Add math udf

core/src/main/java/org/opensearch/sql/calcite/udf/mathUDF/ConvFunction.java

@@ -0,0 +1,65 @@
+package org.opensearch.sql.calcite.udf.mathUDF;
+
+import org.opensearch.sql.calcite.udf.UserDefinedFunction;
+
+import java.math.BigInteger;
+
+public class ConvFunction implements UserDefinedFunction {
+    @Override
+    public Object eval(Object... args) {
+        Object number = args[0];
+        Object fromBase = args[1];
+        Object toBase = args[2];
+
+        String numStr = number.toString();
+        int fromBaseInt = Integer.parseInt(fromBase.toString());
+        int toBaseInt = Integer.parseInt(toBase.toString());
+        return conv(numStr, fromBaseInt, toBaseInt);
+    }
+
+    /**
+     * Convert numStr from fromBase to toBase
+     * @param numStr   the number to convert (case-insensitive for alphanumeric digits, may have a leading '-')
+     * @param fromBase base of the input number (2 to 36)
+     * @param toBase   target base (2 to 36)
+     * @return         the converted number in the target base (uppercase),
+     *                 "0" if the input is invalid, or null if bases are out of range.
+     */
+    private static String conv(String numStr, int fromBase, int toBase) {
+        // Validate base ranges
+        if (fromBase < 2 || fromBase > 36 || toBase < 2 || toBase > 36) {
+            return null;
+        }
+
+        // Check for sign
+        boolean negative = false;
+        if (numStr.startsWith("-")) {
+            negative = true;
+            numStr = numStr.substring(1);
+        }
+
+        // Normalize input (e.g., remove extra whitespace, convert to uppercase)
+        numStr = numStr.trim().toUpperCase();
+
+        // Try parsing the input as a BigInteger of 'fromBase'
+        BigInteger value;
+        try {
+            value = new BigInteger(numStr, fromBase);
+        } catch (NumberFormatException e) {
+            // If numStr contains invalid characters for fromBase
+            return "0";
+        }
+
+        // Re-apply sign if needed
+        if (negative) {
+            value = value.negate();
+        }
+
+        // Convert to the target base; BigInteger's toString(...) yields lowercase above 9
+        String result = value.toString(toBase);
+
+        // Convert to uppercase to align with MySQL's behavior
+        return result.toUpperCase();
+    }
+
+}

core/src/main/java/org/opensearch/sql/calcite/utils/BuiltinFunctionUtils.java

@@ -21,10 +21,7 @@
 import org.apache.calcite.sql.type.ReturnTypes;
 import org.apache.calcite.sql.type.SqlTypeName;
 import org.opensearch.sql.calcite.CalcitePlanContext;
-import org.opensearch.sql.calcite.udf.mathUDF.CRC32Function;
-import org.opensearch.sql.calcite.udf.mathUDF.EulerFunction;
-import org.opensearch.sql.calcite.udf.mathUDF.ModFunction;
-import org.opensearch.sql.calcite.udf.mathUDF.SqrtFunction;
+import org.opensearch.sql.calcite.udf.mathUDF.*;
 
 public interface BuiltinFunctionUtils {
 
@@ -76,17 +73,17 @@ static SqlOperator translate(String op) {
       case "CEILING":
         return SqlStdOperatorTable.CEIL;
       case "CONV":
-        return SqlStdOperatorTable.CONVERT;
+        return TransferUserDefinedFunction(ConvFunction.class, "CONVERT", ReturnTypes.BIGINT);
       case "COS":
         return SqlStdOperatorTable.COS;
       case "COT":
         return SqlStdOperatorTable.COT;
       case "CRC32":
-        return TransferUserDefinedFunction(CRC32Function.class, "crc32", ReturnTypes.BIGINT);
+        return TransferUserDefinedFunction(CRC32Function.class, "CRC32", ReturnTypes.BIGINT);
       case "DEGREES":
         return SqlStdOperatorTable.DEGREES;
       case "E":
-        return TransferUserDefinedFunction(EulerFunction.class, "e", ReturnTypes.DOUBLE);
+        return TransferUserDefinedFunction(EulerFunction.class, "E", ReturnTypes.DOUBLE);
       case "EXP":
         return SqlStdOperatorTable.EXP;
       case "FLOOR":
@@ -100,7 +97,7 @@ static SqlOperator translate(String op) {
       case "LOG10":
         return SqlStdOperatorTable.LOG10;
       case "MOD":
-        return TransferUserDefinedFunction(ModFunction.class, "mod", ReturnTypes.DOUBLE);
+        return TransferUserDefinedFunction(ModFunction.class, "MOD", ReturnTypes.DOUBLE);
       case "PI":
         return SqlStdOperatorTable.PI;
       case "POW", "POWER":
@@ -116,7 +113,7 @@ static SqlOperator translate(String op) {
       case "SIN":
         return SqlStdOperatorTable.SIN;
       case "SQRT":
-        return TransferUserDefinedFunction(SqrtFunction.class, "sqrt", ReturnTypes.DOUBLE);
+        return TransferUserDefinedFunction(SqrtFunction.class, "SQRT", ReturnTypes.DOUBLE);
       case "CBRT":
         return SqlStdOperatorTable.CBRT;
         // Built-in Date Functions