111 lines
2.9 KiB
JavaScript
111 lines
2.9 KiB
JavaScript
// Copyright (C) 2016 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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(function() {
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'use strict';
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const HLJS_PATH = 'bower_components/highlightjs/highlight.min.js';
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const LIB_ROOT_PATTERN = /(.+\/)elements\/gr-app\.html/;
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Polymer({
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is: 'gr-syntax-lib-loader',
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properties: {
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_state: {
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type: Object,
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// NOTE: intended singleton.
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value: {
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configured: false,
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loading: false,
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callbacks: [],
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},
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},
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},
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get() {
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return new Promise((resolve, reject) => {
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// If the lib is totally loaded, resolve immediately.
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if (this._getHighlightLib()) {
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resolve(this._getHighlightLib());
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return;
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}
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// If the library is not currently being loaded, then start loading it.
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if (!this._state.loading) {
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this._state.loading = true;
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this._loadHLJS().then(this._onLibLoaded.bind(this)).catch(reject);
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}
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this._state.callbacks.push(resolve);
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});
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},
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_onLibLoaded() {
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const lib = this._getHighlightLib();
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this._state.loading = false;
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for (const cb of this._state.callbacks) {
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cb(lib);
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}
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this._state.callbacks = [];
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},
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_getHighlightLib() {
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const lib = window.hljs;
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if (lib && !this._state.configured) {
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this._state.configured = true;
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lib.configure({classPrefix: 'gr-diff gr-syntax gr-syntax-'});
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}
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return lib;
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},
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_getLibRoot() {
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if (this._cachedLibRoot) { return this._cachedLibRoot; }
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const appLink = document.head
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.querySelector('link[rel=import][href$="gr-app.html"]');
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if (!appLink) { return null; }
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return this._cachedLibRoot = appLink
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.href
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.match(LIB_ROOT_PATTERN)[1];
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},
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_cachedLibRoot: null,
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_loadHLJS() {
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return new Promise((resolve, reject) => {
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const script = document.createElement('script');
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const src = this._getHLJSUrl();
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if (!src) {
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reject(new Error('Unable to load blank HLJS url.'));
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return;
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}
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script.src = src;
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script.onload = resolve;
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script.onerror = reject;
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Polymer.dom(document.head).appendChild(script);
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});
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},
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_getHLJSUrl() {
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const root = this._getLibRoot();
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if (!root) { return null; }
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return root + HLJS_PATH;
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},
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});
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})();
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