mirror of https://github.com/apache/lucene.git
LUCENE-3846: add new FuzzySuggester
git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1403779 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Michael McCandless
commit
d8e44bd09d
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@ -49,6 +49,10 @@ New Features
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for better search performance.
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(Han Jiang, Adrien Grand, Robert Muir, Mike McCandless)
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* LUCENE-3846: New FuzzySuggester, like AnalyzingSuggester except it
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also finds completions allowing for fuzzy edits in the input string.
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(Robert Muir, Simon Willnauer, Mike McCandless)
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API Changes
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* LUCENE-4399: Deprecated AppendingCodec. Lucene's term dictionaries
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@ -22,6 +22,7 @@ import java.io.IOException;
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import java.io.OutputStreamWriter;
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import java.io.Writer;
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import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
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import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
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import org.apache.lucene.analysis.tokenattributes.PositionLengthAttribute;
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import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute;
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@ -88,6 +89,7 @@ public class TokenStreamToAutomaton {
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final TermToBytesRefAttribute termBytesAtt = in.addAttribute(TermToBytesRefAttribute.class);
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final PositionIncrementAttribute posIncAtt = in.addAttribute(PositionIncrementAttribute.class);
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final PositionLengthAttribute posLengthAtt = in.addAttribute(PositionLengthAttribute.class);
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final BytesRef term = termBytesAtt.getBytesRef();
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in.reset();
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@ -241,6 +241,20 @@ final public class BasicAutomata {
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return a;
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}
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public static Automaton makeString(int[] word, int offset, int length) {
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Automaton a = new Automaton();
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a.setDeterministic(true);
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State s = new State();
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a.initial = s;
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for (int i = offset; i < offset+length; i++) {
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State s2 = new State();
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s.addTransition(new Transition(word[i], s2));
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s = s2;
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}
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s.accept = true;
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return a;
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}
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/**
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* Returns a new (deterministic and minimal) automaton that accepts the union
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* of the given collection of {@link BytesRef}s representing UTF-8 encoded
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@ -33,12 +33,13 @@ public class LevenshteinAutomata {
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/** @lucene.internal */
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public static final int MAXIMUM_SUPPORTED_DISTANCE = 2;
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/* input word */
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final String input;
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final int word[];
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/* the automata alphabet. */
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final int alphabet[];
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/* the maximum symbol in the alphabet (e.g. 255 for UTF-8 or 10FFFF for UTF-32) */
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final int alphaMax;
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/* the unicode ranges outside of alphabet */
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/* the ranges outside of alphabet */
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final int rangeLower[];
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final int rangeUpper[];
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int numRanges = 0;
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@ -50,17 +51,26 @@ public class LevenshteinAutomata {
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* Optionally count transpositions as a primitive edit.
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*/
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public LevenshteinAutomata(String input, boolean withTranspositions) {
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this.input = input;
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int length = Character.codePointCount(input, 0, input.length());
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word = new int[length];
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for (int i = 0, j = 0, cp = 0; i < input.length(); i += Character.charCount(cp)) {
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word[j++] = cp = input.codePointAt(i);
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this(codePoints(input), Character.MAX_CODE_POINT, withTranspositions);
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}
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/**
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* Expert: specify a custom maximum possible symbol
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* (alphaMax); default is Character.MAX_CODE_POINT.
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*/
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public LevenshteinAutomata(int[] word, int alphaMax, boolean withTranspositions) {
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this.word = word;
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this.alphaMax = alphaMax;
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// calculate the alphabet
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SortedSet<Integer> set = new TreeSet<Integer>();
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for (int i = 0; i < word.length; i++)
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set.add(word[i]);
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for (int i = 0; i < word.length; i++) {
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int v = word[i];
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if (v > alphaMax) {
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throw new IllegalArgumentException("alphaMax exceeded by symbol " + v + " in word");
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}
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set.add(v);
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}
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alphabet = new int[set.size()];
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Iterator<Integer> iterator = set.iterator();
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for (int i = 0; i < alphabet.length; i++)
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@ -81,9 +91,9 @@ public class LevenshteinAutomata {
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lower = higher + 1;
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}
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/* add the final endpoint */
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if (lower <= Character.MAX_CODE_POINT) {
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if (lower <= alphaMax) {
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rangeLower[numRanges] = lower;
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rangeUpper[numRanges] = Character.MAX_CODE_POINT;
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rangeUpper[numRanges] = alphaMax;
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numRanges++;
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}
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@ -94,6 +104,15 @@ public class LevenshteinAutomata {
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};
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}
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private static int[] codePoints(String input) {
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int length = Character.codePointCount(input, 0, input.length());
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int word[] = new int[length];
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for (int i = 0, j = 0, cp = 0; i < input.length(); i += Character.charCount(cp)) {
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word[j++] = cp = input.codePointAt(i);
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}
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return word;
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}
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/**
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* Compute a DFA that accepts all strings within an edit distance of <code>n</code>.
