cayenne-server/src/main/java/org/apache/cayenne/exp/parser/EvaluatedMathNode.java

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 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
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package org.apache.cayenne.exp.parser;

import java.math.BigDecimal;

import org.apache.cayenne.util.ConversionUtil;

/**
 * @since 4.0
 */
public abstract class EvaluatedMathNode extends EvaluatedNode {
    protected EvaluatedMathNode(int i) {
        super(i);
    }

    @Override
    protected int getRequiredChildrenCount() {
        return 1;
    }

    @Override
    protected Object evaluateSubNode(Object o, Object[] evaluatedChildren) throws Exception {
        BigDecimal result = ConversionUtil.toBigDecimal(o);
        if(result == null) {
            return null;
        }
        for (int i = 1; i < evaluatedChildren.length; i++) {
            BigDecimal value = ConversionUtil.toBigDecimal(evaluatedChildren[i]);
            if (value == null) {
                return null;
            }
            result = op(result, value);
        }

        return result;
    }

    abstract protected BigDecimal op(BigDecimal result, BigDecimal arg);

}