Rename C interface function to C function for simplicity.

cpp/src/gandiva/CMakeLists.txt

@@ -62,7 +62,7 @@ set(SRC_FILES
     expression_registry.cc
     exported_funcs_registry.cc
     exported_funcs.cc
-    external_c_interface_functions.cc
+    external_c_functions.cc
     filter.cc
     function_ir_builder.cc
     function_holder_maker_registry.cc

cpp/src/gandiva/engine.cc

@@ -449,8 +449,8 @@ void Engine::AddGlobalMappingForFunc(const std::string& name, llvm::Type* ret_ty
 
 arrow::Status Engine::AddGlobalMappings() {
   ARROW_RETURN_NOT_OK(ExportedFuncsRegistry::AddMappings(this));
-  ExternalCInterfaceFunctions c_interface_funcs(function_registry_);
-  return c_interface_funcs.AddMappings(this);
+  ExternalCFunctions c_funcs(function_registry_);
+  return c_funcs.AddMappings(this);
 }
 
 std::string Engine::DumpIR() {

cpp/src/gandiva/exported_funcs.h

@@ -63,9 +63,9 @@ class ExportedHashFunctions : public ExportedFuncsBase {
   arrow::Status AddMappings(Engine* engine) const override;
 };
 
-class ExternalCInterfaceFunctions : public ExportedFuncsBase {
+class ExternalCFunctions : public ExportedFuncsBase {
  public:
-  explicit ExternalCInterfaceFunctions(
+  explicit ExternalCFunctions(
       std::shared_ptr<FunctionRegistry> function_registry)
       : function_registry_(std::move(function_registry)) {}
 

cpp/src/gandiva/external_c_interface_functions.cc → cpp/src/gandiva/external_c_functions.cc

@@ -51,39 +51,38 @@ static arrow::Result<llvm::Type*> AsLLVMType(const DataTypePtr& from_type,
 // map from a NativeFunction's signature to the corresponding LLVM signature
 static arrow::Result<std::pair<std::vector<llvm::Type*>, llvm::Type*>> MapToLLVMSignature(
     const FunctionSignature& sig, const NativeFunction& func, LLVMTypes* types) {
-  std::vector<llvm::Type*> args;
-  args.reserve(sig.param_types().size());
+  std::vector<llvm::Type*> arg_llvm_types;
+  arg_llvm_types.reserve(sig.param_types().size());
   if (func.NeedsContext()) {
-    args.emplace_back(types->i64_type());
+    arg_llvm_types.emplace_back(types->i64_type());
   }
   if (func.NeedsFunctionHolder()) {
-    args.emplace_back(types->i64_type());
+    arg_llvm_types.emplace_back(types->i64_type());
   }
   for (auto const& arg : sig.param_types()) {
     if (arg->id() == arrow::Type::STRING) {
-      args.emplace_back(types->i8_ptr_type());
-      args.emplace_back(types->i32_type());
+      arg_llvm_types.emplace_back(types->i8_ptr_type());
+      arg_llvm_types.emplace_back(types->i32_type());
     } else {
       ARROW_ASSIGN_OR_RAISE(auto arg_llvm_type, AsLLVMType(arg, types));
-      args.emplace_back(arg_llvm_type);
+      arg_llvm_types.emplace_back(arg_llvm_type);
     }
   }
   llvm::Type* ret_llvm_type;
   if (sig.ret_type()->id() == arrow::Type::STRING) {
     // for string output, the last arg is the output length
-    args.emplace_back(types->i32_ptr_type());
+    arg_llvm_types.emplace_back(types->i32_ptr_type());
     ret_llvm_type = types->i8_ptr_type();
   } else {
     ARROW_ASSIGN_OR_RAISE(ret_llvm_type, AsLLVMType(sig.ret_type(), types));
   }
-  auto return_type = AsLLVMType(sig.ret_type(), types);
-  return std::make_pair(args, ret_llvm_type);
+  return std::make_pair(std::move(arg_llvm_types), ret_llvm_type);
 }
 