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* <p>
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@ -106,8 +125,9 @@ public class LevenshteinAutomata {
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* </p>
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*/
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public Automaton toAutomaton(int n) {
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if (n == 0)
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return BasicAutomata.makeString(input);
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if (n == 0) {
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return BasicAutomata.makeString(word, 0, word.length);
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}
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if (n >= descriptions.length)
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return null;
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@ -22,6 +22,8 @@ import java.util.*;
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import org.apache.lucene.util.BytesRef;
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import org.apache.lucene.util.IntsRef;
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import org.apache.lucene.util.fst.FST.Arc;
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import org.apache.lucene.util.fst.FST.BytesReader;
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/** Static helper methods.
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*
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@ -304,7 +306,10 @@ public final class Util {
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path.input.ints[path.input.length++] = path.arc.label;
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final int cmp = bottom.input.compareTo(path.input);
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path.input.length--;
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// We should never see dups:
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assert cmp != 0;
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if (cmp < 0) {
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// Doesn't compete
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return;
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@ -846,4 +851,93 @@ public final class Util {
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w.close();
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}
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*/
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/**
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* Reads the first arc greater or equal that the given label into the provided
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* arc in place and returns it iff found, otherwise return <code>null</code>.
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*
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* @param label the label to ceil on
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* @param fst the fst to operate on
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* @param follow the arc to follow reading the label from
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* @param arc the arc to read into in place
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* @param in the fst's {@link BytesReader}
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*/
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public static <T> Arc<T> readCeilArc(int label, FST<T> fst, Arc<T> follow,
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Arc<T> arc, BytesReader in) throws IOException {
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// TODO maybe this is a useful in the FST class - we could simplify some other code like FSTEnum?
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if (label == FST.END_LABEL) {
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if (follow.isFinal()) {
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if (follow.target <= 0) {
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arc.flags = FST.BIT_LAST_ARC;
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} else {
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arc.flags = 0;
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// NOTE: nextArc is a node (not an address!) in this case:
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arc.nextArc = follow.target;
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arc.node = follow.target;
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}
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arc.output = follow.nextFinalOutput;
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arc.label = FST.END_LABEL;
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return arc;
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} else {
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return null;
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}
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}
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if (!FST.targetHasArcs(follow)) {
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return null;
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}
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fst.readFirstTargetArc(follow, arc, in);
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if (arc.bytesPerArc != 0 && arc.label != FST.END_LABEL) {
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// Arcs are fixed array -- use binary search to find
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// the target.
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int low = arc.arcIdx;
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int high = arc.numArcs - 1;
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int mid = 0;
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// System.out.println("do arc array low=" + low + " high=" + high +
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// " targetLabel=" + targetLabel);
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while (low <= high) {
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mid = (low + high) >>> 1;
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in.pos = arc.posArcsStart;
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in.skip(arc.bytesPerArc * mid + 1);
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final int midLabel = fst.readLabel(in);
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final int cmp = midLabel - label;
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// System.out.println(" cycle low=" + low + " high=" + high + " mid=" +
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// mid + " midLabel=" + midLabel + " cmp=" + cmp);
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if (cmp < 0) {
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low = mid + 1;
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} else if (cmp > 0) {
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high = mid - 1;
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} else {
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arc.arcIdx = mid-1;
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return fst.readNextRealArc(arc, in);
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}
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}
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if (low == arc.numArcs) {
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// DEAD END!
