package codegeneration;

import ast.definition.FuncDefinition;
import ast.definition.VarDefinition;
import ast.statement.Statement;
import ast.type.FunctionType;
import ast.type.RecordField;
import ast.type.RecordType;
import visitor.TraversingVisitor;

public class OffsetVisitor extends TraversingVisitor {

	private int globalBytes = 0, localBytes = 0;

	//Parameters offset
	@Override
	public Object visit (FunctionType f, Object o) {
		localBytes = 0;
		super.visit(f, o);

		for(int i = f.getParameters().size()-1; i >= 0 ; i--) {
			f.getParameters().get(i).setOffset(f.bytesParamsSum);
			f.bytesParamsSum += f.getParameters().get(i).getType().numberOfBytes();
		}

		return null;
	}

	//Record fields offset
	@Override
	public Object visit (RecordType rt, Object o) {
		super.visit(rt, o);

		int fieldsBytes = 0;
		for(RecordField field : rt.getFields()) {
			field.setOffset(fieldsBytes);
			fieldsBytes+=field.getFieldType().numberOfBytes();
		}

		return null;
	}

	//Variables offset
	@Override
	public Object visit (VarDefinition v, Object o) {
		super.visit(v, o);
		//Global variables
		if(v.getScope() == 0) {
			v.setOffset(globalBytes);
			globalBytes+=v.getType().numberOfBytes();
		}

		//Local variables are computed inside function definition

		return null;
	}

	@Override
	public Object visit (FuncDefinition fd, Object o) {
		super.visit(fd, o);

		//Go over all the variables and traverse with this offset visitor.
		for(Statement s : fd.getStatements())
			if(s instanceof VarDefinition)
				((VarDefinition) s).setOffset(localBytes -= ((VarDefinition) s).getType().numberOfBytes());

		fd.getType().bytesLocalSum = localBytes;

		return null;
	}

}