+++ /dev/null
-package org.apache.lucene.util;
-
-/**
- * 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.analysis.NumericTokenStream; // for javadocs
-import org.apache.lucene.document.NumericField; // for javadocs
-import org.apache.lucene.search.NumericRangeQuery; // for javadocs
-import org.apache.lucene.search.NumericRangeFilter; // for javadocs
-
-/**
- * This is a helper class to generate prefix-encoded representations for numerical values
- * and supplies converters to represent float/double values as sortable integers/longs.
- *
- * <p>To quickly execute range queries in Apache Lucene, a range is divided recursively
- * into multiple intervals for searching: The center of the range is searched only with
- * the lowest possible precision in the trie, while the boundaries are matched
- * more exactly. This reduces the number of terms dramatically.
- *
- * <p>This class generates terms to achieve this: First the numerical integer values need to
- * be converted to strings. For that integer values (32 bit or 64 bit) are made unsigned
- * and the bits are converted to ASCII chars with each 7 bit. The resulting string is
- * sortable like the original integer value. Each value is also prefixed
- * (in the first char) by the <code>shift</code> value (number of bits removed) used
- * during encoding.
- *
- * <p>To also index floating point numbers, this class supplies two methods to convert them
- * to integer values by changing their bit layout: {@link #doubleToSortableLong},
- * {@link #floatToSortableInt}. You will have no precision loss by
- * converting floating point numbers to integers and back (only that the integer form
- * is not usable). Other data types like dates can easily converted to longs or ints (e.g.
- * date to long: {@link java.util.Date#getTime}).
- *
- * <p>For easy usage, the trie algorithm is implemented for indexing inside
- * {@link NumericTokenStream} that can index <code>int</code>, <code>long</code>,
- * <code>float</code>, and <code>double</code>. For querying,
- * {@link NumericRangeQuery} and {@link NumericRangeFilter} implement the query part
- * for the same data types.
- *
- * <p>This class can also be used, to generate lexicographically sortable (according
- * {@link String#compareTo(String)}) representations of numeric data types for other
- * usages (e.g. sorting).
- *
- * @lucene.internal
- *
- * @since 2.9
- */
-public final class NumericUtils {
-
- private NumericUtils() {} // no instance!
-
- /**
- * The default precision step used by {@link NumericField}, {@link NumericTokenStream},
- * {@link NumericRangeQuery}, and {@link NumericRangeFilter} as default
- */
- public static final int PRECISION_STEP_DEFAULT = 4;
-
- /**
- * Expert: Longs are stored at lower precision by shifting off lower bits. The shift count is
- * stored as <code>SHIFT_START_LONG+shift</code> in the first character
- */
- public static final char SHIFT_START_LONG = (char)0x20;
-
- /**
- * Expert: The maximum term length (used for <code>char[]</code> buffer size)
- * for encoding <code>long</code> values.
- * @see #longToPrefixCoded(long,int,char[])
- */
- public static final int BUF_SIZE_LONG = 63/7 + 2;
-
- /**
- * Expert: Integers are stored at lower precision by shifting off lower bits. The shift count is
- * stored as <code>SHIFT_START_INT+shift</code> in the first character
- */
- public static final char SHIFT_START_INT = (char)0x60;
-
- /**
- * Expert: The maximum term length (used for <code>char[]</code> buffer size)
- * for encoding <code>int</code> values.
- * @see #intToPrefixCoded(int,int,char[])
- */
- public static final int BUF_SIZE_INT = 31/7 + 2;
-
- /**
- * Expert: Returns prefix coded bits after reducing the precision by <code>shift</code> bits.
- * This is method is used by {@link NumericTokenStream}.
- * @param val the numeric value
- * @param shift how many bits to strip from the right
- * @param buffer that will contain the encoded chars, must be at least of {@link #BUF_SIZE_LONG}
- * length
- * @return number of chars written to buffer
- */
- public static int longToPrefixCoded(final long val, final int shift, final char[] buffer) {
- if (shift>63 || shift<0)
- throw new IllegalArgumentException("Illegal shift value, must be 0..63");
- int nChars = (63-shift)/7 + 1, len = nChars+1;
- buffer[0] = (char)(SHIFT_START_LONG + shift);
- long sortableBits = val ^ 0x8000000000000000L;
- sortableBits >>>= shift;
- while (nChars>=1) {
- // Store 7 bits per character for good efficiency when UTF-8 encoding.
