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- /**
- * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
- * For licensing, see LICENSE.md.
- */
- /**
- * @module engine/model/schema
- */
- import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
- import ObservableMixin from '@ckeditor/ckeditor5-utils/src/observablemixin';
- import mix from '@ckeditor/ckeditor5-utils/src/mix';
- import Range from './range';
- /**
- * The model's schema. It defines allowed and disallowed structures of nodes as well as nodes' attributes.
- * The schema is usually defined by features and based on them the editing framework and features
- * make decisions how to change and process the model.
- *
- * The instance of schema is available in {@link module:engine/model/model~Model#schema `editor.model.schema`}.
- *
- * # Schema definitions
- *
- * Schema defines allowed model structures and allowed attributes separately. They are also checked separately
- * by using the {@link ~Schema#checkChild} and {@link ~Schema#checkAttribute} methods.
- *
- * ## Defining allowed structures
- *
- * When a feature introduces a model element it should register it in the schema. Besides
- * defining that such an element may exist in the model, the feature also needs to define where
- * this element may be placed:
- *
- * schema.register( 'myElement', {
- * allowIn: '$root'
- * } );
- *
- * This lets the schema know that `<myElement>` may be a child of the `<$root>` element. `$root` is one of generic
- * nodes defined by the editing framework. By default, the editor names the main root element a `<$root>`,
- * so the above definition allows `<myElement>` in the main editor element.
- *
- * In other words, this would be correct:
- *
- * <$root><myElement></myElement></$root>
- *
- * While this would not be correct:
- *
- * <$root><foo><myElement></myElement></foo></$root>
- *
- * ## Generic items
- *
- * There are three basic generic items: `$root`, `$block` and `$text`.
- * They are defined as follows:
- *
- * this.schema.register( '$root', {
- * isLimit: true
- * } );
- * this.schema.register( '$block', {
- * allowIn: '$root',
- * isBlock: true
- * } );
- * this.schema.register( '$text', {
- * allowIn: '$block'
- * } );
- *
- * These definitions can then be reused by features to create their own definitions in a more extensible way.
- * For example, the {@link module:paragraph/paragraph~Paragraph} feature will define its item as:
- *
- * schema.register( 'paragraph', {
- * inheritAllFrom: '$block'
- * } );
- *
- * Which translates to:
- *
- * schema.register( 'paragraph', {
- * allowWhere: '$block',
- * allowContentOf: '$block',
- * allowAttributesOf: '$block',
- * inheritTypesFrom: '$block'
- * } );
- *
- * Which can be read as:
- *
- * * The `<paragraph>` element will be allowed in elements in which `<$block>` is allowed (e.g. in `<$root>`).
- * * The `<paragraph>` element will allow all nodes which are allowed in `<$block>` (e.g. `$text`).
- * * The `<paragraph>` element will allow all attributes allowed on `<$block>`.
- * * The `<paragraph>` element will inherit all `is*` properties of `<$block>` (e.g. `isBlock`).
- *
- * Thanks to the fact that `<paragraph>`'s definition is inherited from `<$block>` other features can use the `<$block>`
- * type to indirectly extend `<paragraph>`'s definition. For example, the {@link module:block-quote/blockquote~BlockQuote}
- * feature does this:
- *
- * schema.register( 'blockQuote', {
- * allowWhere: '$block',
- * allowContentOf: '$root'
- * } );
- *
- * Thanks to that, despite the fact that block quote and paragraph features know nothing about themselves, paragraphs
- * will be allowed in block quotes and block quotes will be allowed in all places where blocks are. So if anyone will
- * register a `<section>` element (with `allowContentOf: '$root'` rule), that `<section>` elements will allow
- * block quotes too.
- *
- * The side effect of such a definition inheritance is that now `<blockQuote>` is allowed in `<blockQuote>` which needs to be
- * resolved by a callback which will disallow this specific structure.
- *
- * You can read more about the format of an item definition in {@link module:engine/model/schema~SchemaItemDefinition}.
- *
- * ## Defining advanced rules in `checkChild()`'s callbacks
- *
- * The {@link ~Schema#checkChild} method which is the base method used to check whether some element is allowed in a given structure
- * is {@link module:utils/observablemixin~ObservableMixin#decorate a decorated method}.
- * It means that you can add listeners to implement your specific rules which are not limited by the declarative
- * {@link module:engine/model/schema~SchemaItemDefinition API}.
- *
- * Those listeners can be added either by listening directly to the {@link ~Schema#event:checkChild} event or
- * by using the handy {@link ~Schema#addChildCheck} method.
- *
- * For instance, the block quote feature defines such a listener to disallow nested `<blockQuote>` structures:
- *
- * schema.addChildCheck( context, childDefinition ) => {
- * // Note that context is automatically normalized to SchemaContext instance and
- * // child to its definition (SchemaCompiledItemDefinition).
- *
- * // If checkChild() is called with a context that ends with blockQuote and blockQuote as a child
- * // to check, make the checkChild() method return false.
- * if ( context.endsWith( 'blockQuote' ) && childDefinition.name == 'blockQuote' ) {
- * return false;
- * }
- * } );
- *
- * ## Defining attributes
- *
- * TODO
- *
- * ## Implementing additional constraints
- *
- * Schema's capabilities were limited to simple (and atomic) {@link ~Schema#checkChild} and
- * {@link ~Schema#checkAttribute} checks on purpose.
- * One may imagine that schema should support defining more complex rules such as
- * "element `<x>` must be always followed by `<y>`".
- * While it is feasible to create an API which would enable feeding the schema with such definitions,
- * it is unfortunately unrealistic to then expect that every editing feature will consider those rules when processing the model.
- * It is also unrealistic to expect that it will be done automatically by the schema and the editing engine themselves.
