Add tests for pcall, add error() builtin, fix assert(), error levels.

src/main/java/lua/Builtin.java

@@ -24,6 +24,8 @@ final class Builtin extends JavaFunction {
 		"type", 
 		"pcall", 
 		"ipairs", 
+		"error",
+		"assert",
 		};
 	private static final int PRINT = 0;
 	private static final int PAIRS = 1;
@@ -32,6 +34,8 @@ final class Builtin extends JavaFunction {
 	private static final int TYPE = 4;
 	private static final int PCALL = 5;
 	private static final int IPAIRS = 6;
+	private static final int ERROR = 7;
+	private static final int ASSERT = 8;
 	
 	private static PrintStream stdout = System.out;
 	
@@ -90,6 +94,16 @@ final class Builtin extends JavaFunction {
 				return 2;
 			}
 		}
+		case ERROR: {
+			vm.error(vm.tostring(1), vm.gettop()>1? vm.tointeger(2): 1);
+		}
+		case ASSERT: {
+			if ( ! vm.toboolean(1) ) {
+				vm.error( vm.gettop()>1? vm.tostring(2): "assertion failed!", 0 );
+			} else {
+				return vm.gettop();
+			}
+		}
 		default:
 			luaUnsupportedOperation();
 			return 0;

src/main/java/lua/VM.java

@@ -357,6 +357,14 @@ public interface VM {
 	 */
 	public void error();
 
+	/**
+	 * Raises an error with the default level.   
+	 * 
+	 * In the java implementation this throws a RuntimeException, possibly filling 
+	 * line number information first.
+	 */
+	public void error(String message);
+	
 	/**
 	 * Raises an error.   The message is pushed onto the stack and used as the error message.  
 	 * It also adds at the beginning of the message the file name and the line number where 
@@ -365,7 +373,7 @@ public interface VM {
 	 * In the java implementation this throws a RuntimeException, possibly filling 
 	 * line number information first.
 	 */
-	public void error(String message);
+	public void error(String message, int level);
 	
 	/**
 	 * Controls the garbage collector. <span class="apii">[-0, +0, <em>e</em>]</span>

src/main/java/lua/debug/DebugStackState.java

@@ -94,11 +94,16 @@ public class DebugStackState extends StackState implements DebugRequestListener
 		return source+":"+line+"("+func+")";
 	}
 	
-	
 	// override and fill in line number info 
-	public void error(String message) {
-		super.error( getFileLine(cc)+": "+message );
+	public void error(String message, int level) {
+		super.error( level<=0? message: getFileLine(cc+1-level)+": "+message );
 	}
+
+	// use line numbers by default
+	public void error(String message) {
+		error(message, 1);
+	}
+	
 	
 	private void printLuaTrace() {
 		System.out.println( "Lua location: "+getFileLine(cc) );
@@ -112,11 +117,10 @@ public class DebugStackState extends StackState implements DebugRequestListener
 			super.exec();
 		} catch (AbortException e) {
             // ignored. Client aborts the debugging session.
-        } catch ( Exception t ) {        
-			t.printStackTrace();
-			printLuaTrace();
-			System.out.flush();
 		}
+		// let other exceptions be processed 
+		// the same as the base class to minimize differences
+		// between the debug and non-debug behavior
 	}
 	
 	

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

@@ -54,10 +54,9 @@ public class LThread extends LValue {
 	public void resumeFrom(VM vm, int nargs) {
 
 		if ( status == STATUS_DEAD ) {
-			vm.error("cannot resume dead coroutine");
-//			vm.settop(0);
-//			vm.pushboolean(false);
-//			vm.pushstring("cannot resume dead coroutine");
+			vm.settop(0);
+			vm.pushboolean(false);
+			vm.pushstring("cannot resume dead coroutine");
 			return;
 		}