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return null;
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}
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arc.arcIdx = (low > high ? high : low);
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return fst.readNextRealArc(arc, in);
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}
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// Linear scan
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fst.readFirstRealTargetArc(follow.target, arc, in);
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while (true) {
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// System.out.println(" non-bs cycle");
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// TODO: we should fix this code to not have to create
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// object for the output of every arc we scan... only
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// for the matching arc, if found
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if (arc.label >= label) {
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// System.out.println(" found!");
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return arc;
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} else if (arc.isLast()) {
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return null;
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} else {
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fst.readNextRealArc(arc, in);
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}
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}
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}
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}
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@ -31,6 +31,7 @@ import java.util.Set;
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import org.apache.lucene.analysis.Analyzer;
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import org.apache.lucene.analysis.TokenStream;
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import org.apache.lucene.analysis.TokenStreamToAutomaton;
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import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute;
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import org.apache.lucene.search.spell.TermFreqIterator;
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import org.apache.lucene.search.suggest.Lookup;
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import org.apache.lucene.search.suggest.fst.Sort;
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@ -310,7 +311,7 @@ public class AnalyzingSuggester extends Lookup {
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}
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}
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private TokenStreamToAutomaton getTokenStreamToAutomaton() {
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TokenStreamToAutomaton getTokenStreamToAutomaton() {
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if (preserveSep) {
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return new EscapingTokenStreamToAutomaton();
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} else {
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@ -332,6 +333,7 @@ public class AnalyzingSuggester extends Lookup {
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BytesRef scratch = new BytesRef();
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TokenStreamToAutomaton ts2a = getTokenStreamToAutomaton();
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// analyzed sequence + 0(byte) + weight(int) + surface + analyzedLength(short)
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boolean success = false;
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byte buffer[] = new byte[8];
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@ -339,29 +341,8 @@ public class AnalyzingSuggester extends Lookup {
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ByteArrayDataOutput output = new ByteArrayDataOutput(buffer);
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BytesRef surfaceForm;
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while ((surfaceForm = iterator.next()) != null) {
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Set<IntsRef> paths = toFiniteStrings(surfaceForm, ts2a);
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// Analyze surface form:
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TokenStream ts = indexAnalyzer.tokenStream("", new StringReader(surfaceForm.utf8ToString()));
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// Create corresponding automaton: labels are bytes
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// from each analyzed token, with byte 0 used as
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// separator between tokens:
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Automaton automaton = ts2a.toAutomaton(ts);
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ts.end();
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ts.close();
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replaceSep(automaton);
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assert SpecialOperations.isFinite(automaton);
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// Get all paths from the automaton (there can be
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// more than one path, eg if the analyzer created a
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// graph using SynFilter or WDF):
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// TODO: we could walk & add simultaneously, so we
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// don't have to alloc [possibly biggish]
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// intermediate HashSet in RAM:
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Set<IntsRef> paths = SpecialOperations.getFiniteStrings(automaton, maxGraphExpansions);
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maxAnalyzedPathsForOneInput = Math.max(maxAnalyzedPathsForOneInput, paths.size());
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for (IntsRef path : paths) {
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@ -510,27 +491,10 @@ public class AnalyzingSuggester extends Lookup {
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}
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//System.out.println("lookup key=" + key + " num=" + num);
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final BytesRef utf8Key = new BytesRef(key);
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try {
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// TODO: is there a Reader from a CharSequence?
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// Turn tokenstream into automaton:
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TokenStream ts = queryAnalyzer.tokenStream("", new StringReader(key.toString()));
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Automaton automaton = getTokenStreamToAutomaton().toAutomaton(ts);
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ts.end();
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ts.close();
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// TODO: we could use the end offset to "guess"
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// whether the final token was a partial token; this
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// would only be a heuristic ... but maybe an OK one.
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// This way we could eg differentiate "net" from "net ",
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// which we can't today...
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replaceSep(automaton);
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// TODO: we can optimize this somewhat by determinizing
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// while we convert
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BasicOperations.determinize(automaton);
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Automaton lookupAutomaton = toLookupAutomaton(key);
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final CharsRef spare = new CharsRef();
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@ -538,8 +502,7 @@ public class AnalyzingSuggester extends Lookup {
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// Intersect automaton w/ suggest wFST and get all
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// prefix starting nodes & their outputs:
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final List<FSTUtil.Path<Pair<Long,BytesRef>>> prefixPaths;
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prefixPaths = FSTUtil.intersectPrefixPaths(automaton, fst);
