src/model/differ.js
/**
* @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
*/
/**
* @module engine/model/differ
*/
import Position from './position';
import Range from './range';
/**
* Calculates the difference between two model states.
*
* Receives operations that are to be applied on the model document. Marks parts of the model document tree which
* are changed and saves the state of these elements before the change. Then, it compares saved elements with the
* changed elements, after all changes are applied on the model document. Calculates the diff between saved
* elements and new ones and returns a change set.
*/
export default class Differ {
/**
* Creates a `Differ` instance.
*
* @param {module:engine/model/markercollection~MarkerCollection} markerCollection Model's marker collection.
*/
constructor( markerCollection ) {
/**
* Reference to the model's marker collection.
*
* @private
* @type {module:engine/model/markercollection~MarkerCollection}
*/
this._markerCollection = markerCollection;
/**
* A map that stores changes that happened in a given element.
*
* The keys of the map are references to the model elements.
* The values of the map are arrays with changes that were done on this element.
*
* @private
* @type {Map}
*/
this._changesInElement = new Map();
/**
* A map that stores "element's children snapshots". A snapshot is representing children of a given element before
* the first change was applied on that element. Snapshot items are objects with two properties: `name`,
* containing the element name (or `'$text'` for a text node) and `attributes` which is a map of the node's attributes.
*
* @private
* @type {Map}
*/
this._elementSnapshots = new Map();
/**
* A map that stores all changed markers.
*
* The keys of the map are marker names.
* The values of the map are objects with the `oldRange` and `newRange` properties. They store the marker range
* state before and after the change.
*
* @private
* @type {Map}
*/
this._changedMarkers = new Map();
/**
* Stores the number of changes that were processed. Used to order the changes chronologically. It is important
* when changes are sorted.
*
* @private
* @type {Number}
*/
this._changeCount = 0;
/**
* For efficiency purposes, `Differ` stores the change set returned by the differ after {@link #getChanges} call.
* Cache is reset each time a new operation is buffered. If the cache has not been reset, {@link #getChanges} will
* return the cached value instead of calculating it again.
*
* This property stores those changes that did not take place in graveyard root.
*
* @private
* @type {Array.<Object>|null}
*/
this._cachedChanges = null;
/**
* For efficiency purposes, `Differ` stores the change set returned by the differ after the {@link #getChanges} call.
* The cache is reset each time a new operation is buffered. If the cache has not been reset, {@link #getChanges} will
* return the cached value instead of calculating it again.
*
* This property stores all changes evaluated by `Differ`, including those that took place in the graveyard.
*
* @private
* @type {Array.<Object>|null}
*/
this._cachedChangesWithGraveyard = null;
}
/**
* Informs whether there are any changes buffered in `Differ`.
*
* @readonly
* @type {Boolean}
*/
get isEmpty() {
return this._changesInElement.size == 0 && this._changedMarkers.size == 0;
}
/**
* Marks given `item` in differ to be "refreshed". It means that the item will be marked as removed and inserted in the differ changes
* set, so it will be effectively re-converted when differ changes will be handled by a dispatcher.
*
* @param {module:engine/model/item~Item} item Item to refresh.
*/
refreshItem( item ) {
if ( this._isInInsertedElement( item.parent ) ) {
return;
}
this._markRemove( item.parent, item.startOffset, item.offsetSize );
this._markInsert( item.parent, item.startOffset, item.offsetSize );
const range = Range._createOn( item );
for ( const marker of this._markerCollection.getMarkersIntersectingRange( range ) ) {
const markerRange = marker.getRange();
this.bufferMarkerChange( marker.name, markerRange, markerRange, marker.affectsData );
}
// Clear cache after each buffered operation as it is no longer valid.
this._cachedChanges = null;
}
/**
* Buffers the given operation. An operation has to be buffered before it is executed.
*
* Operation type is checked and it is checked which nodes it will affect. These nodes are then stored in `Differ`
* in the state before the operation is executed.
*
* @param {module:engine/model/operation/operation~Operation} operation An operation to buffer.
*/
bufferOperation( operation ) {
// Below we take an operation, check its type, then use its parameters in marking (private) methods.
// The general rule is to not mark elements inside inserted element. All inserted elements are re-rendered.
// Marking changes in them would cause a "double" changing then.
