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/*
* Copyright 2013, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.jf.util;
import java.text.DecimalFormat;
public class NumberUtils {
private static final int canonicalFloatNaN = Float.floatToRawIntBits(Float.NaN);
private static final int maxFloat = Float.floatToRawIntBits(Float.MAX_VALUE);
private static final int piFloat = Float.floatToRawIntBits((float)Math.PI);
private static final int eFloat = Float.floatToRawIntBits((float)Math.E);
private static final long canonicalDoubleNaN = Double.doubleToRawLongBits(Double.NaN);
private static final long maxDouble = Double.doubleToLongBits(Double.MAX_VALUE);
private static final long piDouble = Double.doubleToLongBits(Math.PI);
private static final long eDouble = Double.doubleToLongBits(Math.E);
private static final DecimalFormat format = new DecimalFormat("0.####################E0");
public static boolean isLikelyFloat(int value) {
// Check for some common named float values
// We don't check for Float.MIN_VALUE, which has an integer representation of 1
if (value == canonicalFloatNaN ||
value == maxFloat ||
value == piFloat ||
value == eFloat) {
return true;
}
// Check for some named integer values
if (value == Integer.MAX_VALUE || value == Integer.MIN_VALUE) {
return false;
}
// Check for likely resource id
int packageId = value >> 24;
int resourceType = value >> 16 & 0xff;
int resourceId = value & 0xffff;
if ((packageId == 0x7f || packageId == 1) && resourceType < 0x1f && resourceId < 0xfff) {
return false;
}
// a non-canocical NaN is more likely to be an integer
float floatValue = Float.intBitsToFloat(value);
if (Float.isNaN(floatValue)) {
return false;
}
// Otherwise, whichever has a shorter scientific notation representation is more likely.
// Integer wins the tie
String asInt = format.format(value);
String asFloat = format.format(floatValue);
// try to strip off any small imprecision near the end of the mantissa
int decimalPoint = asFloat.indexOf('.');
int exponent = asFloat.indexOf("E");
int zeros = asFloat.indexOf("000");
if (zeros > decimalPoint && zeros < exponent) {
asFloat = asFloat.substring(0, zeros) + asFloat.substring(exponent);
} else {
int nines = asFloat.indexOf("999");
if (nines > decimalPoint && nines < exponent) {
asFloat = asFloat.substring(0, nines) + asFloat.substring(exponent);
}
}
return asFloat.length() < asInt.length();
}
public static boolean isLikelyDouble(long value) {
// Check for some common named double values
// We don't check for Double.MIN_VALUE, which has a long representation of 1
if (value == canonicalDoubleNaN ||
value == maxDouble ||
value == piDouble ||
value == eDouble) {
return true;
}
// Check for some named long values
if (value == Long.MAX_VALUE || value == Long.MIN_VALUE) {
return false;
}
// a non-canocical NaN is more likely to be an long
double doubleValue = Double.longBitsToDouble(value);
if (Double.isNaN(doubleValue)) {
return false;
}
// Otherwise, whichever has a shorter scientific notation representation is more likely.
// Long wins the tie
String asLong = format.format(value);
String asDouble = format.format(doubleValue);
// try to strip off any small imprecision near the end of the mantissa
int decimalPoint = asDouble.indexOf('.');
int exponent = asDouble.indexOf("E");
int zeros = asDouble.indexOf("000");
if (zeros > decimalPoint && zeros < exponent) {
asDouble = asDouble.substring(0, zeros) + asDouble.substring(exponent);
} else {
int nines = asDouble.indexOf("999");
if (nines > decimalPoint && nines < exponent) {
asDouble = asDouble.substring(0, nines) + asDouble.substring(exponent);
}
}
return asDouble.length() < asLong.length();
}
}
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