/** * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved. * For licensing, see LICENSE.md. */ 'use strict'; import CharacterProxy from './characterproxy.js'; import TextProxy from './textproxy.js'; import Element from './element.js'; import Position from './position.js'; import CKEditorError from '../../utils/ckeditorerror.js'; /** * Position iterator class. It allows to iterate forward and backward over the document. * * @memberOf engine.model */ 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 {engine.model.Range} [options.boundaries=null] Range to define boundaries of the iterator. * @param {engine.model.Position} [options.startPosition] Starting position. * @param {'FORWARD'|'BACKWARD'} [options.direction='FORWARD'] Walking direction. * @param {Boolean} [options.singleCharacters=false] Flag indicating whether all consecutive characters with the same attributes * should be returned one by one as multiple {@link engine.model.CharacterProxy} (`true`) objects or as one * {@link engine.model.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 `ELEMENT_END` tag. * @param {Boolean} [options.ignoreElementEnd=false] Flag indicating whether iterator should ignore `ELEMENT_END` * tags. If the option is true walker will not return a parent node of start position. If this option is `true` * each {@link engine.model.Element} will be returned once, while if the option is `false` they might be returned * twice: for `'ELEMENT_START'` and `'ELEMENT_END'`. */ constructor( { boundaries = null, startPosition, direction = 'FORWARD', singleCharacters = false, shallow = false, ignoreElementEnd = false, } = {} ) { if ( !boundaries && !startPosition ) { /** * Neither boundaries nor starting position have been defined. * * @error tree-walker-no-start-position */ throw new CKEditorError( 'tree-walker-no-start-position: Neither boundaries nor starting position have been defined.' ); } if ( direction != 'FORWARD' && direction != 'BACKWARD' ) { throw new CKEditorError( 'tree-walker-unknown-direction: Only `BACKWARD` and `FORWARD` direction allowed.', { 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 {engine.model.Range} engine.model.TreeWalker#boundaries */ this.boundaries = boundaries; /** * Iterator position. This is always static position, even if the initial position was a * {@link engine.model.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 {engine.model.Position} engine.model.TreeWalker#position */ if ( startPosition ) { this.position = Position.createFromPosition( startPosition ); } else { this.position = Position.createFromPosition( boundaries[ direction == 'BACKWARD' ? 'end' : 'start' ] ); } /** * Walking direction. Defaults `FORWARD`. * * @readonly * @member {'BACKWARD'|'FORWARD'} engine.model.TreeWalker#direction */ this.direction = direction; /** * Flag indicating whether all consecutive characters with the same attributes should be * returned as one {@link engine.model.CharacterProxy} (`true`) or one by one (`false`). * * @readonly * @member {Boolean} engine.model.TreeWalker#singleCharacters */ this.singleCharacters = !!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 `ELEMENT_END` tag. * * @readonly * @member {Boolean} engine.model.TreeWalker#shallow */ this.shallow = !!shallow; /** * Flag indicating whether iterator should ignore `ELEMENT_END` tags. If the option is true walker will not * return a parent node of the start position. If this option is `true` each {@link engine.model.Element} will * be returned once, while if the option is `false` they might be returned twice: * for `'ELEMENT_START'` and `'ELEMENT_END'`. * * @readonly * @member {Boolean} engine.model.TreeWalker#ignoreElementEnd */ this.ignoreElementEnd = !!ignoreElementEnd; /** * Start boundary cached for optimization purposes. * * @private * @member {engine.model.Element} engine.model.TreeWalker#_boundaryStartParent */ this._boundaryStartParent = this.boundaries ? this.boundaries.start.parent : null; /** * End boundary cached for optimization purposes. * * @private * @member {engine.model.Element} engine.model.TreeWalker#_boundaryEndParent */ this._boundaryEndParent = this.boundaries ? this.boundaries.end.parent : null; /** * Parent of the most recently visited node. Cached for optimization purposes. * * @private * @member {engine.model.Element|engine.model.DocumentFragment} engine.model.TreeWalker#_visitedParent */ this._visitedParent = this.position.parent; } /** * Iterator interface. */ [ Symbol.iterator ]() { return this; } /** * Iterator interface method. * Detects walking direction and makes step forward or backward. * * @returns {Object} Object implementing iterator interface, returning information about taken step. */ 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 {engine.model.TreeWalkerValue} return.value Information about taken step. */ _next() { const previousPosition = this.position; const position = Position.createFromPosition( this.position ); const parent = this._visitedParent; // We are at the end of the root. if ( parent.parent === null && position.offset === parent.getChildCount() ) { return { done: true }; } // We reached the walker boundary. if ( parent === this._boundaryEndParent && position.offset == this.boundaries.end.offset ) { return { done: true }; } const node = parent.getChild( position.offset ); 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( 'ELEMENT_START', node, previousPosition, position, 1 ); } else if ( node instanceof CharacterProxy ) { if ( this.singleCharacters ) { position.offset++; this.position = position; return formatReturnValue( 'CHARACTER', node, previousPosition, position, 1 ); } else { let charactersCount = node._nodeListText.text.length - node._index; let offset = position.offset + charactersCount; if ( this._boundaryEndParent == parent && this.boundaries.end.offset < offset ) { offset = this.boundaries.end.offset; charactersCount = offset - position.offset; } let textProxy = new TextProxy( node, charactersCount ); position.offset = offset; this.position = position; return formatReturnValue( 'TEXT', textProxy, 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( 'ELEMENT_END', 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 {engine.model.TreeWalkerValue} return.value Information about taken step. */ _previous() { const previousPosition = this.position; const position = Position.createFromPosition( 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 = parent.getChild( position.offset - 1 ); if ( node instanceof Element ) { position.offset--; if ( !this.shallow ) { position.path.push( node.getChildCount() ); this.position = position; this._visitedParent = node; if ( this.ignoreElementEnd ) { return this._previous(); } else { return formatReturnValue( 'ELEMENT_END', node, previousPosition, position ); } } else { this.position = position; return formatReturnValue( 'ELEMENT_START', node, previousPosition, position, 1 ); } } else if ( node instanceof CharacterProxy ) { if ( this.singleCharacters ) { position.offset--; this.position = position; return formatReturnValue( 'CHARACTER', node, previousPosition, position, 1 ); } else { let charactersCount = node._index + 1; let offset = position.offset - charactersCount; if ( this._boundaryStartParent == parent && this.boundaries.start.offset > offset ) { offset = this.boundaries.start.offset; charactersCount = position.offset - offset; } let textFragment = new TextProxy( parent.getChild( offset ), charactersCount ); position.offset = offset; this.position = position; return formatReturnValue( 'TEXT', textFragment, 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( 'ELEMENT_START', parent, previousPosition, position, 1 ); } } } function formatReturnValue( type, item, previousPosition, nextPosition, length ) { return { done: false, value: { type: type, item: item, previousPosition: previousPosition, nextPosition: nextPosition, length: length } }; } /** * Type of the step made by {@link engine.model.TreeWalker}. * Possible values: `'ELEMENT_START'` if walker is at the beginning of a node, `'ELEMENT_END'` 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 engine.model.TreeWalker#constructor}). * * @typedef {String} engine.model.TreeWalkerValueType */ /** * Object returned by {@link engine.model.TreeWalker} when traversing tree model. * * @typedef {Object} engine.model.TreeWalkerValue * @property {engine.model.TreeWalkerValueType} type * @property {engine.model.Item} item Item between old and new positions of {@link engine.model.TreeWalker}. * @property {engine.model.Position} previousPosition Previous position of the iterator. * * Forward iteration: For `'ELEMENT_END'` 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 engine.model.Position.createBefore}. It is also more efficient to get the * position after node by shifting `previousPosition` by `length`, using {@link engine.model.Position#getShiftedBy}, * then calculate the position using {@link engine.model.Position.createAfter}. * * Backward iteration: For `'ELEMENT_START'` it is the first position inside the element. For all other types it is * the position after item. * @property {engine.model.Position} nextPosition Next position of the iterator. * * Forward iteration: For `'ELEMENT_START'` it is the first position inside the element. For all other types it is * the position after the item. * * Backward iteration: For `'ELEMENT_END'` 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 `'ELEMENT_START'` and `'CHARACTER'` it is 1. For `'TEXT'` it is * the length of the text. For `'ELEMENT_END'` it is undefined. */ /** * Tree walking directions. * * @typedef {'FORWARD'|'BACKWARD'} engine.view.TreeWalkerDirection */