--- /dev/null
+package org.apache.lucene.search;
+
+/**
+ * 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 java.io.IOException;
+import java.util.LinkedList;
+
+import org.apache.lucene.analysis.NumericTokenStream; // for javadocs
+import org.apache.lucene.document.NumericField; // for javadocs
+import org.apache.lucene.document.NumericField.DataType;
+import org.apache.lucene.util.NumericUtils;
+import org.apache.lucene.util.ToStringUtils;
+import org.apache.lucene.util.StringHelper;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.index.TermEnum;
+
+/**
+ * <p>A {@link Query} that matches numeric values within a
+ * specified range. To use this, you must first index the
+ * numeric values using {@link NumericField} (expert: {@link
+ * NumericTokenStream}). If your terms are instead textual,
+ * you should use {@link TermRangeQuery}. {@link
+ * NumericRangeFilter} is the filter equivalent of this
+ * query.</p>
+ *
+ * <p>You create a new NumericRangeQuery with the static
+ * factory methods, eg:
+ *
+ * <pre>
+ * Query q = NumericRangeQuery.newFloatRange("weight", 0.03f, 0.10f, true, true);
+ * </pre>
+ *
+ * matches all documents whose float valued "weight" field
+ * ranges from 0.03 to 0.10, inclusive.
+ *
+ * <p>The performance of NumericRangeQuery is much better
+ * than the corresponding {@link TermRangeQuery} because the
+ * number of terms that must be searched is usually far
+ * fewer, thanks to trie indexing, described below.</p>
+ *
+ * <p>You can optionally specify a <a
+ * href="#precisionStepDesc"><code>precisionStep</code></a>
+ * when creating this query. This is necessary if you've
+ * changed this configuration from its default (4) during
+ * indexing. Lower values consume more disk space but speed
+ * up searching. Suitable values are between <b>1</b> and
+ * <b>8</b>. A good starting point to test is <b>4</b>,
+ * which is the default value for all <code>Numeric*</code>
+ * classes. See <a href="#precisionStepDesc">below</a> for
+ * details.
+ *
+ * <p>This query defaults to {@linkplain
+ * MultiTermQuery#CONSTANT_SCORE_AUTO_REWRITE_DEFAULT} for
+ * 32 bit (int/float) ranges with precisionStep ≤8 and 64
+ * bit (long/double) ranges with precisionStep ≤6.
+ * Otherwise it uses {@linkplain
+ * MultiTermQuery#CONSTANT_SCORE_FILTER_REWRITE} as the
+ * number of terms is likely to be high. With precision
+ * steps of ≤4, this query can be run with one of the
+ * BooleanQuery rewrite methods without changing
+ * BooleanQuery's default max clause count.
+ *
+ * <br><h3>How it works</h3>
+ *
+ * <p>See the publication about <a target="_blank" href="http://www.panfmp.org">panFMP</a>,
+ * where this algorithm was described (referred to as <code>TrieRangeQuery</code>):
+ *
+ * <blockquote><strong>Schindler, U, Diepenbroek, M</strong>, 2008.
+ * <em>Generic XML-based Framework for Metadata Portals.</em>
+ * Computers & Geosciences 34 (12), 1947-1955.
+ * <a href="http://dx.doi.org/10.1016/j.cageo.2008.02.023"
+ * target="_blank">doi:10.1016/j.cageo.2008.02.023</a></blockquote>
+ *
+ * <p><em>A quote from this paper:</em> Because Apache Lucene is a full-text
+ * search engine and not a conventional database, it cannot handle numerical ranges
+ * (e.g., field value is inside user defined bounds, even dates are numerical values).
+ * We have developed an extension to Apache Lucene that stores
+ * the numerical values in a special string-encoded format with variable precision
+ * (all numerical values like doubles, longs, floats, and ints are converted to
+ * lexicographic sortable string representations and stored with different precisions
+ * (for a more detailed description of how the values are stored,
+ * see {@link NumericUtils}). A range is then divided recursively into multiple intervals for searching:
+ * The center of the range is searched only with the lowest possible precision in the <em>trie</em>,
+ * while the boundaries are matched more exactly. This reduces the number of terms dramatically.</p>
+ *
+ * <p>For the variant that stores long values in 8 different precisions (each reduced by 8 bits) that
+ * uses a lowest precision of 1 byte, the index contains only a maximum of 256 distinct values in the
+ * lowest precision. Overall, a range could consist of a theoretical maximum of
+ * <code>7*255*2 + 255 = 3825</code> distinct terms (when there is a term for every distinct value of an
+ * 8-byte-number in the index and the range covers almost all of them; a maximum of 255 distinct values is used
+ * because it would always be possible to reduce the full 256 values to one term with degraded precision).
