/** * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved. * For licensing, see LICENSE.md. */ /** * @module engine/conversion/viewconversiondispatcher */ import ViewConsumable from './viewconsumable.js'; import ViewElement from '../view/element.js'; import ViewText from '../view/text.js'; import EmitterMixin from '../../utils/emittermixin.js'; import mix from '../../utils/mix.js'; import extend from '../../utils/lib/lodash/extend.js'; /** * `ViewConversionDispatcher` is a central point of {@link module:engine/view/view view} conversion, which is a process of * converting given {@link module:engine/view/documentfragment~DocumentFragment view document fragment} or * {@link module:engine/view/element~Element} * into another structure. In default application, {@link module:engine/view/view view} is converted to {@link module:engine/model/model}. * * During conversion process, for all {@link module:engine/view/node~Node view nodes} from the converted view document fragment, * `ViewConversionDispatcher` fires corresponding events. Special callbacks called "converters" should listen to * `ViewConversionDispatcher` for those events. * * Each callback, as a first argument, is passed a special object `data` that has `input` and `output` properties. * `input` property contains {@link module:engine/view/node~Node view node} or * {@link module:engine/view/documentfragment~DocumentFragment view document fragment} * that is converted at the moment and might be handled by the callback. `output` property should be used to save the result * of conversion. Keep in mind that the `data` parameter is customizable and may contain other values - see * {@link ~ViewConversionDispatcher#convert}. It is also shared by reference by all callbacks * listening to given event. **Note**: in view to model conversion - `data` contains `context` property that is an array * of {@link module:engine/model/element~Element model elements}. These are model elements that will be the parent of currently * converted view item. `context` property is used in examples below. * * The second parameter passed to a callback is an instance of {@link module:engine/conversion/viewconsumable~ViewConsumable}. It stores * information about what parts of processed view item are still waiting to be handled. After a piece of view item * was converted, appropriate consumable value should be {@link module:engine/conversion/viewconsumable~ViewConsumable#consume consumed}. * * The third parameter passed to a callback is an instance of {@link ~ViewConversionDispatcher} * which provides additional tools for converters. * * Examples of providing callbacks for `ViewConversionDispatcher`: * * // Converter for paragraphs (

). * viewDispatcher.on( 'element:p', ( evt, data, consumable, conversionApi ) => { * const paragraph = new ModelElement( 'paragraph' ); * const schemaQuery = { * name: 'paragraph', * inside: data.context * }; * * if ( conversionApi.schema.check( schemaQuery ) ) { * if ( !consumable.consume( data.input, { name: true } ) ) { * // Before converting this paragraph's children we have to update their context by this paragraph. * data.context.push( paragraph ); * const children = conversionApi.convertChildren( data.input, consumable, data ); * data.context.pop(); * paragraph.appendChildren( children ); * data.output = paragraph; * } * } * } ); * * // Converter for links (). * viewDispatcher.on( 'element:a', ( evt, data, consumable, conversionApi ) => { * if ( consumable.consume( data.input, { name: true, attributes: [ 'href' ] } ) ) { * // element is inline and is represented by an attribute in the model. * // This is why we are not updating `context` property. * data.output = conversionApi.convertChildren( data.input, consumable, data ); * * for ( let item of Range.createFrom( data.output ) ) { * const schemaQuery = { * name: item.name || '$text', * attribute: 'link', * inside: data.context * }; * * if ( conversionApi.schema.check( schemaQuery ) ) { * item.setAttribute( 'link', data.input.getAttribute( 'href' ) ); * } * } * } * } ); * * // Fire conversion. * // Always take care where the converted model structure will be appended to. If this `viewDocumentFragment` * // is going to be appended directly to a '$root' element, use that in `context`. * viewDispatcher.convert( viewDocumentFragment, { context: [ '$root' ] } ); * * Before each conversion process, `ViewConversionDispatcher` fires {@link ~ViewConversionDispatcher#event:viewCleanup} * event which can be used to prepare tree view for conversion. * * @mixes module:utils/emittermixin~EmitterMixin * @fires viewCleanup * @fires element * @fires text * @fires documentFragment */ export default class ViewConversionDispatcher { /** * Creates a `ViewConversionDispatcher` that operates using passed API. * * @see module:engine/conversion/viewconversiondispatcher~ViewConversionApi * @param {Object} [conversionApi] Additional properties for interface that will be passed to events fired * by `ViewConversionDispatcher`. */ constructor( conversionApi = {} ) { /** * Interface passed by dispatcher to the events callbacks. * * @member {module:engine/conversion/viewconversiondispatcher~ViewConversionApi} */ this.conversionApi = extend( {}, conversionApi ); // `convertItem` and `convertChildren` are bound to this `ViewConversionDispatcher` instance and // set on `conversionApi`. This way only a part of `ViewConversionDispatcher` API is exposed. this.conversionApi.convertItem = this._convertItem.bind( this ); this.conversionApi.convertChildren = this._convertChildren.bind( this ); } /** * Starts the conversion process. The entry point for the conversion. * * @fires element * @fires text * @fires documentFragment * @param {module:engine/view/documentfragment~DocumentFragment|module:engine/view/element~Element} * viewItem Part of the view to be converted. * @param {Object} [additionalData] Additional data to be passed in `data` argument when firing `ViewConversionDispatcher` * events. See also {@link ~ViewConversionDispatcher#event:element element event}. * @returns {module:engine/model/documentfragment~DocumentFragment} Model