-arrow::Status ExternalCInterfaceFunctions::AddMappings(Engine* engine) const {
-  auto const& c_interface_funcs = function_registry_->GetCInterfaceFunctions();
+arrow::Status ExternalCFunctions::AddMappings(Engine* engine) const {
+  auto const& c_funcs = function_registry_->GetCFunctions();
   auto types = engine->types();
-  for (auto& [func, func_ptr] : c_interface_funcs) {
+  for (auto& [func, func_ptr] : c_funcs) {
     for (auto const& sig : func.signatures()) {
       ARROW_ASSIGN_OR_RAISE(auto llvm_signature, MapToLLVMSignature(sig, func, types));
       auto& [args, ret_llvm_type] = llvm_signature;

cpp/src/gandiva/function_holder_maker_registry.cc

@@ -19,6 +19,7 @@
 
 #include <functional>
 
+#include "arrow/util/string.h"
 #include "gandiva/function_holder.h"
 #include "gandiva/interval_holder.h"
 #include "gandiva/random_generator_holder.h"
@@ -27,18 +28,14 @@
 
 namespace gandiva {
 
+using arrow::internal::AsciiToLower;
+
 FunctionHolderMakerRegistry::FunctionHolderMakerRegistry()
     : function_holder_makers_(DefaultHolderMakers()) {}
 
-static std::string to_lower(const std::string& str) {
-  std::string data = str;
-  std::transform(data.begin(), data.end(), data.begin(),
-                 [](unsigned char c) { return std::tolower(c); });
-  return data;
-}
 arrow::Status FunctionHolderMakerRegistry::Register(const std::string& name,
                                                     FunctionHolderMaker holder_maker) {
-  function_holder_makers_.emplace(to_lower(name), std::move(holder_maker));
+  function_holder_makers_.emplace(AsciiToLower(name), std::move(holder_maker));
   return arrow::Status::OK();
 }
 
@@ -51,7 +48,7 @@ static arrow::Result<FunctionHolderPtr> HolderMaker(const FunctionNode& node) {
 
 arrow::Result<FunctionHolderPtr> FunctionHolderMakerRegistry::Make(
     const std::string& name, const FunctionNode& node) {
-  auto lowered_name = to_lower(name);
+  auto lowered_name = AsciiToLower(name);
   auto found = function_holder_makers_.find(lowered_name);
   if (found == function_holder_makers_.end()) {
     return Status::Invalid("function holder not registered for function " + name);

cpp/src/gandiva/function_registry.cc

@@ -110,15 +110,15 @@ arrow::Status FunctionRegistry::Register(const std::vector<NativeFunction>& func
 }
 
 arrow::Status FunctionRegistry::Register(
-    NativeFunction func, void* stub_function_ptr,
+    NativeFunction func, void* c_function_ptr,
     std::optional<FunctionHolderMaker> function_holder_maker) {
   if (function_holder_maker.has_value()) {
     // all signatures should have the same base name, use the first signature's base name
     auto const& func_base_name = func.signatures().begin()->base_name();
     ARROW_RETURN_NOT_OK(holder_maker_registry_.Register(
         func_base_name, std::move(function_holder_maker.value())));
   }
-  c_interface_functions_.emplace_back(func, stub_function_ptr);
+  c_functions_.emplace_back(func, c_function_ptr);
   ARROW_RETURN_NOT_OK(FunctionRegistry::Add(std::move(func)));
   return Status::OK();
 }
@@ -128,9 +128,9 @@ const std::vector<std::shared_ptr<arrow::Buffer>>& FunctionRegistry::GetBitcodeB
   return bitcode_memory_buffers_;
 }
 
-const std::vector<std::pair<NativeFunction, void*>>&
-FunctionRegistry::GetCInterfaceFunctions() const {
-  return c_interface_functions_;
+const std::vector<std::pair<NativeFunction, void*>>& FunctionRegistry::GetCFunctions()
+    const {
+  return c_functions_;
 }
 
 const FunctionHolderMakerRegistry& FunctionRegistry::GetFunctionHolderMakerRegistry()

cpp/src/gandiva/function_registry.h

@@ -58,21 +58,21 @@ class GANDIVA_EXPORT FunctionRegistry {
   arrow::Status Register(const std::vector<NativeFunction>& funcs,
                          std::shared_ptr<arrow::Buffer> bitcode_buffer);
 