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//final PathIntersector intersector = getPathIntersector(lookupAutomaton, fst);
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//System.out.println(" prefixPaths: " + prefixPaths.size());
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@ -549,6 +512,8 @@ public class AnalyzingSuggester extends Lookup {
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final List<LookupResult> results = new ArrayList<LookupResult>();
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List<FSTUtil.Path<Pair<Long,BytesRef>>> prefixPaths = FSTUtil.intersectPrefixPaths(lookupAutomaton, fst);
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if (exactFirst) {
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int count = 0;
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@ -593,9 +558,9 @@ public class AnalyzingSuggester extends Lookup {
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// nodes we have and the
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// maxSurfaceFormsPerAnalyzedForm:
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for(MinResult<Pair<Long,BytesRef>> completion : completions) {
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if (utf8Key.bytesEquals(completion.output.output2)) {
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spare.grow(completion.output.output2.length);
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UnicodeUtil.UTF8toUTF16(completion.output.output2, spare);
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if (CHARSEQUENCE_COMPARATOR.compare(spare, key) == 0) {
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results.add(new LookupResult(spare.toString(), decodeWeight(completion.output.output1)));
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break;
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}
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@ -630,9 +595,7 @@ public class AnalyzingSuggester extends Lookup {
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// In exactFirst mode, don't accept any paths
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// matching the surface form since that will
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// create duplicate results:
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spare.grow(output.output2.length);
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UnicodeUtil.UTF8toUTF16(output.output2, spare);
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if (CHARSEQUENCE_COMPARATOR.compare(spare, key) == 0) {
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if (utf8Key.bytesEquals(output.output2)) {
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// We found exact match, which means we should
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// have already found it in the first search:
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assert results.size() == 1;
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@ -644,6 +607,8 @@ public class AnalyzingSuggester extends Lookup {
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}
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};
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prefixPaths = getFullPrefixPaths(prefixPaths, lookupAutomaton, fst);
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for (FSTUtil.Path<Pair<Long,BytesRef>> path : prefixPaths) {
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searcher.addStartPaths(path.fstNode, path.output, true, path.input);
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}
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@ -654,6 +619,10 @@ public class AnalyzingSuggester extends Lookup {
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spare.grow(completion.output.output2.length);
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UnicodeUtil.UTF8toUTF16(completion.output.output2, spare);
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LookupResult result = new LookupResult(spare.toString(), decodeWeight(completion.output.output1));
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// TODO: for fuzzy case would be nice to return
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// how many edits were required
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//System.out.println(" result=" + result);
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results.add(result);
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@ -670,6 +639,63 @@ public class AnalyzingSuggester extends Lookup {
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}
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}
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/** Returns all prefix paths to initialize the search. */
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protected List<FSTUtil.Path<Pair<Long,BytesRef>>> getFullPrefixPaths(List<FSTUtil.Path<Pair<Long,BytesRef>>> prefixPaths,
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Automaton lookupAutomaton,
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FST<Pair<Long,BytesRef>> fst)
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throws IOException {
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return prefixPaths;
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}
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final Set<IntsRef> toFiniteStrings(final BytesRef surfaceForm, final TokenStreamToAutomaton ts2a) throws IOException {
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// Analyze surface form:
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TokenStream ts = indexAnalyzer.tokenStream("", new StringReader(surfaceForm.utf8ToString()));
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// Create corresponding automaton: labels are bytes
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// from each analyzed token, with byte 0 used as
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// separator between tokens:
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Automaton automaton = ts2a.toAutomaton(ts);
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ts.end();
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ts.close();
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replaceSep(automaton);
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assert SpecialOperations.isFinite(automaton);
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// Get all paths from the automaton (there can be
|
||||
// more than one path, eg if the analyzer created a
|
||||
// graph using SynFilter or WDF):
|
||||
|
||||
// TODO: we could walk & add simultaneously, so we
|
||||
// don't have to alloc [possibly biggish]
|
||||
// intermediate HashSet in RAM:
|
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return SpecialOperations.getFiniteStrings(automaton, maxGraphExpansions);
|
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}
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final Automaton toLookupAutomaton(final CharSequence key) throws IOException {
|
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// TODO: is there a Reader from a CharSequence?
|
||||
// Turn tokenstream into automaton:
|
||||
TokenStream ts = queryAnalyzer.tokenStream("", new StringReader(key.toString()));
|
||||
Automaton automaton = (getTokenStreamToAutomaton()).toAutomaton(ts);
|
||||
ts.end();
|
||||
ts.close();
|
||||
|
||||
// TODO: we could use the end offset to "guess"
|
||||
// whether the final token was a partial token; this
|
||||
// would only be a heuristic ... but maybe an OK one.
|
||||
// This way we could eg differentiate "net" from "net ",
|
||||
// which we can't today...
|
||||
|
||||
replaceSep(automaton);
|
||||
|
||||
// TODO: we can optimize this somewhat by determinizing
|
||||
// while we convert
|
||||
BasicOperations.determinize(automaton);
|
||||
return automaton;
|
||||
}
|
||||
|
||||
|
||||
|
||||
/**
|
||||
* Returns the weight associated with an input string,
|
||||
* or null if it does not exist.
|
||||
|
|
|
|||
|
|
@ -26,6 +26,7 @@ import org.apache.lucene.util.automaton.Automaton;
|
|||
import org.apache.lucene.util.automaton.State;
|
||||
import org.apache.lucene.util.automaton.Transition;
|
||||
import org.apache.lucene.util.fst.FST;
|
||||
import org.apache.lucene.util.fst.Util;
|
||||
|
||||
// TODO: move to core? nobody else uses it yet though...
|
||||
|
||||
|
|
@ -62,57 +63,78 @@ public class FSTUtil {
|
|||
}
|
||||
}
|
||||
|
||||
/** Enumerates all paths in the automaton that also
|
||||
* intersect the FST, accumulating the FST end node and
|
||||
* output for each path. */
|
||||
public static<T> List<Path<T>> intersectPrefixPaths(Automaton a, FST<T> fst) throws IOException {
|
||||
/**
|
||||
* Enumerates all minimal prefix paths in the automaton that also intersect the FST,
|
||||
* accumulating the FST end node and output for each path.
