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- /**
- * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
- * For licensing, see LICENSE.md.
- */
- /**
- * @module engine/model/treewalker
- */
- import Text from './text';
- import TextProxy from './textproxy';
- import Element from './element';
- import Position from './position';
- import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
- /**
- * Position iterator class. It allows to iterate forward and backward over the document.
- */
- export default class TreeWalker {
- /**
- * Creates a range iterator. All parameters are optional, but you have to specify either `boundaries` or `startPosition`.
- *
- * @constructor
- * @param {Object} [options={}] Object with configuration.
- * @param {'forward'|'backward'} [options.direction='forward'] Walking direction.
- * @param {module:engine/model/range~Range} [options.boundaries=null] Range to define boundaries of the iterator.
- * @param {module:engine/model/position~Position} [options.startPosition] Starting position.
- * @param {Boolean} [options.singleCharacters=false] Flag indicating whether all consecutive characters with the same attributes
- * should be returned one by one as multiple {@link module:engine/model/textproxy~TextProxy} (`true`) objects or as one
- * {@link module:engine/model/textproxy~TextProxy} (`false`).
- * @param {Boolean} [options.shallow=false] Flag indicating whether iterator should enter elements or not. If the
- * iterator is shallow child nodes of any iterated node will not be returned along with `elementEnd` tag.
- * @param {Boolean} [options.ignoreElementEnd=false] Flag indicating whether iterator should ignore `elementEnd`
- * tags. If the option is true walker will not return a parent node of start position. If this option is `true`
- * each {@link module:engine/model/element~Element} will be returned once, while if the option is `false` they might be returned
- * twice: for `'elementStart'` and `'elementEnd'`.
- */
- constructor( options = {} ) {
- if ( !options.boundaries && !options.startPosition ) {
- /**
- * Neither boundaries nor starting position of a `TreeWalker` have been defined.
- *
- * @error model-tree-walker-no-start-position
- */
- throw new CKEditorError( 'model-tree-walker-no-start-position: Neither boundaries nor starting position have been defined.' );
- }
- const direction = options.direction || 'forward';
- if ( direction != 'forward' && direction != 'backward' ) {
- throw new CKEditorError(
- 'model-tree-walker-unknown-direction: Only `backward` and `forward` direction allowed.',
- { direction }
- );
- }
- /**
- * Walking direction. Defaults `'forward'`.
- *
- * @readonly
- * @member {'backward'|'forward'} module:engine/model/treewalker~TreeWalker#direction
- */
- this.direction = direction;
- /**
- * Iterator boundaries.
- *
- * When the iterator is walking `'forward'` on the end of boundary or is walking `'backward'`
- * on the start of boundary, then `{ done: true }` is returned.
- *
- * If boundaries are not defined they are set before first and after last child of the root node.
- *
- * @readonly
- * @member {module:engine/model/range~Range} module:engine/model/treewalker~TreeWalker#boundaries
- */
- this.boundaries = options.boundaries || null;
- /**
- * Iterator position. This is always static position, even if the initial position was a
- * {@link module:engine/model/liveposition~LivePosition live position}. If start position is not defined then position depends
- * on {@link #direction}. If direction is `'forward'` position starts form the beginning, when direction
- * is `'backward'` position starts from the end.
- *
- * @readonly
- * @member {module:engine/model/position~Position} module:engine/model/treewalker~TreeWalker#position
- */
- if ( options.startPosition ) {
- this.position = Position._createAt( options.startPosition );
- } else {
- this.position = Position._createAt( this.boundaries[ this.direction == 'backward' ? 'end' : 'start' ] );
- }
- // Reset position stickiness in case it was set to other value, as the stickiness is kept after cloning.
- this.position.stickiness = 'toNone';
- /**
- * Flag indicating whether all consecutive characters with the same attributes should be
- * returned as one {@link module:engine/model/textproxy~TextProxy} (`true`) or one by one (`false`).
- *
- * @readonly
- * @member {Boolean} module:engine/model/treewalker~TreeWalker#singleCharacters
- */
- this.singleCharacters = !!options.singleCharacters;
- /**
- * Flag indicating whether iterator should enter elements or not. If the iterator is shallow child nodes of any
- * iterated node will not be returned along with `elementEnd` tag.
- *
- * @readonly
- * @member {Boolean} module:engine/model/treewalker~TreeWalker#shallow
- */
- this.shallow = !!options.shallow;
- /**
- * Flag indicating whether iterator should ignore `elementEnd` tags. If the option is true walker will not
- * return a parent node of the start position. If this option is `true` each {@link module:engine/model/element~Element} will
- * be returned once, while if the option is `false` they might be returned twice:
- * for `'elementStart'` and `'elementEnd'`.
