/* -*- 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;
/**
* This class implements generator objects. See
* http://developer.mozilla.org/en/docs/New_in_JavaScript_1.7#Generators
*
* @author Norris Boyd
*/
public final class NativeGenerator extends IdScriptableObject {
private static final long serialVersionUID = 1645892441041347273L;
private static final Object GENERATOR_TAG = "Generator";
static NativeGenerator init(ScriptableObject scope, boolean sealed) {
// Generator
// Can't use "NativeGenerator().exportAsJSClass" since we don't want
// to define "Generator" as a constructor in the top-level scope.
NativeGenerator prototype = new NativeGenerator();
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 NativeGenerator() { }
public NativeGenerator(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);
NativeGenerator prototype = (NativeGenerator)
ScriptableObject.getTopScopeValue(top, GENERATOR_TAG);
this.setPrototype(prototype);
}
public static final int GENERATOR_SEND = 0,
GENERATOR_THROW = 1,
GENERATOR_CLOSE = 2;
@Override
public String getClassName() {
return "Generator";
}
private static class CloseGeneratorAction implements ContextAction {
private NativeGenerator generator;
CloseGeneratorAction(NativeGenerator generator) {
this.generator = generator;
}
public Object run(Context cx) {
Scriptable scope = ScriptableObject.getTopLevelScope(generator);
Callable closeGenerator = new Callable() {
public Object call(Context cx, Scriptable scope,
Scriptable thisObj, Object[] args) {
return ((NativeGenerator)thisObj).resume(cx, scope,
GENERATOR_CLOSE, new GeneratorClosedException());
}
};
return ScriptRuntime.doTopCall(closeGenerator, cx, scope,
generator, null);
}
}
@Override
protected void initPrototypeId(int id) {
String s;
int arity;
switch (id) {
case Id_close: arity=1; s="close"; break;
case Id_next: arity=1; s="next"; break;
case Id_send: arity=0; s="send"; break;
case Id_throw: arity=0; s="throw"; break;
case Id___iterator__: arity=1; s="__iterator__"; 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 NativeGenerator))
throw incompatibleCallError(f);
NativeGenerator generator = (NativeGenerator) thisObj;
switch (id) {
case Id_close:
// need to run any pending finally clauses
return generator.resume(cx, scope, GENERATOR_CLOSE,
new GeneratorClosedException());
case Id_next:
// arguments to next() are ignored
generator.firstTime = false;
return generator.resume(cx, scope, GENERATOR_SEND,
Undefined.instance);
case Id_send: {
Object arg = args.length > 0 ? args[0] : Undefined.instance;
if (generator.firstTime && !arg.equals(Undefined.instance)) {
throw ScriptRuntime.typeError0("msg.send.newborn");
}
return generator.resume(cx, scope, GENERATOR_SEND, arg);
}
case Id_throw:
return generator.resume(cx, scope, GENERATOR_THROW,
args.length > 0 ? args[0] : Undefined.instance);
case Id___iterator__:
return thisObj;
default:
throw new IllegalArgumentException(String.valueOf(id));
}
}
private Object resume(Context cx, Scriptable scope, int operation,
Object value)
{
if (savedState == null) {
if (operation == GENERATOR_CLOSE)
return Undefined.instance;
Object thrown;
if (operation == GENERATOR_THROW) {
thrown = value;
} else {
thrown = NativeIterator.getStopIterationObject(scope);
}
throw new JavaScriptException(thrown, lineSource, lineNumber);
}
try {
synchronized (this) {
// generator execution is necessarily single-threaded and
// non-reentrant.
// See https://bugzilla.mozilla.org/show_bug.cgi?id=349263
if (locked)
throw ScriptRuntime.typeError0("msg.already.exec.gen");
locked = true;
}
return function.resumeGenerator(cx, scope, operation, savedState,
value);
} catch (GeneratorClosedException e) {
// On closing a generator in the compile path, the generator
// throws a special exception. This ensures execution of all pending
// finalizers and will not get caught by user code.
return Undefined.instance;
} catch (RhinoException e) {
lineNumber = e.lineNumber();
lineSource = e.lineSource();
savedState = null;
throw e;
} finally {
synchronized (this) {
locked = false;
}
if (operation == GENERATOR_CLOSE)
savedState = null;
}
}
// #string_id_map#
@Override
protected int findPrototypeId(String s) {
int id;
// #generated# Last update: 2007-06-14 13:13:03 EDT
L0: { id = 0; String X = null; int c;
int s_length = s.length();
if (s_length==4) {
c=s.charAt(0);
if (c=='n') { X="next";id=Id_next; }
else if (c=='s') { X="send";id=Id_send; }
}
else if (s_length==5) {
c=s.charAt(0);
if (c=='c') { X="close";id=Id_close; }
else if (c=='t') { X="throw";id=Id_throw; }
}
else if (s_length==12) { X="__iterator__";id=Id___iterator__; }
if (X!=null && X!=s && !X.equals(s)) id = 0;
break L0;
}
// #/generated#
return id;
}
private static final int
Id_close = 1,
Id_next = 2,
Id_send = 3,
Id_throw = 4,
Id___iterator__ = 5,
MAX_PROTOTYPE_ID = 5;
// #/string_id_map#
private NativeFunction function;
private Object savedState;
private String lineSource;
private int lineNumber;
private boolean firstTime = true;
private boolean locked;
public static class GeneratorClosedException extends RuntimeException {
private static final long serialVersionUID = 2561315658662379681L;
}
}