|
||||
*/
|
||||
public static <T> List<Path<T>> intersectPrefixPaths(Automaton a, FST<T> fst)
|
||||
throws IOException {
|
||||
assert a.isDeterministic();
|
||||
final List<Path<T>> queue = new ArrayList<Path<T>>();
|
||||
final List<Path<T>> endNodes = new ArrayList<Path<T>>();
|
||||
|
||||
queue.add(new Path<T>(a.getInitialState(),
|
||||
fst.getFirstArc(new FST.Arc<T>()),
|
||||
fst.outputs.getNoOutput(),
|
||||
queue.add(new Path<T>(a.getInitialState(), fst
|
||||
.getFirstArc(new FST.Arc<T>()), fst.outputs.getNoOutput(),
|
||||
new IntsRef()));
|
||||
|
||||
final FST.Arc<T> scratchArc = new FST.Arc<T>();
|
||||
final FST.BytesReader fstReader = fst.getBytesReader(0);
|
||||
|
||||
//System.out.println("fst/a intersect");
|
||||
|
||||
while (queue.size() != 0) {
|
||||
final Path<T> path = queue.remove(queue.size() - 1);
|
||||
//System.out.println(" cycle path=" + path);
|
||||
if (path.state.isAccept()) {
|
||||
endNodes.add(path);
|
||||
// we can stop here if we accept this path,
|
||||
// we accept all further paths too
|
||||
continue;
|
||||
}
|
||||
|
||||
IntsRef currentInput = path.input;
|
||||
for (Transition t : path.state.getTransitions()) {
|
||||
|
||||
// TODO: we can fix this if necessary:
|
||||
if (t.getMin() != t.getMax()) {
|
||||
throw new IllegalStateException("can only handle Transitions that match one character");
|
||||
}
|
||||
|
||||
//System.out.println(" t=" + (char) t.getMin());
|
||||
|
||||
final FST.Arc<T> nextArc = fst.findTargetArc(t.getMin(), path.fstNode, scratchArc, fstReader);
|
||||
final int min = t.getMin();
|
||||
final int max = t.getMax();
|
||||
if (min == max) {
|
||||
final FST.Arc<T> nextArc = fst.findTargetArc(t.getMin(),
|
||||
path.fstNode, scratchArc, fstReader);
|
||||
if (nextArc != null) {
|
||||
//System.out.println(" fst matches");
|
||||
// Path continues:
|
||||
IntsRef newInput = new IntsRef(currentInput.length + 1);
|
||||
final IntsRef newInput = new IntsRef(currentInput.length + 1);
|
||||
newInput.copyInts(currentInput);
|
||||
newInput.ints[currentInput.length] = t.getMin();
|
||||
newInput.length = currentInput.length + 1;
|
||||
|
||||
queue.add(new Path<T>(t.getDest(),
|
||||
new FST.Arc<T>().copyFrom(nextArc),
|
||||
fst.outputs.add(path.output, nextArc.output),
|
||||
newInput));
|
||||
queue.add(new Path<T>(t.getDest(), new FST.Arc<T>()
|
||||
.copyFrom(nextArc), fst.outputs
|
||||
.add(path.output, nextArc.output), newInput));
|
||||
}
|
||||
} else {
|
||||
// TODO: if this transition's TO state is accepting, and
|
||||
// it accepts the entire range possible in the FST (ie. 0 to 255),
|
||||
// we can simply use the prefix as the accepted state instead of
|
||||
// looking up all the ranges and terminate early
|
||||
// here. This just shifts the work from one queue
|
||||
// (this one) to another (the completion search
|
||||
// done in AnalyzingSuggester).
|
||||
FST.Arc<T> nextArc = Util.readCeilArc(min, fst, path.fstNode,
|
||||
scratchArc, fstReader);
|
||||
while (nextArc != null && nextArc.label <= max) {
|
||||
assert nextArc.label <= max;
|
||||
assert nextArc.label >= min : nextArc.label + " "
|
||||
+ min;
|
||||
final IntsRef newInput = new IntsRef(currentInput.length + 1);
|
||||
newInput.copyInts(currentInput);
|
||||
newInput.ints[currentInput.length] = nextArc.label;
|
||||
newInput.length = currentInput.length + 1;
|
||||
queue.add(new Path<T>(t.getDest(), new FST.Arc<T>()
|
||||
.copyFrom(nextArc), fst.outputs
|
||||
.add(path.output, nextArc.output), newInput));
|
||||
final int label = nextArc.label; // used in assert
|
||||
nextArc = nextArc.isLast() ? null : fst.readNextRealArc(nextArc,
|
||||
fstReader);
|
||||
assert nextArc == null || label < nextArc.label : "last: " + label
|
||||
+ " next: " + nextArc.label;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return endNodes;
|
||||
}
|
||||
|
||||
}
|
||||
|
|
|
|||
|
|
@ -0,0 +1,226 @@
|
|||
package org.apache.lucene.search.suggest.analyzing;
|
||||
/*
|
||||
* 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.FileOutputStream;
|
||||
import java.io.IOException;
|
||||
import java.io.OutputStreamWriter;
|
||||
import java.io.Writer;
|
||||
import java.util.Arrays;
|
||||
import java.util.List;
|
||||
import java.util.Set;
|
||||
|
||||
import org.apache.lucene.analysis.Analyzer;
|
||||
import org.apache.lucene.analysis.TokenStream;
|
||||
import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute; // javadocs
|
||||
import org.apache.lucene.util.BytesRef;
|
||||
import org.apache.lucene.util.IntsRef;
|
||||
import org.apache.lucene.util.automaton.Automaton;
|
||||
import org.apache.lucene.util.automaton.BasicAutomata;
|
||||
import org.apache.lucene.util.automaton.BasicOperations;
|
||||
import org.apache.lucene.util.automaton.LevenshteinAutomata;
|
||||
import org.apache.lucene.util.automaton.SpecialOperations;
|
||||
import org.apache.lucene.util.fst.FST;
|
||||
import org.apache.lucene.util.fst.PairOutputs.Pair;
|
||||
|
||||
/**
|
||||
* Implements a fuzzy {@link AnalyzingSuggester}. The similarity measurement is
|
||||
* based on the Damerau-Levenshtein (optimal string alignment) algorithm, though
|
||||
* you can explicitly choose classic Levenshtein by passing <code>false</code>
|
||||
* for the <code>transpositions</code> parameter.
