class Item {
public:
	Item(const char *name) { Item::name=name; }
	virtual ~Item() {};

	//Bool hasQS(const char *statename);
	virtual int queryState(const char *statename) =0;
	//Bool hasSS(const char *statename);
	virtual void setState(const char *statename, int newState) =0;

        const char *queryName() { return name; }
private:
	const char *name;
};


class SCM;

class Dependency {
public:
	Dependency(Item *item, const char *stateName, const char *expression)
	  { Dependency::item=item; state=stateName; expr=expression; }

	virtual ~Dependency() {}

private:
	friend class SCM;
	void apply(SCM *scm);
	const char *queryState(SCM *scm, const char *p, int *b);

	Item *item;
	const char *state;

	const char *expr;
};


class SCM {
public:
	SCM();
	virtual ~SCM();

	void addItem(Item *item);
	void addDependency(const char *itemName, const char *stateName, const char *expr);

	void changed(const char *itemName);
	void changed();

        int queryItemState(const char *itemName, const char *stateName);
private:
	Item **itemTable;
	unsigned items,itemsAlloc;
	Dependency **dependencyTable;
	unsigned dependencies,dependenciesAlloc;
};











/*
...
scm.addItem(MakeItem(c_lzw,"b1"));
scm.addDependency("b1","e","a1.c");			//b1.e = a1.c
...
scm.addDependency("d1","e","a1.c|a2.c|a3.c|a4.c");
*/