/* ==================================================================== | |
Licensed to the Apache Software Foundation (ASF) under one or more | |
contributor license agreements. See the NOTICE file distributed with | |
this work for additional information regarding copyright ownership. | |
The ASF licenses this file to You 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.apache.poi.ss.formula.functions; | |
/** | |
* <p>Some utils for converting from and to any base<p/> | |
* | |
* @author cedric dot walter @ gmail dot com | |
*/ | |
public class BaseNumberUtils { | |
public static double convertToDecimal(String value, int base, int maxNumberOfPlaces) throws IllegalArgumentException { | |
if (value == null || value.length() == 0) { | |
return 0.0; | |
} | |
long stringLength = value.length(); | |
if (stringLength > maxNumberOfPlaces) { | |
throw new IllegalArgumentException(); | |
} | |
double decimalValue = 0.0; | |
long signedDigit = 0; | |
boolean hasSignedDigit = true; | |
char[] characters = value.toCharArray(); | |
for (char character : characters) { | |
long digit; | |
if ('0' <= character && character <= '9') { | |
digit = character - '0'; | |
} else if ('A' <= character && character <= 'Z') { | |
digit = 10 + (character - 'A'); | |
} else if ('a' <= character && character <= 'z') { | |
digit = 10 + (character - 'a'); | |
} else { | |
digit = base; | |
} | |
if (digit < base) { | |
if (hasSignedDigit) { | |
hasSignedDigit = false; | |
signedDigit = digit; | |
} | |
decimalValue = decimalValue * base + digit; | |
} else { | |
throw new IllegalArgumentException("character not allowed"); | |
} | |
} | |
boolean isNegative = (!hasSignedDigit && stringLength == maxNumberOfPlaces && (signedDigit >= base / 2)); | |
if (isNegative) { | |
decimalValue = getTwoComplement(base, maxNumberOfPlaces, decimalValue); | |
decimalValue = decimalValue * -1.0; | |
} | |
return decimalValue; | |
} | |
private static double getTwoComplement(double base, double maxNumberOfPlaces, double decimalValue) { | |
return (Math.pow(base, maxNumberOfPlaces) - decimalValue); | |
} | |
} |