- // The whole number is right-justified so that lucene can prefix-encode
- // the terms more efficiently.
- buffer[nChars--] = (char)(sortableBits & 0x7f);
- sortableBits >>>= 7;
- }
- return len;
- }
-
- /*
- * Expert: Returns prefix coded bits after reducing the precision by <code>shift</code> bits.
- * This is method is used by {@link LongRangeBuilder}.
- * @param val the numeric value
- * @param shift how many bits to strip from the right
- */
- public static String longToPrefixCoded(final long val, final int shift) {
- final char[] buffer = new char[BUF_SIZE_LONG];
- final int len = longToPrefixCoded(val, shift, buffer);
- return new String(buffer, 0, len);
- }
-
- /*
- * This is a convenience method, that returns prefix coded bits of a long without
- * reducing the precision. It can be used to store the full precision value as a
- * stored field in index.
- * <p>To decode, use {@link #prefixCodedToLong}.
- */
- public static String longToPrefixCoded(final long val) {
- return longToPrefixCoded(val, 0);
- }
-
- /**
- * Expert: Returns prefix coded bits after reducing the precision by <code>shift</code> bits.
- * This is method is used by {@link NumericTokenStream}.
- * @param val the numeric value
- * @param shift how many bits to strip from the right
- * @param buffer that will contain the encoded chars, must be at least of {@link #BUF_SIZE_INT}
- * length
- * @return number of chars written to buffer
- */
- public static int intToPrefixCoded(final int val, final int shift, final char[] buffer) {
- if (shift>31 || shift<0)
- throw new IllegalArgumentException("Illegal shift value, must be 0..31");
- int nChars = (31-shift)/7 + 1, len = nChars+1;
- buffer[0] = (char)(SHIFT_START_INT + shift);
- int sortableBits = val ^ 0x80000000;
- sortableBits >>>= shift;
- while (nChars>=1) {
- // Store 7 bits per character for good efficiency when UTF-8 encoding.
- // The whole number is right-justified so that lucene can prefix-encode
- // the terms more efficiently.
- buffer[nChars--] = (char)(sortableBits & 0x7f);
- sortableBits >>>= 7;
- }
- return len;
- }
-
- /*
- * Expert: Returns prefix coded bits after reducing the precision by <code>shift</code> bits.
- * This is method is used by {@link IntRangeBuilder}.
- * @param val the numeric value
- * @param shift how many bits to strip from the right
- */
- public static String intToPrefixCoded(final int val, final int shift) {
- final char[] buffer = new char[BUF_SIZE_INT];
- final int len = intToPrefixCoded(val, shift, buffer);
- return new String(buffer, 0, len);
- }
-
- /*
- * This is a convenience method, that returns prefix coded bits of an int without
- * reducing the precision. It can be used to store the full precision value as a
- * stored field in index.
- * <p>To decode, use {@link #prefixCodedToInt}.
- */
- public static String intToPrefixCoded(final int val) {
- return intToPrefixCoded(val, 0);
- }
-
- /*
- * Returns a long from prefixCoded characters.
- * Rightmost bits will be zero for lower precision codes.
- * This method can be used to decode e.g. a stored field.
- * @throws NumberFormatException if the supplied string is
- * not correctly prefix encoded.
- * @see #longToPrefixCoded(long)
- */
- public static long prefixCodedToLong(final String prefixCoded) {
- final int shift = prefixCoded.charAt(0)-SHIFT_START_LONG;
- if (shift>63 || shift<0)
- throw new NumberFormatException("Invalid shift value in prefixCoded string (is encoded value really a LONG?)");
- long sortableBits = 0L;
- for (int i=1, len=prefixCoded.length(); i<len; i++) {
- sortableBits <<= 7;
- final char ch = prefixCoded.charAt(i);
- if (ch>0x7f) {
- throw new NumberFormatException(
- "Invalid prefixCoded numerical value representation (char "+
- Integer.toHexString(ch)+" at position "+i+" is invalid)"
- );
- }
- sortableBits |= ch;
- }
- return (sortableBits << shift) ^ 0x8000000000000000L;
- }
-
- /*
- * Returns an int from prefixCoded characters.
- * Rightmost bits will be zero for lower precision codes.
- * This method can be used to decode e.g. a stored field.
- * @throws NumberFormatException if the supplied string is
- * not correctly prefix encoded.
