--- /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 org.apache.lucene.index.TermDocs;
+
+/** Expert: A <code>Scorer</code> for documents matching a <code>Term</code>.
+ */
+final class TermScorer extends Scorer {
+ private final TermDocs termDocs;
+ private final byte[] norms;
+ private float weightValue;
+ private int doc = -1;
+ private int freq;
+
+ private final int[] docs = new int[32]; // buffered doc numbers
+ private final int[] freqs = new int[32]; // buffered term freqs
+ private int pointer;
+ private int pointerMax;
+
+ private static final int SCORE_CACHE_SIZE = 32;
+ private final float[] scoreCache = new float[SCORE_CACHE_SIZE];
+
+ /**
+ * Construct a <code>TermScorer</code>.
+ *
+ * @param weight
+ * The weight of the <code>Term</code> in the query.
+ * @param td
+ * An iterator over the documents matching the <code>Term</code>.
+ * @param similarity
+ * The </code>Similarity</code> implementation to be used for score
+ * computations.
+ * @param norms
+ * The field norms of the document fields for the <code>Term</code>.
+ */
+ TermScorer(Weight weight, TermDocs td, Similarity similarity, byte[] norms) {
+ super(similarity, weight);
+
+ this.termDocs = td;
+ this.norms = norms;
+ this.weightValue = weight.getValue();
+
+ for (int i = 0; i < SCORE_CACHE_SIZE; i++)
+ scoreCache[i] = getSimilarity().tf(i) * weightValue;
+ }
+
+ @Override
+ public void score(Collector c) throws IOException {
+ score(c, Integer.MAX_VALUE, nextDoc());
+ }
+
+ // firstDocID is ignored since nextDoc() sets 'doc'
+ @Override
+ protected boolean score(Collector c, int end, int firstDocID) throws IOException {
+ c.setScorer(this);
+ while (doc < end) { // for docs in window
+ c.collect(doc); // collect score
+
+ if (++pointer >= pointerMax) {
+ pointerMax = termDocs.read(docs, freqs); // refill buffers
+ if (pointerMax != 0) {
+ pointer = 0;
+ } else {
+ termDocs.close(); // close stream
+ doc = Integer.MAX_VALUE; // set to sentinel value
+ return false;
+ }
+ }
+ doc = docs[pointer];
+ freq = freqs[pointer];
+ }
+ return true;
+ }
+
+ @Override
+ public int docID() { return doc; }
+
+ @Override
+ public float freq() {
+ return freq;
+ }
+
+ /**
+ * Advances to the next document matching the query. <br>
+ * The iterator over the matching documents is buffered using
+ * {@link TermDocs#read(int[],int[])}.
+ *
+ * @return the document matching the query or NO_MORE_DOCS if there are no more documents.
+ */
+ @Override
+ public int nextDoc() throws IOException {
+ pointer++;
+ if (pointer >= pointerMax) {
+ pointerMax = termDocs.read(docs, freqs); // refill buffer
+ if (pointerMax != 0) {
+ pointer = 0;
+ } else {
+ termDocs.close(); // close stream
+ return doc = NO_MORE_DOCS;
+ }
+ }
+ doc = docs[pointer];
+ freq = freqs[pointer];
+ return doc;
+ }
+
+ @Override
+ public float score() {
+ assert doc != -1;
+ float raw = // compute tf(f)*weight
+ freq < SCORE_CACHE_SIZE // check cache
+ ? scoreCache[freq] // cache hit
+ : getSimilarity().tf(freq)*weightValue; // cache miss
+
+ return norms == null ? raw : raw * getSimilarity().decodeNormValue(norms[doc]); // normalize for field
+ }
+
+ /**
+ * Advances to the first match beyond the current whose document number is
+ * greater than or equal to a given target. <br>
+ * The implementation uses {@link TermDocs#skipTo(int)}.
+ *
+ * @param target
+ * The target document number.
+ * @return the matching document or NO_MORE_DOCS if none exist.
+ */
+ @Override
+ public int advance(int target) throws IOException {
+ // first scan in cache
+ for (pointer++; pointer < pointerMax; pointer++) {
+ if (docs[pointer] >= target) {
+ freq = freqs[pointer];
+ return doc = docs[pointer];
+ }
+ }
+
+ // not found in cache, seek underlying stream
+ boolean result = termDocs.skipTo(target);
+ if (result) {
+ pointerMax = 1;
+ pointer = 0;
+ docs[pointer] = doc = termDocs.doc();
+ freqs[pointer] = freq = termDocs.freq();
+ } else {
+ doc = NO_MORE_DOCS;
+ }
+ return doc;
+ }
+
+ /** Returns a string representation of this <code>TermScorer</code>. */
+ @Override
+ public String toString() { return "scorer(" + weight + ")"; }
+
+}
fnp / pylucene.git / blobdiff