Use Locale.ROOT in toLowercase() when building AST

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

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

@@ -233,7 +233,7 @@ public UnresolvedExpression visitTakeAggFunctionCall(
   /** Eval function. */
   @Override
   public UnresolvedExpression visitBooleanFunctionCall(BooleanFunctionCallContext ctx) {
-    final String functionName = ctx.conditionFunctionName().getText().toLowerCase();
+    final String functionName = ctx.conditionFunctionName().getText().toLowerCase(Locale.ROOT);
     return buildFunction(
         FUNCTION_NAME_MAPPING.getOrDefault(functionName, functionName),
         ctx.functionArgs().functionArg());
@@ -287,15 +287,15 @@ private Function buildFunction(
   public UnresolvedExpression visitSingleFieldRelevanceFunction(
       SingleFieldRelevanceFunctionContext ctx) {
     return new Function(
-        ctx.singleFieldRelevanceFunctionName().getText().toLowerCase(),
+        ctx.singleFieldRelevanceFunctionName().getText().toLowerCase(Locale.ROOT),
         singleFieldRelevanceArguments(ctx));
   }
 
   @Override
   public UnresolvedExpression visitMultiFieldRelevanceFunction(
       MultiFieldRelevanceFunctionContext ctx) {
     return new Function(
-        ctx.multiFieldRelevanceFunctionName().getText().toLowerCase(),
+        ctx.multiFieldRelevanceFunctionName().getText().toLowerCase(Locale.ROOT),
         multiFieldRelevanceArguments(ctx));
   }
 
@@ -506,7 +506,7 @@ private List<UnresolvedExpression> singleFieldRelevanceArguments(
             v ->
                 builder.add(
                     new UnresolvedArgument(
-                        v.relevanceArgName().getText().toLowerCase(),
+                        v.relevanceArgName().getText().toLowerCase(Locale.ROOT),
                         new Literal(
                             StringUtils.unquoteText(v.relevanceArgValue().getText()),
                             DataType.STRING))));
@@ -534,7 +534,7 @@ private List<UnresolvedExpression> multiFieldRelevanceArguments(
             v ->
                 builder.add(
                     new UnresolvedArgument(
-                        v.relevanceArgName().getText().toLowerCase(),
+                        v.relevanceArgName().getText().toLowerCase(Locale.ROOT),
                         new Literal(
                             StringUtils.unquoteText(v.relevanceArgValue().getText()),
                             DataType.STRING))));

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

@@ -72,6 +72,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Collectors;
@@ -152,7 +153,7 @@ public UnresolvedExpression visitHighlightFunctionCall(HighlightFunctionCallCont
         .forEach(
             v ->
                 builder.put(
-                    v.highlightArgName().getText().toLowerCase(),
+                    v.highlightArgName().getText().toLowerCase(Locale.ROOT),
                     new Literal(
                         StringUtils.unquoteText(v.highlightArgValue().getText()),
                         DataType.STRING)));
@@ -416,22 +417,23 @@ public UnresolvedExpression visitPercentileApproxFunctionCall(
   @Override
   public UnresolvedExpression visitNoFieldRelevanceFunction(NoFieldRelevanceFunctionContext ctx) {
     return new Function(
-        ctx.noFieldRelevanceFunctionName().getText().toLowerCase(), noFieldRelevanceArguments(ctx));
+        ctx.noFieldRelevanceFunctionName().getText().toLowerCase(Locale.ROOT),
+        noFieldRelevanceArguments(ctx));
   }
 
   @Override
   public UnresolvedExpression visitSingleFieldRelevanceFunction(
       SingleFieldRelevanceFunctionContext ctx) {
     return new Function(
-        ctx.singleFieldRelevanceFunctionName().getText().toLowerCase(),
+        ctx.singleFieldRelevanceFunctionName().getText().toLowerCase(Locale.ROOT),
         singleFieldRelevanceArguments(ctx));
   }
 
   @Override
   public UnresolvedExpression visitAltSingleFieldRelevanceFunction(
       AltSingleFieldRelevanceFunctionContext ctx) {
     return new Function(
-        ctx.altSyntaxFunctionName.getText().toLowerCase(),
+        ctx.altSyntaxFunctionName.getText().toLowerCase(Locale.ROOT),
         altSingleFieldRelevanceFunctionArguments(ctx));
   }
 
@@ -446,11 +448,11 @@ public UnresolvedExpression visitMultiFieldRelevanceFunction(
             || funcName.equalsIgnoreCase(BuiltinFunctionName.MULTIMATCHQUERY.toString()))
         && !ctx.getRuleContexts(AlternateMultiMatchQueryContext.class).isEmpty()) {
       return new Function(
-          ctx.multiFieldRelevanceFunctionName().getText().toLowerCase(),
+          ctx.multiFieldRelevanceFunctionName().getText().toLowerCase(Locale.ROOT),
           alternateMultiMatchArguments(ctx));
     } else {
       return new Function(
-          ctx.multiFieldRelevanceFunctionName().getText().toLowerCase(),
+          ctx.multiFieldRelevanceFunctionName().getText().toLowerCase(Locale.ROOT),
           multiFieldRelevanceArguments(ctx));
     }
   }
@@ -459,7 +461,7 @@ public UnresolvedExpression visitMultiFieldRelevanceFunction(
   public UnresolvedExpression visitAltMultiFieldRelevanceFunction(
       AltMultiFieldRelevanceFunctionContext ctx) {
     return new Function(
-        ctx.altSyntaxFunctionName.getText().toLowerCase(),
+        ctx.altSyntaxFunctionName.getText().toLowerCase(Locale.ROOT),
         altMultiFieldRelevanceFunctionArguments(ctx));
   }
 
@@ -504,12 +506,12 @@ private void fillRelevanceArgs(
             builder.add(
                 v.argName == null
                     ? new UnresolvedArgument(
-                        v.relevanceArgName().getText().toLowerCase(),
+                        v.relevanceArgName().getText().toLowerCase(Locale.ROOT),
                         new Literal(
                             StringUtils.unquoteText(v.relevanceArgValue().getText()),
                             DataType.STRING))
                     : new UnresolvedArgument(
-                        StringUtils.unquoteText(v.argName.getText()).toLowerCase(),
+                        StringUtils.unquoteText(v.argName.getText()).toLowerCase(Locale.ROOT),
                         new Literal(
                             StringUtils.unquoteText(v.argVal.getText()), DataType.STRING))));
   }