//
switch ( operation.type ) {
case 'insert': {
if ( this._isInInsertedElement( operation.position.parent ) ) {
return;
}
this._markInsert( operation.position.parent, operation.position.offset, operation.nodes.maxOffset );
break;
}
case 'addAttribute':
case 'removeAttribute':
case 'changeAttribute': {
for ( const item of operation.range.getItems( { shallow: true } ) ) {
if ( this._isInInsertedElement( item.parent ) ) {
continue;
}
this._markAttribute( item );
}
break;
}
case 'remove':
case 'move':
case 'reinsert': {
// When range is moved to the same position then not mark it as a change.
// See: https://github.com/ckeditor/ckeditor5-engine/issues/1664.
if (
operation.sourcePosition.isEqual( operation.targetPosition ) ||
operation.sourcePosition.getShiftedBy( operation.howMany ).isEqual( operation.targetPosition )
) {
return;
}
const sourceParentInserted = this._isInInsertedElement( operation.sourcePosition.parent );
const targetParentInserted = this._isInInsertedElement( operation.targetPosition.parent );
if ( !sourceParentInserted ) {
this._markRemove( operation.sourcePosition.parent, operation.sourcePosition.offset, operation.howMany );
}
if ( !targetParentInserted ) {
this._markInsert( operation.targetPosition.parent, operation.getMovedRangeStart().offset, operation.howMany );
}
break;
}
case 'rename': {
if ( this._isInInsertedElement( operation.position.parent ) ) {
return;
}
this._markRemove( operation.position.parent, operation.position.offset, 1 );
this._markInsert( operation.position.parent, operation.position.offset, 1 );
const range = Range._createFromPositionAndShift( operation.position, 1 );
for ( const marker of this._markerCollection.getMarkersIntersectingRange( range ) ) {
const markerRange = marker.getRange();
this.bufferMarkerChange( marker.name, markerRange, markerRange, marker.affectsData );
}
break;
}
case 'split': {
const splitElement = operation.splitPosition.parent;
// Mark that children of the split element were removed.
if ( !this._isInInsertedElement( splitElement ) ) {
this._markRemove( splitElement, operation.splitPosition.offset, operation.howMany );
}
// Mark that the new element (split copy) was inserted.
if ( !this._isInInsertedElement( operation.insertionPosition.parent ) ) {
this._markInsert( operation.insertionPosition.parent, operation.insertionPosition.offset, 1 );
}
// If the split took the element from the graveyard, mark that the element from the graveyard was removed.
if ( operation.graveyardPosition ) {
this._markRemove( operation.graveyardPosition.parent, operation.graveyardPosition.offset, 1 );
}
break;
}
case 'merge': {
// Mark that the merged element was removed.
const mergedElement = operation.sourcePosition.parent;
if ( !this._isInInsertedElement( mergedElement.parent ) ) {
this._markRemove( mergedElement.parent, mergedElement.startOffset, 1 );
}
// Mark that the merged element was inserted into graveyard.
const graveyardParent = operation.graveyardPosition.parent;
this._markInsert( graveyardParent, operation.graveyardPosition.offset, 1 );
// Mark that children of merged element were inserted at new parent.
const mergedIntoElement = operation.targetPosition.parent;
if ( !this._isInInsertedElement( mergedIntoElement ) ) {
this._markInsert( mergedIntoElement, operation.targetPosition.offset, mergedElement.maxOffset );
}
break;
}
}
// Clear cache after each buffered operation as it is no longer valid.
this._cachedChanges = null;
}
/**
* Buffers a marker change.
*
* @param {String} markerName The name of the marker that changed.
* @param {module:engine/model/range~Range|null} oldRange Marker range before the change or `null` if the marker has just
* been created.
* @param {module:engine/model/range~Range|null} newRange Marker range after the change or `null` if the marker was removed.
* @param {Boolean} affectsData Flag indicating whether marker affects the editor data.
*/
bufferMarkerChange( markerName, oldRange, newRange, affectsData ) {
const buffered = this._changedMarkers.get( markerName );
if ( !buffered ) {
this._changedMarkers.set( markerName, {
oldRange,
newRange,
affectsData
} );
} else {
buffered.newRange = newRange;
buffered.affectsData = affectsData;
if ( buffered.oldRange == null && buffered.newRange == null ) {
// The marker is going to be removed (`newRange == null`) but it did not exist before the first buffered change
// (`buffered.oldRange == null`). In this case, do not keep the marker in buffer at all.
this._changedMarkers.delete( markerName );
}
}
}
/**
* Returns all markers that should be removed as a result of buffered changes.
*
* @returns {Array.<Object>} Markers to remove. Each array item is an object containing the `name` and `range` properties.
