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/*
 * This software and all files contained in it are distrubted under the MIT license.
 *
 * Copyright (c) 2013 Cogito Learning Ltd
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package uk.co.cogitolearning.cogpar;

/**
 * An ExpressionNode that handles additions and subtractions. The node can hold
 * an arbitrary number of terms that are either added or subtraced from the sum.
 */
public class AdditionExpressionNode extends SequenceExpressionNode {

    /**
     * Constructor to create an addition with the first term already added.
     *
     * @param node the term to be added
     * @param positive a flag indicating whether the term is added or subtracted
     */
    public AdditionExpressionNode(ExpressionNode node, boolean positive) {
        super(node, positive);
    }

    /**
     * Returns the type of the node, in this case ExpressionNode.ADDITION_NODE
     */
    public int getType() {
        return ADDITION_NODE;
    }

    /**
     * Returns the value of the sub-expression that is rooted at this node.
     * All the terms are evaluated and added or subtracted from the total sum.
     */
    public double getValue() {
        double sum = 0.0;
        for (Term t : terms) {
            if (t.positive)
                sum += t.expression.getValue();
            else
                sum -= t.expression.getValue();
        }
        return sum;
    }

    /**
     * Implementation of the visitor design pattern.
     * Calls visit on the visitor and then passes the visitor on to the accept
     * method of all the terms in the sum.
     *
     * @param visitor the visitor
     */
    public void accept(ExpressionNodeVisitor visitor) {
        visitor.visit(this);
        for (Term t : terms)
            t.expression.accept(visitor);
    }

}