package frontend.ast.exp;

import frontend.ast.Node;
import frontend.ast.NodeStack;
import frontend.ast.SyntaxType;
import frontend.lexer.TokenStream;
import frontend.lexer.TokenType;
import frontend.ast.token.TokenNode;
import error.Errors;

public class EqExp extends Node {
    public EqExp(TokenStream ts) {
        super(SyntaxType.EQ_EXP, ts);
    }

    public void parse(Errors errors) {
        NodeStack stack = new NodeStack();
        while (true) {
            RelExp relexp = new RelExp(this.ts);
            relexp.parse(errors);
            stack.push(relexp);
            if (isEqOp()) {
                stack.push(new TokenNode(ts)); // eqop
            } else {
                break;
            }
        }
        if(stack.size() == 1) {
            this.addChild((RelExp)stack.pop());
        } else {
            EqExp temp = this;
            while (stack.size() > 1) {
                EqExp eep = new EqExp(this.ts);
                RelExp relexp = (RelExp)stack.pop();
                TokenNode eqop = (TokenNode)stack.pop();
                temp.addChild(eep);
                temp.addChild(eqop);
                temp.addChild(relexp);
                temp = eep;
            }
            temp.addChild((RelExp)stack.pop());
        }
    }

    public boolean isEqOp() {
        TokenType t = getCurrToken().getType();
        return t == TokenType.EQL || t == TokenType.NEQ;
    }
}