com.adobe.cq.searchcollections.lucene.DecimalField Maven / Gradle / Ivy
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* Copyright 2012 Adobe Systems Incorporated
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package com.adobe.cq.searchcollections.lucene;
import java.math.BigDecimal;
import java.math.BigInteger;
/**
* The DecimalField class is a utility to convert
* java.math.BigDecimal values to String
* values that are lexicographically sortable according to the decimal value.
*
* The string format uses the characters '0' to '9' and consists of:
*
* { value signum +2 }
* { exponent signum +2 }
* { exponent length -1 }
* { exponent value }
* { value (-1 if inverted) }
*
* Only the signum is encoded if the value is zero. The exponent is not
* encoded if zero. Negative values are "inverted" character by character
* ('0' -> 9, '1' -> '8', and so on). The same applies to the exponent.
*
* Examples:
* 0 => "2"
* 2 => "322" (signum 1; exponent 0; value 2)
* 120 => "330212" (signum 1; exponent signum 1, length 1, value 2; value 12).
* -1 => "179" (signum -1, rest inverted; exponent 0; value 1 (-1, inverted).
*
* Values between BigDecimal(BigInteger.ONE, Integer.MIN_VALUE) and
* BigDecimal(BigInteger.ONE, Integer.MAX_VALUE) are supported.
*
* @deprecated
*/
public class DecimalField {
/**
* Convert a BigDecimal to a String.
*
* @param value the BigDecimal
* @return the String
*/
public static String decimalToString(BigDecimal value) {
switch (value.signum()) {
case -1:
return "1" + invert(positiveDecimalToString(value.negate()), 1);
case 0:
return "2";
default:
return "3" + positiveDecimalToString(value);
}
}
/**
* Convert a String to a BigDecimal.
*
* @param value the String
* @return the BigDecimal
*/
public static BigDecimal stringToDecimal(String value) {
int sig = value.charAt(0) - '2';
if (sig == 0) {
return BigDecimal.ZERO;
} else if (sig < 0) {
value = invert(value, 1);
}
long expSig = value.charAt(1) - '2', exp;
if (expSig == 0) {
exp = 0;
value = value.substring(2);
} else {
int expSize = value.charAt(2) - '0' + 1;
if (expSig < 0) {
expSize = 11 - expSize;
}
String e = value.substring(3, 3 + expSize);
exp = expSig * Long.parseLong(expSig < 0 ? invert(e, 0) : e);
value = value.substring(3 + expSize);
}
BigInteger x = new BigInteger(value);
int scale = (int) (value.length() - exp - 1);
return new BigDecimal(sig < 0 ? x.negate() : x, scale);
}
private static String positiveDecimalToString(BigDecimal value) {
StringBuilder buff = new StringBuilder();
long exp = value.precision() - value.scale() - 1;
// exponent signum and size
if (exp == 0) {
buff.append('2');
} else {
String e = String.valueOf(Math.abs(exp));
// exponent size is prepended
e = String.valueOf(e.length() - 1) + e;
// exponent signum
if (exp > 0) {
buff.append('3').append(e);
} else {
buff.append('1').append(invert(e, 0));
}
}
String s = value.unscaledValue().toString();
// remove trailing 0s
int max = s.length() - 1;
while (s.charAt(max) == '0') {
max--;
}
return buff.append(s.substring(0, max + 1)).toString();
}
/**
* "Invert" a number digit by digit (0 becomes 9, 9 becomes 0, and so on).
*
* @param s the original string
* @param incLast how much to increment the last character
* @return the negated string
*/
private static String invert(String s, int incLast) {
char[] chars = s.toCharArray();
for (int i = 0; i < chars.length; i++) {
chars[i] = (char) ('9' - chars[i] + '0');
}
chars[chars.length - 1] += incLast;
return String.valueOf(chars);
}
}