--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/src/luan/LuanBit.java	Sun Jun 22 05:41:22 2014 +0000
@@ -0,0 +1,126 @@
+package luan;
+
+import java.util.List;
+
+
+public final class LuanBit {
+	public final LuanState luan;
+	public final LuanElement el;
+
+	LuanBit(LuanState luan,LuanElement el) {
+		this.luan = luan;
+		this.el = el;
+	}
+
+	public LuanException exception(Object msg) {
+		return new LuanException(this,msg);
+	}
+
+	public String stackTrace() {
+		StringBuilder buf = new StringBuilder();
+		LuanElement el = this.el;
+		for( int i  = luan.stackTrace.size() - 1; i>=0; i-- ) {
+			StackTraceElement stackTraceElement = luan.stackTrace.get(i);
+			buf.append( "\n\t" ).append( el.toString(stackTraceElement.fnName) );
+			el = stackTraceElement.call;
+		}
+		return buf.toString();
+	}
+
+	public void dumpStack() {
+		System.err.println( stackTrace() );
+	}
+
+	public Object call(LuanFunction fn,String fnName,Object[] args) throws LuanException {
+		List<StackTraceElement> stackTrace = luan.stackTrace;
+		stackTrace.add( new StackTraceElement(el,fnName) );
+		try {
+			return fn.call(luan,args);
+		} finally {
+			stackTrace.remove(stackTrace.size()-1);
+		}
+	}
+
+	public String checkString(Object obj) throws LuanException {
+		String s = Luan.asString(obj);
+		if( s == null )
+			throw exception( "attempt to use a " + Luan.type(obj) + " as a string" );
+		return s;
+	}
+
+	public Number checkNumber(Object obj) throws LuanException {
+		Number n = Luan.toNumber(obj);
+		if( n == null )
+			throw exception( "attempt to perform arithmetic on a " + Luan.type(obj) + " value" );
+		return n;
+	}
+
+	public LuanFunction checkFunction(Object obj) throws LuanException {
+		if( obj instanceof LuanFunction )
+			return (LuanFunction)obj;
+		throw exception( "attempt to call a " + Luan.type(obj) + " value" );
+	}
+
+	public Boolean checkBoolean(Object obj) throws LuanException {
+		if( obj instanceof Boolean )
+			return (Boolean)obj;
+		throw exception( "attempt to use a " + Luan.type(obj) + " as a boolean" );
+	}
+
+	public String toString(Object obj) throws LuanException {
+		LuanFunction fn = getHandlerFunction("__tostring",obj);
+		if( fn != null )
+			return checkString( Luan.first( call(fn,"__tostring",new Object[]{obj}) ) );
+		return Luan.toString(obj);
+	}
+
+	public String repr(Object obj) throws LuanException {
+		LuanFunction fn = getHandlerFunction("__repr",obj);
+		if( fn != null )
+			return checkString( Luan.first( call(fn,"__repr",new Object[]{obj}) ) );
+		String repr = Luan.repr(obj);
+		if( repr==null )
+			throw exception( "value '" + obj + "' doesn't support repr()" );
+		return repr;
+	}
+
+	public LuanFunction getHandlerFunction(String op,Object obj) throws LuanException {
+		Object f = luan.getHandler(op,obj);
+		if( f == null )
+			return null;
+		return checkFunction(f);
+	}
+
+	public LuanFunction getBinHandler(String op,Object o1,Object o2) throws LuanException {
+		LuanFunction f1 = getHandlerFunction(op,o1);
+		if( f1 != null )
+			return f1;
+		return getHandlerFunction(op,o2);
+	}
+
+	public boolean isLessThan(Object o1,Object o2) throws LuanException {
+		if( o1 instanceof Number && o2 instanceof Number ) {
+			Number n1 = (Number)o1;
+			Number n2 = (Number)o2;
+			return n1.doubleValue() < n2.doubleValue();
+		}
+		if( o1 instanceof String && o2 instanceof String ) {
+			String s1 = (String)o1;
+			String s2 = (String)o2;
+			return s1.compareTo(s2) < 0;
+		}
+		LuanFunction fn = getBinHandler("__lt",o1,o2);
+		if( fn != null )
+			return Luan.toBoolean( Luan.first(call(fn,"__lt",new Object[]{o1,o2})) );
+		throw exception( "attempt to compare " + Luan.type(o1) + " with " + Luan.type(o2) );
+	}
+
+	public Object arithmetic(String op,Object o1,Object o2) throws LuanException {
+		LuanFunction fn = getBinHandler(op,o1,o2);
+		if( fn != null )
+			return Luan.first(call(fn,op,new Object[]{o1,o2}));
+		String type = Luan.toNumber(o1)==null ? Luan.type(o1) : Luan.type(o2);
+		throw exception("attempt to perform arithmetic on a "+type+" value");
+	}
+
+}