ckeditor/ckeditor5-core

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src/context.js

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/**
 * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
 */

/**
 * @module core/context
 */

import Config from '@ckeditor/ckeditor5-utils/src/config';
import Collection from '@ckeditor/ckeditor5-utils/src/collection';
import PluginCollection from './plugincollection';
import Locale from '@ckeditor/ckeditor5-utils/src/locale';
import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';

/**
 * Provides a common, higher-level environment for solutions that use multiple {@link module:core/editor/editor~Editor editors}
 * or plugins that work outside the editor. Use it instead of {@link module:core/editor/editor~Editor.create `Editor.create()`}
 * in advanced application integrations.
 *
 * All configuration options passed to a context will be used as default options for editor instances initialized in that context.
 *
 * {@link module:core/contextplugin~ContextPlugin Context plugins} passed to a context instance will be shared among all
 * editor instances initialized in this context. These will be the same plugin instances for all the editors.
 *
 * **Note:** The context can only be initialized with {@link module:core/contextplugin~ContextPlugin context plugins}
 * (e.g. [comments](https://ckeditor.com/collaboration/comments/)). Regular {@link module:core/plugin~Plugin plugins} require an
 * editor instance to work and cannot be added to a context.
 *
 * **Note:** You can add a context plugin to an editor instance, though.
 *
 * If you are using multiple editor instances on one page and use any context plugins, create a context to share the configuration and
 * plugins among these editors. Some plugins will use the information about all existing editors to better integrate between them.
 *
 * If you are using plugins that do not require an editor to work (e.g. [comments](https://ckeditor.com/collaboration/comments/)),
 * enable and configure them using the context.
 *
 * If you are using only a single editor on each page, use {@link module:core/editor/editor~Editor.create `Editor.create()`} instead.
 * In such case, a context instance will be created by the editor instance in a transparent way.
 *
 * See {@link module:core/context~Context.create `Context.create()`} for usage examples.
 */
export default class Context {
    /**
     * Creates a context instance with a given configuration.
     *
     * Usually not to be used directly. See the static {@link module:core/context~Context.create `create()`} method.
     *
     * @param {Object} [config={}] The context configuration.
     */
    constructor( config ) {
        /**
         * Stores all the configurations specific to this context instance.
         *
         * @readonly
         * @type {module:utils/config~Config}
         */
        this.config = new Config( config, this.constructor.defaultConfig );

        const availablePlugins = this.constructor.builtinPlugins;

        this.config.define( 'plugins', availablePlugins );

        /**
         * The plugins loaded and in use by this context instance.
         *
         * @readonly
         * @type {module:core/plugincollection~PluginCollection}
         */
        this.plugins = new PluginCollection( this, availablePlugins );

        const languageConfig = this.config.get( 'language' ) || {};

        /**
         * @readonly
         * @type {module:utils/locale~Locale}
         */
        this.locale = new Locale( {
            uiLanguage: typeof languageConfig === 'string' ? languageConfig : languageConfig.ui,
            contentLanguage: this.config.get( 'language.content' )
        } );

        /**
         * Shorthand for {@link module:utils/locale~Locale#t}.
         *
         * @see module:utils/locale~Locale#t
         * @method #t
         */
        this.t = this.locale.t;

        /**
         * A list of editors that this context instance is injected to.
         *
         * @readonly
         * @type {module:utils/collection~Collection}
         */
        this.editors = new Collection();

        /**
         * Reference to the editor which created the context.
         * Null when the context was created outside of the editor.
         *
         * It is used to destroy the context when removing the editor that has created the context.
         *
         * @private
         * @type {module:core/editor/editor~Editor|null}
         */
        this._contextOwner = null;
    }

    /**
     * Loads and initializes plugins specified in the configuration.
     *
     * @returns {Promise.<module:core/plugin~LoadedPlugins>} A promise which resolves
     * once the initialization is completed, providing an array of loaded plugins.
     */
    initPlugins() {
        const plugins = this.config.get( 'plugins' ) || [];

        for ( const Plugin of plugins ) {
            if ( typeof Plugin != 'function' ) {
                /**
                 * Only a constructor function is allowed as a {@link module:core/contextplugin~ContextPlugin context plugin}.
                 *
                 * @error context-initplugins-constructor-only
                 */
                throw new CKEditorError(
                    'context-initplugins-constructor-only: Only a constructor function is allowed as a context plugin.',
                    null,
                    { Plugin }
                );
            }

            if ( Plugin.isContextPlugin !== true ) {
                /**
                 * Only a plugin marked as a {@link module:core/contextplugin~ContextPlugin.isContextPlugin context plugin}
                 * is allowed to be used with a context.
                 *
                 * @error context-initplugins-invalid-plugin
                 */
                throw new CKEditorError(
                    'context-initplugins-invalid-plugin: Only a plugin marked as a context plugin is allowed to be used with a context.',
                    null,
                    { Plugin }
                );
            }
        }

        return this.plugins.init( plugins );
    }

    /**
     * Destroys the context instance and all editors used with the context,
     * releasing all resources used by the context.
     *
     * @returns {Promise} A promise that resolves once the context instance is fully destroyed.
     */
    destroy() {
        return Promise.all( Array.from( this.editors, editor => editor.destroy() ) )
            .then( () => this.plugins.destroy() );
    }

