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Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically
embedded into Java applications to provide scripting to end users.
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* 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/. */
package org.mozilla.javascript;
public final class ES6Generator extends IdScriptableObject {
private static final long serialVersionUID = 1645892441041347273L;
private static final Object GENERATOR_TAG = "Generator";
static ES6Generator init(ScriptableObject scope, boolean sealed) {
ES6Generator prototype = new ES6Generator();
if (scope != null) {
prototype.setParentScope(scope);
prototype.setPrototype(getObjectPrototype(scope));
}
prototype.activatePrototypeMap(MAX_PROTOTYPE_ID);
if (sealed) {
prototype.sealObject();
}
// Need to access Generator prototype when constructing
// Generator instances, but don't have a generator constructor
// to use to find the prototype. Use the "associateValue"
// approach instead.
if (scope != null) {
scope.associateValue(GENERATOR_TAG, prototype);
}
return prototype;
}
/**
* Only for constructing the prototype object.
*/
private ES6Generator() { }
public ES6Generator(Scriptable scope, NativeFunction function,
Object savedState)
{
this.function = function;
this.savedState = savedState;
// Set parent and prototype properties. Since we don't have a
// "Generator" constructor in the top scope, we stash the
// prototype in the top scope's associated value.
Scriptable top = ScriptableObject.getTopLevelScope(scope);
this.setParentScope(top);
ES6Generator prototype =
(ES6Generator)ScriptableObject.getTopScopeValue(top, GENERATOR_TAG);
this.setPrototype(prototype);
}
@Override
public String getClassName() {
return "Generator";
}
@Override
protected void initPrototypeId(int id) {
if (id == SymbolId_iterator) {
initPrototypeMethod(GENERATOR_TAG, id, SymbolKey.ITERATOR, "[Symbol.iterator]", 0);
return;
}
String s;
int arity;
switch (id) {
case Id_next: arity=1; s="next"; break;
case Id_return: arity=1; s="return"; break;
case Id_throw: arity=1; s="throw"; break;
default: throw new IllegalArgumentException(String.valueOf(id));
}
initPrototypeMethod(GENERATOR_TAG, id, s, arity);
}
@Override
public Object execIdCall(IdFunctionObject f, Context cx, Scriptable scope,
Scriptable thisObj, Object[] args)
{
if (!f.hasTag(GENERATOR_TAG)) {
return super.execIdCall(f, cx, scope, thisObj, args);
}
int id = f.methodId();
if (!(thisObj instanceof ES6Generator)) {
throw incompatibleCallError(f);
}
ES6Generator generator = (ES6Generator) thisObj;
Object value = args.length >= 1 ? args[0] : Undefined.instance;
switch (id) {
case Id_return:
if (generator.delegee == null) {
return generator.resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_CLOSE, value);
}
return generator.resumeDelegeeReturn(cx, scope, value);
case Id_next:
if (generator.delegee == null) {
return generator.resumeLocal(cx, scope, value);
}
return generator.resumeDelegee(cx, scope, value);
case Id_throw:
if (generator.delegee == null) {
return generator.resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_THROW, value);
}
return generator.resumeDelegeeThrow(cx, scope, value);
case SymbolId_iterator:
return thisObj;
default:
throw new IllegalArgumentException(String.valueOf(id));
}
}
private Scriptable resumeDelegee(Context cx, Scriptable scope, Object value)
{
try {
// Be super-careful and only pass an arg to next if it expects one
Object[] nextArgs = Undefined.instance.equals(value) ? ScriptRuntime.emptyArgs : new Object[] { value };
Callable nextFn = ScriptRuntime.getPropFunctionAndThis(delegee, ES6Iterator.NEXT_METHOD, cx, scope);
Scriptable nextThis = ScriptRuntime.lastStoredScriptable(cx);
Object nr = nextFn.call(cx, scope, nextThis, nextArgs);
Scriptable nextResult = ScriptableObject.ensureScriptable(nr);
if (ScriptRuntime.isIteratorDone(cx, nextResult)) {
// Iterator is "done".
delegee = null;
// Return a result to the original generator
return resumeLocal(cx, scope, ScriptableObject.getProperty(nextResult, ES6Iterator.VALUE_PROPERTY));
}
// Otherwise, we have a normal result and should continue
return nextResult;
} catch (RhinoException re) {
// Exceptions from the delegee should be handled by the enclosing
// generator, including if they're because functions can't be found.
delegee = null;
return resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_THROW, re);
}
}
private Scriptable resumeDelegeeThrow(Context cx, Scriptable scope, Object value) {
boolean returnCalled = false;
try {
// Delegate to "throw" method. If it's not defined we'll get an error here.