- *
- * For instance, let's get back to the "element `<x>` must be always followed by `<y>`" rule and this initial content:
- *
- * <$root>
- * <x>foo</x>
- * <y>bar[bom</y>
- * <z>bom]bar</z>
- * </$root>
- *
- * Now, imagine that the user presses the "block quote" button. Usually it would wrap the two selected blocks
- * (`<y>` and `<z>`) with a `<blockQuote>` element:
- *
- * <$root>
- * <x>foo</x>
- * <blockQuote>
- * <y>bar[bom</y>
- * <z>bom]bar</z>
- * </blockQuote>
- * </$root>
- *
- * But it turns out that this creates an incorrect structure – `<x>` is not followed by `<y>` anymore.
- *
- * What should happen instead? There are at least 4 possible solutions: the block quote feature should not be
- * applicable in such a context, someone should create a new `<y>` right after `<x>`, `<x>` should be moved
- * inside `<blockQuote>` together with `<y>` or vice versa.
- *
- * While this is a relatively simple scenario (unlike most real-time collaboration scenarios),
- * it turns out that it's already hard to say what should happen and who should react to fix this content.
- *
- * Therefore, if your editor needs to implement such rules, you should do that through model's post-fixers
- * fixing incorrect content or actively prevent such situations (e.g. by disabling certain features).
- * It means that those constraints will be defined specifically for your scenario by your code which
- * makes their implementation much easier.
- *
- * So the answer for who and how should implement additional constraints is your features or your editor
- * through CKEditor 5's rich and open API.
- *
- * @mixes module:utils/observablemixin~ObservableMixin
- */
- export default class Schema {
- /**
- * Creates schema instance.
- */
- constructor() {
- this._sourceDefinitions = {};
- this.decorate( 'checkChild' );
- this.decorate( 'checkAttribute' );
- this.on( 'checkAttribute', ( evt, args ) => {
- args[ 0 ] = new SchemaContext( args[ 0 ] );
- }, { priority: 'highest' } );
- this.on( 'checkChild', ( evt, args ) => {
- args[ 0 ] = new SchemaContext( args[ 0 ] );
- args[ 1 ] = this.getDefinition( args[ 1 ] );
- }, { priority: 'highest' } );
- }
- /**
- * Registers schema item. Can only be called once for every item name.
- *
- * schema.register( 'paragraph', {
- * inheritAllFrom: '$block'
- * } );
- *
- * @param {String} itemName
- * @param {module:engine/model/schema~SchemaItemDefinition} definition
- */
- register( itemName, definition ) {
- if ( this._sourceDefinitions[ itemName ] ) {
- // TODO docs
- throw new CKEditorError( 'schema-cannot-register-item-twice: A single item cannot be registered twice in the schema.', {
- itemName
- } );
- }
- this._sourceDefinitions[ itemName ] = [
- Object.assign( {}, definition )
- ];
- this._clearCache();
- }
- /**
- * Extends a {@link #register registered} item's definition.
- *
- * Extending properties such as `allowIn` will add more items to the existing properties,
- * while redefining properties such as `isBlock` will override the previously defined ones.
- *
- * schema.register( 'foo', {
- * allowIn: '$root',
- * isBlock: true;
- * } );
- * schema.extend( 'foo', {
- * allowIn: 'blockQuote',
- * isBlock: false
- * } );
- *
- * schema.getDefinition( 'foo' );
- * // {
- * // allowIn: [ '$root', 'blockQuote' ],
- * // isBlock: false
- * // }
- *
- * @param {String} itemName
- * @param {module:engine/model/schema~SchemaItemDefinition} definition
- */
- extend( itemName, definition ) {
- if ( !this._sourceDefinitions[ itemName ] ) {
- // TODO docs
- throw new CKEditorError( 'schema-cannot-extend-missing-item: Cannot extend an item which was not registered yet.', {
- itemName
- } );
- }
- this._sourceDefinitions[ itemName ].push( Object.assign( {}, definition ) );
- this._clearCache();
- }
- /**
- * Returns all registered items.
- *
- * @returns {Object.<String,module:engine/model/schema~SchemaCompiledItemDefinition>}
- */
- getDefinitions() {
- if ( !this._compiledDefinitions ) {
- this._compile();
- }
- return this._compiledDefinitions;
- }
- /**
- * Returns a definition of the given item or `undefined` if item is not registered.
- *
- * @param {module:engine/model/item~Item|module:engine/model/schema~SchemaContextItem|String} item
- * @returns {module:engine/model/schema~SchemaCompiledItemDefinition}
- */
- getDefinition( item ) {
- let itemName;
- if ( typeof item == 'string' ) {
- itemName = item;
- } else if ( item.is && ( item.is( 'text' ) || item.is( 'textProxy' ) ) ) {
- itemName = '$text';
- }
- // Element or module:engine/model/schema~SchemaContextItem.
- else {
- itemName = item.name;
- }
- return this.getDefinitions()[ itemName ];
- }
- /**
- * Returns `true` if the given item is registered in the schema.
- *
- * schema.isRegistered( 'paragraph' ); // -> true
- * schema.isRegistered( editor.model.document.getRoot() ); // -> true
- * schema.isRegistered( 'foo' ); // -> false
- *
- * @param {module:engine/model/item~Item|module:engine/model/schema~SchemaContextItem|String} item
- */
- isRegistered( item ) {
- return !!this.getDefinition( item );
- }
- /**
- * Returns `true` if the given item is defined to be
- * a block by {@link module:engine/model/schema~SchemaItemDefinition}'s `isBlock` property.