+ * In practice, we have seen up to 300 terms in most cases (index with 500,000 metadata records
+ * and a uniform value distribution).</p>
+ *
+ * <a name="precisionStepDesc"><h3>Precision Step</h3>
+ * <p>You can choose any <code>precisionStep</code> when encoding values.
+ * Lower step values mean more precisions and so more terms in index (and index gets larger).
+ * On the other hand, the maximum number of terms to match reduces, which optimized query speed.
+ * The formula to calculate the maximum term count is:
+ * <pre>
+ * n = [ (bitsPerValue/precisionStep - 1) * (2^precisionStep - 1 ) * 2 ] + (2^precisionStep - 1 )
+ * </pre>
+ * <p><em>(this formula is only correct, when <code>bitsPerValue/precisionStep</code> is an integer;
+ * in other cases, the value must be rounded up and the last summand must contain the modulo of the division as
+ * precision step)</em>.
+ * For longs stored using a precision step of 4, <code>n = 15*15*2 + 15 = 465</code>, and for a precision
+ * step of 2, <code>n = 31*3*2 + 3 = 189</code>. But the faster search speed is reduced by more seeking
+ * in the term enum of the index. Because of this, the ideal <code>precisionStep</code> value can only
+ * be found out by testing. <b>Important:</b> You can index with a lower precision step value and test search speed
+ * using a multiple of the original step value.</p>
+ *
+ * <p>Good values for <code>precisionStep</code> are depending on usage and data type:
+ * <ul>
+ * <li>The default for all data types is <b>4</b>, which is used, when no <code>precisionStep</code> is given.
+ * <li>Ideal value in most cases for <em>64 bit</em> data types <em>(long, double)</em> is <b>6</b> or <b>8</b>.
+ * <li>Ideal value in most cases for <em>32 bit</em> data types <em>(int, float)</em> is <b>4</b>.
+ * <li>For low cardinality fields larger precision steps are good. If the cardinality is < 100, it is
+ * fair to use {@link Integer#MAX_VALUE} (see below).
+ * <li>Steps <b>≥64</b> for <em>long/double</em> and <b>≥32</b> for <em>int/float</em> produces one token
+ * per value in the index and querying is as slow as a conventional {@link TermRangeQuery}. But it can be used
+ * to produce fields, that are solely used for sorting (in this case simply use {@link Integer#MAX_VALUE} as
+ * <code>precisionStep</code>). Using {@link NumericField NumericFields} for sorting
+ * is ideal, because building the field cache is much faster than with text-only numbers.
+ * These fields have one term per value and therefore also work with term enumeration for building distinct lists
+ * (e.g. facets / preselected values to search for).
+ * Sorting is also possible with range query optimized fields using one of the above <code>precisionSteps</code>.
+ * </ul>
+ *
+ * <p>Comparisons of the different types of RangeQueries on an index with about 500,000 docs showed
+ * that {@link TermRangeQuery} in boolean rewrite mode (with raised {@link BooleanQuery} clause count)
+ * took about 30-40 secs to complete, {@link TermRangeQuery} in constant score filter rewrite mode took 5 secs
+ * and executing this class took <100ms to complete (on an Opteron64 machine, Java 1.5, 8 bit
+ * precision step). This query type was developed for a geographic portal, where the performance for
+ * e.g. bounding boxes or exact date/time stamps is important.</p>
+ *
+ * @since 2.9
+ **/
+public final class NumericRangeQuery<T extends Number> extends MultiTermQuery {
+
+ private NumericRangeQuery(final String field, final int precisionStep, final DataType dataType,
+ T min, T max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ if (precisionStep < 1)
+ throw new IllegalArgumentException("precisionStep must be >=1");
+ this.field = StringHelper.intern(field);
+ this.precisionStep = precisionStep;
+ this.dataType = dataType;
+ this.min = min;
+ this.max = max;
+ this.minInclusive = minInclusive;
+ this.maxInclusive = maxInclusive;
+
+ // For bigger precisionSteps this query likely
+ // hits too many terms, so set to CONSTANT_SCORE_FILTER right off
+ // (especially as the FilteredTermEnum is costly if wasted only for AUTO tests because it
+ // creates new enums from IndexReader for each sub-range)
+ switch (dataType) {
+ case LONG:
+ case DOUBLE:
+ setRewriteMethod( (precisionStep > 6) ?
+ CONSTANT_SCORE_FILTER_REWRITE :
+ CONSTANT_SCORE_AUTO_REWRITE_DEFAULT
+ );
+ break;
+ case INT:
+ case FLOAT:
+ setRewriteMethod( (precisionStep > 8) ?
