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Add an RAII ifndef helper for C++ codegen.
This can be used in headers to automatically generate ifdef guards. PiperOrigin-RevId: 618204633
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‎pkg/BUILD.bazel

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@@ -174,6 +174,7 @@ cc_dist_library(
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"//src/google/protobuf:arena_align",
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"//src/google/protobuf:cmake_wkt_cc_proto",
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"//src/google/protobuf/compiler:importer",
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"//src/google/protobuf/io/cpp_utils:ifndef_guard",
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"//src/google/protobuf/json",
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"//src/google/protobuf/util:delimited_message_util",
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"//src/google/protobuf/util:differencer",

‎src/google/protobuf/io/cpp_utils/BUILD.bazel

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# Utilities for generating C++ code
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load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
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load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
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load("//build_defs:cpp_opts.bzl", "COPTS")
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package(
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default_visibility = ["//visibility:public"],
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)
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cc_library(
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name = "ifndef_guard",
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srcs = ["ifndef_guard.cc"],
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hdrs = ["ifndef_guard.h"],
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copts = COPTS,
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strip_include_prefix = "/src",
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deps = [
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"//src/google/protobuf/io:printer",
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"@com_google_absl//absl/functional:any_invocable",
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"@com_google_absl//absl/log:die_if_null",
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"@com_google_absl//absl/strings",
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"@com_google_absl//absl/strings:string_view",
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],
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)
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cc_test(
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name = "ifndef_guard_unittest",
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srcs = ["ifndef_guard_unittest.cc"],
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deps = [
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":ifndef_guard",
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"//src/google/protobuf/io",
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"//src/google/protobuf/io:printer",
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"@com_google_absl//absl/log:absl_check",
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"@com_google_absl//absl/strings:string_view",
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"@com_google_absl//absl/types:optional",
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"@com_google_googletest//:gtest",
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"@com_google_googletest//:gtest_main",
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],
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)
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################################################################################
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# Distribution packaging
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################################################################################
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pkg_files(
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name = "dist_files",
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srcs = glob(["**/*"]),
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strip_prefix = strip_prefix.from_root(""),
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visibility = ["//src:__pkg__"],
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)
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filegroup(
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name = "test_srcs",
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srcs = glob([
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"*unittest.cc",
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]),
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visibility = ["//pkg:__pkg__"],
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)

‎src/google/protobuf/io/cpp_utils/ifndef_guard.cc

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// Protocol Buffers - Google's data interchange format
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// Copyright 2024 Google LLC. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#include "google/protobuf/io/cpp_utils/ifndef_guard.h"
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#include <string>
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#include "absl/functional/any_invocable.h"
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#include "absl/log/die_if_null.h"
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#include "absl/strings/ascii.h"
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#include "absl/strings/str_cat.h"
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#include "absl/strings/str_replace.h"
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#include "absl/strings/string_view.h"
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#include "absl/strings/substitute.h"
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#include "google/protobuf/io/printer.h"
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namespace google {
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namespace protobuf {
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namespace io {
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namespace cpp {
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namespace {
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std::string MakeIfdefGuardIdentifier(const absl::string_view header_path) {
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return absl::StrCat(absl::AsciiStrToUpper(absl::StrReplaceAll(header_path,
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{
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{"/", "_"},
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{".", "_"},
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})),
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"_");
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}
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} // namespace
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IfdefGuardPrinter::IfdefGuardPrinter(google::protobuf::io::Printer* const p,
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const absl::string_view filename)
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: IfdefGuardPrinter(p, filename, MakeIfdefGuardIdentifier) {}
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IfdefGuardPrinter::IfdefGuardPrinter(
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google::protobuf::io::Printer* const p, const absl::string_view filename,
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absl::AnyInvocable<std::string(absl::string_view)> make_ifdef_identifier)
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: p_(ABSL_DIE_IF_NULL(p)),
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ifdef_identifier_(make_ifdef_identifier(filename)) {
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// We can't use variable substitution, because we don't know what delimiter
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// to use.
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p->Print(absl::Substitute(
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R"(#ifndef $0
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#define $0
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)",
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ifdef_identifier_));
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}
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IfdefGuardPrinter::~IfdefGuardPrinter() {
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// We can't use variable substitution, because we don't know what delimiter
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// to use.
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p_->Print(absl::Substitute(
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R"(
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#endif // $0
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)",
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ifdef_identifier_));
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}
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} // namespace cpp
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} // namespace io
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} // namespace protobuf
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} // namespace google

