зеркало из https://github.com/mozilla/gecko-dev.git
487 строки
18 KiB
JavaScript
487 строки
18 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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var EXPORTED_SYMBOLS = ["WebsiteMetadata"];
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ChromeUtils.defineModuleGetter(this, "EventDispatcher", "resource://gre/modules/Messaging.jsm");
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var WebsiteMetadata = {
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/**
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* Asynchronously parse the document extract metadata. A 'Website:Metadata' event with the metadata
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* will be sent.
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*/
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parseAsynchronously: function(doc) {
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let metadata = getMetadata(doc, doc.location.href, {
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image_url: metadataRules.image_url,
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provider: metadataRules.provider,
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description_length: metadataRules.description_length,
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});
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// No metadata was extracted, so don't bother sending it.
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if (Object.keys(metadata).length === 0) {
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return;
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}
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let msg = {
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type: "Website:Metadata",
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location: doc.location.href,
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hasImage: metadata.image_url && metadata.image_url !== "",
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metadata: JSON.stringify(metadata),
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};
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EventDispatcher.instance.sendRequest(msg);
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},
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};
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// #################################################################################################
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// # Modified version of makeUrlAbsolute() to not import url parser library (and dependencies)
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// #################################################################################################
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function makeUrlAbsolute(context, relative) {
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var a = context.doc.createElement("a");
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a.href = relative;
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return a.href;
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}
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// #################################################################################################
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// # page-metadata-parser
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// # https://github.com/mozilla/page-metadata-parser/
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// # 61c58cbd0f0bf2153df832a388a79c66b288b98c
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// #################################################################################################
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function buildRuleset(name, rules, processors) {
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const reversedRules = Array.from(rules).reverse();
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const builtRuleset = ruleset(...reversedRules.map(([query, handler], order) => rule(
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dom(query),
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node => [{
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score: order,
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flavor: name,
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notes: handler(node),
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}]
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)));
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return (doc, context) => {
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const kb = builtRuleset.score(doc);
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const maxNode = kb.max(name);
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if (maxNode) {
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let value = maxNode.flavors.get(name);
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if (processors) {
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processors.forEach(processor => {
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value = processor(value, context);
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});
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}
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if (value) {
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if (value.trim) {
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return value.trim();
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}
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return value;
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}
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}
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};
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}
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const descriptionRules = [
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['meta[property="og:description"]', node => node.element.getAttribute("content")],
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['meta[name="description"]', node => node.element.getAttribute("content")],
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];
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const metadataRules = {
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description: {
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rules: descriptionRules,
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},
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description_length: {
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rules: descriptionRules,
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processors: [
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(description) => description.length,
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],
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},
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icon_url: {
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rules: [
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['link[rel="apple-touch-icon"]', node => node.element.getAttribute("href")],
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['link[rel="apple-touch-icon-precomposed"]', node => node.element.getAttribute("href")],
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['link[rel="icon"]', node => node.element.getAttribute("href")],
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['link[rel="fluid-icon"]', node => node.element.getAttribute("href")],
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['link[rel="shortcut icon"]', node => node.element.getAttribute("href")],
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['link[rel="Shortcut Icon"]', node => node.element.getAttribute("href")],
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['link[rel="mask-icon"]', node => node.element.getAttribute("href")],
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],
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processors: [
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(icon_url, context) => makeUrlAbsolute(context, icon_url),
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],
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},
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image_url: {
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rules: [
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['meta[property="og:image:secure_url"]', node => node.element.getAttribute("content")],
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['meta[property="og:image:url"]', node => node.element.getAttribute("content")],
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['meta[property="og:image"]', node => node.element.getAttribute("content")],
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['meta[property="twitter:image"]', node => node.element.getAttribute("content")],
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['meta[name="thumbnail"]', node => node.element.getAttribute("content")],
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],
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processors: [
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(image_url, context) => makeUrlAbsolute(context, image_url),
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],
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},
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keywords: {
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rules: [
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['meta[name="keywords"]', node => node.element.getAttribute("content")],
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],
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processors: [
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(keywords) => keywords.split(",").map((keyword) => keyword.trim()),
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],
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},
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title: {
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rules: [
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['meta[property="og:title"]', node => node.element.getAttribute("content")],
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['meta[property="twitter:title"]', node => node.element.getAttribute("content")],
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['meta[name="hdl"]', node => node.element.getAttribute("content")],
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["title", node => node.element.text],
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],
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},
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type: {
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rules: [
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['meta[property="og:type"]', node => node.element.getAttribute("content")],
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],
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},
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url: {
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rules: [
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['meta[property="og:url"]', node => node.element.getAttribute("content")],
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['link[rel="canonical"]', node => node.element.getAttribute("href")],
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],
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},
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provider: {
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rules: [
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['meta[property="og:site_name"]', node => node.element.getAttribute("content")],
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],
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},
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};
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function getMetadata(doc, url, rules) {
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const metadata = {};
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const context = {url, doc};
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const ruleSet = rules || metadataRules;
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Object.keys(ruleSet).map(metadataKey => {
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const metadataRule = ruleSet[metadataKey];
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if (Array.isArray(metadataRule.rules)) {
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const builtRule = buildRuleset(metadataKey, metadataRule.rules, metadataRule.processors);
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metadata[metadataKey] = builtRule(doc, context);
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} else {
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metadata[metadataKey] = getMetadata(doc, url, metadataRule);
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}
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});
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return metadata;
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}
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// #################################################################################################
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// # Fathom dependencies resolved
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// #################################################################################################
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// const {forEach} = require('wu');
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function forEach(fn, obj) {
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for (let x of obj) {
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fn(x);
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}
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}
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function best(iterable, by, isBetter) {
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let bestSoFar, bestKeySoFar;
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let isFirst = true;
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forEach(
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function(item) {
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const key = by(item);
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if (isBetter(key, bestKeySoFar) || isFirst) {
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bestSoFar = item;
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bestKeySoFar = key;
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isFirst = false;
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}
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},
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iterable);
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if (isFirst) {
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throw new Error("Tried to call best() on empty iterable");
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}
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return bestSoFar;
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}
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// const {max} = require('./utils');
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function max(iterable, by = identity) {
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return best(iterable, by, (a, b) => a > b);
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}
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// #################################################################################################
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// # Fathom
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// # https://github.com/mozilla/fathom
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// # cac59e470816f17fc1efd4a34437b585e3e451cd
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// #################################################################################################
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// Get a key of a map, first setting it to a default value if it's missing.
