--- /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.
+ * The sort order (including {@link Double#NaN}) is defined by
+ * {@link Double#compareTo}; {@code NaN} is greater than positive infinity.
+ * @see #sortableLongToDouble
+ */
+ public static long doubleToSortableLong(double val) {
+ long f = Double.doubleToLongBits(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.
+ * The sort order (including {@link Float#NaN}) is defined by
+ * {@link Float#compareTo}; {@code NaN} is greater than positive infinity.
+ * @see #sortableIntToFloat
+ */
+ public static int floatToSortableInt(float val) {
+ int f = Float.floatToIntBits(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