document fragment that is a result of the conversion process. */ convert( viewItem, additionalData = {} ) { this.fire( 'viewCleanup', viewItem ); const consumable = ViewConsumable.createFrom( viewItem ); return this._convertItem( viewItem, consumable, additionalData ); } /** * @private * @see module:engine/conversion/viewconversiondispatcher~ViewConversionApi#convertItem */ _convertItem( input, consumable, additionalData = {} ) { const data = extend( {}, additionalData, { input: input, output: null } ); if ( input instanceof ViewElement ) { this.fire( 'element:' + input.name, data, consumable, this.conversionApi ); } else if ( input instanceof ViewText ) { this.fire( 'text', data, consumable, this.conversionApi ); } else { this.fire( 'documentFragment', data, consumable, this.conversionApi ); } return data.output; } /** * @private * @see module:engine/conversion/viewconversiondispatcher~ViewConversionApi#convertChildren */ _convertChildren( input, consumable, additionalData = {} ) { const viewChildren = Array.from( input.getChildren() ); const convertedChildren = viewChildren.map( ( viewChild ) => this._convertItem( viewChild, consumable, additionalData ) ); // Flatten and remove nulls. return convertedChildren.reduce( ( a, b ) => b ? a.concat( b ) : a, [] ); } /** * Fired before the first conversion event, at the beginning of view to model conversion process. * * @event viewCleanup * @param {module:engine/view/documentfragment~DocumentFragment|module:engine/view/element~Element} * viewItem Part of the view to be converted. */ /** * Fired when {@link module:engine/view/element~Element} is converted. * * `element` is a namespace event for a class of events. Names of actually called events follow this pattern: * `element:` where `elementName` is the name of converted element. This way listeners may listen to * all elements conversion or to conversion of specific elements. * * @event element * @param {Object} data Object containing conversion input and a placeholder for conversion output and possibly other * values (see {@link #convert}). * Keep in mind that this object is shared by reference between all callbacks that will be called. * This means that callbacks can add their own values if needed, * and those values will be available in other callbacks. * @param {module:engine/view/element~Element} data.input Converted element. * @param {*} data.output The current state of conversion result. Every change to converted element should * be reflected by setting or modifying this property. * @param {module:engine/model/schema~SchemaPath} data.context The conversion context. * @param {module:engine/conversion/viewconsumable~ViewConsumable} consumable Values to consume. * @param {Object} conversionApi Conversion interface to be used by callback, passed in `ViewConversionDispatcher` constructor. * Besides of properties passed in constructor, it also has `convertItem` and `convertChildren` methods which are references * to {@link #_convertItem} and * {@link ~ViewConversionDispatcher#_convertChildren}. Those methods are needed to convert * the whole view-tree they were exposed in `conversionApi` for callbacks. */ /** * Fired when {@link module:engine/view/text~Text} is converted. * * @event text * @see #event:element */ /** * Fired when {@link module:engine/view/documentfragment~DocumentFragment} is converted. * * @event documentFragment * @see #event:element */ } mix( ViewConversionDispatcher, EmitterMixin ); /** * Conversion interface that is registered for given {@link module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher} * and is passed as one of parameters when {@link module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher dispatcher} * fires it's events. * * `ViewConversionApi` object is built by {@link module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher} constructor. * The exact list of properties of this object is determined by the object passed to the constructor. * * @interface ViewConversionApi */ /** * Starts conversion of given item by firing an appropriate event. * * Every fired event is passed (as first parameter) an object with `output` property. Every event may set and/or * modify that property. When all callbacks are done, the final value of `output` property is returned by this method. * * @method #convertItem * @fires module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:element * @fires module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:text * @fires module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:documentFragment * @param {module:engine/view/documentfragment~DocumentFragment|module:engine/view/element~Element|module:engine/view/text~Text} * input Item to convert. * @param {module:engine/conversion/viewconsumable~ViewConsumable} consumable Values to consume. * @param {Object} [additionalData] Additional data to be passed in `data` argument when firing `ViewConversionDispatcher` * events. See also {@link module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:element element event}. * @returns {*} The result of item conversion, created and modified by callbacks attached to fired event. */ /** * Starts conversion of all children of given item by firing appropriate events for all those children. * * @method #convertChildren * @fires module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:element * @fires module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:text * @fires module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:documentFragment * @param {module:engine/view/documentfragment~DocumentFragment|module:engine/view/element~Element} * input Item which children will be converted. * @param {module:engine/conversion/viewconsumable~ViewConsumable} consumable Values to consume. * @param {Object} [additionalData] Additional data to be passed in `data` argument when firing `ViewConversionDispatcher` * events. See also {@link module:engine/conversion/viewconversiondispatcher~ViewConversionDispatcher#event:element element event}. * @returns {Array.<*>} Array containing results of conversion of all children of given item. */