- *
- * schema.isBlock( 'paragraph' ); // -> true
- * schema.isBlock( '$root' ); // -> false
- *
- * const paragraphElement = writer.createElement( 'paragraph' );
- * schema.isBlock( paragraphElement ); // -> true
- *
- * @param {module:engine/model/item~Item|module:engine/model/schema~SchemaContextItem|String} item
- */
- isBlock( item ) {
- const def = this.getDefinition( item );
- return !!( def && def.isBlock );
- }
- /**
- * Returns `true` if the given item is defined to be
- * a limit element by {@link module:engine/model/schema~SchemaItemDefinition}'s `isLimit` property.
- *
- * schema.isLimit( 'paragraph' ); // -> false
- * schema.isLimit( '$root' ); // -> true
- * schema.isLimit( editor.model.document.getRoot() ); // -> true
- *
- * @param {module:engine/model/item~Item|module:engine/model/schema~SchemaContextItem|String} item
- */
- isLimit( item ) {
- const def = this.getDefinition( item );
- return !!( def && def.isLimit );
- }
- /**
- * Returns `true` if the given item is defined to be
- * a object element by {@link module:engine/model/schema~SchemaItemDefinition}'s `isObject` property.
- *
- * schema.isObject( 'paragraph' ); // -> false
- * schema.isObject( 'image' ); // -> true
- *
- * const imageElement = writer.createElement( 'image' );
- * schema.isObject( imageElement ); // -> true
- *
- * @param {module:engine/model/item~Item|module:engine/model/schema~SchemaContextItem|String} item
- */
- isObject( item ) {
- const def = this.getDefinition( item );
- return !!( def && def.isObject );
- }
- /**
- * Checks whether the given node (`child`) can be a child of the given context.
- *
- * schema.checkChild( model.document.getRoot(), paragraph ); // -> false
- *
- * schema.register( 'paragraph', {
- * allowIn: '$root'
- * } );
- * schema.checkChild( model.document.getRoot(), paragraph ); // -> true
- *
- * @fires checkChild
- * @param {module:engine/model/schema~SchemaContextDefinition} context Context in which the child will be checked.
- * @param {module:engine/model/node~Node|String} child The child to check.
- */
- checkChild( context, def ) {
- // Note: context and child are already normalized here to a SchemaContext and SchemaCompiledItemDefinition.
- if ( !def ) {
- return false;
- }
- return this._checkContextMatch( def, context );
- }
- /**
- * Checks whether the given attribute can be applied in the given context (on the last
- * item of the context).
- *
- * schema.checkAttribute( textNode, 'bold' ); // -> false
- *
- * schema.extend( '$text', {
- * allowAttributes: 'bold'
- * } );
- * schema.checkAttribute( textNode, 'bold' ); // -> true
- *
- * @fires checkAttribute
- * @param {module:engine/model/schema~SchemaContextDefinition} context
- * @param {String} attributeName
- */
- checkAttribute( context, attributeName ) {
- const def = this.getDefinition( context.last );
- if ( !def ) {
- return false;
- }
- return def.allowAttributes.includes( attributeName );
- }
- /**
- * Allows registering a callback to the {@link #checkChild} method calls.
- *
- * Callbacks allow you to implement rules which are not otherwise possible to achieve
- * by using the declarative API of {@link module:engine/model/schema~SchemaItemDefinition}.
- * For example, by using this method you can disallow elements in specific contexts.
- *
- * This method is a shorthand for using the {@link #event:checkChild} event. For even better control,
- * you can use that event instead.
- *
- * Example:
- *
- * // Disallow heading1 directly inside a blockQuote.
- * schema.addChildCheck( ( ctx, childDefinition ) => {
- * if ( ctx.endsWith( 'blockQuote' ) && childDefinition.name == 'heading1' ) {
- * return false;
- * }
- * } );
- *
- * Which translates to:
- *
- * schema.on( 'checkChild', ( evt, args ) => {
- * const context = args[ 0 ];
- * const childDefinition = args[ 1 ];
- *
- * if ( context.endsWith( 'blockQuote' ) && childDefinition && childDefinition.name == 'heading1' ) {
- * // Prevent next listeners from being called.
- * evt.stop();
- * // Set the checkChild()'s return value.
- * evt.return = false;
- * }
- * }, { priority: 'high' } );
- *
- * @param {Function} callback The callback to be called. It is called with two parameters:
- * {@link module:engine/model/schema~SchemaContext} (context) instance and
- * {@link module:engine/model/schema~SchemaCompiledItemDefinition} (child-to-check definition).
- * The callback may return `true/false` to override `checkChild()`'s return value. If it does not return
- * a boolean value, the default algorithm (or other callbacks) will define `checkChild()`'s return value.
- */
- addChildCheck( callback ) {
- this.on( 'checkChild', ( evt, [ ctx, childDef ] ) => {
- // checkChild() was called with a non-registered child.
- // In 99% cases such check should return false, so not to overcomplicate all callbacks
- // don't even execute them.
- if ( !childDef ) {
- return;
- }
- const retValue = callback( ctx, childDef );
- if ( typeof retValue == 'boolean' ) {
- evt.stop();
- evt.return = retValue;
- }
- }, { priority: 'high' } );
- }
- /**
- * Returns the lowest {@link module:engine/model/schema~Schema#isLimit limit element} containing the entire
- * selection or the root otherwise.
- *
- * @param {module:engine/model/selection~Selection} selection Selection which returns the common ancestor.
- * @returns {module:engine/model/element~Element}
- */
- getLimitElement( selection ) {
- // Find the common ancestor for all selection's ranges.
- let element = Array.from( selection.getRanges() )
- .reduce( ( node, range ) => {
- if ( !node ) {
- return range.getCommonAncestor();
- }
- return node.getCommonAncestor( range.getCommonAncestor() );
- }, null );
- while ( !this.isLimit( element ) ) {
- if ( element.parent ) {
- element = element.parent;
- } else {
- break;
- }
- }
- return element;
- }
- /**
- * Checks whether the attribute is allowed in selection:
- *
- * * if the selection is not collapsed, then checks if the attribute is allowed on any of nodes in that range,
- * * if the selection is collapsed, then checks if on the selection position there's a text with the
- * specified attribute allowed.
