first draft

mapping/document.go

@@ -112,6 +112,17 @@ func (dm *DocumentMapping) analyzerNameForPath(path string) string {
 	return ""
 }
 
+// synonymSourceForPath attempts to first find the field
+// described by this path, then returns the analyzer
+// configured for that field
+func (dm *DocumentMapping) synonymSourceForPath(path string) string {
+	field := dm.fieldDescribedByPath(path)
+	if field != nil {
+		return field.SynonymSource
+	}
+	return ""
+}
+
 func (dm *DocumentMapping) fieldDescribedByPath(path string) *FieldMapping {
 	pathElements := decodePath(path)
 	if len(pathElements) > 1 {

mapping/field.go

@@ -80,6 +80,8 @@ type FieldMapping struct {
 
 	// Applicable to vector fields only - optimization string
 	VectorIndexOptimizedFor string `json:"vector_index_optimized_for,omitempty"`
+
+	SynonymSource string `json:"synonym_source,omitempty"`
 }
 
 // NewTextFieldMapping returns a default field mapping for text

mapping/index.go

@@ -457,3 +457,25 @@ func (im *IndexMappingImpl) FieldMappingForPath(path string) FieldMapping {
 func (im *IndexMappingImpl) DefaultSearchField() string {
 	return im.DefaultField
 }
+
+func (im *IndexMappingImpl) SynonymSourceForPath(path string) string {
+	// first we look for explicit mapping on the field
+	for _, docMapping := range im.TypeMapping {
+		synonymSource := docMapping.synonymSourceForPath(path)
+		if synonymSource != "" {
+			return synonymSource
+		}
+	}
+
+	// now try the default mapping
+	pathMapping, _ := im.DefaultMapping.documentMappingForPath(path)
+	if pathMapping != nil {
+		if len(pathMapping.Fields) > 0 {
+			if pathMapping.Fields[0].SynonymSource != "" {
+				return pathMapping.Fields[0].SynonymSource
+			}
+		}
+	}
+
+	return ""
+}

pre_search.go

@@ -26,6 +26,8 @@ type preSearchResultProcessor interface {
 	finalize(*SearchResult)
 }
 
+// -----------------------------------------------------------------------------
+// KNN preSearchResultProcessor for handling KNN presearch results
 type knnPreSearchResultProcessor struct {
 	addFn      func(sr *SearchResult, indexName string)
 	finalizeFn func(sr *SearchResult)
@@ -44,16 +46,77 @@ func (k *knnPreSearchResultProcessor) finalize(sr *SearchResult) {
 }
 
 // -----------------------------------------------------------------------------
+// Synonym preSearchResultProcessor for handling Synonym presearch results
+type synonymPreSearchResultProcessor struct {
+	addFn      func(sr *SearchResult, indexName string)
+	finalizeFn func(sr *SearchResult)
+}
 
-func finalizePreSearchResult(req *SearchRequest, preSearchResult *SearchResult) {
-	if requestHasKNN(req) {
-		preSearchResult.Hits = finalizeKNNResults(req, preSearchResult.Hits)
+func (s *synonymPreSearchResultProcessor) add(sr *SearchResult, indexName string) {
+	if s.addFn != nil {
+		s.addFn(sr, indexName)
 	}
 }
 
+func (s *synonymPreSearchResultProcessor) finalize(sr *SearchResult) {
+	if s.finalizeFn != nil {
+		s.finalizeFn(sr)
+	}
+}
+
+// -----------------------------------------------------------------------------
+// Master struct that can hold any number of presearch result processors
+type compositePreSearchResultProcessor struct {
+	presearchResultProcessors []preSearchResultProcessor
+}
+
+// Implements the add method, which forwards to all the internal processors
+func (m *compositePreSearchResultProcessor) add(sr *SearchResult, indexName string) {
+	for _, p := range m.presearchResultProcessors {
+		p.add(sr, indexName)
+	}
+}
+
+// Implements the finalize method, which forwards to all the internal processors
+func (m *compositePreSearchResultProcessor) finalize(sr *SearchResult) {
+	for _, p := range m.presearchResultProcessors {
+		p.finalize(sr)
+	}
+}
+
+// -----------------------------------------------------------------------------
+// Function to create the appropriate preSearchResultProcessor(s)
 func createPreSearchResultProcessor(req *SearchRequest) preSearchResultProcessor {
+	var processors []preSearchResultProcessor
+	// Add KNN processor if the request has KNN
+	if requestHasKNN(req) {
+		if knnProcessor := newKnnPreSearchResultProcessor(req); knnProcessor != nil {
+			processors = append(processors, knnProcessor)
+		}
+	}
+	// Add Synonym processor if the request has Synonym
+	if requestHasSynonym(req) {
+		if synonymProcessor := newSynonymPreSearchResultProcessor(req); synonymProcessor != nil {
+			processors = append(processors, synonymProcessor)
+		}
+	}
+	// Return based on the number of processors, optimizing for the common case of 1 processor
+	// If there are no processors, return nil
+	switch len(processors) {
+	case 0:
+		return nil
+	case 1:
+		return processors[0]
+	default:
+		return &compositePreSearchResultProcessor{
+			presearchResultProcessors: processors,
+		}
+	}
+}
+
+// -----------------------------------------------------------------------------
+func finalizePreSearchResult(req *SearchRequest, preSearchResult *SearchResult) {
 	if requestHasKNN(req) {
-		return newKnnPreSearchResultProcessor(req)
+		preSearchResult.Hits = finalizeKNNResults(req, preSearchResult.Hits)
 	}
-	return &knnPreSearchResultProcessor{} // equivalent to nil
 }