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function getDefault(map, key, defaultMaker) {
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if (map.has(key)) {
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return map.get(key);
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}
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const defaultValue = defaultMaker();
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map.set(key, defaultValue);
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return defaultValue;
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}
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// Construct a filtration network of rules.
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function ruleset(...rules) {
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const rulesByInputFlavor = new Map(); // [someInputFlavor: [rule, ...]]
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// File each rule under its input flavor:
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forEach(rule => getDefault(rulesByInputFlavor, rule.source.inputFlavor, () => []).push(rule),
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rules);
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return {
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// Iterate over a DOM tree or subtree, building up a knowledgebase, a
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// data structure holding scores and annotations for interesting
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// elements. Return the knowledgebase.
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//
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// This is the "rank" portion of the rank-and-yank algorithm.
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score: function(tree) {
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const kb = knowledgebase();
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// Introduce the whole DOM into the KB as flavor 'dom' to get
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// things started:
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const nonterminals = [[{tree}, "dom"]]; // [[node, flavor], [node, flavor], ...]
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// While there are new facts, run the applicable rules over them to
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// generate even newer facts. Repeat until everything's fully
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// digested. Rules run in no particular guaranteed order.
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while (nonterminals.length) {
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const [inNode, inFlavor] = nonterminals.pop();
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for (let rule of getDefault(rulesByInputFlavor, inFlavor, () => [])) {
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const outFacts = resultsOf(rule, inNode, inFlavor, kb);
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for (let fact of outFacts) {
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const outNode = kb.nodeForElement(fact.element);
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// No matter whether or not this flavor has been
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// emitted before for this node, we multiply the score.
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// We want to be able to add rules that refine the
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// scoring of a node, without having to rewire the path
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// of flavors that winds through the ruleset.
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//
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// 1 score per Node is plenty. That simplifies our
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// data, our rankers, our flavor system (since we don't
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// need to represent score axes), and our engine. If
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// somebody wants more score axes, they can fake it
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// themselves with notes, thus paying only for what
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// they eat. (We can even provide functions that help
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// with that.) Most rulesets will probably be concerned
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// with scoring only 1 thing at a time anyway. So,
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// rankers return a score multiplier + 0 or more new
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// flavors with optional notes. Facts can never be
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// deleted from the KB by rankers (or order would start
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// to matter); after all, they're *facts*.
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outNode.score *= fact.score;
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// Add a new annotation to a node--but only if there
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// wasn't already one of the given flavor already
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// there; otherwise there's no point.
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//
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// You might argue that we might want to modify an
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// existing note here, but that would be a bad
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// idea. Notes of a given flavor should be
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// considered immutable once laid down. Otherwise, the
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// order of execution of same-flavored rules could
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// matter, hurting pluggability. Emit a new flavor and
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// a new note if you want to do that.
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//
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// Also, choosing not to add a new fact to nonterminals
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// when we're not adding a new flavor saves the work of
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// running the rules against it, which would be
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// entirely redundant and perform no new work (unless
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// the rankers were nondeterministic, but don't do
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// that).
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if (!outNode.flavors.has(fact.flavor)) {
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outNode.flavors.set(fact.flavor, fact.notes);
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kb.indexNodeByFlavor(outNode, fact.flavor); // TODO: better encapsulation rather than indexing explicitly
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nonterminals.push([outNode, fact.flavor]);
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}
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}
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}
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}
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return kb;
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},
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};
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}
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// Construct a container for storing and querying facts, where a fact has a
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// flavor (used to dispatch further rules upon), a corresponding DOM element, a
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// score, and some other arbitrary notes opaque to fathom.
