angular-cn/packages/compiler/test/expression_parser/ast_spec.ts

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/**
* @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
*/
import {AST, Lexer, Parser, RecursiveAstVisitor} from '@angular/compiler';
import {ImplicitReceiver, MethodCall, PropertyRead} from '@angular/compiler/src/compiler';
describe('RecursiveAstVisitor', () => {
it('should visit every node', () => {
const parser = new Parser(new Lexer());
const ast = parser.parseBinding('x.y()', null /* location */, 0 /* absoluteOffset */);
const visitor = new Visitor();
const path: AST[] = [];
visitor.visit(ast.ast, path);
// If the visitor method of RecursiveAstVisitor is implemented correctly,
// then we should have collected the full path from root to leaf.
expect(path.length).toBe(3);
const [methodCall, propertyRead, implicitReceiver] = path;
expectType(methodCall, MethodCall);
expectType(propertyRead, PropertyRead);
expectType(implicitReceiver, ImplicitReceiver);
expect(methodCall.name).toBe('y');
expect(methodCall.args).toEqual([]);
expect(propertyRead.name).toBe('x');
});
});
class Visitor extends RecursiveAstVisitor {
visit(node: AST, path: AST[]) {
path.push(node);
node.visit(this, path);
}
}
type Newable = new (...args: any) => any;
function expectType<T extends Newable>(val: any, t: T): asserts val is InstanceType<T> {
expect(val instanceof t).toBe(true, `expect ${val.constructor.name} to be ${t.name}`);
}