/** * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved. * For licensing, see LICENSE.md. */ /** * @module engine/conversion/upcastdispatcher */ import ViewConsumable from './viewconsumable'; import ModelRange from '../model/range'; import ModelPosition from '../model/position'; import { SchemaContext } from '../model/schema'; import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror'; import EmitterMixin from '@ckeditor/ckeditor5-utils/src/emittermixin'; import mix from '@ckeditor/ckeditor5-utils/src/mix'; /** * `UpcastDispatcher` 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, * `UpcastDispatcher` fires corresponding events. Special callbacks called "converters" should listen to * `UpcastDispatcher` for those events. * * Each callback, as the second argument, is passed a special object `data` that has `viewItem`, `modelCursor` and * `modelRange` properties. `viewItem` 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. `modelRange` property should be used to save the result * of conversion and is always a {@link module:engine/model/range~Range} when conversion result is correct. * `modelCursor` property is a {@link module:engine/model/position~Position position} on which conversion result will be inserted * and is a context according to {@link module:engine/model/schema~Schema schema} will be checked before the conversion. * See also {@link ~UpcastDispatcher#convert}. It is also shared by reference by all callbacks listening to given event. * * The third parameter passed to a callback is an instance of {@link ~UpcastDispatcher} * which provides additional tools for converters. * * Examples of providing callbacks for `UpcastDispatcher`: * * // Converter for links (). * upcastDispatcher.on( 'element:a', ( evt, data, conversionApi ) => { * if ( conversionApi.consumable.consume( data.viewItem, { name: true, attributes: [ 'href' ] } ) ) { * // element is inline and is represented by an attribute in the model. * // This is why we need to convert only children. * const { modelRange } = conversionApi.convertChildren( data.viewItem, data.modelCursor ); * * for ( let item of modelRange.getItems() ) { * if ( conversionApi.schema.checkAttribute( item, 'linkHref' ) ) { * conversionApi.writer.setAttribute( 'linkHref', data.viewItem.getAttribute( 'href' ), item ); * } * } * } * } ); * * // Convert all elements which have no custom converter into paragraph (autoparagraphing). * data.viewToModel.on( 'element', ( evt, data, conversionApi ) => { * // When element is already consumed by higher priority converters then do nothing. * if ( conversionApi.consumable.test( data.viewItem, { name: data.viewItem.name } ) ) { * const paragraph = conversionApi.writer.createElement( 'paragraph' ); * * // Find allowed parent for paragraph that we are going to insert. If current parent does not allow * // to insert paragraph but one of the ancestors does then split nodes to allowed parent. * const splitResult = conversionApi.splitToAllowedParent( paragraph, data.modelCursor ); * * // When there is no split result it means that we can't insert paragraph in this position. * if ( splitResult ) { * // Insert paragraph in allowed position. * conversionApi.writer.insert( paragraph, splitResult.position ); * * // Convert children to paragraph. * const { modelRange } = conversionApi.convertChildren( data.viewItem, Position.createAt( paragraph ) ); * * // Set as conversion result, attribute converters may use this property. * data.modelRange = new Range( Position.createBefore( paragraph ), modelRange.end ); * * // Continue conversion inside paragraph. * data.modelCursor = data.modelRange.end; * } * } * } * }, { priority: 'low' } ); * * Before each conversion process, `UpcastDispatcher` fires {@link ~UpcastDispatcher#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 UpcastDispatcher { /** * Creates a `UpcastDispatcher` that operates using passed API. * * @see module:engine/conversion/upcastdispatcher~ViewConversionApi * @param {Object} [conversionApi] Additional properties for interface that will be passed to events fired * by `UpcastDispatcher`. */ constructor( conversionApi = {} ) { /** * List of elements that will be checked after conversion process and if element in the list will be empty it * will be removed from conversion result. * * After conversion process list is cleared. * * @protected * @type {Set} */ this._removeIfEmpty = new Set(); /** * Position in the temporary structure where the converted content is inserted. The structure reflect the context of * the target position where the content will be inserted. This property is build based on the context parameter of