Make highlighters accessible

Author: kderusso

server/src/main/java/org/elasticsearch/search/SearchModule.java

@@ -278,6 +278,8 @@
  * Sets up things that can be done at search time like queries, aggregations, and suggesters.
  */
 public class SearchModule {
+    private static volatile Map<String, Highlighter> staticHighlighters = Map.of();
+
     public static final Setting<Integer> INDICES_MAX_CLAUSE_COUNT_SETTING = Setting.intSetting(
         "indices.query.bool.max_clause_count",
         4096,
@@ -920,6 +922,20 @@ private static Map<String, Highlighter> setupHighlighters(Settings settings, Lis
         return unmodifiableMap(highlighters.getRegistry());
     }
 
+    /**
+     * Sets the static highlighters map for access by other plugins
+     */
+    private static void setStaticHighlighters(Map<String, Highlighter> highlighters) {
+        staticHighlighters = Map.copyOf(highlighters);
+    }
+
+    /**
+     * Gets the static highlighters map for other plugin access
+     */
+    public static Map<String, Highlighter> getStaticHighlighters() {
+        return staticHighlighters;
+    }
+
     private void registerScoreFunctions(List<SearchPlugin> plugins) {
         // ScriptScoreFunctionBuilder has it own named writable because of a new script_score query
         namedWriteables.add(
@@ -1059,6 +1075,8 @@ private void registerFetchSubPhases(List<SearchPlugin> plugins) {
         registerFetchSubPhase(new HighlightPhase(highlighters));
         registerFetchSubPhase(new FetchScorePhase());
 
+        setStaticHighlighters(highlighters);
+
         FetchPhaseConstructionContext context = new FetchPhaseConstructionContext(highlighters);
         registerFromPlugin(plugins, p -> p.getFetchSubPhases(context), this::registerFetchSubPhase);
     }

server/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/SearchHighlightContext.java

@@ -269,7 +269,7 @@ Builder boundaryScannerLocale(Locale boundaryScannerLocale) {
                 return this;
             }
 
-            Builder highlightQuery(Query highlightQuery) {
+            public Builder highlightQuery(Query highlightQuery) {
                 fieldOptions.highlightQuery = highlightQuery;
                 return this;
             }

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/lucene/HighlighterExpressionEvaluator.java

@@ -50,20 +50,23 @@ public class HighlighterExpressionEvaluator extends LuceneQueryEvaluator<BytesRe
     private final Integer numFragments;
     private final Integer fragmentLength;
     private final SearchContext searchContext;
+    private final Map<String, Highlighter> highlighters;
 
     HighlighterExpressionEvaluator(
         BlockFactory blockFactory,
         ShardConfig[] shardConfigs,
         String fieldName,
         Integer numFragments,
         Integer fragmentLength,
-        SearchContext searchContext
+        SearchContext searchContext,
+        Map<String, Highlighter> highlighters
     ) {
         super(blockFactory, shardConfigs);
         this.fieldName = fieldName;
         this.numFragments = numFragments;
         this.fragmentLength = fragmentLength;
         this.searchContext = searchContext;
+        this.highlighters = highlighters;
     }
 
     @Override
@@ -93,14 +96,7 @@ protected void appendMatch(BytesRefBlock.Builder builder, Scorable scorer, int d
         MappedFieldType fieldType = searchContext.getSearchExecutionContext().getFieldType(fieldName);
         SearchHit searchHit = new SearchHit(docId);
         Source source = Source.lazy(lazyStoredSourceLoader(leafReaderContext, docId));
-        String defaultHighlighter = fieldType.getDefaultHighlighter();
-
-        Highlighter highlighter;
-        // if (SemanticTextHighlighter.NAME.equals(defaultHighlighter)) {
-        // highlighter = new SemanticTextHighlighter();
-        // } else {
-        highlighter = new DefaultHighlighter();
-        // }
+        Highlighter highlighter = highlighters.getOrDefault(fieldType.getDefaultHighlighter(), new DefaultHighlighter());
 
         SearchHighlightContext.FieldOptions.Builder optionsBuilder = new SearchHighlightContext.FieldOptions.Builder();
         optionsBuilder.numberOfFragments(numFragments != null ? numFragments : HighlightBuilder.DEFAULT_NUMBER_OF_FRAGMENTS);
@@ -109,6 +105,7 @@ protected void appendMatch(BytesRefBlock.Builder builder, Scorable scorer, int d
         optionsBuilder.postTags(new String[] { "" });
         optionsBuilder.requireFieldMatch(false);
         optionsBuilder.scoreOrdered(true);
+        optionsBuilder.highlightQuery(query);
         SearchHighlightContext.Field field = new SearchHighlightContext.Field(fieldName, optionsBuilder.build());
 
         FetchSubPhase.HitContext hitContext = new FetchSubPhase.HitContext(searchHit, leafReaderContext, docId, Map.of(), source, null);
@@ -165,7 +162,8 @@ public record Factory(
         String fieldName,
         Integer numFragments,
         Integer fragmentSize,
-        SearchContext searchContext
+        SearchContext searchContext,
+        Map<String, Highlighter> highlighters
     ) implements EvalOperator.ExpressionEvaluator.Factory {
         @Override
         public EvalOperator.ExpressionEvaluator get(DriverContext context) {
@@ -175,7 +173,8 @@ public EvalOperator.ExpressionEvaluator get(DriverContext context) {
                 fieldName,
                 numFragments,
                 fragmentSize,
-                searchContext
+                searchContext,
+                highlighters
             );
         }
     }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/evaluator/EvalMapper.java

