parameter.h
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parameter.h
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	#ifndef _rtech1_parameter_h
	#define _rtech1_parameter_h

	/* parameters are to be used to control the dynamic extent of values. values
	* can be pushed onto the current extent and are automatically popped off
	* upon function return.
	* this is similar to 'parameters' in Racket.
	*
	* This class is not thread safe.
	*/

	#include <vector>
	#include "pointer.h"

	namespace Util{

	/* the static variable `stack' has to be defined somewhere. use this syntax to define it
	* template <class Value> typename Util::Parameter<Value>::container Util::Parameter<Value>::stacks;
	*/
	template <class Value>
	class Parameter{
	public:
	/* push a new value on the stack */
	Parameter(Parameter & parent, const Value & what):
	stack(parent.stack),
	items(0){
	push(what);
	}

	Parameter(Parameter & parent):
	stack(parent.stack),
	items(0){
	}

	Parameter():
	items(0){
	stack = new std::vector<Value>();
	}

	/* pop last value */
	virtual ~Parameter(){
	for (int i = 0; i < items; i++){
	if (stack->size() > 0){
	stack->pop_back();
	}
	}
	}

	void push(const Value & what){
	items += 1;
	stack->push_back(what);
	}

	/* get the current value */
	Value current(){
	if (stack->size() > 0){
	return stack->back();
	}
	return Value();
	}

	ReferenceCount<std::vector<Value> > stack;

	protected:
	/* number of things pushed onto the stack by this object. note this is
	* not the number of items on the stack because if there are multiple
	* parameter objects then each one could have pushed 1 object on. thus
	* the stack will have 2 things in it but each parameter will have an
	* 'items' count of 1.
	*/
	int items;
	};

	}

	#endif