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A dynamic, easy, highly customizable scripting language.
There is a newer version: 2.0.0
/*
 * Copyright (c) 2013-2018, João Vitor Verona Biazibetti - All Rights Reserved
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see .
 *
 * https://www.github.com/BloodShura
 */

package com.github.bloodshura.x.venus.compiler;

import com.github.bloodshura.x.collection.store.impl.XStack;
import com.github.bloodshura.x.venus.exception.compile.UnexpectedTokenException;
import com.github.bloodshura.x.venus.expression.BinaryOperation;
import com.github.bloodshura.x.venus.expression.Expression;
import com.github.bloodshura.x.venus.expression.InContext;
import com.github.bloodshura.x.venus.expression.UnaryOperation;
import com.github.bloodshura.x.venus.operator.BinaryOperator;
import com.github.bloodshura.x.venus.operator.Operator;
import com.github.bloodshura.x.venus.operator.UnaryOperator;

public class BuildingExpression {
	private String inContext;
	private Operator operator;
	private Expression expression;
	private final XStack unaryWhenAlready;

	public BuildingExpression() {
		this.unaryWhenAlready = new XStack<>();
	}

	public void addInContext(VenusParser parser, Token owner, String context) throws UnexpectedTokenException {
		if (inContext != null) {
			parser.bye(owner, "already in object access \"" + inContext + "\"");
		}

		this.inContext = context;
	}

	public void addOperator(VenusParser parser, Token owner, Operator op) throws UnexpectedTokenException {
		if (hasOperator()) {
			if (op instanceof UnaryOperator) {
				unaryWhenAlready.push((UnaryOperator) op);

				return;
			}
			else {
				parser.bye(owner, "already have an operator \"" + operator + "\"");
			}
		}

		if (op instanceof BinaryOperator && !hasResultor()) {
			parser.bye(owner, "no left operation value");
		}

		if (op instanceof UnaryOperator && hasResultor()) {
			parser.bye(owner, "cannot apply unary operator to left-sided value");
		}

		this.operator = op;
	}

	public void addExpression(VenusParser parser, Token owner, Expression rslt) throws UnexpectedTokenException {
		if (!hasResultor()) {
			if (operator instanceof UnaryOperator) {
				while (!unaryWhenAlready.isEmpty()) {
					rslt = new UnaryOperation(unaryWhenAlready.pop(), rslt);
				}

				setExpression(new UnaryOperation((UnaryOperator) operator, rslt));
			}
			else {
				setExpression(rslt);
			}
		}
		else if (hasOperator()) {
			if (operator instanceof BinaryOperator) {
				while (!unaryWhenAlready.isEmpty()) {
					rslt = new UnaryOperation(unaryWhenAlready.pop(), rslt);
				}

				setExpression(new BinaryOperation((BinaryOperator) operator, expression, rslt));
			}
			else {
				parser.bye("Excepted a binary or unary operator, received " + operator.getClass().getSimpleName());
			}

			this.operator = null;
		}
		else {
			parser.bye(owner, "expected operator, found another expression");
		}
	}

	public Expression build() {
		return expression;
	}

	public boolean hasOperator() {
		return operator != null;
	}

	public boolean hasResultor() {
		return expression != null;
	}

	private void setExpression(Expression expression) {
		if (inContext != null) {
			this.expression = new InContext(inContext, expression);

			this.inContext = null;
		}
		else {
			this.expression = expression;
		}
	}
}