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package com.yahoo.language.lucene;
import com.yahoo.component.provider.ComponentRegistry;
import com.yahoo.language.Language;
import com.yahoo.language.process.StemMode;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CharFilterFactory;
import org.apache.lucene.analysis.TokenFilterFactory;
import org.apache.lucene.analysis.TokenizerFactory;
import org.apache.lucene.analysis.custom.CustomAnalyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Logger;
/**
* Analyzers for various languages.
*
* @author dainiusjocas
*/
class AnalyzerFactory {
private static final Logger log = Logger.getLogger(AnalyzerFactory.class.getName());
private final LuceneAnalysisConfig config;
// Registry of analyzers per language
// The idea is to create analyzers ONLY WHEN they are needed
// Analyzers are thread safe so no need to recreate them for every document
private final Map<AnalyzerKey, Analyzer> languageAnalyzers = new ConcurrentHashMap<>();
private final Analyzer defaultAnalyzer = new StandardAnalyzer();
private final static String STANDARD_TOKENIZER = "standard";
private final ComponentRegistry<Analyzer> analyzerComponents;
private final DefaultAnalyzers defaultAnalyzers;
public AnalyzerFactory(LuceneAnalysisConfig config, ComponentRegistry<Analyzer> analyzers) {
this.config = config;
this.analyzerComponents = analyzers;
this.defaultAnalyzers = new DefaultAnalyzers();
log.config("Available in classpath char filters: " + CharFilterFactory.availableCharFilters());
log.config("Available in classpath tokenizers: " + TokenizerFactory.availableTokenizers());
log.config("Available in classpath token filters: " + TokenFilterFactory.availableTokenFilters());
}
/**
* Retrieves an analyzer with a given params.
* Sets up the analyzer if config is provided.
* Default analyzer is the `StandardAnalyzer`.
*/
public Analyzer getAnalyzer(Language language, StemMode stemMode, boolean removeAccents) {
return languageAnalyzers.computeIfAbsent(new AnalyzerKey(language, stemMode, removeAccents),
this::createAnalyzer);
}
private Analyzer createAnalyzer(AnalyzerKey analyzerKey) {
LuceneAnalysisConfig.Analysis analysis = analysisConfig(analyzerKey);
if (null != analysis) {
log.config("Creating analyzer for " + analyzerKey + " from config");
return createAnalyzer(analyzerKey, analysis);
}
Analyzer analyzerFromComponents = fromComponents(analyzerKey);
if (null != analyzerFromComponents) {
log.config("Using analyzer for " + analyzerKey + " from components");
return analyzerFromComponents;
}
if (null != defaultAnalyzers.get(analyzerKey.language())) {
log.config("Using Analyzer for " + analyzerKey + " from a list of default language analyzers");
return defaultAnalyzers.get(analyzerKey.language());
}
// set the default analyzer for the language
log.config("StandardAnalyzer is used for " + analyzerKey);
return defaultAnalyzer;
}
/**
* First, checks if more specific (language + stemMode) analysis is configured.
* Second, checks if analysis is configured only for a languageCode.
*/
private LuceneAnalysisConfig.Analysis analysisConfig(AnalyzerKey analyzerKey) {
LuceneAnalysisConfig.Analysis analysis = config.analysis(analyzerKey.languageCodeAndStemMode());
return (null != analysis) ? analysis : config.analysis(analyzerKey.languageCode());
}
/**
* First, checks if a component is configured for a languageCode + StemMode.
* Second, checks if Analyzer is configured only for a languageCode.
*/
private Analyzer fromComponents(AnalyzerKey analyzerKey) {
Analyzer analyzer = analyzerComponents.getComponent(analyzerKey.languageCodeAndStemMode());
return (null != analyzer) ? analyzer : analyzerComponents.getComponent(analyzerKey.languageCode());
}
private Analyzer createAnalyzer(AnalyzerKey analyzerKey, LuceneAnalysisConfig.Analysis analysis) {
try {
CustomAnalyzer.Builder builder = config.configDir()
// Root config directory for all analysis components in the application package
.map(CustomAnalyzer::builder)
// else load resource files from the classpath
.orElseGet(CustomAnalyzer::builder);
builder = withTokenizer(builder, analysis);
builder = addCharFilters(builder, analysis);
builder = addTokenFilters(builder, analysis);
return builder.build();
} catch (Exception e) {
// Failing to set up the Analyzer, should blow up during testing and VAP should not be deployed.
// Most likely cause for problems is that a specified resource is not available in VAP.
// Unit tests should catch such problems and prevent the VAP being deployed.
throw new RuntimeException("Failed to build analyzer " + analyzerKey +
", with configuration " + analysis, e);
}
}
private CustomAnalyzer.Builder withTokenizer(CustomAnalyzer.Builder builder,
LuceneAnalysisConfig.Analysis analysis) throws IOException {
if (null == analysis) {
// By default we use the "standard" tokenizer
return builder.withTokenizer(STANDARD_TOKENIZER, new HashMap<>());
}
String tokenizerName = analysis.tokenizer().name();
Map<String, String> conf = analysis.tokenizer().conf();
return builder.withTokenizer(tokenizerName, asModifiable(conf));
}
private CustomAnalyzer.Builder addCharFilters(CustomAnalyzer.Builder builder,
LuceneAnalysisConfig.Analysis analysis) throws IOException {
if (null == analysis) {
// by default there are no char filters
return builder;
}
for (LuceneAnalysisConfig.Analysis.CharFilters charFilter : analysis.charFilters()) {
builder.addCharFilter(charFilter.name(), asModifiable(charFilter.conf()));
}
return builder;
}
private CustomAnalyzer.Builder addTokenFilters(CustomAnalyzer.Builder builder,
LuceneAnalysisConfig.Analysis analysis) throws IOException {
if (null == analysis) {
// by default no token filters are added
return builder;
}
for (LuceneAnalysisConfig.Analysis.TokenFilters tokenFilter : analysis.tokenFilters()) {
builder.addTokenFilter(tokenFilter.name(), asModifiable(tokenFilter.conf()));
}
return builder;
}
/**
* A config map coming from the Vespa ConfigInstance is immutable while CustomAnalyzer builders
* mutates the map to mark that a param was consumed. Immutable maps can't be mutated!
* To overcome this conflict we can wrap the ConfigInstance map in a new HashMap.
*/
private Map<String, String> asModifiable(Map<String, String> map) {
return new HashMap<>(map);
}
private record AnalyzerKey(Language language, StemMode stemMode, boolean removeAccents) {
/**
* Combines the languageCode and the stemMode.
* It allows to specify up to 6 (5 StemModes and only language code) analyzers per language.
* The `/` is used so that it doesn't conflict with ComponentRegistry keys.
*/
public String languageCodeAndStemMode() {
return language.languageCode() + "/" + stemMode.toString();
}
public String languageCode() {
return language.languageCode();
}
@Override
public boolean equals(Object o) {
if (o == this) return true;
if ( ! (o instanceof AnalyzerKey other)) return false;
return other.language == this.language && other.stemMode == this.stemMode;
}
@Override
public int hashCode() {
return Objects.hash(language, stemMode);
}
}
}
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