- *
- * @param {module:engine/model/selection~Selection} selection Selection which will be checked.
- * @param {String} attribute The name of the attribute to check.
- * @returns {Boolean}
- */
- checkAttributeInSelection( selection, attribute ) {
- if ( selection.isCollapsed ) {
- // Check whether schema allows for a text with the attribute in the selection.
- return this.checkAttribute( [ ...selection.getFirstPosition().getAncestors(), '$text' ], attribute );
- } else {
- const ranges = selection.getRanges();
- // For all ranges, check nodes in them until you find a node that is allowed to have the attribute.
- for ( const range of ranges ) {
- for ( const value of range ) {
- if ( this.checkAttribute( value.item, attribute ) ) {
- // If we found a node that is allowed to have the attribute, return true.
- return true;
- }
- }
- }
- }
- // If we haven't found such node, return false.
- return false;
- }
- /**
- * Transforms the given set of ranges into a set of ranges where the given attribute is allowed (and can be applied).
- *
- * @param {Array.<module:engine/model/range~Range>} ranges Ranges to be validated.
- * @param {String} attribute The name of the attribute to check.
- * @returns {Array.<module:engine/model/range~Range>} Ranges in which the attribute is allowed.
- */
- getValidRanges( ranges, attribute ) {
- const validRanges = [];
- for ( const range of ranges ) {
- let last = range.start;
- let from = range.start;
- const to = range.end;
- for ( const value of range.getWalker() ) {
- if ( !this.checkAttribute( value.item, attribute ) ) {
- if ( !from.isEqual( last ) ) {
- validRanges.push( new Range( from, last ) );
- }
- from = value.nextPosition;
- }
- last = value.nextPosition;
- }
- if ( from && !from.isEqual( to ) ) {
- validRanges.push( new Range( from, to ) );
- }
- }
- return validRanges;
- }
- /**
- * Removes attributes disallowed by the schema.
- *
- * @param {Iterable.<module:engine/model/node~Node>} nodes Nodes that will be filtered.
- * @param {module:engine/model/writer~Writer} writer
- */
- removeDisallowedAttributes( nodes, writer ) {
- for ( const node of nodes ) {
- for ( const attribute of node.getAttributeKeys() ) {
- if ( !this.checkAttribute( node, attribute ) ) {
- writer.removeAttribute( attribute, node );
- }
- }
- if ( node.is( 'element' ) ) {
- this.removeDisallowedAttributes( node.getChildren(), writer );
- }
- }
- }
- /**
- * @private
- */
- _clearCache() {
- this._compiledDefinitions = null;
- }
- /**
- * @private
- */
- _compile() {
- const compiledDefinitions = {};
- const sourceRules = this._sourceDefinitions;
- const itemNames = Object.keys( sourceRules );
- for ( const itemName of itemNames ) {
- compiledDefinitions[ itemName ] = compileBaseItemRule( sourceRules[ itemName ], itemName );
- }
- for ( const itemName of itemNames ) {
- compileAllowContentOf( compiledDefinitions, itemName );
- }
- for ( const itemName of itemNames ) {
- compileAllowWhere( compiledDefinitions, itemName );
- }
- for ( const itemName of itemNames ) {
- compileAllowAttributesOf( compiledDefinitions, itemName );
- compileInheritPropertiesFrom( compiledDefinitions, itemName );
- }
- for ( const itemName of itemNames ) {
- cleanUpAllowIn( compiledDefinitions, itemName );
- cleanUpAllowAttributes( compiledDefinitions, itemName );
- }
- this._compiledDefinitions = compiledDefinitions;
- }
- /**
- * @private
- * @param {module:engine/model/schema~SchemaCompiledItemDefinition} def
- * @param {module:engine/model/schema~SchemaContext} context
- * @param {Number} contextItemIndex
- */
- _checkContextMatch( def, context, contextItemIndex = context.length - 1 ) {
- const contextItem = context.getItem( contextItemIndex );
- if ( def.allowIn.includes( contextItem.name ) ) {
- if ( contextItemIndex == 0 ) {
- return true;
- } else {
- const parentRule = this.getDefinition( contextItem );
- return this._checkContextMatch( parentRule, context, contextItemIndex - 1 );
- }
- } else {
- return false;
- }
- }
- }
- mix( Schema, ObservableMixin );
- /**
- * Event fired when the {@link #checkChild} method is called. It allows plugging in
- * additional behavior – e.g. implementing rules which cannot be defined using the declarative
- * {@link module:engine/model/schema~SchemaItemDefinition} interface.
- *
- * **Note:** The {@link #addChildCheck} method is a more handy way to register callbacks. Internally,
- * it registers a listener to this event but comes with a simpler API and it is the recommended choice
- * in most of the cases.
- *
- * The {@link #checkChild} method fires an event because it is
- * {@link module:utils/observablemixin~ObservableMixin#decorate decorated} with it. Thanks to that you can
- * use this event in a various way, but the most important use case is overriding standard behaviour of the
- * `checkChild()` method. Let's see a typical listener template:
- *
- * schema.on( 'checkChild', ( evt, args ) => {
- * const context = args[ 0 ];
- * const childDefinition = args[ 1 ];
- * }, { priority: 'high' } );
- *
- * The listener is added with a `high` priority to be executed before the default method is really called. The `args` callback
- * parameter contains arguments passed to `checkChild( context, child )`. However, the `context` parameter is already
- * normalized to a {@link module:engine/model/schema~SchemaContext} instance and `child` to a
- * {@link module:engine/model/schema~SchemaCompiledItemDefinition} instance, so you don't have to worry about
- * the various ways how `context` and `child` may be passed to `checkChild()`.