Callable throwFn = ScriptRuntime.getPropFunctionAndThis(delegee, "throw", cx, scope);
Scriptable nextThis = ScriptRuntime.lastStoredScriptable(cx);
Object throwResult = throwFn.call(cx, scope, nextThis, new Object[] { value });
if (ScriptRuntime.isIteratorDone(cx, throwResult)) {
// Iterator is "done".
try {
// Return a result to the original generator, but first optionally call "return"
returnCalled = true;
callReturnOptionally(cx, scope, Undefined.instance);
} finally {
delegee = null;
}
return resumeLocal(cx, scope,
ScriptRuntime.getObjectProp(throwResult, ES6Iterator.VALUE_PROPERTY, cx, scope));
}
// Otherwise, we have a normal result and should continue
return ensureScriptable(throwResult);
} catch (RhinoException re) {
// Handle all exceptions, including missing methods, by delegating to original.
try {
if (!returnCalled) {
try {
callReturnOptionally(cx, scope, Undefined.instance);
} catch (RhinoException re2) {
return resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_THROW, re2);
}
}
} finally {
delegee = null;
}
return resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_THROW, re);
}
}
private Scriptable resumeDelegeeReturn(Context cx, Scriptable scope, Object value) {
try {
// Call "return" but don't throw if it can't be found
Object retResult = callReturnOptionally(cx, scope, value);
if (retResult != null) {
if (ScriptRuntime.isIteratorDone(cx, retResult)) {
// Iterator is "done".
delegee = null;
// Return a result to the original generator
return resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_CLOSE,
ScriptRuntime.getObjectPropNoWarn(retResult, ES6Iterator.VALUE_PROPERTY, cx, scope));
} else {
// Not actually done yet!
return ensureScriptable(retResult);
}
}
// No "return" -- let the original iterator return the value.
delegee = null;
return resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_CLOSE, value);
} catch (RhinoException re) {
// Exceptions from the delegee should be handled by the enclosing
// generator, including if they're because functions can't be found.
delegee = null;
return resumeAbruptLocal(cx, scope, NativeGenerator.GENERATOR_THROW, re);
}
}
private Scriptable resumeLocal(Context cx, Scriptable scope, Object value)
{
if (state == State.COMPLETED) {
return ES6Iterator.makeIteratorResult(cx, scope, Boolean.TRUE);
}
if (state == State.EXECUTING) {
throw ScriptRuntime.typeError0("msg.generator.executing");
}
Scriptable result = ES6Iterator.makeIteratorResult(cx, scope, Boolean.FALSE);
state = State.EXECUTING;
try {
Object r = function.resumeGenerator(cx, scope,
NativeGenerator.GENERATOR_SEND, savedState, value);
if (r instanceof YieldStarResult) {
// This special result tells us that we are executing a "yield *"
state = State.SUSPENDED_YIELD;
YieldStarResult ysResult = (YieldStarResult)r;
try {
delegee = ScriptRuntime.callIterator(ysResult.getResult(), cx, scope);
} catch (RhinoException re) {
// Need to handle exceptions if the iterator cannot be called.
return resumeAbruptLocal(cx, scope,
NativeGenerator.GENERATOR_THROW, re);
}
Scriptable delResult;
try {
// Re-execute but update state in case we end up back here
// Value shall be Undefined based on the very complex spec!
