Use absl::optional instead or rtc::Optional
BUG: webrtc:9078
Change-Id: I69aedce324d86e8894b81210a2de17c5ef68fd11
Reviewed-on: https://webrtc-review.googlesource.com/77082
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23440}diff --git a/DEPS b/DEPS
index e98c8fd..f4053cd 100644
--- a/DEPS
+++ b/DEPS
@@ -734,4 +734,7 @@
"+rtc_base",
"+test",
"+rtc_tools",
+
+ # Abseil whitelist.
+ "+absl/types/optional.h",
]
diff --git a/api/BUILD.gn b/api/BUILD.gn
index bc498ac..e693814 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -230,16 +230,15 @@
]
}
+# TODO(bugs.webrtc.org/9078): Deprecated, replaced by absl/types:optional.
+# Delete after webrtc and downstreams users are updated.
rtc_source_set("optional") {
visibility = [ "*" ]
sources = [
- "optional.cc",
"optional.h",
]
deps = [
- ":array_view",
- "../rtc_base:checks",
- "../rtc_base:sanitizer",
+ "//third_party/abseil-cpp/absl/types:optional",
]
}
@@ -381,6 +380,9 @@
sources = [
"array_view_unittest.cc",
+
+ # TODO(bugs.webrtc.org/8821): Remove optional_unittests when webrtc starts
+ # running absl unittest on each commit.
"optional_unittest.cc",
"ortc/mediadescription_unittest.cc",
"ortc/sessiondescription_unittest.cc",
diff --git a/api/optional.cc b/api/optional.cc
deleted file mode 100644
index 0f74bd2..0000000
--- a/api/optional.cc
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Copyright 2016 The WebRTC Project Authors. All rights reserved.
- *
- * Use of this source code is governed by a BSD-style license
- * that can be found in the LICENSE file in the root of the source
- * tree. An additional intellectual property rights grant can be found
- * in the file PATENTS. All contributing project authors may
- * be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "api/optional.h"
-
-namespace rtc {
-namespace optional_internal {
-
-#if RTC_HAS_ASAN
-
-const void* FunctionThatDoesNothingImpl(const void* x) {
- return x;
-}
-
-#endif
-
-struct NulloptArg {
- constexpr NulloptArg() {}
-};
-
-static NulloptArg nullopt_arg;
-
-} // namespace optional_internal
-
-const nullopt_t nullopt(rtc::optional_internal::nullopt_arg);
-
-} // namespace rtc
diff --git a/api/optional.h b/api/optional.h
index ba06831..eada13f 100644
--- a/api/optional.h
+++ b/api/optional.h
@@ -8,435 +8,19 @@
* be found in the AUTHORS file in the root of the source tree.
*/
+// TODO(bugs.webrtc.org/9078): Use absl::optional directly.
#ifndef API_OPTIONAL_H_
#define API_OPTIONAL_H_
-#include <algorithm>
-#include <memory>
-#include <utility>
-
-#ifdef UNIT_TEST
-#include <iomanip>
-#include <ostream>
-#endif // UNIT_TEST
-
-#include "api/array_view.h"
-#include "rtc_base/checks.h"
-#include "rtc_base/sanitizer.h"
+#include "absl/types/optional.h"
namespace rtc {
-namespace optional_internal {
-
-#if RTC_HAS_ASAN
-
-// This is a non-inlined function. The optimizer can't see inside it. It
-// prevents the compiler from generating optimized code that reads value_ even
-// if it is unset. Although safe, this causes memory sanitizers to complain.
-const void* FunctionThatDoesNothingImpl(const void*);
+using absl::nullopt_t;
+using absl::nullopt;
template <typename T>
-inline const T* FunctionThatDoesNothing(T* x) {
- return reinterpret_cast<const T*>(
- FunctionThatDoesNothingImpl(reinterpret_cast<const void*>(x)));
-}
-
-#else
-
-template <typename T>
-inline const T* FunctionThatDoesNothing(T* x) {
- return x;
-}
-
-#endif
-
-struct NulloptArg;
-
-} // namespace optional_internal
-
-// nullopt_t must be a non-aggregate literal type with a constexpr constructor
-// that takes some implementation-defined literal type. It mustn't have a
-// default constructor nor an initializer-list constructor.
-// See:
-// http://en.cppreference.com/w/cpp/utility/optional/nullopt_t
-// That page uses int, though this seems to confuse older versions of GCC.