- *
- * **Note:** `childDefinition` may be `undefined` if `checkChild()` was called with a non-registered element.
- *
- * So, in order to implement a rule "disallow `heading1` in `blockQuote`" you can add such a listener:
- *
- * schema.on( 'checkChild', ( evt, args ) => {
- * const context = args[ 0 ];
- * const childDefinition = args[ 1 ];
- *
- * if ( context.endsWith( 'blockQuote' ) && childDefinition && childDefinition.name == 'heading1' ) {
- * // Prevent next listeners from being called.
- * evt.stop();
- * // Set the checkChild()'s return value.
- * evt.return = false;
- * }
- * }, { priority: 'high' } );
- *
- * Allowing elements in specific contexts will be a far less common use case, because it's normally handled by
- * `allowIn` rule from {@link module:engine/model/schema~SchemaItemDefinition} but if you have a complex scenario
- * where `listItem` should be allowed only in element `foo` which must be in element `bar`, then this would be the way:
- *
- * schema.on( 'checkChild', ( evt, args ) => {
- * const context = args[ 0 ];
- * const childDefinition = args[ 1 ];
- *
- * if ( context.endsWith( 'bar foo' ) && childDefinition.name == 'listItem' ) {
- * // Prevent next listeners from being called.
- * evt.stop();
- * // Set the checkChild()'s return value.
- * evt.return = true;
- * }
- * }, { priority: 'high' } );
- *
- * @event checkChild
- * @param {Array} args The `checkChild()`'s arguments.
- */
- /**
- * Event fired when the {@link #checkAttribute} method is called. It allows plugging in
- * additional behavior – e.g. implementing rules which cannot be defined using the declarative
- * {@link module:engine/model/schema~SchemaItemDefinition} interface.
- *
- * The {@link #checkAttribute} method fires an event because it's
- * {@link module:utils/observablemixin~ObservableMixin#decorate decorated} with it. Thanks to that you can
- * use this event in a various way, but the most important use case is overriding standard behaviour of the
- * `checkAttribute()` method. Let's see a typical listener template:
- *
- * schema.on( 'checkAttribute', ( evt, args ) => {
- * const context = args[ 0 ];
- * const attributeName = args[ 1 ];
- * }, { priority: 'high' } );
- *
- * The listener is added with a `high` priority to be executed before the default method is really called. The `args` callback
- * parameter contains arguments passed to `checkAttribute( context, attributeName )`. However, the `context` parameter is already
- * normalized to a {@link module:engine/model/schema~SchemaContext} instance, so you don't have to worry about
- * the various ways how `context` may be passed to `checkAttribute()`.
- *
- * So, in order to implement a rule "disallow `bold` in a text which is in a `heading1` you can add such a listener:
- *
- * schema.on( 'checkAttribute', ( evt, args ) => {
- * const context = args[ 0 ];
- * const atributeName = args[ 1 ];
- *
- * if ( context.endsWith( 'heading1 $text' ) && attributeName == 'bold' ) {
- * // Prevent next listeners from being called.
- * evt.stop();
- * // Set the checkAttribute()'s return value.
- * evt.return = false;
- * }
- * }, { priority: 'high' } );
- *
- * Allowing attributes in specific contexts will be a far less common use case, because it's normally handled by
- * `allowAttributes` rule from {@link module:engine/model/schema~SchemaItemDefinition} but if you have a complex scenario
- * where `bold` should be allowed only in element `foo` which must be in element `bar`, then this would be the way:
- *
- * schema.on( 'checkAttribute', ( evt, args ) => {
- * const context = args[ 0 ];
- * const atributeName = args[ 1 ];
- *
- * if ( context.endsWith( 'bar foo $text' ) && attributeName == 'bold' ) {
- * // Prevent next listeners from being called.
- * evt.stop();
- * // Set the checkAttribute()'s return value.
- * evt.return = true;
- * }
- * }, { priority: 'high' } );
- *
- * @event checkAttribute
- * @param {Array} args The `checkAttribute()`'s arguments.
- */
- /**
- * A definition of a {@link module:engine/model/schema~Schema schema} item.
- *
- * You can define the following rules:
- *
- * * `allowIn` – a string or an array of strings. Defines in which other items this item will be allowed.
- * * `allowAttributes` – a string or an array of strings. Defines allowed attributes of the given item.
- * * `allowContentOf` – a string or an array of strings. Inherit "allowed children" from other items.
- * * `allowWhere` – a string or an array of strings. Inherit "allowed in" from other items.
- * * `allowAttributesOf` – a string or an array of strings. Inherit attributes from other items.
- * * `inheritTypesFrom` – a string or an array of strings. Inherit `is*` properties of other items.
- * * `inheritAllFrom` – a string. A shorthand for `allowContentOf`, `allowWhere`, `allowAttributesOf`, `inheritTypesFrom`.
- * * additionall, you can define the following `is*` properties: `isBlock`, `isLimit`, `isObject`. Read about them below.
- *
- * # The is* properties
- *
- * There are 3 commonly used `is*` properties. Their role is to assign additional semantics to schema items.
- * You can define more properties but you will also need to implement support for them in the existing editor features.
- *
- * * `isBlock` – whether this item is paragraph-like. Generally speaking, a content is usually made out of blocks
- * like paragraphs, list items, images, headings, etc. All these elements are marked as blocks. A block
- * should not allow another block inside. Note: there's also the `$block` generic item which has `isBlock` set to `true`.
- * Most block type items will inherit from `$block` (through `inheritAllFrom`).
- * * `isLimit` – can be understood as whether this element should not be split by <kbd>Enter</kbd>.
- * Examples of limit elements – `$root`, table cell, image caption, etc. In other words, all actions which happen inside
- * a limit element are limitted to its content.
