30 lines
921 B
TypeScript
30 lines
921 B
TypeScript
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/**
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* @license
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* Copyright Google Inc. All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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export class AstPath<T> {
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constructor(private path: T[]) {}
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get empty(): boolean { return !this.path || !this.path.length; }
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get head(): T|undefined { return this.path[0]; }
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get tail(): T|undefined { return this.path[this.path.length - 1]; }
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parentOf(node: T): T|undefined { return this.path[this.path.indexOf(node) - 1]; }
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childOf(node: T): T|undefined { return this.path[this.path.indexOf(node) + 1]; }
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first<N extends T>(ctor: {new (...args: any[]): N}): N|undefined {
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for (let i = this.path.length - 1; i >= 0; i--) {
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let item = this.path[i];
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if (item instanceof ctor) return <N>item;
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}
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}
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push(node: T) { this.path.push(node); }
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pop(): T { return this.path.pop(); }
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}
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