-struct nullopt_t {
- constexpr explicit nullopt_t(rtc::optional_internal::NulloptArg&) {}
-};
-
-// Specification:
-// http://en.cppreference.com/w/cpp/utility/optional/nullopt
-extern const nullopt_t nullopt;
-
-// Simple std::optional-wannabe. It either contains a T or not.
-//
-// A moved-from Optional<T> may only be destroyed, and assigned to if T allows
-// being assigned to after having been moved from. Specifically, you may not
-// assume that it just doesn't contain a value anymore.
-//
-// Examples of good places to use Optional:
-//
-// - As a class or struct member, when the member doesn't always have a value:
-// struct Prisoner {
-// std::string name;
-// Optional<int> cell_number; // Empty if not currently incarcerated.
-// };
-//
-// - As a return value for functions that may fail to return a value on all
-// allowed inputs. For example, a function that searches an array might
-// return an Optional<size_t> (the index where it found the element, or
-// nothing if it didn't find it); and a function that parses numbers might
-// return Optional<double> (the parsed number, or nothing if parsing failed).
-//
-// Examples of bad places to use Optional:
-//
-// - As a return value for functions that may fail because of disallowed
-// inputs. For example, a string length function should not return
-// Optional<size_t> so that it can return nothing in case the caller passed
-// it a null pointer; the function should probably use RTC_[D]CHECK instead,
-// and return plain size_t.
-//
-// - As a return value for functions that may fail to return a value on all
-// allowed inputs, but need to tell the caller what went wrong. Returning
-// Optional<double> when parsing a single number as in the example above
-// might make sense, but any larger parse job is probably going to need to
-// tell the caller what the problem was, not just that there was one.
-//
-// - As a non-mutable function argument. When you want to pass a value of a
-// type T that can fail to be there, const T* is almost always both fastest
-// and cleanest. (If you're *sure* that the the caller will always already
-// have an Optional<T>, const Optional<T>& is slightly faster than const T*,
-// but this is a micro-optimization. In general, stick to const T*.)
-//
-// TODO(kwiberg): Get rid of this class when the standard library has
-// std::optional (and we're allowed to use it).
-template <typename T>
-class Optional final {
- public:
- // Construct an empty Optional.
- Optional() : has_value_(false), empty_('\0') { PoisonValue(); }
-
- Optional(rtc::nullopt_t) // NOLINT(runtime/explicit)
- : Optional() {}
-
- // Construct an Optional that contains a value.
- Optional(const T& value) // NOLINT(runtime/explicit)
- : has_value_(true) {
- new (&value_) T(value);
- }
- Optional(T&& value) // NOLINT(runtime/explicit)
- : has_value_(true) {
- new (&value_) T(std::move(value));
- }
-
- // Copy constructor: copies the value from m if it has one.
- Optional(const Optional& m) : has_value_(m.has_value_) {
- if (has_value_)
- new (&value_) T(m.value_);
- else
- PoisonValue();
- }
-
- // Move constructor: if m has a value, moves the value from m, leaving m
- // still in a state where it has a value, but a moved-from one (the
- // properties of which depends on T; the only general guarantee is that we
- // can destroy m).
- Optional(Optional&& m) : has_value_(m.has_value_) {
- if (has_value_)
- new (&value_) T(std::move(m.value_));
- else
- PoisonValue();
- }
-
- ~Optional() {
- if (has_value_)
- value_.~T();
- else
- UnpoisonValue();
- }
-
- Optional& operator=(rtc::nullopt_t) {
- reset();
- return *this;
- }
-
- // Copy assignment. Uses T's copy assignment if both sides have a value, T's
- // copy constructor if only the right-hand side has a value.
- Optional& operator=(const Optional& m) {
- if (m.has_value_) {
- if (has_value_) {
- value_ = m.value_; // T's copy assignment.
- } else {
- UnpoisonValue();
- new (&value_) T(m.value_); // T's copy constructor.
- has_value_ = true;
- }
- } else {
- reset();
- }
- return *this;
- }
-
- // Move assignment. Uses T's move assignment if both sides have a value, T's
- // move constructor if only the right-hand side has a value. The state of m
- // after it's been moved from is as for the move constructor.
- Optional& operator=(Optional&& m) {
- if (m.has_value_) {
- if (has_value_) {
- value_ = std::move(m.value_); // T's move assignment.
- } else {
- UnpoisonValue();
- new (&value_) T(std::move(m.value_)); // T's move constructor.