- * * `isObject` – whether item is "self-contained" and should be treated as a whole. Examples of object elements –
- * `image`, `table`, `video`, etc.
- *
- * # Generic items
- *
- * There are three basic generic items: `$root`, `$block` and `$text`.
- * They are defined as follows:
- *
- * this.schema.register( '$root', {
- * isLimit: true
- * } );
- * this.schema.register( '$block', {
- * allowIn: '$root',
- * isBlock: true
- * } );
- * this.schema.register( '$text', {
- * allowIn: '$block'
- * } );
- *
- * They reflect a typical editor content which is contained within one root, consists of several blocks
- * (paragraphs, lists items, headings, images) which, in turn, may contain text inside.
- *
- * By inheriting from the generic items you can define new items which will get extended by other editor features.
- * Read more about generic types in the {@linkTODO Defining schema} guide.
- *
- * # Example definitions
- *
- * Allow `paragraph` in roots and block quotes:
- *
- * schema.register( 'paragraph', {
- * allowIn: [ '$root', 'blockQuote' ],
- * isBlock: true
- * } );
- *
- * Allow `paragraph` everywhere where `$block` is allowed (i.e. in `$root`):
- *
- * schema.register( 'paragraph', {
- * allowWhere: '$block',
- * isBlock: true
- * } );
- *
- * Make `image` a block object, which is allowed everywhere where `$block` is.
- * Also, allow `src` and `alt` attributes on it:
- *
- * schema.register( 'image', {
- * allowWhere: '$block',
- * allowAttributes: [ 'src', 'alt' ],
- * isBlock: true,
- * isObject: true
- * } );
- *
- * Make `caption` allowed in `image` and make it allow all the content of `$block`s (usually, `$text`).
- * Also, mark it as a limit element so it can't be split:
- *
- * schema.register( 'caption', {
- * allowIn: 'image',
- * allowContentOf: '$block',
- * isLimit: true
- * } );
- *
- * Make `listItem` inherit all from `$block` but also allow additional attributes:
- *
- * schema.register( 'listItem', {
- * inheritAllFrom: '$block',
- * allowAttributes: [ 'type', 'indent' ]
- * } );
- *
- * Which translates to:
- *
- * schema.register( 'listItem', {
- * allowWhere: '$block',
- * allowContentOf: '$block',
- * allowAttributesOf: '$block',
- * inheritTypesFrom: '$block',
- * allowAttributes: [ 'type', 'indent' ]
- * } );
- *
- * # Tips
- *
- * * Check schema definitions of existing features to see how they are defined.
- * * If you want to publish your feature so other developers can use it, try to use
- * generic items as much as possible.
- * * Keep your model clean – limit it to the actual data and store information in an normalized way.
- * * Remember about definining the `is*` properties. They don't affect the allowed structures, but they can
- * affect how editor features treat your elements.
- *
- * @typedef {Object} module:engine/model/schema~SchemaItemDefinition
- */
- /**
- * A simplified version of {@link module:engine/model/schema~SchemaItemDefinition} after
- * compilation by the {@link module:engine/model/schema~Schema schema}.
- * Rules feed to the schema by {@link module:engine/model/schema~Schema#register}
- * and {@link module:engine/model/schema~Schema#extend} are defined in the
- * {@link module:engine/model/schema~SchemaItemDefinition} format.
- * Later on, they are compiled to `SchemaCompiledItemDefition` so when you use e.g.
- * the {@link module:engine/model/schema~Schema#getDefinition} method you get the compiled version.
- *
- * The compiled version contains only the following properties:
- *
- * * `name` property,
- * * `is*` properties,
- * * `allowIn` array,
- * * `allowAttributes` array.
- *
- * @typedef {Object} module:engine/model/schema~SchemaCompiledItemDefinition
- */
- /**
- * A schema context – a list of ancestors of a given position in the document.
- *
- * Considering such a position:
- *
- * <$root>
- * <blockQuote>
- * <paragraph>
- * ^
- * </paragraph>
- * </blockQuote>
- * </$root>
- *
- * The context of this position is its {@link module:engine/model/position~Position#getAncestors lists of ancestors}:
- *
- * [ rootElement, blockQuoteElement, paragraphElement ]
- *
- * Contexts are used in the {@link module:engine/model/schema~Schema#event:checkChild `Schema#checkChild`} and
- * {@link module:engine/model/schema~Schema#event:checkAttribute `Schema#checkAttribute`} events as a definition
- * of a place in the document where the check occurs. The context instances are created based on the first arguments
- * of the {@link module:engine/model/schema~Schema#checkChild `Schema#checkChild()`} and
- * {@link module:engine/model/schema~Schema#checkAttribute `Schema#checkAttribute()`} methods so when
- * using these methods you need to use {@link module:engine/model/schema~SchemaContextDefinition}s.
- */
- export class SchemaContext {
- /**
- * Creates an instance of the context.
- *
- * @param {module:engine/model/schema~SchemaContextDefinition} context
- */
- constructor( context ) {
- if ( Array.isArray( context ) ) {
- if ( context[ 0 ] && typeof context[ 0 ] != 'string' && context[ 0 ].is( 'documentFragment' ) ) {
- context.shift();
- }
- }
- else {
- // `context` is item or position.
- // Position#getAncestors() doesn't accept any parameters but it works just fine here.
- context = context.getAncestors( { includeSelf: true } );
- if ( context[ 0 ].is( 'documentFragment' ) ) {
- context.shift();
- }
- }
- this._items = context.map( mapContextItem );
- }
- /**
- * Number of items.
- *
- * @type {Number}
- */
- get length() {
- return this._items.length;
- }
- /**
- * The last item (the lowest node).