+ CONSTANT_SCORE_FILTER_REWRITE :
+ CONSTANT_SCORE_AUTO_REWRITE_DEFAULT
+ );
+ break;
+ default:
+ // should never happen
+ throw new IllegalArgumentException("Invalid numeric DataType");
+ }
+
+ // shortcut if upper bound == lower bound
+ if (min != null && min.equals(max)) {
+ setRewriteMethod(CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE);
+ }
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>long</code>
+ * range using the given <a href="#precisionStepDesc"><code>precisionStep</code></a>.
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Long> newLongRange(final String field, final int precisionStep,
+ Long min, Long max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Long>(field, precisionStep, DataType.LONG, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>long</code>
+ * range using the default <code>precisionStep</code> {@link NumericUtils#PRECISION_STEP_DEFAULT} (4).
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Long> newLongRange(final String field,
+ Long min, Long max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Long>(field, NumericUtils.PRECISION_STEP_DEFAULT, DataType.LONG, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>int</code>
+ * range using the given <a href="#precisionStepDesc"><code>precisionStep</code></a>.
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Integer> newIntRange(final String field, final int precisionStep,
+ Integer min, Integer max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Integer>(field, precisionStep, DataType.INT, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>int</code>
+ * range using the default <code>precisionStep</code> {@link NumericUtils#PRECISION_STEP_DEFAULT} (4).
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Integer> newIntRange(final String field,
+ Integer min, Integer max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Integer>(field, NumericUtils.PRECISION_STEP_DEFAULT, DataType.INT, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>double</code>
+ * range using the given <a href="#precisionStepDesc"><code>precisionStep</code></a>.
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>.
+ * {@link Double#NaN} will never match a half-open range, to hit {@code NaN} use a query
+ * with {@code min == max == Double.NaN}. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Double> newDoubleRange(final String field, final int precisionStep,
+ Double min, Double max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Double>(field, precisionStep, DataType.DOUBLE, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>double</code>
+ * range using the default <code>precisionStep</code> {@link NumericUtils#PRECISION_STEP_DEFAULT} (4).
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>.
+ * {@link Double#NaN} will never match a half-open range, to hit {@code NaN} use a query
+ * with {@code min == max == Double.NaN}. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Double> newDoubleRange(final String field,
+ Double min, Double max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Double>(field, NumericUtils.PRECISION_STEP_DEFAULT, DataType.DOUBLE, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>float</code>
+ * range using the given <a href="#precisionStepDesc"><code>precisionStep</code></a>.
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>.
+ * {@link Float#NaN} will never match a half-open range, to hit {@code NaN} use a query
+ * with {@code min == max == Float.NaN}. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Float> newFloatRange(final String field, final int precisionStep,
+ Float min, Float max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Float>(field, precisionStep, DataType.FLOAT, min, max, minInclusive, maxInclusive);
+ }
+
+ /**
+ * Factory that creates a <code>NumericRangeQuery</code>, that queries a <code>float</code>
+ * range using the default <code>precisionStep</code> {@link NumericUtils#PRECISION_STEP_DEFAULT} (4).
+ * You can have half-open ranges (which are in fact </≤ or >/≥ queries)
+ * by setting the min or max value to <code>null</code>.