*/
getMarkersToRemove() {
const result = [];
for ( const [ name, change ] of this._changedMarkers ) {
if ( change.oldRange != null ) {
result.push( { name, range: change.oldRange } );
}
}
return result;
}
/**
* Returns all markers which should be added as a result of buffered changes.
*
* @returns {Array.<Object>} Markers to add. Each array item is an object containing the `name` and `range` properties.
*/
getMarkersToAdd() {
const result = [];
for ( const [ name, change ] of this._changedMarkers ) {
if ( change.newRange != null ) {
result.push( { name, range: change.newRange } );
}
}
return result;
}
/**
* Returns all markers which changed.
*
* @returns {Array.<Object>}
*/
getChangedMarkers() {
return Array.from( this._changedMarkers ).map( item => (
{
name: item[ 0 ],
data: {
oldRange: item[ 1 ].oldRange,
newRange: item[ 1 ].newRange
}
}
) );
}
/**
* Checks whether some of the buffered changes affect the editor data.
*
* Types of changes which affect the editor data:
*
* * model structure changes,
* * attribute changes,
* * changes of markers which were defined as `affectingData`.
*
* @returns {Boolean}
*/
hasDataChanges() {
for ( const [ , change ] of this._changedMarkers ) {
if ( change.affectsData ) {
return true;
}
}
// If markers do not affect the data, check whether there are some changes in elements.
return this._changesInElement.size > 0;
}
/**
* Calculates the diff between the old model tree state (the state before the first buffered operations since the last {@link #reset}
* call) and the new model tree state (actual one). It should be called after all buffered operations are executed.
*
* The diff set is returned as an array of diff items, each describing a change done on the model. The items are sorted by
* the position on which the change happened. If a position {@link module:engine/model/position~Position#isBefore is before}
* another one, it will be on an earlier index in the diff set.
*
* Because calculating the diff is a costly operation, the result is cached. If no new operation was buffered since the
* previous {@link #getChanges} call, the next call will return the cached value.
*
* @param {Object} options Additional options.
* @param {Boolean} [options.includeChangesInGraveyard=false] If set to `true`, also changes that happened
* in the graveyard root will be returned. By default, changes in the graveyard root are not returned.
* @returns {Array.<Object>} Diff between the old and the new model tree state.
*/
getChanges( options = { includeChangesInGraveyard: false } ) {
// If there are cached changes, just return them instead of calculating changes again.
if ( this._cachedChanges ) {
if ( options.includeChangesInGraveyard ) {
return this._cachedChangesWithGraveyard.slice();
} else {
return this._cachedChanges.slice();
}
}
// Will contain returned results.
const diffSet = [];
// Check all changed elements.
for ( const element of this._changesInElement.keys() ) {
// Get changes for this element and sort them.
const changes = this._changesInElement.get( element ).sort( ( a, b ) => {
if ( a.offset === b.offset ) {
if ( a.type != b.type ) {
// If there are multiple changes at the same position, "remove" change should be first.
// If the order is different, for example, we would first add some nodes and then removed them
// (instead of the nodes that we should remove).
return a.type == 'remove' ? -1 : 1;
}
return 0;
}
return a.offset < b.offset ? -1 : 1;
} );
// Get children of this element before any change was applied on it.
const snapshotChildren = this._elementSnapshots.get( element );
// Get snapshot of current element's children.
const elementChildren = _getChildrenSnapshot( element.getChildren() );
// Generate actions basing on changes done on element.
const actions = _generateActionsFromChanges( snapshotChildren.length, changes );
let i = 0; // Iterator in `elementChildren` array -- iterates through current children of element.
let j = 0; // Iterator in `snapshotChildren` array -- iterates through old children of element.
// Process every action.
for ( const action of actions ) {
if ( action === 'i' ) {
// Generate diff item for this element and insert it into the diff set.
diffSet.push( this._getInsertDiff( element, i, elementChildren[ i ].name ) );
i++;
} else if ( action === 'r' ) {
// Generate diff item for this element and insert it into the diff set.
diffSet.push( this._getRemoveDiff( element, i, snapshotChildren[ j ].name ) );
j++;
} else if ( action === 'a' ) {
// Take attributes from saved and current children.