@@ -29,9 +29,16 @@
 import org.elasticsearch.xpack.esql.expression.predicate.logical.BinaryLogic;
 import org.elasticsearch.xpack.esql.expression.predicate.operator.comparison.InsensitiveEqualsMapper;
 import org.elasticsearch.xpack.esql.planner.EsPhysicalOperationProviders.ShardContext;
+import org.elasticsearch.search.SearchModule;
+import org.elasticsearch.search.fetch.subphase.highlight.DefaultHighlighter;
+import org.elasticsearch.search.fetch.subphase.highlight.Highlighter;
+import org.elasticsearch.search.fetch.subphase.highlight.PlainHighlighter;
+import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.xpack.esql.planner.Layout;
 
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public final class EvalMapper {
 
@@ -79,6 +86,11 @@ public FoldContext foldCtx() {
                 public List<ShardContext> shardContexts() {
                     return shardContexts;
                 }
+
+                @Override
+                public Map<String, Highlighter> highlighters() {
+                    return SearchModule.getStaticHighlighters();
+                }
             });
         }
         for (ExpressionMapper em : MAPPERS) {

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/evaluator/mapper/EvaluatorMapper.java

@@ -17,6 +17,7 @@
 import org.elasticsearch.indices.breaker.AllCircuitBreakerStats;
 import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.indices.breaker.CircuitBreakerStats;
+import org.elasticsearch.search.fetch.subphase.highlight.Highlighter;
 import org.elasticsearch.xpack.esql.core.expression.Expression;
 import org.elasticsearch.xpack.esql.core.expression.FoldContext;
 import org.elasticsearch.xpack.esql.core.tree.Source;
@@ -25,6 +26,7 @@
 import org.elasticsearch.xpack.esql.planner.Layout;
 
 import java.util.List;
+import java.util.Map;
 
 import static org.elasticsearch.compute.data.BlockUtils.fromArrayRow;
 import static org.elasticsearch.compute.data.BlockUtils.toJavaObject;
@@ -41,6 +43,10 @@ interface ToEvaluator {
         default List<EsPhysicalOperationProviders.ShardContext> shardContexts() {
             throw new UnsupportedOperationException("Shard contexts should only be needed for evaluation operations");
         }
+
+        default Map<String, Highlighter> highlighters() {
+            throw new UnsupportedOperationException("Highlighters should only be needed for highlight operations");
+        }
     }
 
     /**

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/ExtractSnippets.java

@@ -217,11 +217,6 @@ public ExpressionEvaluator.Factory toEvaluator(ToEvaluator toEvaluator) {
             try {
                 // TODO: Reduce duplication between this method and TextSimilarityRerankingRankFeaturePhaseRankShardContext#prepareForFetch
                 HighlightBuilder highlightBuilder = new HighlightBuilder();
-                if (queryBuilder != null) {
-                    // TODO validate this works and determine why this is not working in query builder resolver
-                    QueryBuilder rewritten = Rewriteable.rewrite(queryBuilder, searchExecutionContext);
-                    highlightBuilder.highlightQuery(rewritten);
-                }
                 // Stripping pre/post tags as they're not useful for snippet creation
                 highlightBuilder.field(field.sourceText()).preTags("").postTags("");
                 // Return highest scoring fragments
@@ -231,6 +226,12 @@ public ExpressionEvaluator.Factory toEvaluator(ToEvaluator toEvaluator) {
                 highlightBuilder.fragmentSize(snippedSize);
                 highlightBuilder.noMatchSize(snippedSize);
 
+                if (queryBuilder != null) {
+                    // TODO validate this works and determine why this is not working in query builder resolver
+                    QueryBuilder rewritten = Rewriteable.rewrite(queryBuilder, searchExecutionContext);
+                    highlightBuilder.highlightQuery(rewritten);
+                }
+
                 SearchHighlightContext highlightContext = highlightBuilder.build(searchExecutionContext);
                 searchContext.highlight(highlightContext);
 
@@ -254,7 +255,14 @@ public ExpressionEvaluator.Factory toEvaluator(ToEvaluator toEvaluator) {
         // Get field name and search context from the first shard context
         String fieldNameStr = field.sourceText();
         SearchContext firstSearchContext = shardContexts.isEmpty() ? null : shardContexts.get(0).searchContext();
-        return new HighlighterExpressionEvaluator.Factory(shardConfigs, fieldNameStr, numSnippets, snippedSize, firstSearchContext);
+        return new HighlighterExpressionEvaluator.Factory(
+            shardConfigs,
+            fieldNameStr,
+            numSnippets,
+            snippedSize,
+            firstSearchContext,
+            toEvaluator.highlighters()
+        );
     }
 
     @Override

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/EsqlPlugin.java

@@ -42,6 +42,9 @@
 import org.elasticsearch.plugins.ActionPlugin;
 import org.elasticsearch.plugins.ExtensiblePlugin;
 import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.plugins.SearchPlugin;
+import org.elasticsearch.search.fetch.subphase.highlight.DefaultHighlighter;
+import org.elasticsearch.search.fetch.subphase.highlight.Highlighter;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestHandler;
 import org.elasticsearch.threadpool.ExecutorBuilder;
@@ -82,12 +85,14 @@
 import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
-public class EsqlPlugin extends Plugin implements ActionPlugin, ExtensiblePlugin {
+public class EsqlPlugin extends Plugin implements ActionPlugin, ExtensiblePlugin, SearchPlugin {
     public static final boolean INLINESTATS_FEATURE_FLAG = new FeatureFlag("esql_inlinestats").isEnabled();
 
     public static final String ESQL_WORKER_THREAD_POOL_NAME = "esql_worker";