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379 lines
15 KiB
TypeScript
379 lines
15 KiB
TypeScript
/**
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* Copyright (c) Microsoft Corporation.
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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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*/
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import { CSSComplexSelector, CSSSimpleSelector, CSSComplexSelectorList, CSSFunctionArgument } from '../common/cssParser';
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export type QueryContext = {
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scope: Element | ShadowRoot | Document;
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// Place for more options, e.g. normalizing whitespace or piercing shadow.
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};
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export type Selector = any; // Opaque selector type.
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export interface SelectorEvaluator {
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query(context: QueryContext, selector: Selector): Element[];
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matches(element: Element, selector: Selector, context: QueryContext): boolean;
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}
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export interface SelectorEngine {
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matches?(element: Element, args: (string | number | Selector)[], context: QueryContext, evaluator: SelectorEvaluator): boolean;
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query?(context: QueryContext, args: (string | number | Selector)[], evaluator: SelectorEvaluator): Element[];
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}
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export class SelectorEvaluatorImpl implements SelectorEvaluator {
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private _engines = new Map<string, SelectorEngine>();
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private _cache = new Map<any, { rest: any[], result: any }[]>();
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constructor(extraEngines: Map<string, SelectorEngine>) {
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for (const [name, engine] of extraEngines)
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this._engines.set(name, engine);
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this._engines.set('not', notEngine);
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this._engines.set('is', isEngine);
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this._engines.set('where', isEngine);
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this._engines.set('has', hasEngine);
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this._engines.set('scope', scopeEngine);
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// TODO: host
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// TODO: host-context?
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}
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// This is the only function we should use for querying, because it does
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// the right thing with caching
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evaluate(context: QueryContext, s: CSSComplexSelectorList): Element[] {
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const result = this.query(context, s);
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this._cache.clear();
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return result;
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}
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private _cached<T>(main: any, rest: any[], cb: () => T): T {
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if (!this._cache.has(main))
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this._cache.set(main, []);
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const entries = this._cache.get(main)!;
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const entry = entries.find(e => {
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return e.rest.length === rest.length &&
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rest.findIndex((value, index) => e.rest[index] !== value) === -1;
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});
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if (entry)
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return entry.result as T;
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const result = cb();
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entries.push({ rest, result });
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return result;
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}
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private _checkSelector(s: Selector): CSSComplexSelector | CSSComplexSelectorList {
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const wellFormed = typeof s === 'object' && s &&
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(Array.isArray(s) || ('simples' in s) && (s.simples.length));
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if (!wellFormed)
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throw new Error(`Malformed selector "${s}"`);
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return s as CSSComplexSelector | CSSComplexSelectorList;
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}
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matches(element: Element, s: Selector, context: QueryContext): boolean {
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const selector = this._checkSelector(s);
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return this._cached<boolean>(element, ['matches', selector, context], () => {
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if (Array.isArray(selector))
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return this._matchesEngine(isEngine, element, selector, context);
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if (!this._matchesSimple(element, selector.simples[selector.simples.length - 1].selector, context))
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return false;
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return this._matchesParents(element, selector, selector.simples.length - 2, context);
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});
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}
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query(context: QueryContext, s: any): Element[] {
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const selector = this._checkSelector(s);
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return this._cached<Element[]>(selector, ['query', context], () => {
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if (Array.isArray(selector))
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return this._queryEngine(isEngine, context, selector);
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const elements = this._querySimple(context, selector.simples[selector.simples.length - 1].selector);
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return elements.filter(element => this._matchesParents(element, selector, selector.simples.length - 2, context));
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});
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}
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private _matchesSimple(element: Element, simple: CSSSimpleSelector, context: QueryContext): boolean {
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return this._cached<boolean>(element, ['_matchesSimple', simple, context], () => {
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const isScopeClause = simple.functions.some(f => f.name === 'scope');
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if (!isScopeClause && element === context.scope)
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return false;
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if (simple.css && !this._matchesCSS(element, simple.css))
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return false;
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for (const func of simple.functions) {
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if (!this._matchesEngine(this._getEngine(func.name), element, func.args, context))
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return false;
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}
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return true;
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});
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}
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private _querySimple(context: QueryContext, simple: CSSSimpleSelector): Element[] {
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return this._cached<Element[]>(simple, ['_querySimple', context], () => {
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let css = simple.css;
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const funcs = simple.functions;
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if (css === '*' && funcs.length)
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css = undefined;
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let elements: Element[];
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let firstIndex = -1;
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if (css !== undefined) {
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elements = this._queryCSS(context, css);
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} else {
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firstIndex = funcs.findIndex(func => this._getEngine(func.name).query !== undefined);
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if (firstIndex === -1)
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firstIndex = 0;
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elements = this._queryEngine(this._getEngine(funcs[firstIndex].name), context, funcs[firstIndex].args);