const elementAttributes = elementChildren[ i ].attributes;
const snapshotAttributes = snapshotChildren[ j ].attributes;
let range;
if ( elementChildren[ i ].name == '$text' ) {
range = new Range( Position._createAt( element, i ), Position._createAt( element, i + 1 ) );
} else {
const index = element.offsetToIndex( i );
range = new Range( Position._createAt( element, i ), Position._createAt( element.getChild( index ), 0 ) );
}
// Generate diff items for this change (there might be multiple attributes changed and
// there is a single diff for each of them) and insert them into the diff set.
diffSet.push( ...this._getAttributesDiff( range, snapshotAttributes, elementAttributes ) );
i++;
j++;
} else {
// `action` is 'equal'. Child not changed.
i++;
j++;
}
}
}
// Then, sort the changes by the position (change at position before other changes is first).
diffSet.sort( ( a, b ) => {
// If the change is in different root, we don't care much, but we'd like to have all changes in given
// root "together" in the array. So let's just sort them by the root name. It does not matter which root
// will be processed first.
if ( a.position.root != b.position.root ) {
return a.position.root.rootName < b.position.root.rootName ? -1 : 1;
}
// If change happens at the same position...
if ( a.position.isEqual( b.position ) ) {
// Keep chronological order of operations.
return a.changeCount - b.changeCount;
}
// If positions differ, position "on the left" should be earlier in the result.
return a.position.isBefore( b.position ) ? -1 : 1;
} );
// Glue together multiple changes (mostly on text nodes).
for ( let i = 1; i < diffSet.length; i++ ) {
const prevDiff = diffSet[ i - 1 ];
const thisDiff = diffSet[ i ];
// Glue remove changes if they happen on text on same position.
const isConsecutiveTextRemove =
prevDiff.type == 'remove' && thisDiff.type == 'remove' &&
prevDiff.name == '$text' && thisDiff.name == '$text' &&
prevDiff.position.isEqual( thisDiff.position );
// Glue insert changes if they happen on text on consecutive fragments.
const isConsecutiveTextAdd =
prevDiff.type == 'insert' && thisDiff.type == 'insert' &&
prevDiff.name == '$text' && thisDiff.name == '$text' &&
prevDiff.position.parent == thisDiff.position.parent &&
prevDiff.position.offset + prevDiff.length == thisDiff.position.offset;
// Glue attribute changes if they happen on consecutive fragments and have same key, old value and new value.
const isConsecutiveAttributeChange =
prevDiff.type == 'attribute' && thisDiff.type == 'attribute' &&
prevDiff.position.parent == thisDiff.position.parent &&
prevDiff.range.isFlat && thisDiff.range.isFlat &&
prevDiff.position.offset + prevDiff.length == thisDiff.position.offset &&
prevDiff.attributeKey == thisDiff.attributeKey &&
prevDiff.attributeOldValue == thisDiff.attributeOldValue &&
prevDiff.attributeNewValue == thisDiff.attributeNewValue;
if ( isConsecutiveTextRemove || isConsecutiveTextAdd || isConsecutiveAttributeChange ) {
diffSet[ i - 1 ].length++;
if ( isConsecutiveAttributeChange ) {
diffSet[ i - 1 ].range.end = diffSet[ i - 1 ].range.end.getShiftedBy( 1 );
}
diffSet.splice( i, 1 );
i--;
}
}
// Remove `changeCount` property from diff items. It is used only for sorting and is internal thing.
for ( const item of diffSet ) {
delete item.changeCount;
if ( item.type == 'attribute' ) {
delete item.position;
delete item.length;
}
}
this._changeCount = 0;
// Cache changes.
this._cachedChangesWithGraveyard = diffSet.slice();
this._cachedChanges = diffSet.slice().filter( _changesInGraveyardFilter );
if ( options.includeChangesInGraveyard ) {
return this._cachedChangesWithGraveyard;
} else {
return this._cachedChanges;
}
}
/**
* Resets `Differ`. Removes all buffered changes.
*/
reset() {
this._changesInElement.clear();
this._elementSnapshots.clear();
this._changedMarkers.clear();
this._cachedChanges = null;
}
/**
* Saves and handles an insert change.
*
* @private
* @param {module:engine/model/element~Element} parent
* @param {Number} offset
* @param {Number} howMany
*/
_markInsert( parent, offset, howMany ) {
const changeItem = { type: 'insert', offset, howMany, count: this._changeCount++ };
this._markChange( parent, changeItem );
}
/**
* Saves and handles a remove change.
*
* @private
* @param {module:engine/model/element~Element} parent
* @param {Number} offset
* @param {Number} howMany
*/
_markRemove( parent, offset, howMany ) {
const changeItem = { type: 'remove', offset, howMany, count: this._changeCount++ };
this._markChange( parent, changeItem );
this._removeAllNestedChanges( parent, offset, howMany );
}
/**
* Saves and handles an attribute change.
