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Separate //cuttlefish/result:expect from //cuttlefish/result
This makes the dependency on the usage macros distinct from the dependency on the support code. Bug: b/471062163
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3 files changed

+223
-195
lines changed

3 files changed

+223
-195
lines changed

‎base/cvd/cuttlefish/result/BUILD.bazel‎

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -15,8 +15,8 @@ cf_cc_library(
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)
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cf_cc_library(
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name = "result",
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hdrs = ["result.h"],
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name = "expect",
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hdrs = ["expect.h"],
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deps = [
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"//cuttlefish/result:error_type",
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"//cuttlefish/result:result_type",
@@ -25,6 +25,15 @@ cf_cc_library(
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],
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)
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cf_cc_library(
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name = "result",
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hdrs = ["result.h"],
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deps = [
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"//cuttlefish/result:expect",
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"//cuttlefish/result:result_type",
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],
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)
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cf_cc_test(
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name = "result_test",
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srcs = ["result_test.cpp"],

‎base/cvd/cuttlefish/result/expect.h‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,211 @@
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//
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// Copyright (C) 2022 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <optional>
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#include <type_traits>
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#include <utility>
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#include <android-base/format.h> // IWYU pragma: export
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#include <android-base/logging.h>
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#include <android-base/result.h> // IWYU pragma: export
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#include "cuttlefish/result/error_type.h"
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#include "cuttlefish/result/result_type.h" // IWYU pragma: export
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namespace cuttlefish {
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/**
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* Error return macro that includes the location in the file in the error
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* message. Use CF_ERRNO when including information from errno, otherwise use
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* the base CF_ERR macro.
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*
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* Example usage:
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*
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* if (mkdir(path.c_str()) != 0) {
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* return CF_ERRNO("mkdir(\"" << path << "\") failed: "
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* << strerror(errno));
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* }
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*
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* This will return an error with the text
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*
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* mkdir(...) failed: ...
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* at path/to/file.cpp:50
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* in Result<std::string> MyFunction()
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*/
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#define CF_ERR(MSG) (CF_STACK_TRACE_ENTRY("") << MSG)
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#define CF_ERRNO(MSG) (CF_STACK_TRACE_ENTRY("") << MSG)
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#define CF_ERRF(MSG, ...) \
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(CF_STACK_TRACE_ENTRY("") << fmt::format(FMT_STRING(MSG), __VA_ARGS__))
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template <typename T>
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T OutcomeDereference(std::optional<T>&& value) {
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return std::move(*value);
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}
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template <typename T>
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typename std::conditional_t<std::is_void_v<T>, bool, T> OutcomeDereference(
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Result<T>&& result) {
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if constexpr (std::is_void<T>::value) {
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return result.ok();
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} else {
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return std::move(*result);
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}
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}
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template <typename T>
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typename std::enable_if<std::is_convertible_v<T, bool>, T>::type
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OutcomeDereference(T&& value) {
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return std::forward<T>(value);
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}
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inline bool TypeIsSuccess(bool value) { return value; }
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template <typename T>
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bool TypeIsSuccess(std::optional<T>& value) {
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return value.has_value();
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}
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template <typename T>
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bool TypeIsSuccess(Result<T>& value) {
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return value.ok();
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}
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template <typename T>
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bool TypeIsSuccess(Result<T>&& value) {
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return value.ok();
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}
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inline auto ErrorFromType(bool) { return StackTraceError(); }
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template <typename T>
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inline auto ErrorFromType(std::optional<T>) {
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return StackTraceError();
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}
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template <typename T>
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auto ErrorFromType(Result<T>& value) {
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return value.error();
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}
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template <typename T>
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auto ErrorFromType(Result<T>&& value) {
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return value.error();
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}
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#define CF_EXPECT_OVERLOAD(_1, _2, NAME, ...) NAME
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#define CF_EXPECT2(RESULT, MSG) \