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}
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for (let i = 0; i < funcs.length; i++) {
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if (i === firstIndex)
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continue;
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const engine = this._getEngine(funcs[i].name);
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if (engine.matches !== undefined)
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elements = elements.filter(e => this._matchesEngine(engine, e, funcs[i].args, context));
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}
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for (let i = 0; i < funcs.length; i++) {
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if (i === firstIndex)
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continue;
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const engine = this._getEngine(funcs[i].name);
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if (engine.matches === undefined)
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elements = elements.filter(e => this._matchesEngine(engine, e, funcs[i].args, context));
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}
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return elements;
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});
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}
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private _matchesParents(element: Element, complex: CSSComplexSelector, index: number, context: QueryContext): boolean {
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return this._cached<boolean>(element, ['_matchesParents', complex, index, context], () => {
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if (index < 0)
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return true;
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const { selector: simple, combinator } = complex.simples[index];
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if (combinator === '>') {
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const parent = parentElementOrShadowHostInScope(element, context.scope);
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if (!parent || !this._matchesSimple(parent, simple, context))
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return false;
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return this._matchesParents(parent, complex, index - 1, context);
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}
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if (combinator === '+') {
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const previousSibling = element === context.scope ? null : element.previousElementSibling;
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if (!previousSibling || !this._matchesSimple(previousSibling, simple, context))
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return false;
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return this._matchesParents(previousSibling, complex, index - 1, context);
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}
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if (combinator === '') {
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let parent = parentElementOrShadowHostInScope(element, context.scope);
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while (parent) {
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if (this._matchesSimple(parent, simple, context)) {
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if (this._matchesParents(parent, complex, index - 1, context))
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return true;
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if (complex.simples[index - 1].combinator === '')
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break;
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}
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parent = parentElementOrShadowHostInScope(parent, context.scope);
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}
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return false;
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}
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if (combinator === '~') {
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let previousSibling = element === context.scope ? null : element.previousElementSibling;
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while (previousSibling) {
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if (this._matchesSimple(previousSibling, simple, context)) {
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if (this._matchesParents(previousSibling, complex, index - 1, context))
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return true;
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if (complex.simples[index - 1].combinator === '~')
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break;
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}
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previousSibling = previousSibling === context.scope ? null : previousSibling.previousElementSibling;
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}
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return false;
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}
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throw new Error(`Unsupported combinator "${combinator}"`);
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});
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}
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private _matchesEngine(engine: SelectorEngine, element: Element, args: CSSFunctionArgument[], context: QueryContext): boolean {
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if (engine.matches)
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return this._callMatches(engine, element, args, context);
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if (engine.query)
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return this._callQuery(engine, args, context).includes(element);
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throw new Error(`Selector engine should implement "matches" or "query"`);
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}
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private _queryEngine(engine: SelectorEngine, context: QueryContext, args: CSSFunctionArgument[]): Element[] {
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if (engine.query)
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return this._callQuery(engine, args, context);
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if (engine.matches)
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return this._queryCSS(context, '*').filter(element => this._callMatches(engine, element, args, context));
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throw new Error(`Selector engine should implement "matches" or "query"`);
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}
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private _callMatches(engine: SelectorEngine, element: Element, args: CSSFunctionArgument[], context: QueryContext): boolean {
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return this._cached<boolean>(element, ['_callMatches', engine, args, context.scope], () => {
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return engine.matches!(element, args, context, this);
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});
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}
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private _callQuery(engine: SelectorEngine, args: CSSFunctionArgument[], context: QueryContext): Element[] {
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return this._cached<Element[]>(args, ['_callQuery', engine, context.scope], () => {
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return engine.query!(context, args, this);
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});
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}
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private _matchesCSS(element: Element, css: string): boolean {
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return this._cached<boolean>(element, ['_matchesCSS', css], () => {
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return element.matches(css);
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});
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}
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private _queryCSS(context: QueryContext, css: string): Element[] {
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return this._cached<Element[]>(css, ['_queryCSS', context], () => {
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const result: Element[] = [];
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function query(root: Element | ShadowRoot | Document) {
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result.push(...root.querySelectorAll(css));
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if ((root as Element).shadowRoot)
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query((root as Element).shadowRoot!);
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for (const element of root.querySelectorAll('*')) {
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if (element.shadowRoot)
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query(element.shadowRoot);
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}
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}
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query(context.scope);
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return result;
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});
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}
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private _getEngine(name: string): SelectorEngine {
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const engine = this._engines.get(name);
