndex, endNode)
 
     startInlines.forEach((child, i) => {
       transform.moveNodeByKey(child.key, startNode.key, i)

lib/transforms/by-key.js

@@ -16,22 +16,28 @@ import uid from '../utils/uid'
 export function addMarkByKey(transform, key, offset, length, mark) {
   mark = Normalize.mark(mark)
 
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const path = document.getPath(key)
-  const path = document.getPath(node)
 
-  node = node.addMark(offset, length, mark)
+  const inverse = {
-  document = document.updateDescendant(node)
+    type: 'remove_mark',
-  state = state.merge({ document })
+    path,
-
+    offset,
-  return transform.add(state, {
-    type: 'add-mark',
     length,
     mark,
-    offset,
+  }
+
+  const operation = {
+    type: 'add_mark',
     path,
-  })
+    offset,
+    length,
+    mark,
+    inverse,
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -45,23 +51,25 @@ export function addMarkByKey(transform, key, offset, length, mark) {
  */
 
 export function insertNodeByKey(transform, key, index, node) {
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let parent = document.key == key ? document : document.assertDescendant(key)
+  const path = document.getPath(key)
-  const isParent = document == parent
+  const newPath = path.slice().push(index)
-  const path = document.getPath(parent)
-  const nodes = parent.nodes.splice(index, 0, node)
 
-  parent = parent.merge({ nodes })
+  const inverse = {
-  document = isParent ? parent : document.updateDescendant(parent)
+    type: 'remove_node',
-  state = state.merge({ document })
+    path: newPath,
+  }
 
-  return transform.add(state, {
+  const operation = {
-    type: 'insert-node',
+    type: 'insert_node',
+    path,
     index,
     node,
-    path,
+    inverse,
-  })
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -76,22 +84,26 @@ export function insertNodeByKey(transform, key, index, node) {
  */
 
 export function insertTextByKey(transform, key, offset, text, marks) {
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const path = document.getPath(key)
-  const path = document.getPath(node)
 
-  node = node.insertText(offset, text, marks)
+  const inverse = {
-  document = document.updateDescendant(node)
+    type: 'remove_text',
-  state = state.merge({ document })
-
-  return transform.add(state, {
-    type: 'insert-text',
-    offset,
-    marks,
     path,
+    offset,
+    length: text.length,
+  }
+
+  const operation = {
+    type: 'insert_text',
+    path,
+    offset,
     text,
-  })
+    marks,
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -105,32 +117,32 @@ export function insertTextByKey(transform, key, offset, text, marks) {
  */
 
 export function moveNodeByKey(transform, key, newKey, newIndex) {
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
   const node = document.assertDescendant(key)
-  const path = document.getPath(node)
+  const path = document.getPath(key)
+  const parent = document.getParent(key)
+  const parentPath = path.slice(0, -1)
+  const parentIndex = path[path.length - 1]
   const newPath = document.getPath(newKey)
-  let parent = document.getParent(node)
+  const nodePath = newPath.slice().concat([newIndex])
-  const isParent = document == parent
-  const index = parent.nodes.indexOf(node)
 
-  parent = parent.removeNode(index)
+  const inverse = {
-  document = isParent ? parent : document.updateDescendant(parent)
+    type: 'move_node',
+    path: nodePath,
+    newPath: parentPath,
+    newIndex: parentIndex,
+  }
 
-  let target = document.key == newKey ? document : document.assertDescendant(newKey)
+  const operation = {
-  const isTarget = document == target
+    type: 'move_node',
-
-  target = target.insertNode(newIndex, node)
-  document = isTarget ? target : document.updateDescendant(target)
-  // document = document.normalize()
-  state = state.merge({ document })
-
-  return transform.add(state, {
-    type: 'move-node',
     path,
     newPath,
     newIndex,
-  })
+    inverse,
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -147,22 +159,28 @@ export function moveNodeByKey(transform, key, newKey, newIndex) {
 export function removeMarkByKey(transform, key, offset, length, mark) {
   mark = Normalize.mark(mark)
 