‎src/google/protobuf/io/cpp_utils/ifndef_guard.h

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// Protocol Buffers - Google's data interchange format
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// Copyright 2024 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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// An RAII type for printing an ifdef guard.
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//
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// This can be used to ensure that appropriate ifdef guards are applied in
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// a generated header file.
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//
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// Example:
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// {
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// Printer printer(output_stream.get(), '$');
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// const IfdefGuardPrinter ifdef_guard(&printer, output_path);
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// // #ifdef guard will be emitted here
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// ...
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// // #endif will be emitted here
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// }
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//
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// By default, the filename will be converted to a macro by substituting '/' and
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// '.' characters with '_'. If a different transformation is required, an
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// optional transformation function can be provided.
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#ifndef GOOGLE_PROTOBUF_IO_CPP_UTILS_IFNDEF_GUARD_H__
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#define GOOGLE_PROTOBUF_IO_CPP_UTILS_IFNDEF_GUARD_H__
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#include <string>
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#include "absl/functional/any_invocable.h"
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#include "absl/strings/string_view.h"
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#include "google/protobuf/io/printer.h"
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namespace google {
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namespace protobuf {
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namespace io {
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namespace cpp {
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class IfdefGuardPrinter final {
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public:
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explicit IfdefGuardPrinter(google::protobuf::io::Printer* p,
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absl::string_view filename);
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explicit IfdefGuardPrinter(
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google::protobuf::io::Printer* p, absl::string_view filename,
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absl::AnyInvocable<std::string(absl::string_view)> make_ifdef_identifier);
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~IfdefGuardPrinter();
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private:
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google::protobuf::io::Printer* const p_;
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const std::string ifdef_identifier_;
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};
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} // namespace cpp
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} // namespace io
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} // namespace protobuf
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} // namespace google
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#endif // GOOGLE_PROTOBUF_IO_CPP_UTILS_IFNDEF_GUARD_H__

‎src/google/protobuf/io/cpp_utils/ifndef_guard_unittest.cc

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#include "google/protobuf/io/cpp_utils/ifndef_guard.h"
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#include <string>
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#include <gtest/gtest.h>
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#include "absl/log/absl_check.h"
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#include "absl/strings/string_view.h"
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#include "absl/types/optional.h"
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#include "google/protobuf/io/printer.h"
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#include "google/protobuf/io/zero_copy_stream.h"
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#include "google/protobuf/io/zero_copy_stream_impl_lite.h"
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namespace google {
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namespace protobuf {
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namespace io {
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namespace cpp {
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namespace {
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class IfnDefGuardTest : public testing::Test {
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protected:
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ZeroCopyOutputStream* output() {
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ABSL_CHECK(stream_.has_value());
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return &*stream_;
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}
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absl::string_view written() {
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stream_.reset();
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return out_;
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}
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std::string out_;
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absl::optional<StringOutputStream> stream_{&out_};
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};
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TEST_F(IfnDefGuardTest, Basic) {
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{
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Printer printer(output(), '$');
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const IfdefGuardPrinter ifdef_guard(&printer, "A/B/E/alpha");
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EXPECT_FALSE(printer.failed());
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}
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EXPECT_EQ(written(),
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"#ifndef A_B_E_ALPHA_\n"
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"#define A_B_E_ALPHA_\n"
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"\n"
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"\n"
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"#endif // A_B_E_ALPHA_\n");
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}
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TEST_F(IfnDefGuardTest, DifferentDelim) {
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{
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Printer printer(output(), '\0');
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const IfdefGuardPrinter ifdef_guard(&printer, "A/B/E/alpha");
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EXPECT_FALSE(printer.failed());
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}
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EXPECT_EQ(written(),
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"#ifndef A_B_E_ALPHA_\n"
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"#define A_B_E_ALPHA_\n"
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"\n"
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"\n"
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"#endif // A_B_E_ALPHA_\n");
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}
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TEST_F(IfnDefGuardTest, DifferentSubstitutionFunction) {
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{
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Printer printer(output(), '$');
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const IfdefGuardPrinter ifdef_guard(
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&printer, "A/B/E/alpha", [](absl::string_view) { return "FOO_BAR_"; });
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EXPECT_FALSE(printer.failed());
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}
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EXPECT_EQ(written(),
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"#ifndef FOO_BAR_\n"
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"#define FOO_BAR_\n"
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"\n"
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"\n"
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"#endif // FOO_BAR_\n");
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}
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} // namespace
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} // namespace cpp
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} // namespace io
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} // namespace protobuf
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} // namespace google

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