the * convert method. * * @private * @type {module:engine/model/position~Position|null} */ this._modelCursor = null; /** * Interface passed by dispatcher to the events callbacks. * * @member {module:engine/conversion/upcastdispatcher~ViewConversionApi} */ this.conversionApi = Object.assign( {}, conversionApi ); // `convertItem`, `convertChildren` and `splitToAllowedParent` are bound to this `UpcastDispatcher` // instance and set on `conversionApi`. This way only a part of `UpcastDispatcher` API is exposed. this.conversionApi.convertItem = this._convertItem.bind( this ); this.conversionApi.convertChildren = this._convertChildren.bind( this ); this.conversionApi.splitToAllowedParent = this._splitToAllowedParent.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 {module:engine/model/writer~Writer} writer Instance of model writer. * @param {module:engine/model/schema~SchemaContextDefinition} [context=['$root']] Elements will be converted according to this context. * @returns {module:engine/model/documentfragment~DocumentFragment} Model data that is a result of the conversion process * wrapped in `DocumentFragment`. Converted marker elements will be set as that document fragment's * {@link module:engine/model/documentfragment~DocumentFragment#markers static markers map}. */ convert( viewItem, writer, context = [ '$root' ] ) { this.fire( 'viewCleanup', viewItem ); // Create context tree and set position in the top element. // Items will be converted according to this position. this._modelCursor = createContextTree( context, writer ); // Store writer in conversion as a conversion API // to be sure that conversion process will use the same batch. this.conversionApi.writer = writer; // Create consumable values list for conversion process. this.conversionApi.consumable = ViewConsumable.createFrom( viewItem ); // Custom data stored by converter for conversion process. this.conversionApi.store = {}; // Do the conversion. const { modelRange } = this._convertItem( viewItem, this._modelCursor ); // Conversion result is always a document fragment so let's create this fragment. const documentFragment = writer.createDocumentFragment(); // When there is a conversion result. if ( modelRange ) { // Remove all empty elements that was added to #_removeIfEmpty list. this._removeEmptyElements(); // Move all items that was converted to context tree to document fragment. for ( const item of Array.from( this._modelCursor.parent.getChildren() ) ) { writer.append( item, documentFragment ); } // Extract temporary markers elements from model and set as static markers collection. documentFragment.markers = extractMarkersFromModelFragment( documentFragment, writer ); } // Clear context position. this._modelCursor = null; // Clear split elements. this._removeIfEmpty.clear(); // Clear conversion API. this.conversionApi.writer = null; this.conversionApi.store = null; // Return fragment as conversion result. return documentFragment; } /** * @private * @see module:engine/conversion/upcastdispatcher~ViewConversionApi#convertItem */ _convertItem( viewItem, modelCursor ) { const data = Object.assign( { viewItem, modelCursor, modelRange: null } ); if ( viewItem.is( 'element' ) ) { this.fire( 'element:' + viewItem.name, data, this.conversionApi ); } else if ( viewItem.is( 'text' ) ) { this.fire( 'text', data, this.conversionApi ); } else { this.fire( 'documentFragment', data, this.conversionApi ); } // Handle incorrect conversion result. if ( data.modelRange && !( data.modelRange instanceof ModelRange ) ) { /** * Incorrect conversion result was dropped. * * {@link module:engine/model/range~Range Model range} should be a conversion result. * * @error view-conversion-dispatcher-incorrect-result */ throw new CKEditorError( 'view-conversion-dispatcher-incorrect-result: Incorrect conversion result was dropped.' ); } return { modelRange: data.modelRange, modelCursor: data.modelCursor }; } /** * @private * @see module:engine/conversion/upcastdispatcher~ViewConversionApi#convertChildren */ _convertChildren( viewItem, modelCursor ) { const modelRange = new ModelRange( modelCursor ); let nextModelCursor = modelCursor; for ( const viewChild of Array.from( viewItem.getChildren() ) ) { const result = this._convertItem( viewChild, nextModelCursor ); if ( result.modelRange instanceof ModelRange ) { modelRange.end = result.modelRange.end; nextModelCursor = result.modelCursor; } } return { modelRange, modelCursor: nextModelCursor }; } /** * @private * @see module:engine/conversion/upcastdispatcher~ViewConversionApi#splitToAllowedParent */ _splitToAllowedParent( node, modelCursor ) { // Try to find allowed parent. const