- *
- * @readonly
- * @member {Boolean} module:engine/model/treewalker~TreeWalker#ignoreElementEnd
- */
- this.ignoreElementEnd = !!options.ignoreElementEnd;
- /**
- * Start boundary cached for optimization purposes.
- *
- * @private
- * @member {module:engine/model/element~Element} module:engine/model/treewalker~TreeWalker#_boundaryStartParent
- */
- this._boundaryStartParent = this.boundaries ? this.boundaries.start.parent : null;
- /**
- * End boundary cached for optimization purposes.
- *
- * @private
- * @member {module:engine/model/element~Element} module:engine/model/treewalker~TreeWalker#_boundaryEndParent
- */
- this._boundaryEndParent = this.boundaries ? this.boundaries.end.parent : null;
- /**
- * Parent of the most recently visited node. Cached for optimization purposes.
- *
- * @private
- * @member {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment}
- * module:engine/model/treewalker~TreeWalker#_visitedParent
- */
- this._visitedParent = this.position.parent;
- }
- /**
- * Iterable interface.
- *
- * @returns {Iterable.<module:engine/model/treewalker~TreeWalkerValue>}
- */
- [ Symbol.iterator ]() {
- return this;
- }
- /**
- * Moves {@link #position} in the {@link #direction} skipping values as long as the callback function returns `true`.
- *
- * For example:
- *
- * walker.skip( value => value.type == 'text' ); // <paragraph>[]foo</paragraph> -> <paragraph>foo[]</paragraph>
- * walker.skip( () => true ); // Move the position to the end: <paragraph>[]foo</paragraph> -> <paragraph>foo</paragraph>[]
- * walker.skip( () => false ); // Do not move the position.
- *
- * @param {Function} skip Callback function. Gets {@link module:engine/model/treewalker~TreeWalkerValue} and should
- * return `true` if the value should be skipped or `false` if not.
- */
- skip( skip ) {
- let done, value, prevPosition, prevVisitedParent;
- do {
- prevPosition = this.position;
- prevVisitedParent = this._visitedParent;
- ( { done, value } = this.next() );
- } while ( !done && skip( value ) );
- if ( !done ) {
- this.position = prevPosition;
- this._visitedParent = prevVisitedParent;
- }
- }
- /**
- * Gets the next tree walker's value.
- *
- * @returns {module:engine/model/treewalker~TreeWalkerValue} Next tree walker's value.
- */
- next() {
- if ( this.direction == 'forward' ) {
- return this._next();
- } else {
- return this._previous();
- }
- }
- /**
- * Makes a step forward in model. Moves the {@link #position} to the next position and returns the encountered value.
- *
- * @private
- * @returns {Object}
- * @returns {Boolean} return.done True if iterator is done.
- * @returns {module:engine/model/treewalker~TreeWalkerValue} return.value Information about taken step.
- */
- _next() {
- const previousPosition = this.position;
- const position = Position._createAt( this.position );
- const parent = this._visitedParent;
- // We are at the end of the root.
- if ( parent.parent === null && position.offset === parent.maxOffset ) {
- return { done: true };
- }
- // We reached the walker boundary.
- if ( parent === this._boundaryEndParent && position.offset == this.boundaries.end.offset ) {
- return { done: true };
- }
- const node = position.textNode ? position.textNode : position.nodeAfter;
- if ( node instanceof Element ) {
- if ( !this.shallow ) {
- // Manual operations on path internals for optimization purposes. Here and in the rest of the method.
- position.path.push( 0 );
- this._visitedParent = node;
- } else {
- position.offset++;
- }
- this.position = position;
- return formatReturnValue( 'elementStart', node, previousPosition, position, 1 );
- } else if ( node instanceof Text ) {
- let charactersCount;
- if ( this.singleCharacters ) {
- charactersCount = 1;
- } else {
- let offset = node.endOffset;
- if ( this._boundaryEndParent == parent && this.boundaries.end.offset < offset ) {
- offset = this.boundaries.end.offset;
- }
- charactersCount = offset - position.offset;
- }
- const offsetInTextNode = position.offset - node.startOffset;
- const item = new TextProxy( node, offsetInTextNode, charactersCount );
- position.offset += charactersCount;
- this.position = position;
- return formatReturnValue( 'text', item, previousPosition, position, charactersCount );
- } else {
- // `node` is not set, we reached the end of current `parent`.
- position.path.pop();
- position.offset++;
- this.position = position;
- this._visitedParent = parent.parent;
- if ( this.ignoreElementEnd ) {
- return this._next();
- } else {
- return formatReturnValue( 'elementEnd', parent, previousPosition, position );
- }
- }
- }
- /**
- * Makes a step backward in model. Moves the {@link #position} to the previous position and returns the encountered value.