+ * {@link Float#NaN} will never match a half-open range, to hit {@code NaN} use a query
+ * with {@code min == max == Float.NaN}. By setting inclusive to false, it will
+ * match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
+ */
+ public static NumericRangeQuery<Float> newFloatRange(final String field,
+ Float min, Float max, final boolean minInclusive, final boolean maxInclusive
+ ) {
+ return new NumericRangeQuery<Float>(field, NumericUtils.PRECISION_STEP_DEFAULT, DataType.FLOAT, min, max, minInclusive, maxInclusive);
+ }
+
+ @Override
+ protected FilteredTermEnum getEnum(final IndexReader reader) throws IOException {
+ return new NumericRangeTermEnum(reader);
+ }
+
+ /** Returns the field name for this query */
+ public String getField() { return field; }
+
+ /** Returns <code>true</code> if the lower endpoint is inclusive */
+ public boolean includesMin() { return minInclusive; }
+
+ /** Returns <code>true</code> if the upper endpoint is inclusive */
+ public boolean includesMax() { return maxInclusive; }
+
+ /** Returns the lower value of this range query */
+ public T getMin() { return min; }
+
+ /** Returns the upper value of this range query */
+ public T getMax() { return max; }
+
+ /** Returns the precision step. */
+ public int getPrecisionStep() { return precisionStep; }
+
+ @Override
+ public String toString(final String field) {
+ final StringBuilder sb = new StringBuilder();
+ if (!this.field.equals(field)) sb.append(this.field).append(':');
+ return sb.append(minInclusive ? '[' : '{')
+ .append((min == null) ? "*" : min.toString())
+ .append(" TO ")
+ .append((max == null) ? "*" : max.toString())
+ .append(maxInclusive ? ']' : '}')
+ .append(ToStringUtils.boost(getBoost()))
+ .toString();
+ }
+
+ @Override
+ public final boolean equals(final Object o) {
+ if (o==this) return true;
+ if (!super.equals(o))
+ return false;
+ if (o instanceof NumericRangeQuery) {
+ final NumericRangeQuery q=(NumericRangeQuery)o;
+ return (
+ field==q.field &&
+ (q.min == null ? min == null : q.min.equals(min)) &&
+ (q.max == null ? max == null : q.max.equals(max)) &&
+ minInclusive == q.minInclusive &&
+ maxInclusive == q.maxInclusive &&
+ precisionStep == q.precisionStep
+ );
+ }
+ return false;
+ }
+
+ @Override
+ public final int hashCode() {
+ int hash = super.hashCode();
+ hash += field.hashCode()^0x4565fd66 + precisionStep^0x64365465;
+ if (min != null) hash += min.hashCode()^0x14fa55fb;
+ if (max != null) hash += max.hashCode()^0x733fa5fe;
+ return hash +
+ (Boolean.valueOf(minInclusive).hashCode()^0x14fa55fb)+
+ (Boolean.valueOf(maxInclusive).hashCode()^0x733fa5fe);
+ }
+
+ // field must be interned after reading from stream
+ private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, ClassNotFoundException {
+ in.defaultReadObject();
+ field = StringHelper.intern(field);
+ }
+
+ // members (package private, to be also fast accessible by NumericRangeTermEnum)
+ String field;
+ final int precisionStep;
+ final DataType dataType;
+ final T min, max;
+ final boolean minInclusive,maxInclusive;
+
+ // used to handle float/double infinity correcty
+ static final long LONG_NEGATIVE_INFINITY =
+ NumericUtils.doubleToSortableLong(Double.NEGATIVE_INFINITY);
+ static final long LONG_POSITIVE_INFINITY =
+ NumericUtils.doubleToSortableLong(Double.POSITIVE_INFINITY);
+ static final int INT_NEGATIVE_INFINITY =
+ NumericUtils.floatToSortableInt(Float.NEGATIVE_INFINITY);
+ static final int INT_POSITIVE_INFINITY =
+ NumericUtils.floatToSortableInt(Float.POSITIVE_INFINITY);
+
+ /**
+ * Subclass of FilteredTermEnum for enumerating all terms that match the
+ * sub-ranges for trie range queries.
+ * <p>
+ * WARNING: This term enumeration is not guaranteed to be always ordered by
+ * {@link Term#compareTo}.
+ * The ordering depends on how {@link NumericUtils#splitLongRange} and
+ * {@link NumericUtils#splitIntRange} generates the sub-ranges. For
+ * {@link MultiTermQuery} ordering is not relevant.
+ */
+ private final class NumericRangeTermEnum extends FilteredTermEnum {
+
+ private final IndexReader reader;
+ private final LinkedList<String> rangeBounds = new LinkedList<String>();
+ private final Term termTemplate = new Term(field);
+ private String currentUpperBound = null;
+
+ NumericRangeTermEnum(final IndexReader reader) throws IOException {
+ this.reader = reader;
+
+ switch (dataType) {
+ case LONG:
+ case DOUBLE: {
+ // lower
+ long minBound;
+ if (dataType == DataType.LONG) {
