fune/js/src/builtin/Generator.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

function GeneratorNext(val) {
  // The IsSuspendedGenerator call below is not necessary for correctness.
  // It's a performance optimization to check for the common case with a
  // single call. It's also inlined in Baseline.

  if (!IsSuspendedGenerator(this)) {
    if (!IsObject(this) || !IsGeneratorObject(this)) {
      return callFunction(
        CallGeneratorMethodIfWrapped,
        this,
        val,
        "GeneratorNext"
      );
    }

    if (GeneratorObjectIsClosed(this)) {
      return { value: undefined, done: true };
    }

    if (GeneratorIsRunning(this)) {
      ThrowTypeError(JSMSG_NESTING_GENERATOR);
    }
  }

  try {
    return resumeGenerator(this, val, "next");
  } catch (e) {
    if (!GeneratorObjectIsClosed(this)) {
      GeneratorSetClosed(this);
    }
    throw e;
  }
}

function GeneratorThrow(val) {
  if (!IsSuspendedGenerator(this)) {
    if (!IsObject(this) || !IsGeneratorObject(this)) {
      return callFunction(
        CallGeneratorMethodIfWrapped,
        this,
        val,
        "GeneratorThrow"
      );
    }

    if (GeneratorObjectIsClosed(this)) {
      throw val;
    }

    if (GeneratorIsRunning(this)) {
      ThrowTypeError(JSMSG_NESTING_GENERATOR);
    }
  }

  try {
    return resumeGenerator(this, val, "throw");
  } catch (e) {
    if (!GeneratorObjectIsClosed(this)) {
      GeneratorSetClosed(this);
    }
    throw e;
  }
}

function GeneratorReturn(val) {
  if (!IsSuspendedGenerator(this)) {
    if (!IsObject(this) || !IsGeneratorObject(this)) {
      return callFunction(
        CallGeneratorMethodIfWrapped,
        this,
        val,
        "GeneratorReturn"
      );
    }

    if (GeneratorObjectIsClosed(this)) {
      return { value: val, done: true };
    }

    if (GeneratorIsRunning(this)) {
      ThrowTypeError(JSMSG_NESTING_GENERATOR);
    }
  }

  try {
    var rval = { value: val, done: true };
    return resumeGenerator(this, rval, "return");
  } catch (e) {
    if (!GeneratorObjectIsClosed(this)) {
      GeneratorSetClosed(this);
    }
    throw e;
  }
}

function InterpretGeneratorResume(gen, val, kind) {
  // If we want to resume a generator in the interpreter, the script containing
  // the resumeGenerator/JSOp::Resume also has to run in the interpreter. The
  // forceInterpreter() call below compiles to a bytecode op that prevents us
  // from JITing this script.
  forceInterpreter();
  if (kind === "next") {
    return resumeGenerator(gen, val, "next");
  }
  if (kind === "throw") {
    return resumeGenerator(gen, val, "throw");
  }
  assert(kind === "return", "Invalid resume kind");
  return resumeGenerator(gen, val, "return");
}