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const path = document.getPath(key)
-  const path = document.getPath(node)
 
-  node = node.removeMark(offset, length, mark)
+  const inverse = {
-  document = document.updateDescendant(node)
+    type: 'add_mark',
-  state = state.merge({ document })
+    path,
-
-  return transform.add(state, {
-    type: 'remove-mark',
     offset,
     length,
     mark,
+  }
+
+  const operation = {
+    type: 'remove_mark',
     path,
-  })
+    offset,
+    length,
+    mark,
+    inverse,
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -174,23 +192,27 @@ export function removeMarkByKey(transform, key, offset, length, mark) {
  */
 
 export function removeNodeByKey(transform, key) {
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
   const node = document.assertDescendant(key)
-  const path = document.getPath(node)
+  const path = document.getPath(key)
-  let parent = document.getParent(node)
+  const parentPath = path.slice(0, -1)
-  const index = parent.nodes.indexOf(node)
+  const parentIndex = path.slice(-1)
-  const isParent = document == parent
 
-  parent = parent.removeNode(index)
+  const inverse = {
-  document = isParent ? parent : document.updateDescendant(parent)
+    type: 'insert_node',
-  document = document.normalize()
+    path: parentPath,
-  state = state.merge({ document })
+    index: parentIndex,
+    node,
+  }
 
-  return transform.add(state, {
+  const operation = {
-    type: 'remove-node',
+    type: 'remove_node',
     path,
-  })
+    inverse,
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -204,22 +226,22 @@ export function removeNodeByKey(transform, key) {
  */
 
 export function removeTextByKey(transform, key, offset, length) {
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const path = document.getPath(key)
-  const path = document.getPath(node)
 
-  node = node.removeText(offset, length)
+  // TODO!
-  document = document.updateDescendant(node)
+  const inverse = {}
-  document = document.normalize()
-  state = state.merge({ document })
 
-  return transform.add(state, {
+  const operation = {
-    type: 'remove-text',
+    type: 'remove_text',
+    path,
     offset,
     length,
-    path,
+    inverse,
-  })
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -237,23 +259,23 @@ export function setMarkByKey(transform, key, offset, length, mark, properties) {
   mark = Normalize.mark(mark)
   properties = Normalize.markProperties(properties)
 
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const path = document.getPath(key)
-  const path = document.getPath(node)
 
-  node = node.updateMark(offset, length, mark, properties)
+  // TODO!
-  document = document.updateDescendant(node)
+  const inverse = {}
-  state = state.merge({ document })
 
-  return transform.add(state, {
+  const operation = {
-    type: 'set-mark',
+    type: 'set_mark',
+    path,
     offset,
     length,
     mark,
-    path,
     properties,
-  })
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -268,21 +290,30 @@ export function setMarkByKey(transform, key, offset, length, mark, properties) {
 export function setNodeByKey(transform, key, properties) {
   properties = Normalize.nodeProperties(properties)
 
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const node = document.assertDescendant(key)
-  const path = document.getPath(node)
+  const path = document.getPath(key)
+  const prevProps = {}
 
-  node = node.merge(properties)
+  for (const k in properties) {
-  document = document.updateDescendant(node)
+    prevProps[k] = node[k]
-  document = document.normalize()
+  }
-  state = state.merge({ document })
 
-  return transform.add(state, {
+  const inverse = {
-    type: 'set-node',
+    type: 'set_node',
+    path,
+    properties: prevProps
+  }
+
+  const operation = {
+    type: 'set_node',
     path,
     properties,
-  })
+    inverse,
+  }
+
+  return transform.operate(operation)
 }
 
