61 lines
1.5 KiB
TypeScript
61 lines
1.5 KiB
TypeScript
/**
|
|
* @license
|
|
* Copyright Google LLC 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
|
|
*/
|
|
|
|
/**
|
|
* A path is an ordered set of elements. Typically a path is to a
|
|
* particular offset in a source file. The head of the list is the top
|
|
* most node. The tail is the node that contains the offset directly.
|
|
*
|
|
* For example, the expression `a + b + c` might have an ast that looks
|
|
* like:
|
|
* +
|
|
* / \
|
|
* a +
|
|
* / \
|
|
* b c
|
|
*
|
|
* The path to the node at offset 9 would be `['+' at 1-10, '+' at 7-10,
|
|
* 'c' at 9-10]` and the path the node at offset 1 would be
|
|
* `['+' at 1-10, 'a' at 1-2]`.
|
|
*/
|
|
export class AstPath<T> {
|
|
constructor(private path: T[], public position: number = -1) {}
|
|
|
|
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()!;
|
|
}
|
|
}
|