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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.query.rewrite.rewriters;
import java.io.*;
import java.util.*;
import java.util.logging.Logger;
import com.yahoo.component.annotation.Inject;
import com.yahoo.component.chain.dependencies.Provides;
import com.yahoo.fsa.FSA;
import com.yahoo.search.query.rewrite.*;
import com.yahoo.search.*;
import com.yahoo.component.ComponentId;
import com.yahoo.filedistribution.fileacquirer.FileAcquirer;
import com.yahoo.search.query.rewrite.RewritesConfig;
import com.yahoo.prelude.querytransform.PhraseMatcher;
/**
* This rewriter would add rewrites to entities (e.g abbreviation, synonym, etc)<br>
* to boost precision
* - FSA dict: [normalized original query]\t[rewrite 1]\t[rewrite 2]\t[etc]<br>
* - Features:<br>
* RewritesAsUnitEquiv flag: add proximity boosted rewrites<br>
* PartialPhraseMatch flag: whether to match whole phrase or partial phrase<br>
* MaxRewrites flag: the maximum number of rewrites to be added<br>
*
* @author Karen Sze Wing Lee
*/
@Provides("GenericExpansionRewriter")
public class GenericExpansionRewriter extends QueryRewriteSearcher {
// Flag for skipping this rewriter if the query has been rewritten
private final boolean SKIP_REWRITER_IF_REWRITTEN = false;
// Name of the rewriter
public static final String REWRITER_NAME = "GenericExpansionRewriter";
// Generic expansion dictionary name
public static final String GENERIC_EXPAND_DICT = "GenericExpansion";
// Default generic expansion dictionary file name
public static final String GENERIC_EXPAND_DICT_FILENAME = "GenericExpansionRewriter.fsa";
// PhraseMatcher created from FSA dict
private PhraseMatcher phraseMatcher;
private Logger logger;
/**
* Constructor for GenericExpansionRewriter.
* Load configs using default format
*/
@Inject
public GenericExpansionRewriter(ComponentId id,
FileAcquirer fileAcquirer,
RewritesConfig config) {
super(id, fileAcquirer, config);
}
/**
* Constructor for GenericExpansionRewriter unit test.
* Load configs using default format
*/
public GenericExpansionRewriter(RewritesConfig config,
HashMap<String, File> fileList) {
super(config, fileList);
}
/**
* Instance creation time config loading besides FSA.
* Create PhraseMatcher from FSA dict
*/
public boolean configure(FileAcquirer fileAcquirer,
RewritesConfig config,
HashMap<String, File> fileList) {
logger = Logger.getLogger(GenericExpansionRewriter.class.getName());
FSA fsa = (FSA)rewriterDicts.get(GENERIC_EXPAND_DICT);
if (fsa==null) {
RewriterUtils.error(logger, "Error retrieving FSA dictionary: " + GENERIC_EXPAND_DICT);
return false;
}
// Create Phrase Matcher
RewriterUtils.log(logger, "Creating PhraseMatcher");
try {
phraseMatcher = new PhraseMatcher(fsa, false);
} catch (IllegalArgumentException e) {
RewriterUtils.error(logger, "Error creating phrase matcher");
return false;
}
// Match single word as well
phraseMatcher.setMatchSingleItems(true);
// Return all matches instead of only the longest match
phraseMatcher.setMatchAll(true);
return true;
}
/**
* Main logic of rewriter<br>
* - Retrieve rewrites from FSA dict<br>
* - rewrite query using features that are enabled by user
*/
public HashMap<String, Object> rewrite(Query query,
String dictKey) throws RuntimeException {
Boolean rewritten = false;
// Pass the original dict key to the next rewriter
HashMap<String, Object> result = new HashMap<>();
result.put(RewriterConstants.REWRITTEN, rewritten);
result.put(RewriterConstants.DICT_KEY, dictKey);
RewriterUtils.log(logger, query,
"In GenericExpansionRewriter, query used for dict retrieval=[" + dictKey + "]");
// Retrieve flags for choosing between whole query match
// or partial query match
String partialPhraseMatch = getQPConfig(query, RewriterConstants.PARTIAL_PHRASE_MATCH);
if(partialPhraseMatch==null) {
RewriterUtils.error(logger, query, "Required param " + RewriterConstants.PARTIAL_PHRASE_MATCH +
" is not set, skipping rewriter");
throw new RuntimeException("Required param " + RewriterConstants.PARTIAL_PHRASE_MATCH +
" is not set, skipping rewriter");
}
// Retrieve max number of rewrites allowed
int maxNumRewrites = 0;
String maxNumRewritesStr = getQPConfig(query, RewriterConstants.MAX_REWRITES);
if(maxNumRewritesStr!=null) {
maxNumRewrites = Integer.parseInt(maxNumRewritesStr);
RewriterUtils.log(logger, query,
"Limiting max number of rewrites to: " + maxNumRewrites);
} else {
RewriterUtils.log(logger, query, "No limit on number of rewrites");
}
// Retrieve flags for choosing whether to add
// the rewrites as phrase, default to false
String rewritesAsUnitEquiv = getQPConfig(query, RewriterConstants.REWRITES_AS_UNIT_EQUIV);
if(rewritesAsUnitEquiv==null) {
rewritesAsUnitEquiv = "false";
}
Set<PhraseMatcher.Phrase> matches;
// Partial Phrase Matching
if(partialPhraseMatch.equalsIgnoreCase("true")) {
RewriterUtils.log(logger, query, "Partial phrase matching");
// Retrieve longest non overlapping matches
matches = RewriterFeatures.getNonOverlappingPartialPhraseMatches(phraseMatcher, query);
// Full Phrase Matching if set to anything else
} else {
RewriterUtils.log(logger, query, "Full phrase matching");
// Retrieve longest non overlapping matches
matches = RewriterFeatures.getNonOverlappingFullPhraseMatches(phraseMatcher, query);
}
if(matches==null) {
return result;
}
// Add expansions to the query
query = RewriterFeatures.addExpansions(query, matches, null, maxNumRewrites, false,
rewritesAsUnitEquiv.equalsIgnoreCase("true"));
rewritten = true;
RewriterUtils.log(logger, query, "GenericExpansionRewriter final query: " + query.toDetailString());
result.put(RewriterConstants.REWRITTEN, rewritten);
return result;
}
/**
* Get the flag which specifies whether this rewriter
* should be skipped if the query has been rewritten
*
* @return true if rewriter should be skipped, false
* otherwise
*/
public boolean getSkipRewriterIfRewritten() {
return SKIP_REWRITER_IF_REWRITTEN;
}
/**
* Get the name of the rewriter
*
* @return Name of the rewriter
*/
public String getRewriterName() {
return REWRITER_NAME;
}
/**
* Get default FSA dictionary names
*
* @return Pair of FSA dictionary name and filename
*/
public HashMap<String, String> getDefaultFSAs() {
HashMap<String, String> defaultDicts = new HashMap<>();
defaultDicts.put(GENERIC_EXPAND_DICT, GENERIC_EXPAND_DICT_FILENAME);
return defaultDicts;
}
}
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