 /**
@@ -295,53 +326,20 @@ export function setNodeByKey(transform, key, properties) {
  */
 
 export function splitNodeByKey(transform, key, offset) {
-  let { state } = transform
+  const { state } = transform
-  let { document } = state
+  const { document } = state
-  let node = document.assertDescendant(key)
+  const path = document.getPath(key)
-  const path = document.getPath(node)
-  let parent = document.getParent(node)
-  const isParent = document == parent
-  const index = parent.nodes.indexOf(node)
 
-  let child = node
+  // TODO!
-  let one
+  const inverse = {}
-  let two
 
-  if (node.kind != 'text') {
+  const operation = {
-    child = node.getTextAtOffset(offset)
+    type: 'split_node',
-  }
-
-  while (child && child != parent) {
-    if (child.kind == 'text') {
-      const i = node.kind == 'text' ? offset : offset - node.getOffset(child)
-      const { characters } = child
-      const oneChars = characters.take(i)
-      const twoChars = characters.skip(i)
-      one = child.merge({ characters: oneChars })
-      two = child.merge({ characters: twoChars, key: uid() })
-    }
-
-    else {
-      const { nodes } = child
-      const oneNodes = nodes.takeUntil(n => n.key == one.key).push(one)
-      const twoNodes = nodes.skipUntil(n => n.key == one.key).rest().unshift(two)
-      one = child.merge({ nodes: oneNodes })
-      two = child.merge({ nodes: twoNodes, key: uid() })
-    }
-
-    child = document.getParent(child)
-  }
-
-  parent = parent.removeNode(index)
-  parent = parent.insertNode(index, two)
-  parent = parent.insertNode(index, one)
-  document = isParent ? parent : document.updateDescendant(parent)
-  state = state.merge({ document })
-
-  return transform.add(state, {
-    type: 'split-node',
-    offset,
     path,
-  })
+    offset,
+    inverse,
+  }
+
+  return transform.operate(operation)
 }
 

lib/transforms/index.js

@@ -98,7 +98,7 @@ import {
   moveTo,
   moveToOffsets,
   moveToRangeOf,
-  updateSelection,
+  setSelection,
 } from './on-selection'
 
 /**
@@ -210,7 +210,7 @@ export default {
   moveTo,
   moveToOffsets,
   moveToRangeOf,
-  updateSelection,
+  setSelection,
 
   /**
    * Normalize.

lib/transforms/on-selection.js

@@ -13,7 +13,15 @@ export function blur(transform) {
   const { state } = transform
   const { selection } = state
   const sel = selection.blur()
-  return transform.updateSelection(sel)
+
+  return transform.operate({
+    type: 'set_selection',
+    selection: sel,
+    inverse: {
+      type: 'set_selection',
+      selection,
+    }
+  })
 }
 
 /**
@@ -27,7 +35,7 @@ export function collapseToAnchor(transform) {
   const { state } = transform
   const { selection } = state
   const sel = selection.collapseToAnchor()
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -41,7 +49,7 @@ export function collapseToFocus(transform) {
   const { state } = transform
   const { selection } = state
   const sel = selection.collapseToFocus()
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -56,7 +64,7 @@ export function collapseToEndOf(transform, node) {
   const { state } = transform
   const { selection } = state
   const sel = selection.collapseToEndOf(node)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -75,7 +83,7 @@ export function collapseToEndOfNextBlock(transform) {
   if (!next) return transform
 
   const sel = selection.collapseToEndOf(next)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -94,7 +102,7 @@ export function collapseToEndOfNextText(transform) {
   if (!next) return transform
 
   const sel = selection.collapseToEndOf(next)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -113,7 +121,7 @@ export function collapseToEndOfPreviousBlock(transform) {
   if (!previous) return transform
 
   const sel = selection.collapseToEndOf(previous)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -132,7 +140,7 @@ export function collapseToEndOfPreviousText(transform) {
   if (!previous) return transform
 
   const sel = selection.collapseToEndOf(previous)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -147,7 +155,7 @@ export function collapseToStartOf(transform, node) {
   const { state } = transform
   const { selection } = state
   const sel = selection.collapseToStartOf(node)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -166,7 +174,7 @@ export function collapseToStartOfNextBlock(transform) {
   if (!next) return transform
 