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({ \
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decltype(RESULT)&& macro_intermediate_result = RESULT; \
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if (!TypeIsSuccess(macro_intermediate_result)) { \
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auto current_entry = CF_STACK_TRACE_ENTRY(#RESULT); \
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current_entry << MSG; \
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auto error = ErrorFromType(macro_intermediate_result); \
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error.PushEntry(std::move(current_entry)); \
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return std::move(error); \
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}; \
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OutcomeDereference(std::move(macro_intermediate_result)); \
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})
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#define CF_EXPECT1(RESULT) CF_EXPECT2(RESULT, "")
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/**
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* Error propagation macro that can be used as an expression.
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*
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* The first argument can be either a Result or a type that is convertible to
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* a boolean. A successful result will return the value inside the result, or
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* a conversion to a `true` value will return the unconverted value. This is
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* useful for e.g. pointers which can be tested through boolean conversion.
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*
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* In the failure case, this macro will return from the containing function
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* with a failing Result. The failing result will include information about the
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* call site, details from the optional second argument if given, and details
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* from the failing inner expression if it is a Result.
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*
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* This macro must be invoked only in functions that return a Result.
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*
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* Example usage:
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*
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* Result<std::string> CreateTempDir();
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*
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* Result<std::string> CreatePopulatedTempDir() {
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* std::string dir = CF_EXPECT(CreateTempDir(), "Failed to create dir");
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* // Do something with dir
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* return dir;
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* }
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*
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* If CreateTempDir fails, the function will returna Result with an error
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* message that looks like
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*
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* Internal error
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* at /path/to/otherfile.cpp:50
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* in Result<std::string> CreateTempDir()
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* Failed to create dir
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* at /path/to/file.cpp:81:
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* in Result<std::string> CreatePopulatedTempDir()
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* for CF_EXPECT(CreateTempDir())
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*/
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#define CF_EXPECT(...) \
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CF_EXPECT_OVERLOAD(__VA_ARGS__, CF_EXPECT2, CF_EXPECT1)(__VA_ARGS__)
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#define CF_EXPECTF(RESULT, MSG, ...) \
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CF_EXPECT(RESULT, fmt::format(FMT_STRING(MSG), __VA_ARGS__))
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#define CF_COMPARE_EXPECT4(COMPARE_OP, LHS_RESULT, RHS_RESULT, MSG) \
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({ \
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auto&& lhs_macro_intermediate_result = LHS_RESULT; \
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auto&& rhs_macro_intermediate_result = RHS_RESULT; \
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bool comparison_result = lhs_macro_intermediate_result COMPARE_OP \
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rhs_macro_intermediate_result; \
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if (!comparison_result) { \
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auto current_entry = CF_STACK_TRACE_ENTRY(""); \
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current_entry << "Expected \"" << #LHS_RESULT << "\" " << #COMPARE_OP \
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<< " \"" << #RHS_RESULT << "\" but was " \
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<< lhs_macro_intermediate_result << " vs " \
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<< rhs_macro_intermediate_result << ". "; \
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current_entry << MSG; \
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auto error = ErrorFromType(false); \
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error.PushEntry(std::move(current_entry)); \
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return std::move(error); \
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}; \
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comparison_result; \
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})
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#define CF_COMPARE_EXPECT3(COMPARE_OP, LHS_RESULT, RHS_RESULT) \
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CF_COMPARE_EXPECT4(COMPARE_OP, LHS_RESULT, RHS_RESULT, "")
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#define CF_COMPARE_EXPECT_OVERLOAD(_1, _2, _3, _4, NAME, ...) NAME
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#define CF_COMPARE_EXPECT(...) \
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CF_COMPARE_EXPECT_OVERLOAD(__VA_ARGS__, CF_COMPARE_EXPECT4, \
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CF_COMPARE_EXPECT3) \
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(__VA_ARGS__)
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#define CF_EXPECT_EQ(LHS_RESULT, RHS_RESULT, ...) \
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CF_COMPARE_EXPECT(==, LHS_RESULT, RHS_RESULT, ##__VA_ARGS__)
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#define CF_EXPECT_NE(LHS_RESULT, RHS_RESULT, ...) \
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CF_COMPARE_EXPECT(!=, LHS_RESULT, RHS_RESULT, ##__VA_ARGS__)
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#define CF_EXPECT_LE(LHS_RESULT, RHS_RESULT, ...) \
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CF_COMPARE_EXPECT(<=, LHS_RESULT, RHS_RESULT, ##__VA_ARGS__)
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#define CF_EXPECT_LT(LHS_RESULT, RHS_RESULT, ...) \
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CF_COMPARE_EXPECT(<, LHS_RESULT, RHS_RESULT, ##__VA_ARGS__)
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#define CF_EXPECT_GE(LHS_RESULT, RHS_RESULT, ...) \
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CF_COMPARE_EXPECT(>=, LHS_RESULT, RHS_RESULT, ##__VA_ARGS__)
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#define CF_EXPECT_GT(LHS_RESULT, RHS_RESULT, ...) \
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CF_COMPARE_EXPECT(>, LHS_RESULT, RHS_RESULT, ##__VA_ARGS__)
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} // namespace cuttlefish

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