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/**
* @license
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import {PolymerElement} from '@polymer/polymer/polymer-element';
import {PluginApi} from '../../../api/plugin';
import {HookApi, HookCallback, PluginElement} from '../../../api/hook';
export class GrDomHooksManager {
private hooks: Record<string, GrDomHook<PluginElement>>;
private plugin: PluginApi;
constructor(plugin: PluginApi) {
this.plugin = plugin;
this.hooks = {};
}
_getHookName(endpointName: string, moduleName?: string) {
if (moduleName) {
return endpointName + ' ' + moduleName;
} else {
// lowercase in case plugin's name contains uppercase letters
// TODO: this still can not prevent if plugin has invalid char
// other than uppercase, but is the first step
// https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name
const pluginName: string = this.plugin.getPluginName() || 'unknownplugin';
return pluginName.toLowerCase() + '-autogenerated-' + endpointName;
}
}
getDomHook<T extends PluginElement>(
endpointName: string,
moduleName?: string
): HookApi<T> {
const hookName = this._getHookName(endpointName, moduleName);
if (!this.hooks[hookName]) {
this.hooks[hookName] = new GrDomHook<T>(
hookName,
moduleName
) as unknown as GrDomHook<PluginElement>;
}
return this.hooks[hookName] as unknown as GrDomHook<T>;
}
}
export class GrDomHook<T extends PluginElement> implements HookApi<T> {
private instances: HTMLElement[] = [];
private attachCallbacks: HookCallback<T>[] = [];
private detachCallbacks: HookCallback<T>[] = [];
/**
* The name of the (custom) element that is going to be created. Matches the T
* type parameter.
*/
private readonly moduleName: string;
private lastAttachedPromise: Promise<HTMLElement> | null = null;
constructor(hookName: string, moduleName?: string) {
if (moduleName) {
this.moduleName = moduleName;
} else {
this.moduleName = hookName;
this._createPlaceholder(hookName);
}
}
_createPlaceholder(hookName: string) {
class HookPlaceholder extends PolymerElement {
static get is() {
return hookName;
}
static get properties() {
return {
plugin: Object,
content: Object,
};
}
}
customElements.define(HookPlaceholder.is, HookPlaceholder);
}
handleInstanceDetached(instance: T) {
const index = this.instances.indexOf(instance);
if (index !== -1) {
this.instances.splice(index, 1);
}
this.detachCallbacks.forEach(callback => callback(instance));
}
handleInstanceAttached(instance: T) {
this.instances.push(instance);
this.attachCallbacks.forEach(callback => callback(instance));
}
/**
* Get instance of last DOM hook element attached into the endpoint.
* Returns a Promise, that's resolved when attachment is done.
*/
getLastAttached(): Promise<HTMLElement> {
if (this.instances.length) {
return Promise.resolve(this.instances.slice(-1)[0]);
}
if (!this.lastAttachedPromise) {
let resolve: HookCallback<T>;
const promise = new Promise<HTMLElement>(r => {
resolve = r;
this.attachCallbacks.push(resolve);
});
this.lastAttachedPromise = promise.then((element: HTMLElement) => {
this.lastAttachedPromise = null;
const index = this.attachCallbacks.indexOf(resolve);
if (index !== -1) {
this.attachCallbacks.splice(index, 1);
}
return element;
});
}
return this.lastAttachedPromise;
}
/**
* Get all DOM hook elements.
*/
getAllAttached() {
return this.instances;
}
/**
* Install a new callback to invoke when a new instance of DOM hook element
* is attached.
*/
onAttached(callback: HookCallback<T>) {
this.attachCallbacks.push(callback);
return this;
}
/**
* Install a new callback to invoke when an instance of DOM hook element
* is detached.
*
*/
onDetached(callback: HookCallback<T>) {
this.detachCallbacks.push(callback);
return this;
}
/**
* Name of DOM hook element that will be installed into the endpoint.
*/
getModuleName() {
return this.moduleName;
}
}
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