-  /// \brief register a C interface function into the function registry
+  /// \brief register a C function into the function registry
   /// @param func the registered function's metadata
-  /// @param c_interface_function_ptr the function pointer to the
+  /// @param c_function_ptr the function pointer to the
   /// registered function's implementation
   /// @param function_holder_maker this will be used as the function holder if the
   /// function requires a function holder
   arrow::Status Register(
-      NativeFunction func, void* c_interface_function_ptr,
+      NativeFunction func, void* c_function_ptr,
       std::optional<FunctionHolderMaker> function_holder_maker = std::nullopt);
 
   /// \brief get a list of bitcode memory buffers saved in the registry
   const std::vector<std::shared_ptr<arrow::Buffer>>& GetBitcodeBuffers() const;
 
-  /// \brief get a list of C interface functions saved in the registry
-  const std::vector<std::pair<NativeFunction, void*>>& GetCInterfaceFunctions() const;
+  /// \brief get a list of C functions saved in the registry
+  const std::vector<std::pair<NativeFunction, void*>>& GetCFunctions() const;
 
   const FunctionHolderMakerRegistry& GetFunctionHolderMakerRegistry() const;
 
@@ -86,7 +86,7 @@ class GANDIVA_EXPORT FunctionRegistry {
   std::vector<NativeFunction> pc_registry_;
   SignatureMap pc_registry_map_;
   std::vector<std::shared_ptr<arrow::Buffer>> bitcode_memory_buffers_;
-  std::vector<std::pair<NativeFunction, void*>> c_interface_functions_;
+  std::vector<std::pair<NativeFunction, void*>> c_functions_;
   FunctionHolderMakerRegistry holder_maker_registry_;
 
   Status Add(NativeFunction func);

cpp/src/gandiva/gdv_string_function_stubs.cc

@@ -15,8 +15,6 @@
 // specific language governing permissions and limitations
 // under the License.
 
-// #pragma once
-
 #include "gandiva/gdv_function_stubs.h"
 
 #include <utf8proc.h>

cpp/src/gandiva/llvm_generator_test.cc

@@ -139,9 +139,9 @@ TEST_F(TestLLVMGenerator, VerifyExtendedPCFunctions) {
   });
 }
 
-TEST_F(TestLLVMGenerator, VerifyExtendedCInterfaceFunctions) {
+TEST_F(TestLLVMGenerator, VerifyExtendedCFunctions) {
   VerifyFunctionMapping("multiply_by_three_int32", [](auto registry) {
-    return TestConfigWithCInterfaceFunction(std::move(registry));
+    return TestConfigWithCFunction(std::move(registry));
   });
 
   VerifyFunctionMapping("multiply_by_n_int32_int32", [](auto registry) {

cpp/src/gandiva/tests/projector_test.cc

@@ -3608,7 +3608,7 @@ TEST_F(TestProjector, TestExtendedFunctions) {
   EXPECT_ARROW_ARRAY_EQUALS(out, outs.at(0));
 }
 
-TEST_F(TestProjector, TestExtendedCInterfaceFunctions) {
+TEST_F(TestProjector, TestExtendedCFunctions) {
   auto in_field = field("in", arrow::int32());
   auto schema = arrow::schema({in_field});
   auto out_field = field("out", arrow::int64());
@@ -3617,8 +3617,7 @@ TEST_F(TestProjector, TestExtendedCInterfaceFunctions) {
 
   std::shared_ptr<Projector> projector;
   auto external_registry = std::make_shared<FunctionRegistry>();
-  auto config_with_func_registry =
-      TestConfigWithCInterfaceFunction(std::move(external_registry));
+  auto config_with_func_registry = TestConfigWithCFunction(std::move(external_registry));
   ARROW_EXPECT_OK(
       Projector::Make(schema, {multiply}, config_with_func_registry, &projector));
 
@@ -3632,7 +3631,7 @@ TEST_F(TestProjector, TestExtendedCInterfaceFunctions) {
   EXPECT_ARROW_ARRAY_EQUALS(out, outs.at(0));
 }
 
-TEST_F(TestProjector, TestExtendedCInterfaceFunctionsWithFunctionHolder) {
+TEST_F(TestProjector, TestExtendedCFunctionsWithFunctionHolder) {
   auto multiple = TreeExprBuilder::MakeLiteral(5);
   auto in_field = field("in", arrow::int32());
   auto schema = arrow::schema({in_field});
@@ -3660,7 +3659,7 @@ TEST_F(TestProjector, TestExtendedCInterfaceFunctionsWithFunctionHolder) {
   EXPECT_ARROW_ARRAY_EQUALS(out, outs.at(0));
 }
 
