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Groovy example source code file (NumberMath.java)

This example Groovy source code file (NumberMath.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

bigdecimal, bigdecimal, biginteger, biginteger, cannot, double, float, integer, math, number, number, numbermath, shift, unsupportedoperationexception, unsupportedoperationexception

The Groovy NumberMath.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.runtime.typehandling;

import java.math.BigDecimal;
import java.math.BigInteger;


/**
 * Stateless objects used to perform math on the various Number subclasses.
 * Instances are required so that polymorphic calls work properly, but each
 * subclass creates a singleton instance to minimize garbage.  All methods
 * must be thread-safe.
 * 
 * The design goals of this class are as follows:
 * <ol>
 * <li>Support a 'least surprising' math model to scripting language users.  This
 * means that exact, or decimal math should be used for default calculations.  This
 * scheme assumes that by default, groovy literals with decimal points are instantiated
 * as BigDecimal objects rather than binary floating points (Float, Double). 
 * <li>Do not force the appearance of exactness on a number that is by definition not 
 * guaranteed to be exact.  In particular this means that if an operand in a NumberMath 
 * operation is a binary floating point number, ensure that the result remains a binary floating point 
 * number (i.e. never automatically promote a binary floating point number to a BigDecimal).  
 * This has the effect of preserving the expectations of binary floating point users and helps performance.
 * <li>Provide an implementation that is as close as practical to the Java 1.5 BigDecimal math model 
 * which implements precision based floating point decimal math (ANSI X3.274-1996 and 
 * ANSI X3.274-1996/AM 1-2000 (section 7.4).  
 * </ol>
 * 
 * @author Steve Goetze
 */
public abstract class NumberMath {
        
    public static Number abs(Number number) {
        return getMath(number).absImpl(number);
    }
    
    public static Number add(Number left, Number right) {
        return getMath(left, right).addImpl(left,right);
    }
    
    public static Number subtract(Number left, Number right) {
        return getMath(left,right).subtractImpl(left,right);
    }
    
    public static Number multiply(Number left, Number right) {
        return getMath(left,right).multiplyImpl(left,right);
    }
    
    public static Number divide(Number left, Number right) {
        return getMath(left,right).divideImpl(left,right);
     }
      
    public static int compareTo(Number left, Number right) {
        return getMath(left,right).compareToImpl(left, right);
    }
    
    public static Number or(Number left, Number right) {
        return getMath(left,right).orImpl(left, right);
    }
    
    public static Number and(Number left, Number right) {
        return getMath(left,right).andImpl(left, right);
    }
    
    public static Number xor(Number left, Number right) {
        return getMath(left,right).xorImpl(left, right);
    }
    
    public static Number intdiv(Number left, Number right) {
        return getMath(left,right).intdivImpl(left,right);
     }

    public static Number mod(Number left, Number right) {
        return getMath(left,right).modImpl(left, right);
    }

    /**
     * For this operation, consider the operands independently.  Throw an exception if the right operand
     * (shift distance) is not an integral type.  For the left operand (shift value) also require an integral
     * type, but do NOT promote from Integer to Long.  This is consistent with Java, and makes sense for the
     * shift operators.
     */
    public static Number leftShift(Number left, Number right) {
        if (isFloatingPoint(right) || isBigDecimal(right)) {
            throw new UnsupportedOperationException("Shift distance must be an integral type, but " +  right + " (" + right.getClass().getName() + ") was supplied");
        }
        return getMath(left).leftShiftImpl(left,right);
    }
    
    /**
     * For this operation, consider the operands independently.  Throw an exception if the right operand
     * (shift distance) is not an integral type.  For the left operand (shift value) also require an integral
     * type, but do NOT promote from Integer to Long.  This is consistent with Java, and makes sense for the
     * shift operators.
     */
    public static Number rightShift(Number left, Number right) {
        if (isFloatingPoint(right) || isBigDecimal(right)) {
            throw new UnsupportedOperationException("Shift distance must be an integral type, but " +  right + " (" + right.getClass().getName() + ") was supplied");
        }
        return getMath(left).rightShiftImpl(left,right);
    }
    
