style - remove some verbose comments

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

core/src/main/java/org/opensearch/sql/calcite/CalciteRelNodeVisitor.java

@@ -175,18 +175,15 @@ public RelNode visitFilter(Filter node, CalcitePlanContext context) {
   public RelNode visitRegex(Regex node, CalcitePlanContext context) {
     visitChildren(node, context);
 
-    // Analyze the field and pattern expressions
     RexNode fieldRex = rexVisitor.analyze(node.getField(), context);
     RexNode patternRex = rexVisitor.analyze(node.getPattern(), context);
 
-    // Create RexNode using the REGEX_MATCH UDF
     RexNode regexCondition =
         context.rexBuilder.makeCall(
             org.opensearch.sql.expression.function.PPLBuiltinOperators.REGEX_MATCH,
             fieldRex,
             patternRex);
 
-    // If negated, wrap with NOT
     if (node.isNegated()) {
       regexCondition = context.rexBuilder.makeCall(SqlStdOperatorTable.NOT, regexCondition);
     }

core/src/main/java/org/opensearch/sql/expression/ExpressionNodeVisitor.java

@@ -10,6 +10,7 @@
 import org.opensearch.sql.expression.conditional.cases.CaseClause;
 import org.opensearch.sql.expression.conditional.cases.WhenClause;
 import org.opensearch.sql.expression.function.FunctionImplementation;
+import org.opensearch.sql.expression.operator.predicate.RegexMatch;
 import org.opensearch.sql.expression.parse.ParseExpression;
 
 /**
@@ -102,8 +103,7 @@ public T visitNamedArgument(NamedArgumentExpression node, C context) {
     return visitNode(node, context);
   }
 
-  public T visitRegex(org.opensearch.sql.expression.operator.predicate.RegexMatch node, C context) {
-    // Visit field and pattern expressions to ensure field extraction works properly
+  public T visitRegex(RegexMatch node, C context) {
     T result = defaultResult();
     T fieldResult = node.getField().accept(this, context);
     result = aggregateResult(result, fieldResult);

core/src/main/java/org/opensearch/sql/expression/function/PPLBuiltinOperators.java

@@ -47,6 +47,7 @@
 import org.opensearch.sql.expression.function.jsonUDF.JsonSetFunctionImpl;
 import org.opensearch.sql.expression.function.udf.CryptographicFunction;
 import org.opensearch.sql.expression.function.udf.GrokFunction;
+import org.opensearch.sql.expression.function.udf.RegexMatchFunctionImpl;
 import org.opensearch.sql.expression.function.udf.RelevanceQueryFunction;
 import org.opensearch.sql.expression.function.udf.SpanFunction;
 import org.opensearch.sql.expression.function.udf.condition.EarliestFunction;
@@ -382,8 +383,7 @@ public class PPLBuiltinOperators extends ReflectiveSqlOperatorTable {
       new NumberToStringFunction().toUDF("NUMBER_TO_STRING");
 
   // Custom regex operator for Calcite engine
-  public static final SqlOperator REGEX_MATCH =
-      new org.opensearch.sql.expression.function.udf.RegexMatchFunctionImpl().toUDF("REGEX_MATCH");
+  public static final SqlOperator REGEX_MATCH = new RegexMatchFunctionImpl().toUDF("REGEX_MATCH");
 
   /**
    * Returns the PPL specific operator table, creating it if necessary.

core/src/main/java/org/opensearch/sql/expression/operator/predicate/RegexMatch.java

@@ -43,15 +43,13 @@ public ExprValue valueOf(Environment<Expression, ExprValue> valueEnv) {
     ExprValue fieldValue = field.valueOf(valueEnv);
     ExprValue patternValue = pattern.valueOf(valueEnv);
 
-    // Handle null/missing values
     if (fieldValue.isNull()
         || fieldValue.isMissing()
         || patternValue.isNull()
         || patternValue.isMissing()) {
       return ExprValueUtils.booleanValue(false);
     }
 
-    // Convert field value to string (handles non-string types)
     String text = RegexCommonUtils.toStringValue(fieldValue);
     String regex = patternValue.stringValue();
 
@@ -60,10 +58,8 @@ public ExprValue valueOf(Environment<Expression, ExprValue> valueEnv) {
     }
 
     try {
-      // Use shared utility for pattern matching
       boolean matches = RegexCommonUtils.matchesPartial(text, regex);
 
-      // Apply negation if needed
       return ExprValueUtils.booleanValue(negated ? !matches : matches);
 
     } catch (PatternSyntaxException e) {

core/src/main/java/org/opensearch/sql/expression/parse/RegexCommonUtils.java

@@ -116,12 +116,10 @@ public static String toStringValue(ExprValue value) {
       return null;
     }
 
-    // If already a string, return it directly
     if (value.type() == ExprCoreType.STRING) {
       return value.stringValue();
     }
 
-    // Auto-convert non-string types to string
     return value.value().toString();
   }
 }