allowedParent = this.conversionApi.schema.findAllowedParent( node, modelCursor ); // When there is no parent that allows to insert node then return `null`. if ( !allowedParent ) { return null; } // When current position parent allows to insert node then return this position. if ( allowedParent === modelCursor.parent ) { return { position: modelCursor }; } // When allowed parent is in context tree. if ( this._modelCursor.parent.getAncestors().includes( allowedParent ) ) { return null; } // Split element to allowed parent. const splitResult = this.conversionApi.writer.split( modelCursor, allowedParent ); // Remember all elements that are created as a result of split. // This is important because at the end of conversion we want to remove all empty split elements. // // Loop through positions between elements in range (except split result position) and collect parents. // [pos][pos][omit][pos][pos] for ( const position of splitResult.range.getPositions() ) { if ( !position.isEqual( splitResult.position ) ) { this._removeIfEmpty.add( position.parent ); } } return { position: splitResult.position, cursorParent: splitResult.range.end.parent }; } /** * Checks if {@link #_removeIfEmpty} contains empty elements and remove them. * We need to do it smart because there could be elements that are not empty because contains * other empty elements and after removing its children they become available to remove. * We need to continue iterating over split elements as long as any element will be removed. * * @private */ _removeEmptyElements() { let removed = false; for ( const element of this._removeIfEmpty ) { if ( element.isEmpty ) { this.conversionApi.writer.remove( element ); this._removeIfEmpty.delete( element ); removed = true; } } if ( removed ) { this._removeEmptyElements(); } } /** * Fired before the first conversion event, at the beginning of upcast (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 Conversion data. Keep in mind that this object is shared by reference between all * callbacks that will be called. This means that callbacks can override values if needed, and those values will * be available in other callbacks. * @param {module:engine/view/item~Item} data.viewItem Converted item. * @param {module:engine/model/position~Position} data.modelCursor Position where a converter should start changes. * Change this value for the next converter to tell where the conversion should continue. * @param {module:engine/model/range~Range} data.modelRange The current state of conversion result. Every change to * converted element should be reflected by setting or modifying this property. * @param {ViewConversionApi} conversionApi Conversion utilities to be used by callback. */ /** * 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( UpcastDispatcher, EmitterMixin ); // Traverses given model item and searches elements which marks marker range. Found element is removed from // DocumentFragment but path of this element is stored in a Map which is then returned. // // @param {module:engine/view/documentfragment~DocumentFragment|module:engine/view/node~Node} modelItem Fragment of model. // @returns {Map} List of static markers. function extractMarkersFromModelFragment( modelItem, writer ) { const markerElements = new Set(); const markers = new Map(); // Create ModelTreeWalker. const range = ModelRange.createIn( modelItem ).getItems(); // Walk through DocumentFragment and collect marker elements. for ( const item of range ) { // Check if current element is a marker. if ( item.name == '$marker' ) { markerElements.add( item ); } } // Walk through collected marker elements store its path and remove its from the DocumentFragment. for ( const markerElement of markerElements ) { const markerName = markerElement.getAttribute( 'data-name' ); const currentPosition = ModelPosition.createBefore( markerElement ); // When marker of given name is not stored it means that we have found the beginning of the range. if ( !markers.has( markerName ) ) { markers.set( markerName, new ModelRange( ModelPosition.createFromPosition( currentPosition ) ) ); // Otherwise is means that we have found end of the marker range. } else { markers.get( markerName ).end = ModelPosition.createFromPosition( currentPosition ); } // Remove marker element from DocumentFragment. writer.remove( markerElement ); } return markers; } // Creates model fragment according to given context and returns position in top element. function createContextTree( contextDefinition, writer ) { let position; for ( const item of new SchemaContext( contextDefinition ) ) { const attributes = {}; for ( const key of item.getAttributeKeys() ) { attributes[ key ] = item.getAttribute( key ); } const current = writer.createElement( item.name, attributes ); if ( position ) { writer.append( current, position ); } position = ModelPosition.createAt( current ); } return position; } /** * Conversion interface that is registered for given {@link module:engine/conversion/upcastdispatcher~UpcastDispatcher} * and is passed as one of parameters when {@link module:engine/conversion/upcastdispatcher~UpcastDispatcher dispatcher} * fires it's events. * * @interface ViewConversionApi */ /** * Starts conversion of given item by firing an appropriate event. * * Every fired event is passed (as first parameter) an object with `modelRange` property. Every event may set and/or * modify that property. When all callbacks are done, the final value of `modelRange` property is returned by this method. * The `modelRange` must be {@link module:engine/model/range~Range model range} or `null` (as set by default). * * @method #convertItem * @fires module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:element * @fires module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:text * @fires module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:documentFragment * @param {module:engine/view/item~Item} viewItem Item to convert. * @param {module:engine/model/position~Position} modelCursor Position of conversion. * @returns {Object} result Conversion result. * @returns {module:engine/model/range~Range|null} result.modelRange Model range containing result of item conversion, * created and modified by callbacks attached to fired event, or `null` if the conversion result was incorrect. * @returns {module:engine/model/position~Position} result.modelCursor Position where conversion should be continued. */ /** * Starts conversion of all children of given item by firing appropriate events for all those children. * * @method #convertChildren * @fires module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:element * @fires module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:text * @fires module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:documentFragment * @param {module:engine/view/item~Item} viewItem Item to convert. * @param {module:engine/model/position~Position} modelCursor Position of conversion. * @returns {Object} result Conversion result. * @returns {module:engine/model/range~Range} result.modelRange Model range containing results of conversion of all children of given item. * When no children was converted then range is collapsed. * @returns {module:engine/model/position~Position} result.modelCursor Position where conversion should be continued. */ /** * Checks {@link module:engine/model/schema~Schema schema} to find allowed parent for element that we are going to insert * starting from given position. If current parent does not allow to insert element but one of the ancestors does then * split nodes to allowed parent. * * If schema allows to insert node in given position, nothing is split and object with that position is returned. * * If it was not possible to find allowed parent, `null` is returned, nothing is split. * * Otherwise, ancestors are split and object with position and the copy of the split element is returned. * * For instance, if `` is not allowed in `` but is allowed in `$root`: * * foo[]bar * * -> split for `` -> * * foo[]bar * * In the sample above position between `` elements will be returned as `position` and the second `paragraph` * as `cursorParent`. * * @method #splitToAllowedParent * @param {module:engine/model/position~Position} position Position on which element is going to be inserted. * @param {module:engine/model/node~Node} node Node to insert. * @returns {Object|null} Split result. If it was not possible to find allowed position `null` is returned. * @returns {module:engine/model/position~Position} position between split elements. * @returns {module:engine/model/element~Element} [cursorParent] Element inside which cursor should be placed to * continue conversion. When element is not defined it means that there was no split. */ /** * 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}. * * @param {Object} #consumable */ /** * Custom data stored by converters for conversion process. Custom properties of this object can be defined and use to * pass parameters between converters. * * The difference between this property and `data` parameter of * {@link module:engine/conversion/upcastdispatcher~UpcastDispatcher#event:element} is that `data` parameters allows you * to pass parameters within a single event and `store` within the whole conversion. * * @param {Object} #store */