delResult = resumeDelegee(cx, scope, Undefined.instance);
} finally {
state = State.EXECUTING;
}
if (ScriptRuntime.isIteratorDone(cx, delResult)) {
state = State.COMPLETED;
}
return delResult;
}
ScriptableObject.putProperty(result, ES6Iterator.VALUE_PROPERTY, r);
} catch (NativeGenerator.GeneratorClosedException gce) {
state = State.COMPLETED;
} catch (JavaScriptException jse) {
state = State.COMPLETED;
if (jse.getValue() instanceof NativeIterator.StopIteration) {
ScriptableObject.putProperty(result, ES6Iterator.VALUE_PROPERTY,
((NativeIterator.StopIteration)jse.getValue()).getValue());
} else {
lineNumber = jse.lineNumber();
lineSource = jse.lineSource();
if (jse.getValue() instanceof RhinoException) {
throw (RhinoException)jse.getValue();
}
throw jse;
}
} catch (RhinoException re) {
lineNumber = re.lineNumber();
lineSource = re.lineSource();
throw re;
} finally {
if (state == State.COMPLETED) {
ScriptableObject.putProperty(result, ES6Iterator.DONE_PROPERTY, Boolean.TRUE);
} else {
state = State.SUSPENDED_YIELD;
}
}
return result;
}
private Scriptable resumeAbruptLocal(Context cx, Scriptable scope, int op, Object value)
{
if (state == State.EXECUTING) {
throw ScriptRuntime.typeError0("msg.generator.executing");
}
if (state == State.SUSPENDED_START) {
// Throw right away if we never started
state = State.COMPLETED;
}
Scriptable result = ES6Iterator.makeIteratorResult(cx, scope, Boolean.FALSE);
if (state == State.COMPLETED) {
if (op == NativeGenerator.GENERATOR_THROW) {
throw new JavaScriptException(value, lineSource, lineNumber);
}
ScriptableObject.putProperty(result, ES6Iterator.DONE_PROPERTY, Boolean.TRUE);
return result;
}
state = State.EXECUTING;
Object throwValue = value;
if (op == NativeGenerator.GENERATOR_CLOSE) {
if (!(value instanceof NativeGenerator.GeneratorClosedException)) {
throwValue = new NativeGenerator.GeneratorClosedException();
}
} else {
if (value instanceof JavaScriptException) {
throwValue = ((JavaScriptException)value).getValue();
} else if (value instanceof RhinoException) {
throwValue = ScriptRuntime.wrapException((Throwable)value, scope, cx);
}
}
try {
Object r = function.resumeGenerator(cx, scope, op, savedState, throwValue);
ScriptableObject.putProperty(result, ES6Iterator.VALUE_PROPERTY, r);
// If we get here without an exception we can still run.
state = State.SUSPENDED_YIELD;
} catch (NativeGenerator.GeneratorClosedException gce) {
state = State.COMPLETED;
} catch (JavaScriptException jse) {
state = State.COMPLETED;
if (jse.getValue() instanceof NativeIterator.StopIteration) {
ScriptableObject.putProperty(result, ES6Iterator.VALUE_PROPERTY,
((NativeIterator.StopIteration)jse.getValue()).getValue());
} else {
lineNumber = jse.lineNumber();
lineSource = jse.lineSource();
if (jse.getValue() instanceof RhinoException) {
throw (RhinoException)jse.getValue();
}
throw jse;
}
} catch (RhinoException re) {
state = State.COMPLETED;
lineNumber = re.lineNumber();
lineSource = re.lineSource();
throw re;
} finally {
// After an abrupt completion we are always, umm, complete,
// and we will never delegate to the delegee again
if (state == State.COMPLETED) {
delegee = null;
ScriptableObject.putProperty(result, ES6Iterator.DONE_PROPERTY, Boolean.TRUE);
}
}
return result;
}
private Object callReturnOptionally(Context cx, Scriptable scope, Object value) {
Object[] retArgs = Undefined.instance.equals(value) ? ScriptRuntime.emptyArgs
: new Object[] { value };
// Delegate to "return" method. If it's not defined we ignore it
Object retFnObj = ScriptRuntime.getObjectPropNoWarn(
delegee, ES6Iterator.RETURN_METHOD, cx, scope);
if (!Undefined.instance.equals(retFnObj)) {
if (!(retFnObj instanceof Callable)) {
throw ScriptRuntime.typeError2("msg.isnt.function", ES6Iterator.RETURN_METHOD,
ScriptRuntime.typeof(retFnObj));
}
return ((Callable)retFnObj).call(cx, scope, ensureScriptable(delegee), retArgs);
}
return null;
}
@Override
protected int findPrototypeId(Symbol k) {
if (SymbolKey.ITERATOR.equals(k)) {
return SymbolId_iterator;
}
return 0;
}
// #string_id_map#
@Override
protected int findPrototypeId(String s) {
int id;
// #generated# Last update: 2017-08-04 17:30:46 PDT
L0: { id = 0; String X = null;
int s_length = s.length();
if (s_length==4) { X="next";id=Id_next; }
else if (s_length==5) { X="throw";id=Id_throw; }
else if (s_length==6) { X="return";id=Id_return; }
if (X!=null && X!=s && !X.equals(s)) id = 0;
break L0;
}
// #/generated#
return id;
}
private static final int
Id_next = 1,
Id_return = 2,
Id_throw = 3,
SymbolId_iterator = 4,
MAX_PROTOTYPE_ID = SymbolId_iterator;
// #/string_id_map#
private NativeFunction function;
private Object savedState;
private String lineSource;
private int lineNumber;
private State state = State.SUSPENDED_START;
private Object delegee;
enum State { SUSPENDED_START, SUSPENDED_YIELD, EXECUTING, COMPLETED }
public static final class YieldStarResult {
private Object result;
public YieldStarResult(Object result) {
this.result = result;
}
Object getResult() { return result; }
}
}
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