traceur/src/codegeneration/generator/AwaitState.js

ES6 to ES5 compiler

// Copyright 2012 Traceur Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {State} from './State.js';
import {parseStatements} from '../PlaceholderParser.js';

export class AwaitState extends State {
  /**
   * @param {number} id
   * @param {ParseTree} expression
   * @param {number} callbackState
   * @param {Array.<ParseTree>} statements
   */
  constructor(id, callbackState, expression) {
    super(id),
    this.callbackState = callbackState;
    this.expression = expression;
  }

  /**
   * @param {number} oldState
   * @param {number} newState
   * @return {AwaitState}
   */
  replaceState(oldState, newState) {
    return new AwaitState(
        State.replaceStateId(this.id, oldState, newState),
        State.replaceStateId(this.callbackState, oldState, newState),
        this.expression);
  }

  /**
   * @param {FinallyState} enclosingFinally
   * @param {number} machineEndState
   * @param {ErrorReporter} reporter
   * @return {Array.<ParseTree>}
   */
  transform(enclosingFinally, machineEndState, reporter) {
    let stateId, statements;
    if (State.isFinallyExit(enclosingFinally, this.callbackState)) {
      stateId = enclosingFinally.finallyState;
      statements =
          parseStatements `$ctx.finallyFallThrough = ${this.callbackState}`;
    } else {
      stateId = this.callbackState;
      statements = [];
    }

    statements.push(
      ...parseStatements `Promise.resolve(${this.expression}).then(
          $ctx.createCallback(${stateId}), $ctx.errback);
          return;`);
    return statements;
  }
}