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Add GetStringView() and GetRepeatedStringView() with scratch.
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PiperOrigin-RevId: 608636288
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@protobuf-github-bot @copybara-github
protobuf-github-bot authored and copybara-github committed Feb 20, 2024
1 parent 6c58b9a commit a3f5af0
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44 changes: 44 additions & 0 deletions src/google/protobuf/generated_message_reflection.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1868,6 +1868,32 @@ absl::Cord Reflection::GetCord(const Message& message,
}
}

absl::string_view Reflection::GetStringView(const Message& message,
const FieldDescriptor* field,
ScratchSpace& scratch) const {
USAGE_CHECK_ALL(GetStringView, SINGULAR, STRING);

if (field->is_extension()) {
return GetExtensionSet(message).GetString(field->number(),
field->default_value_string());
}
if (schema_.InRealOneof(field) && !HasOneofField(message, field)) {
return field->default_value_string();
}

switch (internal::cpp::EffectiveStringCType(field)) {
case FieldOptions::CORD: {
const auto& cord = schema_.InRealOneof(field)
? *GetField<absl::Cord*>(message, field)
: GetField<absl::Cord>(message, field);
return scratch.CopyFromCord(cord);
}
default:
auto str = GetField<ArenaStringPtr>(message, field);
return str.IsDefault() ? field->default_value_string() : str.Get();
}
}


void Reflection::SetString(Message* message, const FieldDescriptor* field,
std::string value) const {
Expand Down Expand Up @@ -2002,6 +2028,24 @@ const std::string& Reflection::GetRepeatedStringReference(
}
}

// See GetStringView(), above.
absl::string_view Reflection::GetRepeatedStringView(
const Message& message, const FieldDescriptor* field, int index,
ScratchSpace& scratch) const {
(void)scratch;
USAGE_CHECK_ALL(GetRepeatedStringView, REPEATED, STRING);

if (field->is_extension()) {
return GetExtensionSet(message).GetRepeatedString(field->number(), index);
}

switch (internal::cpp::EffectiveStringCType(field)) {
case FieldOptions::STRING:
default:
return GetRepeatedPtrField<std::string>(message, field, index);
}
}


void Reflection::SetRepeatedString(Message* message,
const FieldDescriptor* field, int index,
Expand Down
93 changes: 93 additions & 0 deletions src/google/protobuf/generated_message_reflection_unittest.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,99 @@ TEST(GeneratedMessageReflectionTest, GetStringReferenceCopy) {
&cord_scratch));
}

TEST(GeneratedMessageReflectionTest, GetStringView) {
unittest::TestAllTypes message;
TestUtil::SetAllFields(&message);

const Reflection* reflection = message.GetReflection();
Reflection::ScratchSpace scratch;

EXPECT_EQ("115",
reflection->GetStringView(message, F("optional_string"), scratch));
EXPECT_EQ("124", reflection->GetStringView(
message, F("optional_string_piece"), scratch));
EXPECT_EQ("125",
reflection->GetStringView(message, F("optional_cord"), scratch));
}

TEST(GeneratedMessageReflectionTest, GetStringViewWithExtensions) {
unittest::TestAllExtensions message;
google::protobuf::FileDescriptor const* descriptor_file =
message.GetDescriptor()->file();
google::protobuf::FieldDescriptor const* string_ext =
descriptor_file->FindExtensionByName("optional_string_extension");
google::protobuf::FieldDescriptor const* string_piece_ext =
descriptor_file->FindExtensionByName("optional_string_piece_extension");
google::protobuf::FieldDescriptor const* cord_ext =
descriptor_file->FindExtensionByName("optional_cord_extension");
message.SetExtension(protobuf_unittest::optional_string_extension, "foo");
message.SetExtension(protobuf_unittest::optional_string_piece_extension, "bar");
message.SetExtension(protobuf_unittest::optional_cord_extension, "baz");
const Reflection* reflection = message.GetReflection();
Reflection::ScratchSpace scratch;

EXPECT_EQ("foo", reflection->GetStringView(message, string_ext, scratch));
EXPECT_EQ("bar",
reflection->GetStringView(message, string_piece_ext, scratch));
EXPECT_EQ("baz", reflection->GetStringView(message, cord_ext, scratch));
}

TEST(GeneratedMessageReflectionTest, GetStringViewWithOneof) {
unittest::TestOneof2 message;
const Reflection* reflection = message.GetReflection();
const FieldDescriptor* string_field =
message.GetDescriptor()->FindFieldByName("foo_string");
const FieldDescriptor* string_piece_field =
message.GetDescriptor()->FindFieldByName("foo_string_piece");
Reflection::ScratchSpace scratch;

message.set_foo_string("foo");
EXPECT_EQ("foo", reflection->GetStringView(message, string_field, scratch));
EXPECT_EQ("",
reflection->GetStringView(message, string_piece_field, scratch));

}

TEST(GeneratedMessageReflectionTest, GetRepeatedStringView) {
unittest::TestAllTypes message;
TestUtil::AddRepeatedFields1(&message);
TestUtil::AddRepeatedFields2(&message);

const Reflection* reflection = message.GetReflection();
Reflection::ScratchSpace scratch;