- *
- * @private
- * @returns {Object}
- * @returns {Boolean} return.done True if iterator is done.
- * @returns {module:engine/model/treewalker~TreeWalkerValue} return.value Information about taken step.
- */
- _previous() {
- const previousPosition = this.position;
- const position = Position._createAt( this.position );
- const parent = this._visitedParent;
- // We are at the beginning of the root.
- if ( parent.parent === null && position.offset === 0 ) {
- return { done: true };
- }
- // We reached the walker boundary.
- if ( parent == this._boundaryStartParent && position.offset == this.boundaries.start.offset ) {
- return { done: true };
- }
- // Get node just before current position
- const node = position.textNode ? position.textNode : position.nodeBefore;
- if ( node instanceof Element ) {
- position.offset--;
- if ( !this.shallow ) {
- position.path.push( node.maxOffset );
- this.position = position;
- this._visitedParent = node;
- if ( this.ignoreElementEnd ) {
- return this._previous();
- } else {
- return formatReturnValue( 'elementEnd', node, previousPosition, position );
- }
- } else {
- this.position = position;
- return formatReturnValue( 'elementStart', node, previousPosition, position, 1 );
- }
- } else if ( node instanceof Text ) {
- let charactersCount;
- if ( this.singleCharacters ) {
- charactersCount = 1;
- } else {
- let offset = node.startOffset;
- if ( this._boundaryStartParent == parent && this.boundaries.start.offset > offset ) {
- offset = this.boundaries.start.offset;
- }
- charactersCount = position.offset - offset;
- }
- const offsetInTextNode = position.offset - node.startOffset;
- const item = new TextProxy( node, offsetInTextNode - charactersCount, charactersCount );
- position.offset -= charactersCount;
- this.position = position;
- return formatReturnValue( 'text', item, previousPosition, position, charactersCount );
- } else {
- // `node` is not set, we reached the beginning of current `parent`.
- position.path.pop();
- this.position = position;
- this._visitedParent = parent.parent;
- return formatReturnValue( 'elementStart', parent, previousPosition, position, 1 );
- }
- }
- }
- function formatReturnValue( type, item, previousPosition, nextPosition, length ) {
- return {
- done: false,
- value: {
- type,
- item,
- previousPosition,
- nextPosition,
- length
- }
- };
- }
- /**
- * Type of the step made by {@link module:engine/model/treewalker~TreeWalker}.
- * Possible values: `'elementStart'` if walker is at the beginning of a node, `'elementEnd'` if walker is at the end of node,
- * `'character'` if walker traversed over a character, or `'text'` if walker traversed over multiple characters (available in
- * character merging mode, see {@link module:engine/model/treewalker~TreeWalker#constructor}).
- *
- * @typedef {'elementStart'|'elementEnd'|'character'|'text'} module:engine/model/treewalker~TreeWalkerValueType
- */
- /**
- * Object returned by {@link module:engine/model/treewalker~TreeWalker} when traversing tree model.
- *
- * @typedef {Object} module:engine/model/treewalker~TreeWalkerValue
- * @property {module:engine/model/treewalker~TreeWalkerValueType} type
- * @property {module:engine/model/item~Item} item Item between old and new positions of {@link module:engine/model/treewalker~TreeWalker}.
- * @property {module:engine/model/position~Position} previousPosition Previous position of the iterator.
- * * Forward iteration: For `'elementEnd'` it is the last position inside the element. For all other types it is the
- * position before the item. Note that it is more efficient to use this position then calculate the position before
- * the node using {@link module:engine/model/position~Position._createBefore}. It is also more efficient to get the
- * position after node by shifting `previousPosition` by `length`, using {@link module:engine/model/position~Position#getShiftedBy},
- * then calculate the position using {@link module:engine/model/position~Position._createAfter}.
- * * Backward iteration: For `'elementStart'` it is the first position inside the element. For all other types it is
- * the position after item.
- * @property {module:engine/model/position~Position} nextPosition Next position of the iterator.
- * * Forward iteration: For `'elementStart'` it is the first position inside the element. For all other types it is
- * the position after the item.
- * * Backward iteration: For `'elementEnd'` it is last position inside element. For all other types it is the position
- * before the item.
- * @property {Number} [length] Length of the item. For `'elementStart'` and `'character'` it is 1. For `'text'` it is
- * the length of the text. For `'elementEnd'` it is undefined.
- */
- /**
- * Tree walking directions.
- *
- * @typedef {'forward'|'backward'} module:engine/view/treewalker~TreeWalkerDirection
- */
|