Initial draft of coroutines library.

src/addon/java/lua/addon/luacompat/CoroutinesLib.java

@@ -0,0 +1,95 @@
+package lua.addon.luacompat;
+
+import lua.GlobalState;
+import lua.VM;
+import lua.io.Closure;
+import lua.value.LFunction;
+import lua.value.LTable;
+import lua.value.LThread;
+
+
+public class CoroutinesLib extends LFunction {
+
+	public static void install() {
+		LTable lib = new LTable(0,6);
+		lib.put("create", new CoroutinesLib(1));
+		lib.put("resume", new CoroutinesLib(2));
+		lib.put("running", new CoroutinesLib(3));
+		lib.put("status", new CoroutinesLib(4));
+		lib.put("wrap", new CoroutinesLib(5));
+		lib.put("yield", new CoroutinesLib(6));
+		GlobalState.getGlobalsTable().put("coroutine",lib);
+	}
+	
+	private int id = 0;
+	
+	private static LThread running;
+	
+	public CoroutinesLib() {
+		this(0);
+	}
+	
+	private CoroutinesLib( int id ) {
+		this.id = id;
+	}
+	
+	public boolean luaStackCall( VM vm ) {
+		switch ( id ) {
+			case 0: { // load lib
+				install();
+				vm.pushnil();
+				break;
+			}
+			case 1: { // create
+				Closure c = (Closure) vm.topointer(2);
+				vm.pushlvalue( new LThread(c) );
+				break;
+			}
+			case 2: {// resume
+				LThread t = (LThread) vm.topointer(2);
+				LThread prior = running;
+				try {
+					// whatever is left on the stack by the resumeFrom() implementation 
+					// becomes return values!
+					running = t;
+					t.resumeFrom( vm, prior );
+					return false;
+				} finally {
+					running = prior;
+				}
+			}
+			case 3: { // running
+				if ( running != null ) {
+					vm.pushlvalue( running );
+				} else {
+					vm.pushnil();					
+				}
+				break;
+			}
+			case 4: { // status
+				vm.pushstring( ((LThread) vm.topointer(2)).getStatus() );
+				break;
+			}
+			case 5: { // wrap
+				vm.error( "wrap() not supported" );
+				return false;
+			}
+			case 6: { // yield
+				if ( running == null )
+					vm.error("main thread can't yield");
+				else {
+					return running.yield();
+				}
+			}
+			case 7: { // wrapped resume
+				vm.error( "wrap() not supported" );
+				return false;
+			}
+		}
+		vm.insert(1);
+		vm.settop(1);
+		return false;
+	}
+	
+	
+}

src/addon/java/lua/addon/luacompat/LuaCompat.java

@@ -55,6 +55,9 @@ public class LuaCompat extends LFunction {
 		LTable table = new LTable();
 		installNames( pckg,  TABLE_NAMES, TABLES_BASE );
 		globals.put( "table", pckg );
+		
+		// coroutines
+		CoroutinesLib.install();
 	}
 
 	private static void installNames( LTable table, String[] names, int indexBase ) {

src/main/java/lua/VM.java

@@ -1382,7 +1382,7 @@ public interface VM {
 	 * This function pops <code>n</code> values from the stack
 	 * <code>from</code>, and pushes them onto the stack <code>to</code>.
 	 */
-	public void xmove(StackState to, int n);
+	public void xmove(VM to, int n);
 
 	/**
 	 * Yields a coroutine. <span class="apii">[-?, +?, <em>-</em>]</span>

src/main/java/lua/io/Closure.java

@@ -3,20 +3,35 @@ package lua.io;
 import lua.StackState;
 import lua.VM;
 import lua.value.LFunction;
-import lua.value.LValue;
+import lua.value.LTable;
 
 public class Closure extends LFunction {
-	public LValue env;
+	public LTable env;
 	public Proto p;
 	public UpVal[] upVals;
 	
-	// TODO: change arg type to VM? 
+	/**
+	 * @deprecated construct with environment instead 
+	 * @param state
+	 * @param p
+	 */ 
 	public Closure(StackState state, Proto p) {
 		this.env = state._G;
 		this.p = p;
 		upVals = new UpVal[p.nups];
 	}
 