|
||||
* <p>
|
||||
* At most, this query will match terms up to
|
||||
* {@value org.apache.lucene.util.automaton.LevenshteinAutomata#MAXIMUM_SUPPORTED_DISTANCE}
|
||||
* edits. Higher distances are not supported. Note that the
|
||||
* fuzzy distance is measured in "byte space" on the bytes
|
||||
* returned by the {@link TokenStream}'s {@link
|
||||
* TermToBytesRefAttribute}, usually UTF8. By default
|
||||
* the analyzed bytes must be at least 3 {@link
|
||||
* #DEFAULT_MIN_FUZZY_LENGTH} bytes before any edits are
|
||||
* considered. Furthermore, the first 1 {@link
|
||||
* #DEFAULT_NON_FUZZY_PREFIX} byte is not allowed to be
|
||||
* edited. We allow up to 1 (@link
|
||||
* #DEFAULT_MAX_EDITS} edit.
|
||||
*
|
||||
* <p>
|
||||
* NOTE: This suggester does not boost suggestions that
|
||||
* required no edits over suggestions that did require
|
||||
* edits. This is a known limitation.
|
||||
*
|
||||
* <p>
|
||||
* Note: complex query analyzers can have a significant impact on the lookup
|
||||
* performance. It's recommended to not use analyzers that drop or inject terms
|
||||
* like synonyms to keep the complexity of the prefix intersection low for good
|
||||
* lookup performance. At index time, complex analyzers can safely be used.
|
||||
* </p>
|
||||
*/
|
||||
public final class FuzzySuggester extends AnalyzingSuggester {
|
||||
private final int maxEdits;
|
||||
private final boolean transpositions;
|
||||
private final int nonFuzzyPrefix;
|
||||
private final int minFuzzyLength;
|
||||
|
||||
/**
|
||||
* The default minimum length of the key passed to {@link
|
||||
* #lookup} before any edits are allowed.
|
||||
*/
|
||||
public static final int DEFAULT_MIN_FUZZY_LENGTH = 3;
|
||||
|
||||
/**
|
||||
* The default prefix length where edits are not allowed.
|
||||
*/
|
||||
public static final int DEFAULT_NON_FUZZY_PREFIX = 1;
|
||||
|
||||
/**
|
||||
* The default maximum number of edits for fuzzy
|
||||
* suggestions.
|
||||
*/
|
||||
public static final int DEFAULT_MAX_EDITS = 1;
|
||||
|
||||
/**
|
||||
* Creates a {@link FuzzySuggester} instance initialized with default values.
|
||||
*
|
||||
* @param analyzer the analyzer used for this suggester
|
||||
*/
|
||||
public FuzzySuggester(Analyzer analyzer) {
|
||||
this(analyzer, analyzer);
|
||||
}
|
||||
|
||||
/**
|
||||
* Creates a {@link FuzzySuggester} instance with an index & a query analyzer initialized with default values.
|
||||
*
|
||||
* @param indexAnalyzer
|
||||
* Analyzer that will be used for analyzing suggestions while building the index.
|
||||
* @param queryAnalyzer
|
||||
* Analyzer that will be used for analyzing query text during lookup
|
||||
*/
|
||||
public FuzzySuggester(Analyzer indexAnalyzer, Analyzer queryAnalyzer) {
|
||||
this(indexAnalyzer, queryAnalyzer, EXACT_FIRST | PRESERVE_SEP, 256, -1, DEFAULT_MAX_EDITS, true,
|
||||
DEFAULT_NON_FUZZY_PREFIX, DEFAULT_MIN_FUZZY_LENGTH);
|
||||
}
|
||||
|
||||
/**
|
||||
* Creates a {@link FuzzySuggester} instance.