+ minBound = (min == null) ? Long.MIN_VALUE : min.longValue();
+ } else {
+ assert dataType == DataType.DOUBLE;
+ minBound = (min == null) ? LONG_NEGATIVE_INFINITY
+ : NumericUtils.doubleToSortableLong(min.doubleValue());
+ }
+ if (!minInclusive && min != null) {
+ if (minBound == Long.MAX_VALUE) break;
+ minBound++;
+ }
+
+ // upper
+ long maxBound;
+ if (dataType == DataType.LONG) {
+ maxBound = (max == null) ? Long.MAX_VALUE : max.longValue();
+ } else {
+ assert dataType == DataType.DOUBLE;
+ maxBound = (max == null) ? LONG_POSITIVE_INFINITY
+ : NumericUtils.doubleToSortableLong(max.doubleValue());
+ }
+ if (!maxInclusive && max != null) {
+ if (maxBound == Long.MIN_VALUE) break;
+ maxBound--;
+ }
+
+ NumericUtils.splitLongRange(new NumericUtils.LongRangeBuilder() {
+ @Override
+ public final void addRange(String minPrefixCoded, String maxPrefixCoded) {
+ rangeBounds.add(minPrefixCoded);
+ rangeBounds.add(maxPrefixCoded);
+ }
+ }, precisionStep, minBound, maxBound);
+ break;
+ }
+
+ case INT:
+ case FLOAT: {
+ // lower
+ int minBound;
+ if (dataType == DataType.INT) {
+ minBound = (min == null) ? Integer.MIN_VALUE : min.intValue();
+ } else {
+ assert dataType == DataType.FLOAT;
+ minBound = (min == null) ? INT_NEGATIVE_INFINITY
+ : NumericUtils.floatToSortableInt(min.floatValue());
+ }
+ if (!minInclusive && min != null) {
+ if (minBound == Integer.MAX_VALUE) break;
+ minBound++;
+ }
+
+ // upper
+ int maxBound;
+ if (dataType == DataType.INT) {
+ maxBound = (max == null) ? Integer.MAX_VALUE : max.intValue();
+ } else {
+ assert dataType == DataType.FLOAT;
+ maxBound = (max == null) ? INT_POSITIVE_INFINITY
+ : NumericUtils.floatToSortableInt(max.floatValue());
+ }
+ if (!maxInclusive && max != null) {
+ if (maxBound == Integer.MIN_VALUE) break;
+ maxBound--;
+ }
+
+ NumericUtils.splitIntRange(new NumericUtils.IntRangeBuilder() {
+ @Override
+ public final void addRange(String minPrefixCoded, String maxPrefixCoded) {
+ rangeBounds.add(minPrefixCoded);
+ rangeBounds.add(maxPrefixCoded);
+ }
+ }, precisionStep, minBound, maxBound);
+ break;
+ }
+
+ default:
+ // should never happen
+ throw new IllegalArgumentException("Invalid numeric DataType");
+ }
+
+ // seek to first term
+ next();
+ }
+
+ @Override
+ public float difference() {
+ return 1.0f;
+ }
+
+ /** this is a dummy, it is not used by this class. */
+ @Override
+ protected boolean endEnum() {
+ throw new UnsupportedOperationException("not implemented");
+ }
+
+ /** this is a dummy, it is not used by this class. */
+ @Override
+ protected void setEnum(TermEnum tenum) {
+ throw new UnsupportedOperationException("not implemented");
+ }
+
+ /**
+ * Compares if current upper bound is reached.
+ * In contrast to {@link FilteredTermEnum}, a return value
+ * of <code>false</code> ends iterating the current enum
+ * and forwards to the next sub-range.
+ */
+ @Override
+ protected boolean termCompare(Term term) {
+ return (term.field() == field && term.text().compareTo(currentUpperBound) <= 0);
+ }
+
+ /** Increments the enumeration to the next element. True if one exists. */
+ @Override
+ public boolean next() throws IOException {
+ // if a current term exists, the actual enum is initialized:
+ // try change to next term, if no such term exists, fall-through
+ if (currentTerm != null) {
+ assert actualEnum != null;
+ if (actualEnum.next()) {
+ currentTerm = actualEnum.term();
+ if (termCompare(currentTerm))
+ return true;
+ }
+ }
+
+ // if all above fails, we go forward to the next enum,
+ // if one is available
+ currentTerm = null;
+ while (rangeBounds.size() >= 2) {
+ assert rangeBounds.size() % 2 == 0;
+ // close the current enum and read next bounds
+ if (actualEnum != null) {
+ actualEnum.close();
+ actualEnum = null;
+ }
+ final String lowerBound = rangeBounds.removeFirst();
+ this.currentUpperBound = rangeBounds.removeFirst();
+ // create a new enum
+ actualEnum = reader.terms(termTemplate.createTerm(lowerBound));
+ currentTerm = actualEnum.term();
+ if (currentTerm != null && termCompare(currentTerm))
+ return true;
+ // clear the current term for next iteration
+ currentTerm = null;
+ }
+
+ // no more sub-range enums available
+ assert rangeBounds.size() == 0 && currentTerm == null;
+ return false;
+ }
+
+ /** Closes the enumeration to further activity, freeing resources. */
+ @Override
+ public void close() throws IOException {
+ rangeBounds.clear();
+ currentUpperBound = null;
+ super.close();
+ }
+
+ }
+
+}
fnp / pylucene.git / blobdiff