    /**
     * For this operation, consider the operands independently.  Throw an exception if the right operand
     * (shift distance) is not an integral type.  For the left operand (shift value) also require an integral
     * type, but do NOT promote from Integer to Long.  This is consistent with Java, and makes sense for the
     * shift operators.
     */
    public static Number rightShiftUnsigned(Number left, Number right) {
        if (isFloatingPoint(right) || isBigDecimal(right)) {
            throw new UnsupportedOperationException("Shift distance must be an integral type, but " +  right + " (" + right.getClass().getName() + ") was supplied");
        }
        return getMath(left).rightShiftUnsignedImpl(left,right);
    }
    
    public static Number unaryMinus(Number left) {
        return getMath(left).unaryMinusImpl(left);
    }
    
    public static boolean isFloatingPoint(Number number) {
        return number instanceof Double || number instanceof Float;
    }

    public static boolean isInteger(Number number) {
        return number instanceof Integer;
    }

    public static boolean isLong(Number number) {
        return number instanceof Long;
    }

    public static boolean isBigDecimal(Number number) {
        return number instanceof BigDecimal;
    }

    public static boolean isBigInteger(Number number) {
        return number instanceof BigInteger;
    }

    public static BigDecimal toBigDecimal(Number n) {
        return (n instanceof BigDecimal ? (BigDecimal) n : new BigDecimal(n.toString()));
    }
                
    public static BigInteger toBigInteger(Number n) {
        return (n instanceof BigInteger ? (BigInteger) n : new BigInteger(n.toString()));
    }
                    
    /**
     * Determine which NumberMath instance to use, given the supplied operands.  This method implements
     * the type promotion rules discussed in the documentation.  Note that by the time this method is
     * called, any Byte, Character or Short operands will have been promoted to Integer.  For reference,
     * here is the promotion matrix:
     *    bD bI  D  F  L  I
     * bD bD bD  D  D bD bD
     * bI bD bI  D  D bI bI
     *  D  D  D  D  D  D  D
     *  F  D  D  D  D  D  D
     *  L bD bI  D  D  L  L
     *  I bD bI  D  D  L  I
     * 
     * Note that for division, if either operand isFloatingPoint, the result will be floating.  Otherwise,
     * the result is BigDecimal
     */
    public static NumberMath getMath(Number left, Number right) {
        if (isFloatingPoint(left) || isFloatingPoint(right)) {
            return FloatingPointMath.INSTANCE;
        }
        if (isBigDecimal(left) || isBigDecimal(right)) {
            return BigDecimalMath.INSTANCE;
        }
        if (isBigInteger(left) || isBigInteger(right)) {
            return BigIntegerMath.INSTANCE;
        }
        if (isLong(left) || isLong(right)){
            return LongMath.INSTANCE;
        }
        return IntegerMath.INSTANCE;
    }

    private static NumberMath getMath(Number number) {
        if (isLong(number)) {
            return LongMath.INSTANCE;
        }
        if (isFloatingPoint(number)) {
            return FloatingPointMath.INSTANCE;
        }            
        if (isBigDecimal(number)) {
            return BigDecimalMath.INSTANCE;
        }
        if (isBigInteger(number)) {
            return BigIntegerMath.INSTANCE;
        }
        return IntegerMath.INSTANCE;
    }
    
    //Subclasses implement according to the type promotion hierarchy rules
    protected abstract Number absImpl(Number number);
    public abstract Number addImpl(Number left, Number right);
    public abstract Number subtractImpl(Number left, Number right);
    public abstract Number multiplyImpl(Number left, Number right);
    public abstract Number divideImpl(Number left, Number right);
    public abstract int compareToImpl(Number left, Number right);
    protected abstract Number unaryMinusImpl(Number left);


    protected Number orImpl(Number left, Number right) {
        throw createUnsupportedException("or()", left);
    }
    
    protected Number andImpl(Number left, Number right) {
        throw createUnsupportedException("and()", left);
    }

    protected Number xorImpl(Number left, Number right) {
        throw createUnsupportedException("xor()", left);
    }
    
    protected Number modImpl(Number left, Number right) {
        throw createUnsupportedException("mod()", left);
    }
    
    protected Number intdivImpl(Number left, Number right) {
        throw createUnsupportedException("intdiv()", left);
    }
    
    protected Number leftShiftImpl(Number left, Number right) {
        throw createUnsupportedException("leftShift()", left);
    }

    protected Number rightShiftImpl(Number left, Number right) {
        throw createUnsupportedException("rightShift()", left);
    }

    protected Number rightShiftUnsignedImpl(Number left, Number right) {
        throw createUnsupportedException("rightShiftUnsigned()", left);
    }

    protected UnsupportedOperationException createUnsupportedException(String operation, Number left) {
        return new UnsupportedOperationException("Cannot use " + operation + " on this number type: " + left.getClass().getName() + " with value: " + left);
    }
}

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