- has_value_ = true;
- }
- } else {
- reset();
- }
- return *this;
- }
-
- // Swap the values if both m1 and m2 have values; move the value if only one
- // of them has one.
- friend void swap(Optional& m1, Optional& m2) {
- if (m1.has_value_) {
- if (m2.has_value_) {
- // Both have values: swap.
- using std::swap;
- swap(m1.value_, m2.value_);
- } else {
- // Only m1 has a value: move it to m2.
- m2.UnpoisonValue();
- new (&m2.value_) T(std::move(m1.value_));
- m1.value_.~T(); // Destroy the moved-from value.
- m1.has_value_ = false;
- m2.has_value_ = true;
- m1.PoisonValue();
- }
- } else if (m2.has_value_) {
- // Only m2 has a value: move it to m1.
- m1.UnpoisonValue();
- new (&m1.value_) T(std::move(m2.value_));
- m2.value_.~T(); // Destroy the moved-from value.
- m1.has_value_ = true;
- m2.has_value_ = false;
- m2.PoisonValue();
- }
- }
-
- // Destroy any contained value. Has no effect if we have no value.
- void reset() {
- if (!has_value_)
- return;
- value_.~T();
- has_value_ = false;
- PoisonValue();
- }
-
- template <class... Args>
- void emplace(Args&&... args) {
- if (has_value_)
- value_.~T();
- else
- UnpoisonValue();
- new (&value_) T(std::forward<Args>(args)...);
- has_value_ = true;
- }
-
- // Conversion to bool to test if we have a value.
- explicit operator bool() const { return has_value_; }
- bool has_value() const { return has_value_; }
-
- // Dereferencing. Only allowed if we have a value.
- const T* operator->() const {
- RTC_DCHECK(has_value_);
- return &value_;
- }
- T* operator->() {
- RTC_DCHECK(has_value_);
- return &value_;
- }
- const T& operator*() const {
- RTC_DCHECK(has_value_);
- return value_;
- }
- T& operator*() {
- RTC_DCHECK(has_value_);
- return value_;
- }
- const T& value() const {
- RTC_DCHECK(has_value_);
- return value_;
- }
- T& value() {
- RTC_DCHECK(has_value_);
- return value_;
- }
-
- // Dereference with a default value in case we don't have a value.
- const T& value_or(const T& default_val) const {
- // The no-op call prevents the compiler from generating optimized code that
- // reads value_ even if !has_value_, but only if FunctionThatDoesNothing is
- // not completely inlined; see its declaration.).
- return has_value_ ? *optional_internal::FunctionThatDoesNothing(&value_)
- : default_val;
- }
-
- // Equality tests. Two Optionals are equal if they contain equivalent values,
- // or if they're both empty.
- friend bool operator==(const Optional& m1, const Optional& m2) {
- return m1.has_value_ && m2.has_value_ ? m1.value_ == m2.value_
- : m1.has_value_ == m2.has_value_;
- }
- friend bool operator==(const Optional& opt, const T& value) {
- return opt.has_value_ && opt.value_ == value;
- }
- friend bool operator==(const T& value, const Optional& opt) {
- return opt.has_value_ && value == opt.value_;
- }
-
- friend bool operator==(const Optional& opt, rtc::nullopt_t) {
- return !opt.has_value_;
- }
-
- friend bool operator==(rtc::nullopt_t, const Optional& opt) {
- return !opt.has_value_;
- }
-
- friend bool operator!=(const Optional& m1, const Optional& m2) {
- return m1.has_value_ && m2.has_value_ ? m1.value_ != m2.value_
- : m1.has_value_ != m2.has_value_;
- }
- friend bool operator!=(const Optional& opt, const T& value) {
- return !opt.has_value_ || opt.value_ != value;
- }
- friend bool operator!=(const T& value, const Optional& opt) {
- return !opt.has_value_ || value != opt.value_;
- }
-
- friend bool operator!=(const Optional& opt, rtc::nullopt_t) {
- return opt.has_value_;
- }
-
- friend bool operator!=(rtc::nullopt_t, const Optional& opt) {
- return opt.has_value_;
- }
-
- private:
- // Tell sanitizers that value_ shouldn't be touched.
- void PoisonValue() {
- rtc::AsanPoison(rtc::MakeArrayView(&value_, 1));
- rtc::MsanMarkUninitialized(rtc::MakeArrayView(&value_, 1));
- }
-
- // Tell sanitizers that value_ is OK to touch again.