- *
- * @type {module:engine/model/schema~SchemaContextItem}
- */
- get last() {
- return this._items[ this._items.length - 1 ];
- }
- /**
- * Iterable interface.
- *
- * Iterates over all context items.
- *
- * @returns {Iterable.<module:engine/model/schema~SchemaContextItem>}
- */
- [ Symbol.iterator ]() {
- return this._items[ Symbol.iterator ]();
- }
- /**
- * Gets an item on the given index.
- *
- * @returns {module:engine/model/schema~SchemaContextItem}
- */
- getItem( index ) {
- return this._items[ index ];
- }
- /**
- * Returns the names of items.
- *
- * @returns {Iterable.<String>}
- */
- * getNames() {
- yield* this._items.map( item => item.name );
- }
- /**
- * Checks whether the context ends with the given nodes.
- *
- * const ctx = new SchemaContext( [ rootElement, paragraphElement, textNode ] );
- *
- * ctx.endsWith( '$text' ); // -> true
- * ctx.endsWith( 'paragraph $text' ); // -> true
- * ctx.endsWith( '$root' ); // -> false
- * ctx.endsWith( 'paragraph' ); // -> false
- *
- * @param {String} query
- * @returns {Boolean}
- */
- endsWith( query ) {
- return Array.from( this.getNames() ).join( ' ' ).endsWith( query );
- }
- }
- /**
- * The definition of a {@link module:engine/model/schema~SchemaContext schema context}.
- *
- * Contexts can be created in multiple ways:
- *
- * * By defining a **node** – in this cases this node and all its ancestors will be used.
- * * By defining a **position** in the document – in this case all its ancestors will be used.
- * * By defining an **array of nodes** – in this case this array defines the entire context.
- * * By defining an **array of node names** (potentially, mixed with real nodes) – in this case
- * nodes definied by strings will be "mocked". Using strings is not recommended as it
- * means that the context will be unrealistic (e.g. attributes of these nodes are not specified).
- * However, at times this may be the only way to define the context (e.g. when checking some
- * hypothetical situation).
- *
- * Examples of context definitions passed to the {@link module:engine/model/schema~Schema#checkChild `Schema#checkChild()`}
- * method:
- *
- * // Assuming that we have a $root > blockQuote > paragraph structure, the following code
- * // will check node 'foo' in the following context:
- * // [ rootElement, blockQuoteElement, paragraphElement ]
- * const contextDefinition = paragraphElement;
- * const childToCheck = 'foo';
- * schema.checkChild( contextDefinition, childToCheck );
- *
- * // Also check in [ rootElement, blockQuoteElement, paragraphElement ].
- * schema.checkChild( Position.createAt( paragraphElement ), 'foo' );
- *
- * // Check in [ rootElement, paragraphElement ].
- * schema.checkChild( [ rootElement, paragraphElement ], 'foo' );
- *
- * // Check in [ fakeRootElement, fakeBarElement, paragraphElement ].
- * schema.checkChild( [ '$root', 'bar', paragraphElement ], 'foo' );
- *
- * All these `checkChild()` calls will fire {@link module:engine/model/schema~Schema#event:checkChild `Schema#checkChild`}
- * events in which `args[ 0 ]` is an instance of the context. Therefore, you can write a listener like this:
- *
- * schema.on( 'checkChild', ( evt, args ) => {
- * const ctx = args[ 0 ];
- *
- * console.log( Array.from( ctx.getNames() ) );
- * } );
- *
- * Which will log the following:
- *
- * [ '$root', 'blockQuote', 'paragraph' ]
- * [ '$root', 'paragraph' ]
- * [ '$root', 'bar', 'paragraph' ]
- *
- * Note: When using the {@link module:engine/model/schema~Schema#checkAttribute `Schema#checkAttribute()`} method
- * you may want to check whether a text node may have an attribute. A {@link module:engine/model/text~Text} is a
- * correct way to define a context so you can do this:
- *
- * schema.checkAttribute( textNode, 'bold' );
- *
- * But sometimes you want to check whether a text at a given position might've had some attribute,
- * in which case you can create a context by mising an array of elements with a `'$text'` string:
- *
- * // Check in [ rootElement, paragraphElement, textNode ].
- * schema.checkChild( [ ...positionInParagraph.getAncestors(), '$text' ], 'bold' );
- *
- * @typedef {module:engine/model/node~Node|module:engine/model/position~Position|
- * Array.<String|module:engine/model/node~Node>} module:engine/model/schema~SchemaContextDefinition
- */
- /**
- * An item of the {@link module:engine/model/schema~SchemaContext schema context}.
- *
- * It contains 3 properties:
- *
- * * `name` – the name of this item,
- * * `* getAttributeKeys()` – a generator of keys of item attributes,
- * * `getAttribute( keyName )` – a method to get attribute values.
- *
- * The context item interface is a highly simplified version of {@link module:engine/model/node~Node} and its role
- * is to expose only the information which schema checks are able to provide (which is the name of the node and
- * node's attributes).
- *
- * schema.on( 'checkChild', ( evt, args ) => {
- * const ctx = args[ 0 ];
- * const firstItem = ctx.getItem( 0 );
- *
- * console.log( firstItem.name ); // -> '$root'
- * console.log( firstItem.getAttribute( 'foo' ) ); // -> 'bar'
- * console.log( Array.from( firstItem.getAttributeKeys() ) ); // -> [ 'foo', 'faa' ]
- * } );
- *
- * @typedef {Object} module:engine/model/schema~SchemaContextItem
- */
- function compileBaseItemRule( sourceItemRules, itemName ) {
- const itemRule = {
- name: itemName,
- allowIn: [],
- allowContentOf: [],
- allowWhere: [],
- allowAttributes: [],
- allowAttributesOf: [],
- inheritTypesFrom: []
- };
- copyTypes( sourceItemRules, itemRule );
- copyProperty( sourceItemRules, itemRule, 'allowIn' );
- copyProperty( sourceItemRules, itemRule, 'allowContentOf' );
- copyProperty( sourceItemRules, itemRule, 'allowWhere' );
- copyProperty( sourceItemRules, itemRule, 'allowAttributes' );
- copyProperty( sourceItemRules, itemRule, 'allowAttributesOf' );
- copyProperty( sourceItemRules, itemRule, 'inheritTypesFrom' );
- makeInheritAllWork( sourceItemRules, itemRule );
- return itemRule;
- }
- function compileAllowContentOf( compiledDefinitions, itemName ) {
- for ( const allowContentOfItemName of compiledDefinitions[ itemName ].allowContentOf ) {
- // The allowContentOf property may point to an unregistered element.