*
* @private
* @param {module:engine/model/item~Item} item
*/
_markAttribute( item ) {
const changeItem = { type: 'attribute', offset: item.startOffset, howMany: item.offsetSize, count: this._changeCount++ };
this._markChange( item.parent, changeItem );
}
/**
* Saves and handles a model change.
*
* @private
* @param {module:engine/model/element~Element} parent
* @param {Object} changeItem
*/
_markChange( parent, changeItem ) {
// First, make a snapshot of this parent's children (it will be made only if it was not made before).
this._makeSnapshot( parent );
// Then, get all changes that already were done on the element (empty array if this is the first change).
const changes = this._getChangesForElement( parent );
// Then, look through all the changes, and transform them or the new change.
this._handleChange( changeItem, changes );
// Add the new change.
changes.push( changeItem );
// Remove incorrect changes. During transformation some change might be, for example, included in another.
// In that case, the change will have `howMany` property set to `0` or less. We need to remove those changes.
for ( let i = 0; i < changes.length; i++ ) {
if ( changes[ i ].howMany < 1 ) {
changes.splice( i, 1 );
i--;
}
}
}
/**
* Gets an array of changes that have already been saved for a given element.
*
* @private
* @param {module:engine/model/element~Element} element
* @returns {Array.<Object>}
*/
_getChangesForElement( element ) {
let changes;
if ( this._changesInElement.has( element ) ) {
changes = this._changesInElement.get( element );
} else {
changes = [];
this._changesInElement.set( element, changes );
}
return changes;
}
/**
* Saves a children snapshot for a given element.
*
* @private
* @param {module:engine/model/element~Element} element
*/
_makeSnapshot( element ) {
if ( !this._elementSnapshots.has( element ) ) {
this._elementSnapshots.set( element, _getChildrenSnapshot( element.getChildren() ) );
}
}
/**
* For a given newly saved change, compares it with a change already done on the element and modifies the incoming
* change and/or the old change.
*
* @private
* @param {Object} inc Incoming (new) change.
* @param {Array.<Object>} changes An array containing all the changes done on that element.
*/
_handleChange( inc, changes ) {
// We need a helper variable that will store how many nodes are to be still handled for this change item.
// `nodesToHandle` (how many nodes still need to be handled) and `howMany` (how many nodes were affected)
// needs to be differentiated.
//
// This comes up when there are multiple changes that are affected by `inc` change item.
//
// For example: assume two insert changes: `{ offset: 2, howMany: 1 }` and `{ offset: 5, howMany: 1 }`.
// Assume that `inc` change is remove `{ offset: 2, howMany: 2, nodesToHandle: 2 }`.
//
// Then, we:
// - "forget" about first insert change (it is "eaten" by remove),
// - because of that, at the end we will want to remove only one node (`nodesToHandle = 1`),
// - but still we have to change offset of the second insert change from `5` to `3`!
//
// So, `howMany` does not change throughout items transformation and keeps information about how many nodes were affected,
// while `nodesToHandle` means how many nodes need to be handled after the change item is transformed by other changes.
inc.nodesToHandle = inc.howMany;
for ( const old of changes ) {
const incEnd = inc.offset + inc.howMany;
const oldEnd = old.offset + old.howMany;
if ( inc.type == 'insert' ) {
if ( old.type == 'insert' ) {
if ( inc.offset <= old.offset ) {
old.offset += inc.howMany;
} else if ( inc.offset < oldEnd ) {
old.howMany += inc.nodesToHandle;
inc.nodesToHandle = 0;
}
}
if ( old.type == 'remove' ) {
if ( inc.offset < old.offset ) {
old.offset += inc.howMany;
}
}
if ( old.type == 'attribute' ) {
if ( inc.offset <= old.offset ) {
old.offset += inc.howMany;
} else if ( inc.offset < oldEnd ) {
// This case is more complicated, because attribute change has to be split into two.