- void UnpoisonValue() { rtc::AsanUnpoison(rtc::MakeArrayView(&value_, 1)); }
-
- bool has_value_; // True iff value_ contains a live value.
- union {
- // empty_ exists only to make it possible to initialize the union, even when
- // it doesn't contain any data. If the union goes uninitialized, it may
- // trigger compiler warnings.
- char empty_;
- // By placing value_ in a union, we get to manage its construction and
- // destruction manually: the Optional constructors won't automatically
- // construct it, and the Optional destructor won't automatically destroy
- // it. Basically, this just allocates a properly sized and aligned block of
- // memory in which we can manually put a T with placement new.
- T value_;
- };
-};
-
-#ifdef UNIT_TEST
-namespace optional_internal {
-
-// Checks if there's a valid PrintTo(const T&, std::ostream*) call for T.
-template <typename T>
-struct HasPrintTo {
- private:
- struct No {};
-
- template <typename T2>
- static auto Test(const T2& obj)
- -> decltype(PrintTo(obj, std::declval<std::ostream*>()));
-
- template <typename>
- static No Test(...);
-
- public:
- static constexpr bool value =
- !std::is_same<decltype(Test<T>(std::declval<const T&>())), No>::value;
-};
-
-// Checks if there's a valid operator<<(std::ostream&, const T&) call for T.
-template <typename T>
-struct HasOstreamOperator {
- private:
- struct No {};
-
- template <typename T2>
- static auto Test(const T2& obj)
- -> decltype(std::declval<std::ostream&>() << obj);
-
- template <typename>
- static No Test(...);
-
- public:
- static constexpr bool value =
- !std::is_same<decltype(Test<T>(std::declval<const T&>())), No>::value;
-};
-
-// Prefer using PrintTo to print the object.
-template <typename T>
-typename std::enable_if<HasPrintTo<T>::value, void>::type OptionalPrintToHelper(
- const T& value,
- std::ostream* os) {
- PrintTo(value, os);
-}
-
-// Fall back to operator<<(std::ostream&, ...) if it exists.
-template <typename T>
-typename std::enable_if<HasOstreamOperator<T>::value && !HasPrintTo<T>::value,
- void>::type
-OptionalPrintToHelper(const T& value, std::ostream* os) {
- *os << value;
-}
-
-inline void OptionalPrintObjectBytes(const unsigned char* bytes,
- size_t size,
- std::ostream* os) {
- *os << "<optional with " << size << "-byte object [";
- for (size_t i = 0; i != size; ++i) {
- *os << (i == 0 ? "" : ((i & 1) ? "-" : " "));
- *os << std::hex << std::setw(2) << std::setfill('0')
- << static_cast<int>(bytes[i]);
- }
- *os << "]>";
-}
-
-// As a final back-up, just print the contents of the objcets byte-wise.
-template <typename T>
-typename std::enable_if<!HasOstreamOperator<T>::value && !HasPrintTo<T>::value,
- void>::type
-OptionalPrintToHelper(const T& value, std::ostream* os) {
- OptionalPrintObjectBytes(reinterpret_cast<const unsigned char*>(&value),
- sizeof(value), os);
-}
-
-} // namespace optional_internal
-
-// PrintTo is used by gtest to print out the results of tests. We want to ensure
-// the object contained in an Optional can be printed out if it's set, while
-// avoiding touching the object's storage if it is undefined.
-template <typename T>
-void PrintTo(const rtc::Optional<T>& opt, std::ostream* os) {
- if (opt) {
- optional_internal::OptionalPrintToHelper(*opt, os);
- } else {
- *os << "<empty optional>";
- }
-}
-
-#endif // UNIT_TEST
+using Optional = absl::optional<T>;
} // namespace rtc
diff --git a/api/optional_unittest.cc b/api/optional_unittest.cc
index ad700dc..f56dc6d 100644
--- a/api/optional_unittest.cc
+++ b/api/optional_unittest.cc
@@ -8,6 +8,9 @@
* be found in the AUTHORS file in the root of the source tree.
*/
+// TODO(bugs.webrtc.org/8821): Delete this file when absl unittests run on
+// webrtc bots.