   const sel = selection.collapseToStartOf(next)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -185,7 +193,7 @@ export function collapseToStartOfNextText(transform) {
   if (!next) return transform
 
   const sel = selection.collapseToStartOf(next)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -204,7 +212,7 @@ export function collapseToStartOfPreviousBlock(transform) {
   if (!previous) return transform
 
   const sel = selection.collapseToStartOf(previous)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -223,7 +231,7 @@ export function collapseToStartOfPreviousText(transform) {
   if (!previous) return transform
 
   const sel = selection.collapseToStartOf(previous)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -238,7 +246,7 @@ export function extendBackward(transform, n) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.extendBackward(n).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -253,7 +261,7 @@ export function extendForward(transform, n) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.extendForward(n).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -268,7 +276,7 @@ export function extendToEndOf(transform, node) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.extendToEndOf(node).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -283,7 +291,7 @@ export function extendToStartOf(transform, node) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.extendToStartOf(node).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -297,7 +305,7 @@ export function focus(transform) {
   const { state } = transform
   const { selection } = state
   const sel = selection.focus()
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -312,7 +320,7 @@ export function moveBackward(transform, n) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.moveBackward(n).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -327,7 +335,7 @@ export function moveForward(transform, n) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.moveForward(n).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -343,7 +351,7 @@ export function moveTo(transform, properties) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.merge(properties).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -359,7 +367,7 @@ export function moveToOffsets(transform, anchor, fokus) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.moveToOffsets(anchor, fokus)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
@@ -375,27 +383,31 @@ export function moveToRangeOf(transform, start, end) {
   const { state } = transform
   const { document, selection } = state
   const sel = selection.moveToRangeOf(start, end).normalize(document)
-  return transform.updateSelection(sel)
+  return transform.setSelection(sel)
 }
 
 /**
- * Update the selection with a new `selection`.
+ * Set the selection to a new `selection`.
  *
  * @param {Transform} transform
- * @param {Mixed} sel
+ * @param {Mixed} selection
  * @return {Transform}
  */
 
-export function updateSelection(transform, sel) {
+export function setSelection(transform, selection) {
-  sel = Normalize.selection(sel)
+  selection = Normalize.selection(selection)
+  const { state } = transform
 
-  let { state } = transform
+  const inverse = {
-  let { selection } = state
+    type: 'set_selection',
-  selection = selection.merge(sel)
+    selection: state.selection,
-  state = state.merge({ selection })
+  }
 
-  return transform.add(state, {
+  const operation = {
-    type: 'update-selection',
+    type: 'set_selection',
     selection,
-  })
+    inverse,
+  }
+
+  return transform.operate(operation)
 }

