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MathUtil.java
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MathUtil.java
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/*
* Copyright (c) 2002-2016 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.helpers;
import java.math.BigDecimal;
public abstract class MathUtil
{
private static final long NON_DOUBLE_LONG = 0xFFE0_0000_0000_0000L; // doubles are exact integers up to 53 bits
public static boolean numbersEqual( double fpn, long in )
{
if ( in < 0 )
{
if ( fpn < 0.0 )
{
if ( (NON_DOUBLE_LONG & in) == NON_DOUBLE_LONG ) // the high order bits are only sign bits
{ // no loss of precision if converting the long to a double, so it's safe to compare as double
return fpn == in;
}
else if ( fpn < Long.MIN_VALUE )
{ // the double is too big to fit in a long, they cannot be equal
return false;
}
else if ( (fpn == Math.floor( fpn )) && !Double.isInfinite( fpn ) ) // no decimals
{ // safe to compare as long
return in == (long) fpn;
}
}
}
else
{
if ( !(fpn < 0.0) )
{
if ( (NON_DOUBLE_LONG & in) == 0 ) // the high order bits are only sign bits
{ // no loss of precision if converting the long to a double, so it's safe to compare as double
return fpn == in;
}
else if ( fpn > Long.MAX_VALUE )
{ // the double is too big to fit in a long, they cannot be equal
return false;
}
else if ( (fpn == Math.floor( fpn )) && !Double.isInfinite( fpn ) ) // no decimals
{ // safe to compare as long
return in == (long) fpn;
}
}
}
return false;
}
// Tested by PropertyValueComparisonTest
public static int compareDoubleAgainstLong( double lhs, long rhs )
{
if ( (NON_DOUBLE_LONG & rhs ) != NON_DOUBLE_LONG )
{
if ( Double.isNaN( lhs ) )
{
return +1;
}
if ( Double.isInfinite( lhs ) )
{
return lhs < 0 ? -1 : +1;
}
return BigDecimal.valueOf( lhs ).compareTo( BigDecimal.valueOf( rhs ) );
}
return Double.compare( lhs, rhs );
}
// Tested by PropertyValueComparisonTest
public static int compareLongAgainstDouble( long lhs, double rhs )
{
return - compareDoubleAgainstLong( rhs, lhs );
}
/**
* Return an integer one less than the given integer, or throw {@link ArithmeticException} if the given integer is
* zero.
*/
public static int decrementExactNotPastZero( int value )
{
if ( value == 0 )
{
throw new ArithmeticException( "integer underflow past zero" );
}
return value - 1;
}
}