// Example (assume that uppercase and lowercase letters mean different attributes):
//
// initial state: abcxyz
// attribute change: aBCXYz
// incoming insert: aBCfooXYz
//
// Change ranges cannot intersect because each item has to be described exactly (it was either
// not changed, inserted, removed, or its attribute was changed). That's why old attribute
// change has to be split and both parts has to be handled separately from now on.
const howMany = old.howMany;
old.howMany = inc.offset - old.offset;
// Add the second part of attribute change to the beginning of processed array so it won't
// be processed again in this loop.
changes.unshift( {
type: 'attribute',
offset: incEnd,
howMany: howMany - old.howMany,
count: this._changeCount++
} );
}
}
}
if ( inc.type == 'remove' ) {
if ( old.type == 'insert' ) {
if ( incEnd <= old.offset ) {
old.offset -= inc.howMany;
} else if ( incEnd <= oldEnd ) {
if ( inc.offset < old.offset ) {
const intersectionLength = incEnd - old.offset;
old.offset = inc.offset;
old.howMany -= intersectionLength;
inc.nodesToHandle -= intersectionLength;
} else {
old.howMany -= inc.nodesToHandle;
inc.nodesToHandle = 0;
}
} else {
if ( inc.offset <= old.offset ) {
inc.nodesToHandle -= old.howMany;
old.howMany = 0;
} else if ( inc.offset < oldEnd ) {
const intersectionLength = oldEnd - inc.offset;
old.howMany -= intersectionLength;
inc.nodesToHandle -= intersectionLength;
}
}
}
if ( old.type == 'remove' ) {
if ( incEnd <= old.offset ) {
old.offset -= inc.howMany;
} else if ( inc.offset < old.offset ) {
inc.nodesToHandle += old.howMany;
old.howMany = 0;
}
}
if ( old.type == 'attribute' ) {
if ( incEnd <= old.offset ) {
old.offset -= inc.howMany;
} else if ( inc.offset < old.offset ) {
const intersectionLength = incEnd - old.offset;
old.offset = inc.offset;
old.howMany -= intersectionLength;
} else if ( inc.offset < oldEnd ) {
if ( incEnd <= oldEnd ) {
// On first sight in this case we don't need to split attribute operation into two.
// However the changes set is later converted to actions (see `_generateActionsFromChanges`).
// For that reason, no two changes may intersect.
// So we cannot have an attribute change that "contains" remove change.
// Attribute change needs to be split.
const howMany = old.howMany;
old.howMany = inc.offset - old.offset;
const howManyAfter = howMany - old.howMany - inc.nodesToHandle;
// Add the second part of attribute change to the beginning of processed array so it won't
// be processed again in this loop.
changes.unshift( {
type: 'attribute',
offset: inc.offset,
howMany: howManyAfter,
count: this._changeCount++
} );
} else {
old.howMany -= oldEnd - inc.offset;
}
}
}
}
if ( inc.type == 'attribute' ) {
// In case of attribute change, `howMany` should be kept same as `nodesToHandle`. It's not an error.
if ( old.type == 'insert' ) {
if ( inc.offset < old.offset && incEnd > old.offset ) {
if ( incEnd > oldEnd ) {
// This case is similar to a case described when incoming change was insert and old change was attribute.
// See comment above.
//
// This time incoming change is attribute. We need to split incoming change in this case too.
// However this time, the second part of the attribute change needs to be processed further
// because there might be other changes that it collides with.
const attributePart = {
type: 'attribute',
offset: oldEnd,
howMany: incEnd - oldEnd,
count: this._changeCount++
};
this._handleChange( attributePart, changes );
changes.push( attributePart );
}
inc.nodesToHandle = old.offset - inc.offset;
inc.howMany = inc.nodesToHandle;
} else if ( inc.offset >= old.offset && inc.offset < oldEnd ) {
if ( incEnd > oldEnd ) {
inc.nodesToHandle = incEnd - oldEnd;
inc.offset = oldEnd;
} else {
inc.nodesToHandle = 0;
}
}
}
if ( old.type == 'remove' ) {
// This is a case when attribute change "contains" remove change.
// The attribute change needs to be split into two because changes cannot intersect.
if ( inc.offset < old.offset && incEnd > old.offset ) {
const attributePart = {
type: 'attribute',
offset: old.offset,
howMany: incEnd - old.offset,
count: this._changeCount++
};
this._handleChange( attributePart, changes );
changes.push( attributePart );
inc.nodesToHandle = old.offset - inc.offset;
inc.howMany = inc.nodesToHandle;
}
}
if ( old.type == 'attribute' ) {
// There are only two conflicting scenarios possible here:
if ( inc.offset >= old.offset && incEnd <= oldEnd ) {
// `old` change includes `inc` change, or they are the same.
inc.nodesToHandle = 0;
inc.howMany = 0;
inc.offset = 0;
} else if ( inc.offset <= old.offset && incEnd >= oldEnd ) {
// `inc` change includes `old` change.
old.howMany = 0;
}
}
}
}
inc.howMany = inc.nodesToHandle;
delete inc.nodesToHandle;
}
/**
* Returns an object with a single insert change description.