EXPECT_EQ("215", reflection->GetRepeatedStringView(
message, F("repeated_string"), 0, scratch));
EXPECT_EQ("224", reflection->GetRepeatedStringView(
message, F("repeated_string_piece"), 0, scratch));
EXPECT_EQ("225", reflection->GetRepeatedStringView(
message, F("repeated_cord"), 0, scratch));
}

TEST(GeneratedMessageReflectionTest, GetRepeatedStringViewWithExtensions) {
unittest::TestAllExtensions message;
google::protobuf::FileDescriptor const* descriptor_file =
message.GetDescriptor()->file();
google::protobuf::FieldDescriptor const* string_ext =
descriptor_file->FindExtensionByName("repeated_string_extension");
google::protobuf::FieldDescriptor const* string_piece_ext =
descriptor_file->FindExtensionByName("repeated_string_piece_extension");
google::protobuf::FieldDescriptor const* cord_ext =
descriptor_file->FindExtensionByName("repeated_cord_extension");
message.AddExtension(protobuf_unittest::repeated_string_extension, "foo");
message.AddExtension(protobuf_unittest::repeated_string_piece_extension, "bar");
message.AddExtension(protobuf_unittest::repeated_cord_extension, "baz");
const Reflection* reflection = message.GetReflection();
Reflection::ScratchSpace scratch;

EXPECT_EQ("foo",
reflection->GetRepeatedStringView(message, string_ext, 0, scratch));
EXPECT_EQ("bar", reflection->GetRepeatedStringView(message, string_piece_ext,
0, scratch));
EXPECT_EQ("baz",
reflection->GetRepeatedStringView(message, cord_ext, 0, scratch));
}


class GeneratedMessageReflectionSwapTest : public testing::TestWithParam<bool> {
protected:
Expand Down
38 changes: 38 additions & 0 deletions src/google/protobuf/message.h
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@

#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
#include <type_traits>
#include <vector>
Expand All @@ -97,6 +98,7 @@
#include "absl/base/call_once.h"
#include "google/protobuf/stubs/common.h"
#include "absl/log/absl_check.h"
#include "absl/memory/memory.h"
#include "absl/strings/cord.h"
#include "absl/strings/string_view.h"
#include "google/protobuf/arena.h"
Expand Down Expand Up @@ -585,6 +587,37 @@ class PROTOBUF_EXPORT Reflection final {
absl::Cord GetCord(const Message& message,
const FieldDescriptor* field) const;

// Enables GetStringView() and GetRepeatedStringView() APIs to return
// absl::string_view even though the underlying implementation doesn't have
// contiguous bytes; e.g. absl::Cord.
class ScratchSpace {
public:
ScratchSpace() = default;

ScratchSpace(const ScratchSpace&) = delete;
ScratchSpace& operator=(const ScratchSpace&) = delete;

private:
friend class Reflection;

absl::string_view CopyFromCord(const absl::Cord& cord) {
if (!buffer_) {
buffer_ = absl::make_unique<std::string>();
}
absl::CopyCordToString(cord, buffer_.get());
return *buffer_;
}

std::unique_ptr<std::string> buffer_;
};

// Returns a view into the contents of a string field. "scratch" is used to
// flatten bytes if it is non-contiguous. The lifetime of absl::string_view is
// either tied to "message" (contiguous) or "scratch" (otherwise).
absl::string_view GetStringView(
const Message& message, const FieldDescriptor* field,
ScratchSpace& scratch ABSL_ATTRIBUTE_LIFETIME_BOUND) const;


// Singular field mutators -----------------------------------------
// These mutate the value of a non-repeated field.
Expand Down Expand Up @@ -706,6 +739,11 @@ class PROTOBUF_EXPORT Reflection final {
int index,
std::string* scratch) const;

// See GetStringView(), above.
absl::string_view GetRepeatedStringView(
const Message& message, const FieldDescriptor* field, int index,
ScratchSpace& scratch ABSL_ATTRIBUTE_LIFETIME_BOUND) const;


// Repeated field mutators -----------------------------------------
// These mutate the value of one element of a repeated field.
Expand Down
12 changes: 12 additions & 0 deletions src/google/protobuf/string_view_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,9 @@ TEST(StringViewFieldTest, SingularSetAndGetByReflection) {
reflection->SetString(&message, field, std::string{STRING_PAYLOAD});

EXPECT_THAT(reflection->GetString(message, field), StrEq(STRING_PAYLOAD));
Reflection::ScratchSpace scratch;
EXPECT_THAT(reflection->GetStringView(message, field, scratch),
StrEq(STRING_PAYLOAD));
EXPECT_THAT(message.singular_string(), StrEq(STRING_PAYLOAD));
}

Expand Down Expand Up @@ -292,6 +295,15 @@ TEST(StringViewFieldTest, RepeatedSetAndGetByReflection) {
EXPECT_THAT(rep_str,
ElementsAre("000000000000", "111111111111", "222222222222"));
}

// GetRepeatedStringView.
Reflection::ScratchSpace scratch;
EXPECT_THAT(reflection->GetRepeatedStringView(message, field, 0, scratch),
StrEq("000000000000"));
EXPECT_THAT(reflection->GetRepeatedStringView(message, field, 1, scratch),
StrEq("111111111111"));
EXPECT_THAT(reflection->GetRepeatedStringView(message, field, 2, scratch),
StrEq("222222222222"));
}

} // namespace
Expand Down

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