package ec.gp.syntactic.simplification.numeric;

import ec.EvolutionState;
import ec.app.semanticGP.func.numeric.Sub;
import ec.app.semanticGP.func.numeric.Sum;
import ec.gp.GPNode;
import ec.gp.syntactic.simplification.IRule;
import ec.util.Parameter;

class SumSubRule implements IRule {

	@Override
	public void setup(EvolutionState state, Parameter base) {
		// TODO Auto-generated method stub

	}

	@Override
	public boolean match(GPNode subtree) {
		if (!(subtree instanceof Sum))
			return false;

		if (subtree.children[1] instanceof Sub) {
			return subtree.children[0].rootedTreeEquals(subtree.children[1].children[1]);
		} else if (subtree.children[0] instanceof Sub) {
			return subtree.children[1].rootedTreeEquals(subtree.children[0].children[1]);
		}
		
		return false;
	}

	@Override
	public GPNode replace(GPNode subtree) {
		assert match(subtree) : "The given tree is not a form of (a + (b - a))";
		
		if (subtree.children[1] instanceof Sub) {
			return subtree.children[0];
		} else {
			assert subtree.children[0] instanceof Sub;
			return subtree.children[1];
		}
	}
}