lib/transforms/operations.js

@@ -0,0 +1,279 @@
+
+import uid from '../utils/uid'
+
+/**
+ * Add mark to text at `offset` and `length` in node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function addMark(state, operation) {
+  const { path, offset, length, mark } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  node = node.addMark(offset, length, mark)
+  document = document.updateDescendant(node)
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Insert a `node` at `index` in a node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function insertNode(state, operation) {
+  const { path, index, node } = operation
+  let { document } = state
+  let parent = document.assertPath(path)
+  const isParent = document == parent
+  const nodes = parent.nodes.splice(index, 0, node)
+  parent = parent.merge({ nodes })
+  document = isParent ? parent : document.updateDescendant(parent)
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Insert `text` at `offset` in node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function insertText(state, operation) {
+  const { path, offset, text, marks } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  node = node.insertText(offset, text, marks)
+  document = document.updateDescendant(node)
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Move a node by `key` to a new parent by `key` and `index`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function moveNode(state, operation) {
+  const { path, newPath, newIndex } = operation
+  let { document } = state
+  const node = document.assertPath(path)
+
+  let parent = document.getParent(node)
+  const isParent = document == parent
+  const index = parent.nodes.indexOf(node)
+  parent = parent.removeNode(index)
+  document = isParent ? parent : document.updateDescendant(parent)
+
+  let target = document.assertPath(newPath)
+  const isTarget = document == target
+  target = target.insertNode(newIndex, node)
+  document = isTarget ? target : document.updateDescendant(target)
+
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Remove mark from text at `offset` and `length` in node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function removeMark(state, operation) {
+  const { path, offset, length, mark } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  node = node.removeMark(offset, length, mark)
+  document = document.updateDescendant(node)
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Remove a node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function removeNode(state, operation) {
+  const { path } = operation
+  let { document } = state
+  const node = document.assertPath(path)
+  let parent = document.getParent(node)
+  const index = parent.nodes.indexOf(node)
+  const isParent = document == parent
+  parent = parent.removeNode(index)
+  document = isParent ? parent : document.updateDescendant(parent)
+  document = document.normalize()
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Remove text at `offset` and `length` in node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function removeText(state, operation) {
+  const { path, offset, length } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  node = node.removeText(offset, length)
+  document = document.updateDescendant(node)
+  document = document.normalize()
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Set `properties` on mark on text at `offset` and `length` in node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function setMark(state, operation) {
+  const { path, offset, length, mark, properties } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  node = node.updateMark(offset, length, mark, properties)
+  document = document.updateDescendant(node)
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Set `properties` on a node by `key`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function setNode(state, operation) {
+  const { path, properties } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  node = node.merge(properties)
+  document = document.updateDescendant(node)
+  document = document.normalize()
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Set the selection to a new `selection`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function setSelection(state, operation) {
+  let { selection } = operation
+  selection = state.selection.merge(selection)
+  state = state.merge({ selection })
+  return state
+}
+
+/**
+ * Split a node by `key` at `offset`.
+ *
+ * @param {State} state
+ * @param {Object} operation
+ * @return {State}
+ */
+
+function splitNode(state, operation) {
+  const { path, offset } = operation
+  let { document } = state
+  let node = document.assertPath(path)
+  let parent = document.getParent(node)
+  const isParent = document == parent
+  const index = parent.nodes.indexOf(node)
+
+  let child = node
+  let one
+  let two
+
+  if (node.kind != 'text') {
+    child = node.getTextAtOffset(offset)
+  }
+
+  while (child && child != parent) {
+    if (child.kind == 'text') {
+      const i = node.kind == 'text' ? offset : offset - node.getOffset(child)
+      const { characters } = child
+      const oneChars = characters.take(i)
+      const twoChars = characters.skip(i)
+      one = child.merge({ characters: oneChars })
+      two = child.merge({ characters: twoChars, key: uid() })
+    }
+
+    else {
+      const { nodes } = child
+      const oneNodes = nodes.takeUntil(n => n.key == one.key).push(one)
+      const twoNodes = nodes.skipUntil(n => n.key == one.key).rest().unshift(two)
+      one = child.merge({ nodes: oneNodes })
+      two = child.merge({ nodes: twoNodes, key: uid() })
+    }
+
+    child = document.getParent(child)
+  }
+
+  parent = parent.removeNode(index)
+  parent = parent.insertNode(index, two)
+  parent = parent.insertNode(index, one)
+  document = isParent ? parent : document.updateDescendant(parent)
+  state = state.merge({ document })
+  return state
+}
+
+/**
+ * Export.
+ *
+ * @type {Object}
+ */
+
+export default {
+
+  // Text operations.
+  insert_text: insertText,
+  remove_text: removeText,
+
+  // Mark operations.
+  add_mark: addMark,
+  remove_mark: removeMark,
+  set_mark: setMark,
+
+  // Node operations.
+  insert_node: insertNode,
+  move_node: moveNode,
+  remove_node: removeNode,
+  set_node: setNode,
+  split_node: splitNode,
+
+  // Selection operations.
+  set_selection: setSelection,
+
+}