-TEST_F(TestProjector, TestExtendedCInterfaceFunctionThatNeedsContext) {
+TEST_F(TestProjector, TestExtendedCFunctionThatNeedsContext) {
   auto in_field = field("in", arrow::utf8());
   auto schema = arrow::schema({in_field});
   auto out_field = field("out", arrow::utf8());

cpp/src/gandiva/tests/test_util.cc

@@ -46,7 +46,7 @@ NativeFunction GetTestExternalFunction() {
   return multiply_by_two_func;
 }
 
-static NativeFunction GetTestExternalCInterfaceFunction() {
+static NativeFunction GetTestExternalCFunction() {
   NativeFunction multiply_by_three_func(
       "multiply_by_three", {}, {arrow::int32()}, arrow::int64(),
       ResultNullableType::kResultNullIfNull, "multiply_by_three_int32");
@@ -89,7 +89,7 @@ class MultiplyHolder : public FunctionHolder {
  public:
   explicit MultiplyHolder(int32_t num) : num_(num) {}
 
-  static Status Make(const FunctionNode& node, std::shared_ptr<MultiplyHolder>* holder) {
+  static arrow::Result<std::shared_ptr<MultiplyHolder>> Make(const FunctionNode& node) {
     ARROW_RETURN_IF(node.children().size() != 2,
                     Status::Invalid("'multiply_by_n' function requires two parameters"));
 
@@ -105,9 +105,8 @@ class MultiplyHolder : public FunctionHolder {
         Status::Invalid(
             "'multiply_by_n' function requires an int32 literal as the 2nd parameter"));
 
-    *holder = std::make_shared<MultiplyHolder>(
+    return std::make_shared<MultiplyHolder>(
         literal->is_null() ? 0 : std::get<int32_t>(literal->holder()));
-    return Status::OK();
   }
 
   int32_t operator()() const { return num_; }
@@ -117,7 +116,7 @@ class MultiplyHolder : public FunctionHolder {
 };
 
 extern "C" {
-// this function is used as an external stub function for testing so it has to be declared
+// this function is used as an external C function for testing so it has to be declared
 // with extern C
 static int64_t multiply_by_three(int32_t value) { return value * 3; }
 
@@ -143,10 +142,10 @@ static const char* multiply_by_two_formula(int64_t ctx, const char* value,
 }
 }
 
-std::shared_ptr<Configuration> TestConfigWithCInterfaceFunction(
+std::shared_ptr<Configuration> TestConfigWithCFunction(
     std::shared_ptr<FunctionRegistry> registry) {
   return BuildConfigurationWithRegistry(std::move(registry), [](auto reg) {
-    return reg->Register(GetTestExternalCInterfaceFunction(),
+    return reg->Register(GetTestExternalCFunction(),
                          reinterpret_cast<void*>(multiply_by_three));
   });
 }
@@ -156,11 +155,7 @@ std::shared_ptr<Configuration> TestConfigWithHolderFunction(
   return BuildConfigurationWithRegistry(std::move(registry), [](auto reg) {
     return reg->Register(
         GetTestFunctionWithFunctionHolder(), reinterpret_cast<void*>(multiply_by_n),
-        [](const FunctionNode& node) -> arrow::Result<FunctionHolderPtr> {
-          std::shared_ptr<MultiplyHolder> derived_instance;
-          ARROW_RETURN_NOT_OK(MultiplyHolder::Make(node, &derived_instance));
-          return derived_instance;
-        });
+        [](const FunctionNode& node) { return MultiplyHolder::Make(node); });
   });
 }
 

cpp/src/gandiva/tests/test_util.h

@@ -103,9 +103,9 @@ std::shared_ptr<Configuration> TestConfiguration();
 std::shared_ptr<Configuration> TestConfigWithFunctionRegistry(
     std::shared_ptr<FunctionRegistry> registry);
 
-// helper function to create a Configuration with an external stub function registered to
+// helper function to create a Configuration with an external C function registered to
 // the given function registry
-std::shared_ptr<Configuration> TestConfigWithCInterfaceFunction(
+std::shared_ptr<Configuration> TestConfigWithCFunction(
     std::shared_ptr<FunctionRegistry> registry);
 
 // helper function to create a Configuration with an external function registered