|
||||
*
|
||||
* @param indexAnalyzer Analyzer that will be used for
|
||||
* analyzing suggestions while building the index.
|
||||
* @param queryAnalyzer Analyzer that will be used for
|
||||
* analyzing query text during lookup
|
||||
* @param options see {@link #EXACT_FIRST}, {@link #PRESERVE_SEP}
|
||||
* @param maxSurfaceFormsPerAnalyzedForm Maximum number of
|
||||
* surface forms to keep for a single analyzed form.
|
||||
* When there are too many surface forms we discard the
|
||||
* lowest weighted ones.
|
||||
* @param maxGraphExpansions Maximum number of graph paths
|
||||
* to expand from the analyzed form. Set this to -1 for
|
||||
* no limit.
|
||||
* @param maxEdits must be >= 0 and <= {@link LevenshteinAutomata#MAXIMUM_SUPPORTED_DISTANCE} .
|
||||
* @param transpositions <code>true</code> if transpositions should be treated as a primitive
|
||||
* edit operation. If this is false, comparisons will implement the classic
|
||||
* Levenshtein algorithm.
|
||||
* @param nonFuzzyPrefix length of common (non-fuzzy) prefix (see default {@link #DEFAULT_NON_FUZZY_PREFIX}
|
||||
* @param minFuzzyLength minimum length of lookup key before any edits are allowed (see default {@link #DEFAULT_MIN_FUZZY_LENGTH})
|
||||
*/
|
||||
public FuzzySuggester(Analyzer indexAnalyzer, Analyzer queryAnalyzer,
|
||||
int options, int maxSurfaceFormsPerAnalyzedForm, int maxGraphExpansions,
|
||||
int maxEdits, boolean transpositions, int nonFuzzyPrefix,
|
||||
int minFuzzyLength) {
|
||||
super(indexAnalyzer, queryAnalyzer, options, maxSurfaceFormsPerAnalyzedForm, maxGraphExpansions);
|
||||
if (maxEdits < 0 || maxEdits > LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE) {
|
||||
throw new IllegalArgumentException("maxEdits must be between 0 and " + LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE);
|
||||
}
|
||||
if (nonFuzzyPrefix < 0) {
|
||||
throw new IllegalArgumentException("nonFuzzyPrefix must not be >= 0 (got " + nonFuzzyPrefix + ")");
|
||||
}
|
||||
if (minFuzzyLength < 0) {
|
||||
throw new IllegalArgumentException("minFuzzyLength must not be >= 0 (got " + minFuzzyLength + ")");
|
||||
}
|
||||
|
||||
this.maxEdits = maxEdits;
|
||||
this.transpositions = transpositions;
|
||||
this.nonFuzzyPrefix = nonFuzzyPrefix;
|
||||
this.minFuzzyLength = minFuzzyLength;
|
||||
}
|
||||
|
||||
@Override
|
||||
protected List<FSTUtil.Path<Pair<Long,BytesRef>>> getFullPrefixPaths(List<FSTUtil.Path<Pair<Long,BytesRef>>> prefixPaths,
|
||||
Automaton lookupAutomaton,
|
||||
FST<Pair<Long,BytesRef>> fst)
|
||||
throws IOException {
|
||||
|
||||
// TODO: right now there's no penalty for fuzzy/edits,
|
||||
// ie a completion whose prefix matched exactly what the
|
||||
// user typed gets no boost over completions that
|
||||
// required an edit, which get no boost over completions
|
||||
// requiring two edits. I suspect a multiplicative
|
||||
// factor is appropriate (eg, say a fuzzy match must be at
|
||||
// least 2X better weight than the non-fuzzy match to
|
||||
// "compete") ... in which case I think the wFST needs
|
||||
// to be log weights or something ...
|
||||
|
||||
Automaton levA = toLevenshteinAutomata(lookupAutomaton);
|
||||
/*
|
||||
Writer w = new OutputStreamWriter(new FileOutputStream("out.dot"), "UTF-8");
|
||||
w.write(levA.toDot());
|
||||
w.close();
|
||||
System.out.println("Wrote LevA to out.dot");
|
||||
*/
|
||||
return FSTUtil.intersectPrefixPaths(levA, fst);
|
||||
}
|
||||
|
||||
Automaton toLevenshteinAutomata(Automaton automaton) {
|
||||
final Set<IntsRef> ref = SpecialOperations.getFiniteStrings(automaton, -1);
|
||||
Automaton subs[] = new Automaton[ref.size()];
|
||||
int upto = 0;
|
||||
for (IntsRef path : ref) {
|
||||
if (path.length <= nonFuzzyPrefix || path.length < minFuzzyLength) {
|
||||
subs[upto] = BasicAutomata.makeString(path.ints, path.offset, path.length);
|
||||
upto++;
|
||||
} else {
|
||||
Automaton prefix = BasicAutomata.makeString(path.ints, path.offset, nonFuzzyPrefix);
|
||||
int ints[] = new int[path.length-nonFuzzyPrefix];
|
||||
System.arraycopy(path.ints, path.offset+nonFuzzyPrefix, ints, 0, ints.length);
|
||||
// TODO: maybe add alphaMin to LevenshteinAutomata,
|
||||
// and pass 1 instead of 0? We probably don't want
|
||||
// to allow the trailing dedup bytes to be
|
||||
// edited... but then 0 byte is "in general" allowed
|
||||
// on input (but not in UTF8).
