package luan.impl;

import luan.Luan;
import luan.LuanFunction;
import luan.LuanState;
import luan.LuanException;
import luan.DeepCloner;
import luan.DeepCloneable;


final class Closure extends LuanFunction implements DeepCloneable {
	final FnDef fnDef;
	private UpValue[] upValues;

	Closure(LuanStateImpl luan,FnDef fnDef) throws LuanException {
		this.fnDef = fnDef;
		UpValue.Getter[] upValueGetters = fnDef.upValueGetters;
		this.upValues = new UpValue[upValueGetters.length];
		for( int i=0; i<upValues.length; i++ ) {
			upValues[i] = upValueGetters[i].get(luan);
		}
	}

	private Closure(Closure c) {
		this.fnDef = c.fnDef;
	}

	@Override public Closure shallowClone() {
		return new Closure(this);
	}

	@Override public void deepenClone(DeepCloneable clone,DeepCloner cloner) {
		((Closure)clone).upValues = (UpValue[])cloner.deepClone(upValues);
	}

	UpValue[] upValues() {
		return upValues;
	}

	@Override public Object call(LuanState ls,Object[] args) throws LuanException {
		LuanStateImpl luan = (LuanStateImpl)ls;
		Object[] varArgs = null;
		if( fnDef.isVarArg ) {
			if( args.length > fnDef.numArgs ) {
				varArgs = new Object[ args.length - fnDef.numArgs ];
				for( int i=0; i<varArgs.length; i++ ) {
					varArgs[i] = args[fnDef.numArgs+i];
				}
			} else {
				varArgs = LuanFunction.NOTHING;
			}
		}
		Object[] stack = luan.newFrame(this,fnDef.stackSize,varArgs);
		final int n = Math.min(args.length,fnDef.numArgs);
		for( int i=0; i<n; i++ ) {
			stack[i] = args[i];
		}
		Object returnValues;
		try {
			return fnDef.run(luan);
		} catch(StackOverflowError e) {
			throw new LuanException( "stack overflow", e );
		} finally {
			luan.popFrame();
		}
	}

}