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