added implementation

Signed-off-by: Kenrick Yap <[email protected]>

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

@@ -683,6 +683,10 @@ public static FunctionExpression notLike(Expression... expressions) {
     return compile(FunctionProperties.None, BuiltinFunctionName.NOT_LIKE, expressions);
   }
 
+  public static FunctionExpression jsonValid(Expression... expressions){
+    return compile(FunctionProperties.None, BuiltinFunctionName.JSON_VALID, expressions);
+  }
+
   public static Aggregator avg(Expression... expressions) {
     return aggregate(BuiltinFunctionName.AVG, expressions);
   }

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

@@ -204,6 +204,9 @@ public enum BuiltinFunctionName {
   TRIM(FunctionName.of("trim")),
   UPPER(FunctionName.of("upper")),
 
+  /** Json Functions. */
+  JSON_VALID(FunctionName.of("json_valid")),
+
   /** NULL Test. */
   IS_NULL(FunctionName.of("is null")),
   IS_NOT_NULL(FunctionName.of("is not null")),

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

@@ -28,6 +28,7 @@
 import org.opensearch.sql.expression.datetime.DateTimeFunctions;
 import org.opensearch.sql.expression.datetime.IntervalClause;
 import org.opensearch.sql.expression.ip.IPFunctions;
+import org.opensearch.sql.expression.json.JsonFunctions;
 import org.opensearch.sql.expression.operator.arthmetic.ArithmeticFunctions;
 import org.opensearch.sql.expression.operator.arthmetic.MathematicalFunctions;
 import org.opensearch.sql.expression.operator.convert.TypeCastOperators;
@@ -83,6 +84,7 @@ public static synchronized BuiltinFunctionRepository getInstance() {
       SystemFunctions.register(instance);
       OpenSearchFunctions.register(instance);
       IPFunctions.register(instance);
+      JsonFunctions.register(instance);
     }
     return instance;
   }

core/src/main/java/org/opensearch/sql/expression/json/JsonFunctions.java

@@ -0,0 +1,46 @@
+package org.opensearch.sql.expression.json;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.experimental.UtilityClass;
+import org.opensearch.sql.data.model.ExprValue;
+import org.opensearch.sql.data.model.ExprValueUtils;
+import org.opensearch.sql.exception.SemanticCheckException;
+import org.opensearch.sql.expression.function.BuiltinFunctionName;
+import org.opensearch.sql.expression.function.BuiltinFunctionRepository;
+import org.opensearch.sql.expression.function.DefaultFunctionResolver;
+
+import static org.opensearch.sql.data.type.ExprCoreType.BOOLEAN;
+import static org.opensearch.sql.data.type.ExprCoreType.STRING;
+import static org.opensearch.sql.expression.function.FunctionDSL.define;
+import static org.opensearch.sql.expression.function.FunctionDSL.impl;
+import static org.opensearch.sql.expression.function.FunctionDSL.nullMissingHandling;
+
+@UtilityClass
+public class JsonFunctions {
+    public void register(BuiltinFunctionRepository repository) {
+
+        repository.register(jsonValid());
+    }
+
+    private DefaultFunctionResolver jsonValid() {
+        return define(
+                BuiltinFunctionName.JSON_VALID.getName(),
+                impl(nullMissingHandling(JsonFunctions::isValidJson), BOOLEAN, STRING));
+    }
+
+    /**
+     * Checks if given JSON string can be parsed as valid JSON.
+     *
+     * @param jsonExprValue JSON string (e.g. "198.51.100.14" or "2001:0db8::ff00:42:8329").
+     * @return true if the string can be parsed as valid JSON, else false.
+     */
+    private ExprValue isValidJson(ExprValue jsonExprValue) {
+        ObjectMapper objectMapper = new ObjectMapper();
+        try {
+            objectMapper.readTree(jsonExprValue.stringValue());
+            return ExprValueUtils.LITERAL_TRUE;
+        } catch (Exception e) {
+            return ExprValueUtils.LITERAL_FALSE;
+        }
+    }
+}

ppl/src/main/antlr/OpenSearchPPLLexer.g4

@@ -332,6 +332,9 @@ ISNULL:                             'ISNULL';
 ISNOTNULL:                          'ISNOTNULL';
 CIDRMATCH:                          'CIDRMATCH';
 
+// JSON FUNCTIONS
+JSON_VALID:                         'JSON_VALID';
+
 // FLOWCONTROL FUNCTIONS
 IFNULL:                             'IFNULL';
 NULLIF:                             'NULLIF';

ppl/src/main/antlr/OpenSearchPPLParser.g4

@@ -662,6 +662,7 @@ conditionFunctionName
    | ISNULL
    | ISNOTNULL
    | CIDRMATCH
+   | JSON_VALID
    ;
 
 // flow control function return non-boolean value