feat: Add json_array_length Spark function

velox/functions/sparksql/JsonArrayLength.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "velox/functions/Macros.h"
+#include "velox/functions/prestosql/types/JsonType.h"
+
+namespace facebook::velox::functions::sparksql {
+
+template <typename T>
+struct JsonArrayLengthFunction {
+  VELOX_DEFINE_FUNCTION_TYPES(T);
+
+  FOLLY_ALWAYS_INLINE bool call(int32_t& len, const arg_type<Json>& json) {
+    simdjson::ondemand::document jsonDoc;
+
+    simdjson::padded_string paddedJson(json.data(), json.size());
+    if (simdjsonParse(paddedJson).get(jsonDoc)) {
+      return false;
+    }
+    if (jsonDoc.type().error()) {
+      return false;
+    }
+
+    if (jsonDoc.type() != simdjson::ondemand::json_type::array) {
+      return false;
+    }
+
+    size_t numElements;
+    if (jsonDoc.count_elements().get(numElements)) {
+      return false;
+    }
+
+    len = numElements;
+    return true;
+  }
+};
+}  // namespace facebook::velox::functions::sparksql
+

velox/functions/sparksql/registration/RegisterJson.cpp

@@ -15,6 +15,7 @@
  */
 #include "velox/functions/lib/RegistrationHelpers.h"
 #include "velox/functions/sparksql/GetJsonObject.h"
+#include "velox/functions/sparksql/JsonArrayLength.h"
 #include "velox/functions/sparksql/JsonObjectKeys.h"
 
 namespace facebook::velox::functions::sparksql {
@@ -24,6 +25,8 @@ void registerJsonFunctions(const std::string& prefix) {
       {prefix + "get_json_object"});
   registerFunction<JsonObjectKeysFunction, Array<Varchar>, Varchar>(
       {prefix + "json_object_keys"});
+  registerFunction<JsonArrayLengthFunction, int32_t, Varchar>(
+      {prefix + "json_array_length"});
 }
 
 } // namespace facebook::velox::functions::sparksql

velox/functions/sparksql/tests/CMakeLists.txt

@@ -36,6 +36,7 @@ add_executable(
   GetJsonObjectTest.cpp
   HashTest.cpp
   InTest.cpp
+  JsonArrayLengthTest.cpp
   JsonObjectKeysTest.cpp
   LeastGreatestTest.cpp
   MakeDecimalTest.cpp

velox/functions/sparksql/tests/JsonArrayLengthTest.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "velox/functions/sparksql/tests/SparkFunctionBaseTest.h"
+
+using namespace facebook::velox::test;
+
+namespace facebook::velox::functions::sparksql::test {
+namespace {
+
+class JsonArrayLengthTest : public SparkFunctionBaseTest {
+ protected:
+  VectorPtr jsonArrayLength(const std::string& json) {
+    auto varcharVector = makeFlatVector<std::string>({json});
+    return evaluate("json_array_length(c0)", makeRowVector({varcharVector}));
+  }
+};
+
+TEST_F(JsonArrayLengthTest, basic) {
+  auto expected = makeConstant<int32_t>(4, 1);
+  assertEqualVectors(expected, jsonArrayLength(R"([1,2,3,4])"));
+
+  expected = makeConstant<int32_t>(5, 1);
+  assertEqualVectors(expected, jsonArrayLength(R"([1,2,3,{"f1":1,"f2":[5,6]},4])"));
+
+  expected = makeNullConstant(TypeKind::INTEGER, 1);
+  assertEqualVectors(expected, jsonArrayLength(R"([1,2)"));
+}
+
+} // namespace
+} // namespace facebook::velox::functions::sparksql::test