*
* @private
* @param {module:engine/model/element~Element} parent The element in which the change happened.
* @param {Number} offset The offset at which change happened.
* @param {String} name The name of the removed element or `'$text'` for a character.
* @returns {Object} The diff item.
*/
_getInsertDiff( parent, offset, name ) {
return {
type: 'insert',
position: Position._createAt( parent, offset ),
name,
length: 1,
changeCount: this._changeCount++
};
}
/**
* Returns an object with a single remove change description.
*
* @private
* @param {module:engine/model/element~Element} parent The element in which change happened.
* @param {Number} offset The offset at which change happened.
* @param {String} name The name of the removed element or `'$text'` for a character.
* @returns {Object} The diff item.
*/
_getRemoveDiff( parent, offset, name ) {
return {
type: 'remove',
position: Position._createAt( parent, offset ),
name,
length: 1,
changeCount: this._changeCount++
};
}
/**
* Returns an array of objects where each one is a single attribute change description.
*
* @private
* @param {module:engine/model/range~Range} range The range where the change happened.
* @param {Map} oldAttributes A map, map iterator or compatible object that contains attributes before the change.
* @param {Map} newAttributes A map, map iterator or compatible object that contains attributes after the change.
* @returns {Array.<Object>} An array containing one or more diff items.
*/
_getAttributesDiff( range, oldAttributes, newAttributes ) {
// Results holder.
const diffs = [];
// Clone new attributes as we will be performing changes on this object.
newAttributes = new Map( newAttributes );
// Look through old attributes.
for ( const [ key, oldValue ] of oldAttributes ) {
// Check what is the new value of the attribute (or if it was removed).
const newValue = newAttributes.has( key ) ? newAttributes.get( key ) : null;
// If values are different (or attribute was removed)...
if ( newValue !== oldValue ) {
// Add diff item.
diffs.push( {
type: 'attribute',
position: range.start,
range: range.clone(),
length: 1,
attributeKey: key,
attributeOldValue: oldValue,
attributeNewValue: newValue,
changeCount: this._changeCount++
} );
}
// Prevent returning two diff items for the same change.
newAttributes.delete( key );
}
// Look through new attributes that weren't handled above.
for ( const [ key, newValue ] of newAttributes ) {
// Each of them is a new attribute. Add diff item.
diffs.push( {
type: 'attribute',
position: range.start,
range: range.clone(),
length: 1,
attributeKey: key,
attributeOldValue: null,
attributeNewValue: newValue,
changeCount: this._changeCount++
} );
}
return diffs;
}
/**
* Checks whether given element or any of its parents is an element that is buffered as an inserted element.
*
* @private
* @param {module:engine/model/element~Element} element Element to check.
* @returns {Boolean}
*/
_isInInsertedElement( element ) {
const parent = element.parent;
if ( !parent ) {
return false;
}
const changes = this._changesInElement.get( parent );
const offset = element.startOffset;
if ( changes ) {
for ( const change of changes ) {
if ( change.type == 'insert' && offset >= change.offset && offset < change.offset + change.howMany ) {
return true;
}
}
}
return this._isInInsertedElement( parent );
}
/**
* Removes deeply all buffered changes that are registered in elements from range specified by `parent`, `offset`
* and `howMany`.
*
* @private
* @param {module:engine/model/element~Element} parent
* @param {Number} offset
* @param {Number} howMany
*/
_removeAllNestedChanges( parent, offset, howMany ) {
const range = new Range( Position._createAt( parent, offset ), Position._createAt( parent, offset + howMany ) );
for ( const item of range.getItems( { shallow: true } ) ) {
if ( item.is( 'element' ) ) {
this._elementSnapshots.delete( item );
this._changesInElement.delete( item );
this._removeAllNestedChanges( item, 0, item.maxOffset );
}
}
}
}
// Returns an array that is a copy of passed child list with the exception that text nodes are split to one or more
// objects, each representing one character and attributes set on that character.
function _getChildrenSnapshot( children ) {
const snapshot = [];
for ( const child of children ) {
if ( child.is( 'text' ) ) {
for ( let i = 0; i < child.data.length; i++ ) {
snapshot.push( {
name: '$text',
attributes: new Map( child.getAttributes() )
} );
}
} else {
snapshot.push( {
name: child.name,
attributes: new Map( child.getAttributes() )
} );
}
}
return snapshot;
}
// Generates array of actions for given changes set.