- * @see #intToPrefixCoded(int)
- */
- public static int prefixCodedToInt(final String prefixCoded) {
- final int shift = prefixCoded.charAt(0)-SHIFT_START_INT;
- if (shift>31 || shift<0)
- throw new NumberFormatException("Invalid shift value in prefixCoded string (is encoded value really an INT?)");
- int sortableBits = 0;
- for (int i=1, len=prefixCoded.length(); i<len; i++) {
- sortableBits <<= 7;
- final char ch = prefixCoded.charAt(i);
- if (ch>0x7f) {
- throw new NumberFormatException(
- "Invalid prefixCoded numerical value representation (char "+
- Integer.toHexString(ch)+" at position "+i+" is invalid)"
- );
- }
- sortableBits |= ch;
- }
- return (sortableBits << shift) ^ 0x80000000;
- }
-
- /**
- * Converts a <code>double</code> value to a sortable signed <code>long</code>.
- * The value is converted by getting their IEEE 754 floating-point "double format"
- * bit layout and then some bits are swapped, to be able to compare the result as long.
- * By this the precision is not reduced, but the value can easily used as a long.
- * @see #sortableLongToDouble
- */
- public static long doubleToSortableLong(double val) {
- long f = Double.doubleToRawLongBits(val);
- if (f<0) f ^= 0x7fffffffffffffffL;
- return f;
- }
-
- /*
- * Convenience method: this just returns:
- * longToPrefixCoded(doubleToSortableLong(val))
- */
- public static String doubleToPrefixCoded(double val) {
- return longToPrefixCoded(doubleToSortableLong(val));
- }
-
- /**
- * Converts a sortable <code>long</code> back to a <code>double</code>.
- * @see #doubleToSortableLong
- */
- public static double sortableLongToDouble(long val) {
- if (val<0) val ^= 0x7fffffffffffffffL;
- return Double.longBitsToDouble(val);
- }
-
- /*
- * Convenience method: this just returns:
- * sortableLongToDouble(prefixCodedToLong(val))
- */
- public static double prefixCodedToDouble(String val) {
- return sortableLongToDouble(prefixCodedToLong(val));
- }
-
- /**
- * Converts a <code>float</code> value to a sortable signed <code>int</code>.
- * The value is converted by getting their IEEE 754 floating-point "float format"
- * bit layout and then some bits are swapped, to be able to compare the result as int.
- * By this the precision is not reduced, but the value can easily used as an int.
- * @see #sortableIntToFloat
- */
- public static int floatToSortableInt(float val) {
- int f = Float.floatToRawIntBits(val);
- if (f<0) f ^= 0x7fffffff;
- return f;
- }
-
- /*
- * Convenience method: this just returns:
- * intToPrefixCoded(floatToSortableInt(val))
- */
- public static String floatToPrefixCoded(float val) {
- return intToPrefixCoded(floatToSortableInt(val));
- }
-
- /**
- * Converts a sortable <code>int</code> back to a <code>float</code>.
- * @see #floatToSortableInt
- */
- public static float sortableIntToFloat(int val) {
- if (val<0) val ^= 0x7fffffff;
- return Float.intBitsToFloat(val);
- }
-
- /*
- * Convenience method: this just returns:
- * sortableIntToFloat(prefixCodedToInt(val))
- */
- public static float prefixCodedToFloat(String val) {
- return sortableIntToFloat(prefixCodedToInt(val));
- }
-
- /**
- * Expert: Splits a long range recursively.
- * You may implement a builder that adds clauses to a
- * {@link org.apache.lucene.search.BooleanQuery} for each call to its
- * {@link LongRangeBuilder#addRange(String,String)}
- * method.
- * <p>This method is used by {@link NumericRangeQuery}.
- */
- public static void splitLongRange(final LongRangeBuilder builder,
- final int precisionStep, final long minBound, final long maxBound
- ) {
- splitRange(builder, 64, precisionStep, minBound, maxBound);
- }
-
- /**
- * Expert: Splits an int range recursively.
- * You may implement a builder that adds clauses to a
- * {@link org.apache.lucene.search.BooleanQuery} for each call to its
- * {@link IntRangeBuilder#addRange(String,String)}
- * method.
- * <p>This method is used by {@link NumericRangeQuery}.