+
#include <memory>
#include <sstream>
#include <string>
@@ -702,31 +705,16 @@
TEST(OptionalTest, TestDereferenceWithDefault) {
auto log = Logger::Setup();
- {
- const Logger a(17), b(42);
- Optional<Logger> x(a);
- Optional<Logger> y;
- log->push_back("-1-");
- EXPECT_EQ(a, x.value_or(Logger(42)));
- log->push_back("-2-");
- EXPECT_EQ(b, y.value_or(Logger(42)));
- log->push_back("-3-");
- EXPECT_EQ(a, Optional<Logger>(Logger(17)).value_or(b));
- log->push_back("-4-");
- EXPECT_EQ(b, Optional<Logger>().value_or(b));
- log->push_back("-5-");
- }
- EXPECT_EQ(
- V("0:17. explicit constructor", "1:42. explicit constructor",
- "2:17. copy constructor (from 0:17)", "-1-",
- "3:42. explicit constructor", "operator== 0:17, 2:17",
- "3:42. destructor", "-2-", "4:42. explicit constructor",
- "operator== 1:42, 4:42", "4:42. destructor", "-3-",
- "5:17. explicit constructor", "6:17. move constructor (from 5:17)",
- "operator== 0:17, 6:17", "6:17. destructor", "5:17. destructor", "-4-",
- "operator== 1:42, 1:42", "-5-", "2:17. destructor", "1:42. destructor",
- "0:17. destructor"),
- *log);
+ const Logger a(17), b(42);
+ Optional<Logger> x(a);
+ Optional<Logger> y;
+ EXPECT_EQ(a, x.value_or(Logger(42)));
+ EXPECT_EQ(b, y.value_or(Logger(42)));
+ EXPECT_EQ(a, Optional<Logger>(Logger(17)).value_or(b));
+ EXPECT_EQ(b, Optional<Logger>().value_or(b));
+ // Can't expect exact list of constructors and destructors because it is
+ // compiler-dependent. i.e. msvc produce different output than clang. Calls
+ // above are subject to copy elision that allow to change behavior.
}
TEST(OptionalTest, TestEquality) {
@@ -871,8 +859,16 @@
*log);
}
-TEST(OptionalTest, TestPrintTo) {
- constexpr char kEmptyOptionalMessage[] = "<empty optional>";
+// Nice printing available only when GTEST aware ABSL is present
+#ifdef GTEST_HAS_ABSL
+#define MaybeTestPrintTo TestPrintTo
+#define MaybeTestUnprintablePrintTo TestUnprintablePrintTo
+#else
+#define MaybeTestPrintTo DISABLED_TestPrintTo
+#define MaybeTestUnprintablePrintTo DISABLED_TestUnprintablePrintTo
+#endif
+TEST(OptionalTest, MaybeTestPrintTo) {
+ constexpr char kEmptyOptionalMessage[] = "(nullopt)";
const Optional<MyUnprintableType> empty_unprintable;
const Optional<MyPrintableType> empty_printable;
const Optional<MyOstreamPrintableType> empty_ostream_printable;
@@ -880,14 +876,22 @@
EXPECT_EQ(kEmptyOptionalMessage, ::testing::PrintToString(empty_printable));
EXPECT_EQ(kEmptyOptionalMessage,
::testing::PrintToString(empty_ostream_printable));
- EXPECT_NE("1", ::testing::PrintToString(Optional<MyUnprintableType>({1})));
- EXPECT_NE("1", ::testing::PrintToString(Optional<MyPrintableType>({1})));
- EXPECT_EQ("The value is 1",
+ EXPECT_NE("(1)", ::testing::PrintToString(Optional<MyUnprintableType>({1})));
+ EXPECT_NE("(1)", ::testing::PrintToString(Optional<MyPrintableType>({1})));
+ EXPECT_EQ("(The value is 1)",
::testing::PrintToString(Optional<MyPrintableType>({1})));
- EXPECT_EQ("1",
+ EXPECT_EQ("(1)",
::testing::PrintToString(Optional<MyOstreamPrintableType>({1})));
}
+TEST(OptionalTest, MaybeTestUnprintablePrintTo) {
+ struct UnprintableType {
+ uint8_t value[5];
+ };
+ Optional<UnprintableType> opt({0xa1, 0xb2, 0xc3, 0xd4, 0xe5});
+ EXPECT_EQ("(5-byte object <A1-B2 C3-D4 E5>)", ::testing::PrintToString(opt));
+}
+
void UnusedFunctionWorkaround() {
// These are here to ensure we don't get warnings about ostream and PrintTo
// for MyPrintableType never getting called.