// It simulates what `diff` function does.
// Generated actions are:
// - 'e' for 'equal' - when item at that position did not change,
// - 'i' for 'insert' - when item at that position was inserted,
// - 'r' for 'remove' - when item at that position was removed,
// - 'a' for 'attribute' - when item at that position has it attributes changed.
//
// Example (assume that uppercase letters have bold attribute, compare with function code):
//
// children before: fooBAR
// children after: foxybAR
//
// changes: type: remove, offset: 1, howMany: 1
// type: insert, offset: 2, howMany: 2
// type: attribute, offset: 4, howMany: 1
//
// expected actions: equal (f), remove (o), equal (o), insert (x), insert (y), attribute (b), equal (A), equal (R)
//
// steps taken by th script:
//
// 1. change = "type: remove, offset: 1, howMany: 1"; offset = 0; oldChildrenHandled = 0
// 1.1 between this change and the beginning is one not-changed node, fill with one equal action, one old child has been handled
// 1.2 this change removes one node, add one remove action
// 1.3 change last visited `offset` to 1
// 1.4 since an old child has been removed, one more old child has been handled
// 1.5 actions at this point are: equal, remove
//
// 2. change = "type: insert, offset: 2, howMany: 2"; offset = 1; oldChildrenHandled = 2
// 2.1 between this change and previous change is one not-changed node, add equal action, another one old children has been handled
// 2.2 this change inserts two nodes, add two insert actions
// 2.3 change last visited offset to the end of the inserted range, that is 4
// 2.4 actions at this point are: equal, remove, equal, insert, insert
//
// 3. change = "type: attribute, offset: 4, howMany: 1"; offset = 4, oldChildrenHandled = 3
// 3.1 between this change and previous change are no not-changed nodes
// 3.2 this change changes one node, add one attribute action
// 3.3 change last visited `offset` to the end of change range, that is 5
// 3.4 since an old child has been changed, one more old child has been handled
// 3.5 actions at this point are: equal, remove, equal, insert, insert, attribute
//
// 4. after loop oldChildrenHandled = 4, oldChildrenLength = 6 (fooBAR is 6 characters)
// 4.1 fill up with two equal actions
//
// The result actions are: equal, remove, equal, insert, insert, attribute, equal, equal.
function _generateActionsFromChanges( oldChildrenLength, changes ) {
const actions = [];
let offset = 0;
let oldChildrenHandled = 0;
// Go through all buffered changes.
for ( const change of changes ) {
// First, fill "holes" between changes with "equal" actions.
if ( change.offset > offset ) {
for ( let i = 0; i < change.offset - offset; i++ ) {
actions.push( 'e' );
}
oldChildrenHandled += change.offset - offset;
}
// Then, fill up actions accordingly to change type.
if ( change.type == 'insert' ) {
for ( let i = 0; i < change.howMany; i++ ) {
actions.push( 'i' );
}
// The last handled offset is after inserted range.
offset = change.offset + change.howMany;
} else if ( change.type == 'remove' ) {
for ( let i = 0; i < change.howMany; i++ ) {
actions.push( 'r' );
}
// The last handled offset is at the position where the nodes were removed.
offset = change.offset;
// We removed `howMany` old nodes, update `oldChildrenHandled`.
oldChildrenHandled += change.howMany;
} else {
actions.push( ...'a'.repeat( change.howMany ).split( '' ) );
// The last handled offset is at the position after the changed range.
offset = change.offset + change.howMany;
// We changed `howMany` old nodes, update `oldChildrenHandled`.
oldChildrenHandled += change.howMany;
}
}
// Fill "equal" actions at the end of actions set. Use `oldChildrenHandled` to see how many children
// has not been changed / removed at the end of their parent.
if ( oldChildrenHandled < oldChildrenLength ) {
for ( let i = 0; i < oldChildrenLength - oldChildrenHandled - offset; i++ ) {
actions.push( 'e' );
}
}
return actions;
}
// Filter callback for Array.filter that filters out change entries that are in graveyard.
function _changesInGraveyardFilter( entry ) {
const posInGy = entry.position && entry.position.root.rootName == '$graveyard';
const rangeInGy = entry.range && entry.range.root.rootName == '$graveyard';
return !posInGy && !rangeInGy;
}