    /**
     * Adds a reference to the editor which is used with this context.
     *
     * When the given editor has created the context, the reference to this editor will be stored
     * as a {@link ~Context#_contextOwner}.
     *
     * This method should only be used by the editor.
     *
     * @protected
     * @param {module:core/editor/editor~Editor} editor
     * @param {Boolean} isContextOwner Stores the given editor as a context owner.
     */
    _addEditor( editor, isContextOwner ) {
        if ( this._contextOwner ) {
            /**
             * Cannot add multiple editors to the context which is created by the editor.
             *
             * @error context-addEditor-private-context
             */
            throw new CKEditorError(
                'context-addEditor-private-context: Cannot add multiple editors to the context which is created by the editor.'
            );
        }

        this.editors.add( editor );

        if ( isContextOwner ) {
            this._contextOwner = editor;
        }
    }

    /**
     * Removes a reference to the editor which was used with this context.
     * When the context was created by the given editor, the context will be destroyed.
     *
     * This method should only be used by the editor.
     *
     * @protected
     * @param {module:core/editor/editor~Editor} editor
     * @return {Promise} A promise that resolves once the editor is removed from the context or when the context was destroyed.
     */
    _removeEditor( editor ) {
        if ( this.editors.has( editor ) ) {
            this.editors.remove( editor );
        }

        if ( this._contextOwner === editor ) {
            return this.destroy();
        }

        return Promise.resolve();
    }

    /**
     * Returns the context configuration which will be copied to the editors created using this context.
     *
     * The configuration returned by this method has the plugins configuration removed &mdash; plugins are shared with all editors
     * through another mechanism.
     *
     * This method should only be used by the editor.
     *
     * @protected
     * @returns {Object} Configuration as a plain object.
     */
    _getEditorConfig() {
        const result = {};

        for ( const name of this.config.names() ) {
            if ( ![ 'plugins', 'removePlugins', 'extraPlugins' ].includes( name ) ) {
                result[ name ] = this.config.get( name );
            }
        }

        return result;
    }

    /**
     * Creates and initializes a new context instance.
     *
     *        const commonConfig = { ... }; // Configuration for all the plugins and editors.
     *        const editorPlugins = [ ... ]; // Regular plugins here.
     *
     *        Context
     *            .create( {
     *                // Only context plugins here.
     *                plugins: [ ... ],
     *
     *                // Configure the language for all the editors (it cannot be overwritten).
     *                language: { ... },
     *
     *                // Configuration for context plugins.
     *                comments: { ... },
     *                ...
     *
     *                // Default configuration for editor plugins.
     *                toolbar: { ... },
     *                image: { ... },
     *                ...
     *            } )
     *            .then( context => {
     *                const promises = [];
     *
     *                promises.push( ClassicEditor.create(
     *                    document.getElementById( 'editor1' ),
     *                    {
     *                        editorPlugins,
     *                        context
     *                    }
     *                ) );
     *
     *                promises.push( ClassicEditor.create(
     *                    document.getElementById( 'editor2' ),
     *                    {
     *                        editorPlugins,
     *                        context,
     *                        toolbar: { ... } // You can overwrite the configuration of the context.
     *                    }
     *                ) );
     *
     *                return Promise.all( promises );
     *            } );
     *
     * @param {Object} [config] The context configuration.
     * @returns {Promise} A promise resolved once the context is ready. The promise resolves with the created context instance.
     */
    static create( config ) {
        return new Promise( resolve => {
            const context = new this( config );

            resolve( context.initPlugins().then( () => context ) );
        } );
    }
}

/**
 * An array of plugins built into the `Context` class.
 *
 * It is used in CKEditor 5 builds featuring `Context` to provide a list of context plugins which are later automatically initialized
 * during the context initialization.
 *
 * They will be automatically initialized by `Context` unless `config.plugins` is passed.
 *
 *        // Build some context plugins into the Context class first.
 *        Context.builtinPlugins = [ FooPlugin, BarPlugin ];
 *
 *        // Normally, you need to define config.plugins, but since Context.builtinPlugins was
 *        // defined, now you can call create() without any configuration.
 *        Context
 *            .create()
 *            .then( context => {
 *                context.plugins.get( FooPlugin ); // -> An instance of the Foo plugin.
 *                context.plugins.get( BarPlugin ); // -> An instance of the Bar plugin.
 *            } );
 *
 * See also {@link module:core/context~Context.defaultConfig `Context.defaultConfig`}
 * and {@link module:core/editor/editor~Editor.builtinPlugins `Editor.builtinPlugins`}.
 *
 * @static
 * @member {Array.<Function>} module:core/context~Context.builtinPlugins
 */

/**
 * The default configuration which is built into the `Context` class.
 *
 * It is used in CKEditor 5 builds featuring `Context` to provide the default configuration options which are later used during the
 * context initialization.
 *
 *        Context.defaultConfig = {
 *            foo: 1,
 *            bar: 2
 *        };
 *
 *        Context
 *            .create()
 *            .then( context => {
 *                context.config.get( 'foo' ); // -> 1
 *                context.config.get( 'bar' ); // -> 2
 *            } );
 *
 *        // The default options can be overridden by the configuration passed to create().
 *        Context
 *            .create( { bar: 3 } )
 *            .then( context => {
 *                context.config.get( 'foo' ); // -> 1
 *                context.config.get( 'bar' ); // -> 3
 *            } );
 *
 * See also {@link module:core/context~Context.builtinPlugins `Context.builtinPlugins`}
 * and {@link module:core/editor/editor~Editor.defaultConfig `Editor.defaultConfig`}.
 *
 * @static
 * @member {Object} module:core/context~Context.defaultConfig
 */