+++ /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;
-
-/** Expert: Scoring functionality for phrase queries.
- * <br>A document is considered matching if it contains the phrase-query terms
- * at "valid" positions. What "valid positions" are
- * depends on the type of the phrase query: for an exact phrase query terms are required
- * to appear in adjacent locations, while for a sloppy phrase query some distance between
- * the terms is allowed. The abstract method {@link #phraseFreq()} of extending classes
- * is invoked for each document containing all the phrase query terms, in order to
- * compute the frequency of the phrase query in that document. A non zero frequency
- * means a match.
- */
-abstract class PhraseScorer extends Scorer {
- protected byte[] norms;
- protected float value;
-
- private boolean firstTime = true;
- private boolean more = true;
- protected PhraseQueue pq;
- protected PhrasePositions first, last;
-
- private float freq; //phrase frequency in current doc as computed by phraseFreq().
-
- PhraseScorer(Weight weight, PhraseQuery.PostingsAndFreq[] postings,
- Similarity similarity, byte[] norms) {
- super(similarity, weight);
- this.norms = norms;
- this.value = weight.getValue();
-
- // convert tps to a list of phrase positions.
- // note: phrase-position differs from term-position in that its position
- // reflects the phrase offset: pp.pos = tp.pos - offset.
- // this allows to easily identify a matching (exact) phrase
- // when all PhrasePositions have exactly the same position.
- for (int i = 0; i < postings.length; i++) {
- PhrasePositions pp = new PhrasePositions(postings[i].postings, postings[i].position, i);
- if (last != null) { // add next to end of list
- last.next = pp;
- } else {
- first = pp;
- }
- last = pp;
- }
-
- pq = new PhraseQueue(postings.length); // construct empty pq
- first.doc = -1;
- }
-
- @Override
- public int docID() { return first.doc; }
-
- @Override
- public int nextDoc() throws IOException {
- if (firstTime) {
- init();
- firstTime = false;
- } else if (more) {
- more = last.next(); // trigger further scanning
- }
- if (!doNext()) {
- first.doc = NO_MORE_DOCS;
- }
- return first.doc;
- }
-
- // next without initial increment
- private boolean doNext() throws IOException {
- while (more) {
- while (more && first.doc < last.doc) { // find doc w/ all the terms
- more = first.skipTo(last.doc); // skip first upto last
- firstToLast(); // and move it to the end
- }
-
- if (more) {
- // found a doc with all of the terms
- freq = phraseFreq(); // check for phrase
- if (freq == 0.0f) // no match
- more = last.next(); // trigger further scanning
- else
- return true; // found a match
- }
- }
- return false; // no more matches
- }
-
- @Override
- public float score() throws IOException {
- //System.out.println("scoring " + first.doc);
- float raw = getSimilarity().tf(freq) * value; // raw score
- return norms == null ? raw : raw * getSimilarity().decodeNormValue(norms[first.doc]); // normalize
- }
-
- @Override
- public int advance(int target) throws IOException {
- firstTime = false;
- for (PhrasePositions pp = first; more && pp != null; pp = pp.next) {
- more = pp.skipTo(target);
- }
- if (more) {
- sort(); // re-sort
- }
- if (!doNext()) {
- first.doc = NO_MORE_DOCS;
- }
- return first.doc;
- }
-
- /**
- * phrase frequency in current doc as computed by phraseFreq().
- */
- @Override
- public final float freq() {
- return freq;
- }
-
- /**
- * For a document containing all the phrase query terms, compute the
- * frequency of the phrase in that document.
- * A non zero frequency means a match.
- * <br>Note, that containing all phrase terms does not guarantee a match - they have to be found in matching locations.
- * @return frequency of the phrase in current doc, 0 if not found.
- */
- protected abstract float phraseFreq() throws IOException;
-
- private void init() throws IOException {
- for (PhrasePositions pp = first; more && pp != null; pp = pp.next) {
- more = pp.next();
- }
- if (more) {
- sort();
- }
- }
-
- private void sort() {
- pq.clear();
- for (PhrasePositions pp = first; pp != null; pp = pp.next) {
- pq.add(pp);
- }
- pqToList();
- }
-
- protected final void pqToList() {
- last = first = null;
- while (pq.top() != null) {
- PhrasePositions pp = pq.pop();
- if (last != null) { // add next to end of list
- last.next = pp;
- } else
- first = pp;
- last = pp;
- pp.next = null;
- }
- }
-
- protected final void firstToLast() {
- last.next = first; // move first to end of list
- last = first;
- first = first.next;
- last.next = null;
- }
-
- @Override
- public String toString() { return "scorer(" + weight + ")"; }
-
-}
fnp / pylucene.git / blobdiff