/*******************************************************************************
* Copyright (c) 2007-2011 LuaJ. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
******************************************************************************/
package org.luaj.vm2.lib;
import org.luaj.vm2.LuaTable;
import org.luaj.vm2.LuaThread;
import org.luaj.vm2.LuaValue;
import org.luaj.vm2.Varargs;
/**
* Subclass of {@link LibFunction} which implements the lua standard {@code coroutine}
* library.
* <p>
* The coroutine library in luaj has the same behavior as the
* coroutine library in C, but is implemented using Java Threads to maintain
* the call state between invocations. Therefore it can be yielded from anywhere,
* similar to the "Coco" yield-from-anywhere patch available for C-based lua.
* However, coroutines that are yielded but never resumed to complete their execution
* may not be collected by the garbage collector.
* <p>
* Typically, this library is included as part of a call to either
* {@link JsePlatform#standardGlobals()} or {@link JmePlatform#standardGlobals()}
* <p>
* To instantiate and use it directly,
* link it into your globals table via {@link LuaValue#load(LuaValue)} using code such as:
* <pre> {@code
* LuaTable _G = new LuaTable();
* _G.load(new CoroutineLib());
* } </pre>
* Doing so will ensure the library is properly initialized
* and loaded into the globals table.
* <p>
* @see LibFunction
* @see JsePlatform
* @see JmePlatform
* @see <a href="http://www.lua.org/manual/5.1/manual.html#5.2">http://www.lua.org/manual/5.1/manual.html#5.2</a>
*/
public class CoroutineLib extends VarArgFunction {
private static final int INIT = 0;
private static final int CREATE = 1;
private static final int RESUME = 2;
private static final int RUNNING = 3;
private static final int STATUS = 4;
private static final int YIELD = 5;
private static final int WRAP = 6;
private static final int WRAPPED = 7;
public CoroutineLib() {
}
private LuaTable init() {
LuaTable t = new LuaTable();
bind(t, CoroutineLib.class, new String[] {
"create", "resume", "running", "status", "yield", "wrap" },
CREATE);
env.set("coroutine", t);
PackageLib.instance.LOADED.set("coroutine", t);
return t;
}
public Varargs invoke(Varargs args) {
switch ( opcode ) {
case INIT: {
return init();
}
case CREATE: {
final LuaValue func = args.checkfunction(1);
return new LuaThread(func, LuaThread.getGlobals() );
}
case RESUME: {
final LuaThread t = args.checkthread(1);
return t.resume( args.subargs(2) );
}
case RUNNING: {
final LuaThread r = LuaThread.getRunning();
return LuaThread.isMainThread(r)? NIL: r;
}
case STATUS: {
return valueOf( args.checkthread(1).getStatus() );
}
case YIELD: {
final LuaThread r = LuaThread.getRunning();
if ( LuaThread.isMainThread( r ) )
error("main thread can't yield");
return r.yield( args );
}
case WRAP: {
final LuaValue func = args.checkfunction(1);
final LuaThread thread = new LuaThread(func, func.getfenv());
CoroutineLib cl = new CoroutineLib();
cl.setfenv(thread);
cl.name = "wrapped";
cl.opcode = WRAPPED;
return cl;
}
case WRAPPED: {
final LuaThread t = (LuaThread) env;
final Varargs result = t.resume( args );
if ( result.arg1().toboolean() ) {
return result.subargs(2);
} else {
error( result.arg(2).tojstring() );
}
}
default:
return NONE;
}
}
}