--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/luan/impl/UpValue.java	Sun Jun 22 04:17:38 2014 +0000
@@ -0,0 +1,105 @@
+package luan.impl;
+
+import luan.DeepCloner;
+import luan.DeepCloneable;
+import luan.LuanException;
+
+
+final class UpValue implements DeepCloneable<UpValue> {
+	private Object[] stack;
+	private int index;
+	private boolean isClosed = false;
+	private Object value;
+
+	UpValue(Object[] stack,int index) {
+		this.stack = stack;
+		this.index = index;
+	}
+
+	UpValue(Object value) {
+		this.value = value;
+		this.isClosed = true;
+	}
+
+	private UpValue() {}
+
+	@Override public UpValue shallowClone() {
+		return new UpValue();
+	}
+
+	@Override public void deepenClone(UpValue clone,DeepCloner cloner) {
+		clone.isClosed = isClosed;
+		if( isClosed ) {
+			clone.value = cloner.get(value);
+		} else {
+			clone.stack = cloner.deepClone(stack);
+			clone.index = index;
+		}
+	}
+
+	Object get() {
+		return isClosed ? value : stack[index];
+	}
+
+	void set(Object value) {
+		if( isClosed ) {
+			this.value = value;
+		} else {
+			stack[index] = value;
+		}
+	}
+
+	void close() {
+		value = stack[index];
+		isClosed = true;
+		stack = null;
+	}
+
+	static interface Getter {
+		public UpValue get(LuanStateImpl luan) throws LuanException;
+	}
+
+	static final class StackGetter implements Getter {
+		private final int index;
+
+		StackGetter(int index) {
+			this.index = index;
+		}
+
+		public UpValue get(LuanStateImpl luan) {
+			return luan.getUpValue(index);
+		}
+	}
+
+	static final class NestedGetter implements Getter {
+		private final int index;
+
+		NestedGetter(int index) {
+			this.index = index;
+		}
+
+		public UpValue get(LuanStateImpl luan) {
+			return luan.closure().upValues()[index];
+		}
+	}
+
+	static final class EnvGetter implements Getter {
+
+		public UpValue get(LuanStateImpl luan) throws LuanException {
+			return luan.getUpValue(this);
+		}
+	}
+
+	static final class ValueGetter implements Getter {
+		private final UpValue upValue;
+
+		ValueGetter(Object value) {
+			this.upValue = new UpValue(value);
+		}
+
+		public UpValue get(LuanStateImpl luan) {
+			return upValue;
+		}
+	}
+
+}