| /* |
| * 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(); |
| } |
| } |