- if ( compiledDefinitions[ allowContentOfItemName ] ) {
- const allowedChildren = getAllowedChildren( compiledDefinitions, allowContentOfItemName );
- allowedChildren.forEach( allowedItem => {
- allowedItem.allowIn.push( itemName );
- } );
- }
- }
- delete compiledDefinitions[ itemName ].allowContentOf;
- }
- function compileAllowWhere( compiledDefinitions, itemName ) {
- for ( const allowWhereItemName of compiledDefinitions[ itemName ].allowWhere ) {
- const inheritFrom = compiledDefinitions[ allowWhereItemName ];
- // The allowWhere property may point to an unregistered element.
- if ( inheritFrom ) {
- const allowedIn = inheritFrom.allowIn;
- compiledDefinitions[ itemName ].allowIn.push( ...allowedIn );
- }
- }
- delete compiledDefinitions[ itemName ].allowWhere;
- }
- function compileAllowAttributesOf( compiledDefinitions, itemName ) {
- for ( const allowAttributeOfItem of compiledDefinitions[ itemName ].allowAttributesOf ) {
- const inheritFrom = compiledDefinitions[ allowAttributeOfItem ];
- if ( inheritFrom ) {
- const inheritAttributes = inheritFrom.allowAttributes;
- compiledDefinitions[ itemName ].allowAttributes.push( ...inheritAttributes );
- }
- }
- delete compiledDefinitions[ itemName ].allowAttributesOf;
- }
- function compileInheritPropertiesFrom( compiledDefinitions, itemName ) {
- const item = compiledDefinitions[ itemName ];
- for ( const inheritPropertiesOfItem of item.inheritTypesFrom ) {
- const inheritFrom = compiledDefinitions[ inheritPropertiesOfItem ];
- if ( inheritFrom ) {
- const typeNames = Object.keys( inheritFrom ).filter( name => name.startsWith( 'is' ) );
- for ( const name of typeNames ) {
- if ( !( name in item ) ) {
- item[ name ] = inheritFrom[ name ];
- }
- }
- }
- }
- delete item.inheritTypesFrom;
- }
- // Remove items which weren't registered (because it may break some checks or we'd need to complicate them).
- // Make sure allowIn doesn't contain repeated values.
- function cleanUpAllowIn( compiledDefinitions, itemName ) {
- const itemRule = compiledDefinitions[ itemName ];
- const existingItems = itemRule.allowIn.filter( itemToCheck => compiledDefinitions[ itemToCheck ] );
- itemRule.allowIn = Array.from( new Set( existingItems ) );
- }
- function cleanUpAllowAttributes( compiledDefinitions, itemName ) {
- const itemRule = compiledDefinitions[ itemName ];
- itemRule.allowAttributes = Array.from( new Set( itemRule.allowAttributes ) );
- }
- function copyTypes( sourceItemRules, itemRule ) {
- for ( const sourceItemRule of sourceItemRules ) {
- const typeNames = Object.keys( sourceItemRule ).filter( name => name.startsWith( 'is' ) );
- for ( const name of typeNames ) {
- itemRule[ name ] = sourceItemRule[ name ];
- }
- }
- }
- function copyProperty( sourceItemRules, itemRule, propertyName ) {
- for ( const sourceItemRule of sourceItemRules ) {
- if ( typeof sourceItemRule[ propertyName ] == 'string' ) {
- itemRule[ propertyName ].push( sourceItemRule[ propertyName ] );
- } else if ( Array.isArray( sourceItemRule[ propertyName ] ) ) {
- itemRule[ propertyName ].push( ...sourceItemRule[ propertyName ] );
- }
- }
- }
- function makeInheritAllWork( sourceItemRules, itemRule ) {
- for ( const sourceItemRule of sourceItemRules ) {
- const inheritFrom = sourceItemRule.inheritAllFrom;
- if ( inheritFrom ) {
- itemRule.allowContentOf.push( inheritFrom );
- itemRule.allowWhere.push( inheritFrom );
- itemRule.allowAttributesOf.push( inheritFrom );
- itemRule.inheritTypesFrom.push( inheritFrom );
- }
- }
- }
- function getAllowedChildren( compiledDefinitions, itemName ) {
- const itemRule = compiledDefinitions[ itemName ];
- return getValues( compiledDefinitions ).filter( def => def.allowIn.includes( itemRule.name ) );
- }
- function getValues( obj ) {
- return Object.keys( obj ).map( key => obj[ key ] );
- }
- function mapContextItem( ctxItem ) {
- if ( typeof ctxItem == 'string' ) {
- return {
- name: ctxItem,
- * getAttributeKeys() {},
- getAttribute() {}
- };
- } else {
- return {
- // '$text' means text nodes and text proxies.
- name: ctxItem.is( 'element' ) ? ctxItem.name : '$text',
- * getAttributeKeys() {
- yield* ctxItem.getAttributeKeys();
- },
- getAttribute( key ) {
- return ctxItem.getAttribute( key );
- }
- };
- }
- }
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