+	/**
+	 * Construct using a prototype and initial environment. 
+	 * @param p
+	 * @param env
+	 */
+	public Closure(Proto p, LTable env) {
+		this.p = p;
+		this.env = env;
+		upVals = new UpVal[p.nups];
+	}
+
 	// called by vm when there is an OP_CALL
 	// in this case, we are on the stack, 
 	// and simply need to cue the VM to treat it as a stack call

src/main/java/lua/value/LThread.java

@@ -1,9 +1,33 @@
 package lua.value;
 
 import lua.Lua;
+import lua.StackState;
+import lua.VM;
+import lua.io.Closure;
 
 public class LThread extends LValue {
 
+	private static final int STATUS_SUSPENDED     = 1;
+	private static final int STATUS_NORMAL        = 2;
+	private static final int STATUS_ACTIVE        = 3;
+	private static final int STATUS_DEAD          = 4;
+	private static final String[] NAMES = { 
+		"suspended", 
+		"normal", 
+		"active", 
+		"dead" };
+	
+	private int status = STATUS_SUSPENDED;
+	
+	private StackState threadVm;
+	
+	
+	public LThread(Closure c) {
+		// TODO: inherit globals!
+		threadVm = new StackState();
+		threadVm.pushlvalue(new Closure(c.p, threadVm._G));
+	}
+
 	public int luaGetType() {
 		return Lua.LUA_TTHREAD;
 	}
@@ -11,4 +35,74 @@ public class LThread extends LValue {
 	public String toJavaString() {
 		return "thread: "+hashCode();
 	}
+
+	public String getStatus() {
+		return NAMES[status];
+	}
+
+	/** This needs to leave any values returned by yield in the corouting 
+	 * on the calling vm stack
+	 * @param vm
+	 * @param prior
+	 */
+	public void resumeFrom(VM vm, LThread prior) {
+
+		if ( status == STATUS_DEAD ) {
+			vm.settop(0);
+			vm.pushboolean(false);
+			vm.pushstring("cannot resume dead coroutine");
+			return;
+		}
+		
+		// set prior thread to normal status while we are running
+		if ( prior != null  )
+			prior.status = STATUS_NORMAL;
+		
+		try {	
+			// copy args in
+			if ( threadVm.cc < 0 ) {
+				vm.xmove(threadVm, vm.gettop() - 2);
+				threadVm.prepStackCall();
+			} else {
+				threadVm.settop(0);
+				vm.xmove(threadVm, vm.gettop() - 2);
+			}
+
+			// run this vm until it yields
+			status = STATUS_ACTIVE;
+			while ( threadVm.cc >= 0 && status == STATUS_ACTIVE )
+				threadVm.exec();
+			
+			// copy return values from yielding stack state
+			vm.settop(0);
+			vm.pushboolean(true);
+			if ( threadVm.cc >= 0 ) { 
+				threadVm.xmove(vm, threadVm.gettop() - 1);
+			} else {
+				threadVm.base = 0;
+				threadVm.xmove(vm, threadVm.gettop());
+			}
+
+		} catch ( Throwable t ) {
+			status = STATUS_DEAD;
+			vm.settop(0);
+			vm.pushboolean(false);
+			vm.pushstring("thread: "+t);
+			
+		} finally {
+			if ( threadVm.cc < 0 )
+				status = STATUS_DEAD;
+			
+			// reset prior thread status
+			if ( prior != null  )
+				prior.status = STATUS_ACTIVE;
+		}
+		
+	}
+
+	public boolean yield() {
+		if ( status == STATUS_ACTIVE )
+			status = STATUS_SUSPENDED;
+		return true;
+	}
 }

src/test/java/lua/LuaJTest.java

@@ -60,6 +60,10 @@ public class LuaJTest extends TestCase {
 		runTest( "coercions" );
 	}
 	
+	public void testCoroutines() throws IOException, InterruptedException {
+		runTest( "coroutines" );
+	}
+	
 	public void testCompare() throws IOException, InterruptedException {
 		runTest( "compare" );
 	}

src/test/res/coroutines.lua

@@ -0,0 +1,18 @@
+function foo (a)
+	print("foo", a)
+    return coroutine.yield(2*a)
+end
+     
+co = coroutine.create(function (a,b)
+	print("co-body", a, b)
+	local r = foo(a+1)
+	print("co-body", r)
+	local r, s = coroutine.yield(a+b, a-b)
+	print("co-body", r, s)
+	return b, "end"
+end)
+            
+print("main", coroutine.resume(co, 1, 10))
+print("main", coroutine.resume(co, "r"))
+print("main", coroutine.resume(co, "x", "y"))
+print("main", coroutine.resume(co, "x", "y"))