- */
- public static void splitIntRange(final IntRangeBuilder builder,
- final int precisionStep, final int minBound, final int maxBound
- ) {
- splitRange(builder, 32, precisionStep, minBound, maxBound);
- }
-
- /** This helper does the splitting for both 32 and 64 bit. */
- private static void splitRange(
- final Object builder, final int valSize,
- final int precisionStep, long minBound, long maxBound
- ) {
- if (precisionStep < 1)
- throw new IllegalArgumentException("precisionStep must be >=1");
- if (minBound > maxBound) return;
- for (int shift=0; ; shift += precisionStep) {
- // calculate new bounds for inner precision
- final long diff = 1L << (shift+precisionStep),
- mask = ((1L<<precisionStep) - 1L) << shift;
- final boolean
- hasLower = (minBound & mask) != 0L,
- hasUpper = (maxBound & mask) != mask;
- final long
- nextMinBound = (hasLower ? (minBound + diff) : minBound) & ~mask,
- nextMaxBound = (hasUpper ? (maxBound - diff) : maxBound) & ~mask;
- final boolean
- lowerWrapped = nextMinBound < minBound,
- upperWrapped = nextMaxBound > maxBound;
-
- if (shift+precisionStep>=valSize || nextMinBound>nextMaxBound || lowerWrapped || upperWrapped) {
- // We are in the lowest precision or the next precision is not available.
- addRange(builder, valSize, minBound, maxBound, shift);
- // exit the split recursion loop
- break;
- }
-
- if (hasLower)
- addRange(builder, valSize, minBound, minBound | mask, shift);
- if (hasUpper)
- addRange(builder, valSize, maxBound & ~mask, maxBound, shift);
-
- // recurse to next precision
- minBound = nextMinBound;
- maxBound = nextMaxBound;
- }
- }
-
- /** Helper that delegates to correct range builder */
- private static void addRange(
- final Object builder, final int valSize,
- long minBound, long maxBound,
- final int shift
- ) {
- // for the max bound set all lower bits (that were shifted away):
- // this is important for testing or other usages of the splitted range
- // (e.g. to reconstruct the full range). The prefixEncoding will remove
- // the bits anyway, so they do not hurt!
- maxBound |= (1L << shift) - 1L;
- // delegate to correct range builder
- switch(valSize) {
- case 64:
- ((LongRangeBuilder)builder).addRange(minBound, maxBound, shift);
- break;
- case 32:
- ((IntRangeBuilder)builder).addRange((int)minBound, (int)maxBound, shift);
- break;
- default:
- // Should not happen!
- throw new IllegalArgumentException("valSize must be 32 or 64.");
- }
- }
-
- /**
- * Expert: Callback for {@link #splitLongRange}.
- * You need to overwrite only one of the methods.
- * <p><font color="red"><b>NOTE:</b> This is a very low-level interface,
- * the method signatures may change in later versions.</font>
- */
- public static abstract class LongRangeBuilder {
-
- /**
- * Overwrite this method, if you like to receive the already prefix encoded range bounds.
- * You can directly build classical (inclusive) range queries from them.
- */
- public void addRange(String minPrefixCoded, String maxPrefixCoded) {
- throw new UnsupportedOperationException();
- }
-
- /**
- * Overwrite this method, if you like to receive the raw long range bounds.
- * You can use this for e.g. debugging purposes (print out range bounds).
- */
- public void addRange(final long min, final long max, final int shift) {
- addRange(longToPrefixCoded(min, shift), longToPrefixCoded(max, shift));
- }
-
- }
-
- /**
- * Expert: Callback for {@link #splitIntRange}.
- * You need to overwrite only one of the methods.
- * <p><font color="red"><b>NOTE:</b> This is a very low-level interface,
- * the method signatures may change in later versions.</font>
- */
- public static abstract class IntRangeBuilder {
-
- /**
- * Overwrite this method, if you like to receive the already prefix encoded range bounds.
- * You can directly build classical range (inclusive) queries from them.
- */
- public void addRange(String minPrefixCoded, String maxPrefixCoded) {
- throw new UnsupportedOperationException();
- }
-
- /**
- * Overwrite this method, if you like to receive the raw int range bounds.
- * You can use this for e.g. debugging purposes (print out range bounds).
- */
- public void addRange(final int min, final int max, final int shift) {
- addRange(intToPrefixCoded(min, shift), intToPrefixCoded(max, shift));
- }
-
- }
-
-}
fnp / pylucene.git / blobdiff