Simplifying parser logic with alternate multi_match syntax parsing.

Author: forestmvey

sql/src/main/antlr/OpenSearchSQLParser.g4

@@ -509,17 +509,12 @@ alternateMultiMatchArgName
     | stringLiteral
     ;
 
-alternateMultiMatchArgVal
-    : qualifiedName
-    | stringLiteral
-    ;
-
 alternateMultiMatchQuery
-    : argName=alternateMultiMatchArgName EQUAL_SYMBOL argVal=alternateMultiMatchArgVal
+    : argName=alternateMultiMatchArgName EQUAL_SYMBOL argVal=relevanceArgValue
     ;
 
 alternateMultiMatchField
-    : argName=alternateMultiMatchArgName EQUAL_SYMBOL argVal=alternateMultiMatchArgVal
+    : argName=alternateMultiMatchArgName EQUAL_SYMBOL argVal=relevanceArgValue
     | argName=alternateMultiMatchArgName EQUAL_SYMBOL
-    LT_SQR_PRTHS argVal=alternateMultiMatchArgVal RT_SQR_PRTHS
+    LT_SQR_PRTHS argVal=relevanceArgValue RT_SQR_PRTHS
     ;

sql/src/main/java/org/opensearch/sql/sql/parser/AstExpressionBuilder.java

@@ -81,9 +81,7 @@
 import org.opensearch.sql.ast.expression.When;
 import org.opensearch.sql.ast.expression.WindowFunction;
 import org.opensearch.sql.ast.tree.Sort.SortOption;
-import org.opensearch.sql.catalog.model.auth.AuthenticationType;
 import org.opensearch.sql.common.utils.StringUtils;
-import org.opensearch.sql.exception.SemanticCheckException;
 import org.opensearch.sql.expression.function.BuiltinFunctionName;
 import org.opensearch.sql.sql.antlr.parser.OpenSearchSQLParser;
 import org.opensearch.sql.sql.antlr.parser.OpenSearchSQLParser.AndExpressionContext;
@@ -458,7 +456,7 @@ private QualifiedName visitIdentifiers(List<IdentContext> identifiers) {
   private void fillRelevanceArgs(List<OpenSearchSQLParser.RelevanceArgContext> args,
                                  ImmutableList.Builder<UnresolvedExpression> builder) {
     // To support old syntax we must support argument keys as quoted strings.
-    args.forEach(v -> builder.add(v.relevanceArgName() != null
+    args.forEach(v -> builder.add(v.argName == null
         ? new UnresolvedArgument(v.relevanceArgName().getText().toLowerCase(),
             new Literal(StringUtils.unquoteText(v.relevanceArgValue().getText()),
             DataType.STRING))