applied recommended changes

Signed-off-by: Asif Bashar <[email protected]>

Author: asifabashar

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

@@ -417,11 +417,19 @@ public RexNode visitFunction(Function node, CalcitePlanContext context) {
         context.setInCoalesceFunction(false);
       }
     }
-
+    if (node.getFuncName().equalsIgnoreCase("tostring") && args.size() == 1) {
+      RelDataType targetType =
+          context.relBuilder.getTypeFactory().createSqlType(SqlTypeName.VARCHAR);
+      // Get the source expression from arguments
+      RexNode sourceExpression = arguments.get(0);
+      // Create cast RexNode using ExtendedRexBuilder
+      return context.rexBuilder.makeCast(targetType, sourceExpression);
+    }
     RexNode resolvedNode =
         PPLFuncImpTable.INSTANCE.resolve(
             context.rexBuilder, node.getFuncName(), arguments.toArray(new RexNode[0]));
     if (resolvedNode != null) {
+
       return resolvedNode;
     }
     throw new IllegalArgumentException("Unsupported operator: " + node.getFuncName());

core/src/main/java/org/opensearch/sql/expression/function/udf/ToStringFunction.java

@@ -18,6 +18,7 @@
 import org.apache.calcite.linq4j.tree.Expressions;
 import org.apache.calcite.rex.RexCall;
 import org.apache.calcite.runtime.SqlFunctions;
+import org.apache.calcite.sql.*;
 import org.apache.calcite.sql.type.SqlReturnTypeInference;
 import org.opensearch.sql.calcite.utils.PPLOperandTypes;
 import org.opensearch.sql.calcite.utils.PPLReturnTypes;
@@ -65,17 +66,12 @@ public static class ToStringImplementor implements NotNullImplementor {
     public Expression implement(
         RexToLixTranslator translator, RexCall call, List<Expression> translatedOperands) {
       Expression fieldValue = translatedOperands.get(0);
+
       if (translatedOperands.size() > 1) {
         Expression format = translatedOperands.get(1);
         return Expressions.call(ToStringFunction.class, "toString", fieldValue, format);
       } else {
-        // autoboxes to Boolean
-
-        if (!fieldValue.getType().getTypeName().equals("Boolean")) {
-          return Expressions.call(ToStringFunction.class, "toString", fieldValue);
-        } else {
-          return Expressions.call(ToStringFunction.class, "toString", fieldValue);
-        }
+        return Expressions.call(ToStringFunction.class, "toString", fieldValue);
       }
     }
   }

ppl/src/main/antlr/OpenSearchPPLParser.g4

@@ -848,10 +848,9 @@ evalFunctionCall
    ;
 
 
-// cast, tostring function
+// cast function
 dataTypeFunctionCall
    : CAST LT_PRTHS logicalExpression AS convertedDataType RT_PRTHS
-   | TOSTRING LT_PRTHS functionArgs RT_PRTHS
    ;
 
 
@@ -1219,6 +1218,7 @@ systemFunctionName
 textFunctionName
    : SUBSTR
    | SUBSTRING
+   | TOSTRING
    | TRIM
    | LTRIM
    | RTRIM

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

@@ -19,7 +19,6 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
-import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.ParserRuleContext;
 import org.antlr.v4.runtime.RuleContext;
 import org.antlr.v4.runtime.tree.ParseTree;
@@ -30,10 +29,8 @@
 import org.opensearch.sql.ast.expression.subquery.ScalarSubquery;
 import org.opensearch.sql.ast.tree.Trendline;
 import org.opensearch.sql.calcite.plan.OpenSearchConstants;
-import org.opensearch.sql.common.antlr.CaseInsensitiveCharStream;
 import org.opensearch.sql.common.antlr.SyntaxCheckException;
 import org.opensearch.sql.common.utils.StringUtils;
-import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLLexer;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser.BinaryArithmeticContext;
 import org.opensearch.sql.ppl.antlr.parser.OpenSearchPPLParser.BooleanLiteralContext;
@@ -414,52 +411,10 @@ private Function buildFunction(
         functionName, args.stream().map(this::visitFunctionArg).collect(Collectors.toList()));
   }
 
-  public DataTypeFunctionCallContext createDataTypeFunctionCallContext(String castExpression) {
-    // Create a case-insensitive character stream from the input
-    CaseInsensitiveCharStream charStream = new CaseInsensitiveCharStream(castExpression);
-
-    // Create lexer and parser
-    OpenSearchPPLLexer lexer = new OpenSearchPPLLexer(charStream);
-    CommonTokenStream tokens = new CommonTokenStream(lexer);
-    OpenSearchPPLParser parser = new OpenSearchPPLParser(tokens);
-
-    // Parse the expression - cast is part of evalFunctionCall
-    DataTypeFunctionCallContext evalContext = parser.dataTypeFunctionCall();
-    return evalContext;
-  }
-
   /** Cast function. */
   @Override
   public UnresolvedExpression visitDataTypeFunctionCall(DataTypeFunctionCallContext ctx) {
-    if (ctx.functionArgs() != null) {
-
-      ParseTree rootNode = ctx.getChild(0);
-      String functionName = rootNode.getText();
-      final String mappedName =
-          FUNCTION_NAME_MAPPING.getOrDefault(functionName.toLowerCase(Locale.ROOT), functionName);
-      System.out.println(mappedName);
-      if (mappedName != null && mappedName.equals("tostring")) {
-        if (ctx.functionArgs().functionArg().size() == 1) {
-          List<OpenSearchPPLParser.FunctionArgContext> functionArgs =
-              ctx.functionArgs().functionArg();
-
-          String castExpresstion =
-              String.format("cast( %s as String)", functionArgs.getFirst().getText());
-          DataTypeFunctionCallContext toStringDataTypeConversionContext =
-              this.createDataTypeFunctionCallContext(castExpresstion);
-          return new Cast(
-              visit(toStringDataTypeConversionContext.logicalExpression()),
-              visit(toStringDataTypeConversionContext.convertedDataType()));
-          //
-        } else {
-          return buildFunction(mappedName, ctx.functionArgs().functionArg());
-        }
-      } else {
-        return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
-      }
-    } else {
-      return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
-    }
+    return new Cast(visit(ctx.logicalExpression()), visit(ctx.convertedDataType()));
   }
 
   @Override

ppl/src/test/java/org/opensearch/sql/ppl/calcite/CalcitePPLStringFunctionTest.java

@@ -55,7 +55,7 @@ public void testToStringFormatNotSpecified() {
             + " fields string_value, cast_value";
     RelNode root = getRelNode(ppl);
     String expectedLogical =
-        "LogicalProject(string_value=[SAFE_CAST($3)], cast_value=[SAFE_CAST($3)])\n"
+        "LogicalProject(string_value=[CAST($3):VARCHAR NOT NULL], cast_value=[SAFE_CAST($3)])\n"
             + "  LogicalTableScan(table=[[scott, EMP]])\n";
     String expectedResult =
         "string_value=7902; cast_value=7902\n"
@@ -76,8 +76,7 @@ public void testToStringFormatNotSpecified() {
     verifyResult(root, expectedResult);
 
     String expectedSparkSql =
-        "SELECT SAFE_CAST(`MGR` AS STRING) `string_value`, SAFE_CAST(`MGR` AS STRING)"
-            + " `cast_value`\n"
+        "SELECT CAST(`MGR` AS STRING) `string_value`, SAFE_CAST(`MGR` AS STRING) `cast_value`\n"
             + "FROM `scott`.`EMP`";
     verifyPPLToSparkSQL(root, expectedSparkSql);
   }