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if (!engine)
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throw new Error(`Unknown selector engine "${name}"`);
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return engine;
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}
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}
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const isEngine: SelectorEngine = {
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matches(element: Element, args: any[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
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if (args.length === 0)
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throw new Error(`"is" engine expects non-empty selector list`);
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return args.some(selector => evaluator.matches(element, selector, context));
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},
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query(context: QueryContext, args: any[], evaluator: SelectorEvaluator): Element[] {
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if (args.length === 0)
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throw new Error(`"is" engine expects non-empty selector list`);
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const elements: Element[] = [];
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for (const arg of args)
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elements.push(...evaluator.query(context, arg));
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const result = Array.from(new Set(elements));
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return args.length > 1 ? sortInDOMOrder(result) : result;
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},
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};
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const hasEngine: SelectorEngine = {
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matches(element: Element, args: any[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
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if (args.length === 0)
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throw new Error(`"has" engine expects non-empty selector list`);
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return evaluator.query({ ...context, scope: element }, args).length > 0;
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},
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// TODO: we can implement efficient "query" by matching "args" and returning
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// all parents/descendants, just have to be careful with the ":scope" matching.
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};
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const scopeEngine: SelectorEngine = {
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matches(element: Element, args: any[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
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if (args.length !== 0)
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throw new Error(`"scope" engine expects no arguments`);
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if (context.scope.nodeType === 9 /* Node.DOCUMENT_NODE */)
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return element === (context.scope as Document).documentElement;
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return element === context.scope;
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},
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query(context: QueryContext, args: any[], evaluator: SelectorEvaluator): Element[] {
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if (args.length !== 0)
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throw new Error(`"scope" engine expects no arguments`);
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if (context.scope.nodeType === 9 /* Node.DOCUMENT_NODE */) {
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const root = (context.scope as Document).documentElement;
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return root ? [root] : [];
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}
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if (context.scope.nodeType === 1 /* Node.ELEMENT_NODE */)
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return [context.scope as Element];
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return [];
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},
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};
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const notEngine: SelectorEngine = {
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matches(element: Element, args: any[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
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if (args.length === 0)
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throw new Error(`"not" engine expects non-empty selector list`);
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return !evaluator.matches(element, args, context);
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},
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};
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function parentElementOrShadowHost(element: Element): Element | undefined {
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if (element.parentElement)
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return element.parentElement;
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if (!element.parentNode)
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return;
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if (element.parentNode.nodeType === Node.DOCUMENT_FRAGMENT_NODE && (element.parentNode as ShadowRoot).host)
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return (element.parentNode as ShadowRoot).host;
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}
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function parentElementOrShadowHostInScope(element: Element, scope: Element | ShadowRoot | Document): Element | undefined {
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return element === scope ? undefined : parentElementOrShadowHost(element);
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}
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function sortInDOMOrder(elements: Element[]): Element[] {
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type SortEntry = { children: Element[], taken: boolean };
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const elementToEntry = new Map<Element, SortEntry>();
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const roots: Element[] = [];
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const result: Element[] = [];
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function append(element: Element): SortEntry {
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let entry = elementToEntry.get(element);
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if (entry)
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return entry;
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const parent = parentElementOrShadowHost(element);
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if (parent) {
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const parentEntry = append(parent);
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parentEntry.children.push(element);
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} else {
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roots.push(element);
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}
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entry = { children: [], taken: false };
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elementToEntry.set(element, entry);
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return entry;
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}
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elements.forEach(e => append(e).taken = true);
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function visit(element: Element) {
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const entry = elementToEntry.get(element)!;
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if (entry.taken)
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result.push(element);
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if (entry.children.length > 1) {
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const set = new Set(entry.children);
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entry.children = [];
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let child = element.firstElementChild;
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while (child && entry.children.length < set.size) {
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if (set.has(child))
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entry.children.push(child);
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child = child.nextElementSibling;
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}
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child = element.shadowRoot ? element.shadowRoot.firstElementChild : null;
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while (child && entry.children.length < set.size) {
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if (set.has(child))
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entry.children.push(child);
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child = child.nextElementSibling;
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}
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}
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entry.children.forEach(visit);
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}
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roots.forEach(visit);
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return result;
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}
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