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function knowledgebase() {
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const nodesByFlavor = new Map(); // Map{'texty' -> [NodeA],
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// 'spiffy' -> [NodeA, NodeB]}
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// NodeA = {element: <someElement>,
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//
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// // Global nodewide score. Add
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// // custom ones with notes if
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// // you want.
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// score: 8,
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//
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// // Flavors is a map of flavor names to notes:
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// flavors: Map{'texty' -> {ownText: 'blah',
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// someOtherNote: 'foo',
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// someCustomScore: 10},
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// // This is an empty note:
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// 'fluffy' -> undefined}}
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const nodesByElement = new Map();
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return {
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// Return the "node" (our own data structure that we control) that
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// corresponds to a given DOM element, creating one if necessary.
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nodeForElement: function(element) {
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return getDefault(nodesByElement,
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element,
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() => ({element,
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score: 1,
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flavors: new Map()}));
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},
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// Return the highest-scored node of the given flavor, undefined if
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// there is none.
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max: function(flavor) {
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const nodes = nodesByFlavor.get(flavor);
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return nodes === undefined ? undefined : max(nodes, node => node.score);
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},
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// Let the KB know that a new flavor has been added to an element.
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indexNodeByFlavor: function(node, flavor) {
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getDefault(nodesByFlavor, flavor, () => []).push(node);
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},
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nodesOfFlavor: function(flavor) {
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return getDefault(nodesByFlavor, flavor, () => []);
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},
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};
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}
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// Apply a rule (as returned by a call to rule()) to a fact, and return the
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// new facts that result.
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function resultsOf(rule, node, flavor, kb) {
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// If more types of rule pop up someday, do fancier dispatching here.
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return rule.source.flavor === "flavor" ? resultsOfFlavorRule(rule, node, flavor) : resultsOfDomRule(rule, node, kb);
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}
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// Pull the DOM tree off the special property of the root "dom" fact, and query
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// against it.
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function* resultsOfDomRule(rule, specialDomNode, kb) {
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// Use the special "tree" property of the special starting node:
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const matches = specialDomNode.tree.querySelectorAll(rule.source.selector);
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for (let i = 0; i < matches.length; i++) { // matches is a NodeList, which doesn't conform to iterator protocol
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const element = matches[i];
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const newFacts = explicitFacts(rule.ranker(kb.nodeForElement(element)));
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for (let fact of newFacts) {
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if (fact.element === undefined) {
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fact.element = element;
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}
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if (fact.flavor === undefined) {
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throw new Error("Rankers of dom() rules must return a flavor in each fact. Otherwise, there is no way for that fact to be used later.");
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}
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yield fact;
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}
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}
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}
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function* resultsOfFlavorRule(rule, node, flavor) {
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const newFacts = explicitFacts(rule.ranker(node));
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for (let fact of newFacts) {
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// If the ranker didn't specify a different element, assume it's
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// talking about the one we passed in:
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if (fact.element === undefined) {
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fact.element = node.element;
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}
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if (fact.flavor === undefined) {
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fact.flavor = flavor;
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}
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yield fact;
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}
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}
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// Take the possibly abbreviated output of a ranker function, and make it
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// explicitly an iterable with a defined score.
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//
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// Rankers can return undefined, which means "no facts", a single fact, or an
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// array of facts.
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function* explicitFacts(rankerResult) {
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const array = (rankerResult === undefined) ? [] : (Array.isArray(rankerResult) ? rankerResult : [rankerResult]);
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for (let fact of array) {
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if (fact.score === undefined) {
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fact.score = 1;
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}
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yield fact;
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}
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}
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// TODO: For the moment, a lot of responsibility is on the rankers to return a
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// pretty big data structure of up to 4 properties. This is a bit verbose for
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// an arrow function (as I hope we can use most of the time) and the usual case
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// will probably be returning just a score multiplier. Make that case more
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// concise.
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// TODO: It is likely that rankers should receive the notes of their input type
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// as a 2nd arg, for brevity.
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// Return a condition that uses a DOM selector to find its matches from the
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// original DOM tree.
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//
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// For consistency, Nodes will still be delivered to the transformers, but
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// they'll have empty flavors and score = 1.
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//
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// Condition constructors like dom() and flavor() build stupid, introspectable
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// objects that the query engine can read. They don't actually do the query
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// themselves. That way, the query planner can be smarter than them, figuring
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// out which indices to use based on all of them. (We'll probably keep a heap
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// by each dimension's score and a hash by flavor name, for starters.) Someday,
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// fancy things like this may be possible: rule(and(tag('p'), klass('snork')),
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// ...)
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function dom(selector) {
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return {
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flavor: "dom",
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inputFlavor: "dom",
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selector,
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};
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}
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// Return a condition that discriminates on nodes of the knowledgebase by flavor.
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function flavor(inputFlavor) {
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return {
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flavor: "flavor",
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inputFlavor,
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};
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}
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function rule(source, ranker) {
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return {
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source,
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ranker,
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};
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}
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