package org.apache.lucene.document;
/**
* 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.
*/
import org.apache.lucene.document.NumericField; // for javadocs
import org.apache.lucene.search.NumericRangeQuery; // for javadocs
import org.apache.lucene.util.NumericUtils; // for javadocs
// do not remove this class in 3.0, it may be needed to decode old indexes!
/**
* Provides support for converting longs to Strings, and back again. The strings
* are structured so that lexicographic sorting order is preserved.
*
* <p>
* That is, if l1 is less than l2 for any two longs l1 and l2, then
* NumberTools.longToString(l1) is lexicographically less than
* NumberTools.longToString(l2). (Similarly for "greater than" and "equals".)
*
* <p>
* This class handles <b>all</b> long values (unlike
* {@link org.apache.lucene.document.DateField}).
*
* @deprecated For new indexes use {@link NumericUtils} instead, which
* provides a sortable binary representation (prefix encoded) of numeric
* values.
* To index and efficiently query numeric values use {@link NumericField}
* and {@link NumericRangeQuery}.
* This class is included for use with existing
* indices and will be removed in a future release (possibly Lucene 4.0).
*/
public class NumberTools {
private static final int RADIX = 36;
private static final char NEGATIVE_PREFIX = '-';
// NB: NEGATIVE_PREFIX must be < POSITIVE_PREFIX
private static final char POSITIVE_PREFIX = '0';
//NB: this must be less than
/**
* Equivalent to longToString(Long.MIN_VALUE)
*/
public static final String MIN_STRING_VALUE = NEGATIVE_PREFIX
+ "0000000000000";
/**
* Equivalent to longToString(Long.MAX_VALUE)
*/
public static final String MAX_STRING_VALUE = POSITIVE_PREFIX
+ "1y2p0ij32e8e7";
/**
* The length of (all) strings returned by {@link #longToString}
*/
public static final int STR_SIZE = MIN_STRING_VALUE.length();
/**
* Converts a long to a String suitable for indexing.
*/
public static String longToString(long l) {
if (l == Long.MIN_VALUE) {
// special case, because long is not symmetric around zero
return MIN_STRING_VALUE;
}
StringBuilder buf = new StringBuilder(STR_SIZE);
if (l < 0) {
buf.append(NEGATIVE_PREFIX);
l = Long.MAX_VALUE + l + 1;
} else {
buf.append(POSITIVE_PREFIX);
}
String num = Long.toString(l, RADIX);
int padLen = STR_SIZE - num.length() - buf.length();
while (padLen-- > 0) {
buf.append('0');
}
buf.append(num);
return buf.toString();
}
/**
* Converts a String that was returned by {@link #longToString} back to a
* long.
*
* @throws IllegalArgumentException
* if the input is null
* @throws NumberFormatException
* if the input does not parse (it was not a String returned by
* longToString()).
*/
public static long stringToLong(String str) {
if (str == null) {
throw new NullPointerException("string cannot be null");
}
if (str.length() != STR_SIZE) {
throw new NumberFormatException("string is the wrong size");
}
if (str.equals(MIN_STRING_VALUE)) {
return Long.MIN_VALUE;
}
char prefix = str.charAt(0);
long l = Long.parseLong(str.substring(1), RADIX);
if (prefix == POSITIVE_PREFIX) {
// nop
} else if (prefix == NEGATIVE_PREFIX) {
l = l - Long.MAX_VALUE - 1;
} else {
throw new NumberFormatException(
"string does not begin with the correct prefix");
}
return l;
}
}