freemarker.template.utility.OptimizerUtil Maven / Gradle / Ivy
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Google App Engine compliant variation of FreeMarker.
FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
/*
* Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
*
* 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 freemarker.template.utility;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
*/
public class OptimizerUtil
{
private static final BigInteger INTEGER_MIN = new BigInteger(Integer.toString(Integer.MIN_VALUE));
private static final BigInteger INTEGER_MAX = new BigInteger(Integer.toString(Integer.MAX_VALUE));
private static final BigInteger LONG_MIN = new BigInteger(Long.toString(Long.MIN_VALUE));
private static final BigInteger LONG_MAX = new BigInteger(Long.toString(Long.MAX_VALUE));
private OptimizerUtil()
{
}
public static List optimizeListStorage(List list)
{
switch(list.size())
{
case 0:
{
return Collections.EMPTY_LIST;
}
case 1:
{
return Collections.singletonList(list.get(0));
}
default:
{
if(list instanceof ArrayList)
{
((ArrayList)list).trimToSize();
}
return list;
}
}
}
/**
* This is needed to reverse the extreme conversions in arithmetic
* operations so that numbers can be meaningfully used with models that
* don't know what to do with a BigDecimal. Of course, this will make
* impossible for these models (i.e. Jython) to receive a BigDecimal even if
* it was originally placed as such in the data model. However, since
* arithmetic operations aggressively erase the information regarding the
* original number type, we have no other choice to ensure expected operation
* in majority of cases.
*/
public static Number optimizeNumberRepresentation(Number number)
{
if(number instanceof BigDecimal)
{
BigDecimal bd = (BigDecimal) number;
if(bd.scale() == 0)
{
// BigDecimal -> BigInteger
number = bd.unscaledValue();
}
else
{
double d = bd.doubleValue();
if(d != Double.POSITIVE_INFINITY && d != Double.NEGATIVE_INFINITY)
{
// BigDecimal -> Double
return new Double(d);
}
}
}
if(number instanceof BigInteger)
{
BigInteger bi = (BigInteger)number;
if(bi.compareTo(INTEGER_MAX) <= 0 && bi.compareTo(INTEGER_MIN) >= 0)
{
// BigInteger -> Integer
return new Integer(bi.intValue());
}
if(bi.compareTo(LONG_MAX) <= 0 && bi.compareTo(LONG_MIN) >= 0)
{
// BigInteger -> Long
return new Long(bi.longValue());
}
}
return number;
}
}