add row_constructor_with_null function

velox/expression/ExprCompiler.cpp

@@ -37,6 +37,7 @@ using core::TypedExprPtr;
 const char* const kAnd = "and";
 const char* const kOr = "or";
 const char* const kRowConstructor = "row_constructor";
+const char* const kRowConstructorWithNull = "row_constructor_with_null";
 
 struct ITypedExprHasher {
   size_t operator()(const ITypedExpr* expr) const {
@@ -237,6 +238,26 @@ ExprPtr getRowConstructorExpr(
       trackCpuUsage);
 }
 
+ExprPtr getRowConstructorWithNullExpr(
+    const core::QueryConfig& config,
+    const TypePtr& type,
+    std::vector<ExprPtr>&& compiledChildren,
+    bool trackCpuUsage) {
+  static auto rowConstructorVectorFunction =
+      vectorFunctionFactories().withRLock([&config](auto& functionMap) {
+        auto functionIterator = functionMap.find(exec::kRowConstructorWithNull);
+        return functionIterator->second.factory(
+            exec::kRowConstructorWithNull, {}, config);
+      });
+
+  return std::make_shared<Expr>(
+      type,
+      std::move(compiledChildren),
+      rowConstructorVectorFunction,
+      "row_constructor_with_null",
+      trackCpuUsage);
+}
+
 ExprPtr getSpecialForm(
     const core::QueryConfig& config,
     const std::string& name,
@@ -247,6 +268,10 @@ ExprPtr getSpecialForm(
     return getRowConstructorExpr(
         config, type, std::move(compiledChildren), trackCpuUsage);
   }
+  if (name == kRowConstructorWithNull) {
+    return getRowConstructorWithNullExpr(
+        config, type, std::move(compiledChildren), trackCpuUsage);
+  }
 
   // If we just check the output of constructSpecialForm we'll have moved
   // compiledChildren, and if the function isn't a special form we'll still need

velox/functions/FunctionRegistry.cpp

@@ -109,7 +109,8 @@ std::shared_ptr<const Type> resolveCallableSpecialForm(
     const std::string& functionName,
     const std::vector<TypePtr>& argTypes) {
   // TODO Replace with struct_pack
-  if (functionName == "row_constructor") {
+  if (functionName == "row_constructor" ||
+      functionName == "row_constructor_with_null") {
     auto numInput = argTypes.size();
     std::vector<TypePtr> types(numInput);
     std::vector<std::string> names(numInput);

velox/functions/prestosql/CMakeLists.txt

@@ -46,6 +46,7 @@ add_library(
   Repeat.cpp
   Reverse.cpp
   RowFunction.cpp
+  RowFunctionWithNull.cpp
   Sequence.cpp
   SimpleComparisonMatcher.cpp
   Slice.cpp

velox/functions/prestosql/RowFunctionWithNull.cpp

@@ -0,0 +1,72 @@
+/*
+ * 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/expression/Expr.h"
+#include "velox/expression/VectorFunction.h"
+
+namespace facebook::velox::functions {
+namespace {
+
+class RowFunctionWithNull : public exec::VectorFunction {
+ public:
+  void apply(
+      const SelectivityVector& rows,
+      std::vector<VectorPtr>& args,
+      const TypePtr& outputType,
+      exec::EvalCtx& context,
+      VectorPtr& result) const override {
+    auto argsCopy = args;
+
+    BufferPtr nulls = AlignedBuffer::allocate<char>(
+        bits::nbytes(rows.size()), context.pool(), 1);
+    auto* nullsPtr = nulls->asMutable<uint64_t>();
+    auto cntNull = 0;
+    rows.applyToSelected([&](vector_size_t i) {
+      bits::clearNull(nullsPtr, i);
+      if (!bits::isBitNull(nullsPtr, i)) {
+        for (size_t c = 0; c < argsCopy.size(); c++) {
+          auto arg = argsCopy[c].get();
+          if (arg->mayHaveNulls() && arg->isNullAt(i)) {
+            // If any argument of the struct is null, set the struct as null.
+            bits::setNull(nullsPtr, i, true);
+            cntNull++;
+            break;
+          }
+        }
+      }
+    });
+
+    RowVectorPtr row = std::make_shared<RowVector>(
+        context.pool(),
+        outputType,
+        nulls,
+        rows.size(),
+        std::move(argsCopy),
+        cntNull /*nullCount*/);
+    context.moveOrCopyResult(row, rows, result);
+  }
+
+  bool isDefaultNullBehavior() const override {
+    return false;
+  }
+};
+} // namespace
+
+VELOX_DECLARE_VECTOR_FUNCTION(
+    udf_concat_row_with_null,
+    std::vector<std::shared_ptr<exec::FunctionSignature>>{},
+    std::make_unique<RowFunctionWithNull>());
+
+} // namespace facebook::velox::functions

velox/functions/prestosql/registration/GeneralFunctionsRegistration.cpp

@@ -23,6 +23,8 @@ namespace facebook::velox::functions {
 void registerAllSpecialFormGeneralFunctions() {
   VELOX_REGISTER_VECTOR_FUNCTION(udf_in, "in");
   VELOX_REGISTER_VECTOR_FUNCTION(udf_concat_row, "row_constructor");
+  VELOX_REGISTER_VECTOR_FUNCTION(
+      udf_concat_row_with_null, "row_constructor_with_null");
   registerIsNullFunction("is_null");
 }
 

velox/functions/prestosql/tests/ScalarFunctionRegTest.cpp

@@ -56,6 +56,7 @@ TEST_F(ScalarFunctionRegTest, prefix) {
   scalarVectorFuncMap.erase("in");
   scalarVectorFuncMap.erase("row_constructor");
   scalarVectorFuncMap.erase("is_null");
+  scalarVectorFuncMap.erase("row_constructor_with_null");
 
   for (const auto& entry : scalarVectorFuncMap) {
     EXPECT_EQ(prefix, entry.first.substr(0, prefix.size()));