|
||||
LevenshteinAutomata lev = new LevenshteinAutomata(ints, 255, transpositions);
|
||||
Automaton levAutomaton = lev.toAutomaton(maxEdits);
|
||||
Automaton combined = BasicOperations.concatenate(Arrays.asList(prefix, levAutomaton));
|
||||
combined.setDeterministic(true); // its like the special case in concatenate itself, except we cloneExpanded already
|
||||
subs[upto] = combined;
|
||||
upto++;
|
||||
}
|
||||
}
|
||||
|
||||
if (subs.length == 0) {
|
||||
return BasicAutomata.makeEmpty(); // matches nothing
|
||||
} else if (subs.length == 1) {
|
||||
return subs[0];
|
||||
} else {
|
||||
Automaton a = BasicOperations.union(Arrays.asList(subs));
|
||||
// TODO: we could call toLevenshteinAutomata() before det?
|
||||
// this only happens if you have multiple paths anyway (e.g. synonyms)
|
||||
BasicOperations.determinize(a);
|
||||
|
||||
// Does not seem to help (and hurt maybe a bit: 6-9
|
||||
// prefix went from 19 to 18 kQPS):
|
||||
// a.reduce();
|
||||
return a;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -36,6 +36,7 @@ import org.apache.lucene.analysis.MockAnalyzer;
|
|||
import org.apache.lucene.analysis.MockTokenizer;
|
||||
import org.apache.lucene.search.suggest.Lookup; // javadocs
|
||||
import org.apache.lucene.search.suggest.analyzing.AnalyzingSuggester;
|
||||
import org.apache.lucene.search.suggest.analyzing.FuzzySuggester;
|
||||
import org.apache.lucene.search.suggest.fst.FSTCompletionLookup;
|
||||
import org.apache.lucene.search.suggest.fst.WFSTCompletionLookup;
|
||||
import org.apache.lucene.search.suggest.jaspell.JaspellLookup;
|
||||
|
|
@ -51,17 +52,20 @@ import org.junit.Ignore;
|
|||
public class LookupBenchmarkTest extends LuceneTestCase {
|
||||
@SuppressWarnings("unchecked")
|
||||
private final List<Class<? extends Lookup>> benchmarkClasses = Arrays.asList(
|
||||
FuzzySuggester.class,
|
||||
AnalyzingSuggester.class,
|
||||
JaspellLookup.class,
|
||||
TSTLookup.class,
|
||||
FSTCompletionLookup.class,
|
||||
WFSTCompletionLookup.class,
|
||||
AnalyzingSuggester.class);
|
||||
WFSTCompletionLookup.class
|
||||
|
||||
);
|
||||
|
||||
private final static int rounds = 15;
|
||||
private final static int warmup = 5;
|
||||
|
||||
private final int num = 7;
|
||||
private final boolean onlyMorePopular = true;
|
||||
private final boolean onlyMorePopular = false;
|
||||
|
||||
private final static Random random = new Random(0xdeadbeef);
|
||||
|
||||
|
|
@ -212,8 +216,9 @@ public class LookupBenchmarkTest extends LuceneTestCase {
|
|||
final List<String> input = new ArrayList<String>(benchmarkInput.size());
|
||||
for (TermFreq tf : benchmarkInput) {
|
||||
String s = tf.term.utf8ToString();
|
||||
input.add(s.substring(0, Math.min(s.length(),
|
||||
minPrefixLen + random.nextInt(maxPrefixLen - minPrefixLen + 1))));
|
||||
String sub = s.substring(0, Math.min(s.length(),
|
||||
minPrefixLen + random.nextInt(maxPrefixLen - minPrefixLen + 1)));
|
||||
input.add(sub);
|
||||
}
|
||||
|
||||
BenchmarkResult result = measure(new Callable<Integer>() {
|
||||
|
|
@ -250,7 +255,9 @@ public class LookupBenchmarkTest extends LuceneTestCase {
|
|||
}
|
||||
return new BenchmarkResult(times, warmup, rounds);
|
||||
} catch (Exception e) {
|
||||
e.printStackTrace();
|
||||
throw new RuntimeException(e);
|
||||
|
||||
}
|
||||
}
|
||||
|
||||
|
|
|
|||
File diff suppressed because it is too large
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