folly/test/OptionalTest.cpp

   1 /*
   2  * Copyright 2016 Facebook, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *   http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <folly/Optional.h>
  18 #include <folly/Portability.h>
  19 #include <folly/portability/GTest.h>
  20
  21 #include <memory>
  22 #include <vector>
  23 #include <algorithm>
  24 #include <iomanip>
  25 #include <string>
  26 #include <type_traits>
  27
  28 #include <glog/logging.h>
  29 #include <boost/optional.hpp>
  30
  31 using std::unique_ptr;
  32 using std::shared_ptr;
  33
  34 namespace folly {
  35
  36 template<class V>
  37 std::ostream& operator<<(std::ostream& os, const Optional<V>& v) {
  38   if (v) {
  39     os << "Optional(" << v.value() << ')';
  40   } else {
  41     os << "None";
  42   }
  43   return os;
  44 }
  45
  46 struct NoDefault {
  47   NoDefault(int, int) {}
  48   char a, b, c;
  49 };
  50
  51 static_assert(sizeof(Optional<char>) == 2, "");
  52 static_assert(sizeof(Optional<int>) == 8, "");
  53 static_assert(sizeof(Optional<NoDefault>) == 4, "");
  54 static_assert(sizeof(Optional<char>) == sizeof(boost::optional<char>), "");
  55 static_assert(sizeof(Optional<short>) == sizeof(boost::optional<short>), "");
  56 static_assert(sizeof(Optional<int>) == sizeof(boost::optional<int>), "");
  57 static_assert(sizeof(Optional<double>) == sizeof(boost::optional<double>), "");
  58
  59 TEST(Optional, NoDefault) {
  60   Optional<NoDefault> x;
  61   EXPECT_FALSE(x);
  62   x.emplace(4, 5);
  63   EXPECT_TRUE(bool(x));
  64   x.clear();
  65   EXPECT_FALSE(x);
  66 }
  67
  68 TEST(Optional, String) {
  69   Optional<std::string> maybeString;
  70   EXPECT_FALSE(maybeString);
  71   maybeString = "hello";
  72   EXPECT_TRUE(bool(maybeString));
  73 }
  74
  75 TEST(Optional, Const) {
  76   { // default construct
  77     Optional<const int> opt;
  78     EXPECT_FALSE(bool(opt));
  79     opt.emplace(4);
  80     EXPECT_EQ(*opt, 4);
  81     opt.emplace(5);
  82     EXPECT_EQ(*opt, 5);
  83     opt.clear();
  84     EXPECT_FALSE(bool(opt));
  85   }
  86   { // copy-constructed
  87     const int x = 6;
  88     Optional<const int> opt(x);
  89     EXPECT_EQ(*opt, 6);
  90   }
  91   { // move-constructed
  92     const int x = 7;
  93     Optional<const int> opt(std::move(x));
  94     EXPECT_EQ(*opt, 7);
  95   }
  96   // no assignment allowed
  97 }
  98
  99 TEST(Optional, Simple) {
 100   Optional<int> opt;
 101   EXPECT_FALSE(bool(opt));
 102   EXPECT_EQ(42, opt.value_or(42));
 103   opt = 4;
 104   EXPECT_TRUE(bool(opt));
 105   EXPECT_EQ(4, *opt);
 106   EXPECT_EQ(4, opt.value_or(42));
 107   opt = 5;
 108   EXPECT_EQ(5, *opt);
 109   opt.clear();
 110   EXPECT_FALSE(bool(opt));
 111 }
 112
 113 class MoveTester {
 114 public:
 115   /* implicit */ MoveTester(const char* s) : s_(s) {}
 116   MoveTester(const MoveTester&) = default;
 117   MoveTester(MoveTester&& other) noexcept {
 118     s_ = std::move(other.s_);
 119     other.s_ = "";
 120   }
 121   MoveTester& operator=(const MoveTester&) = default;
 122   MoveTester& operator=(MoveTester&& other) noexcept {
 123     s_ = std::move(other.s_);
 124     other.s_ = "";
 125     return *this;
 126   }
 127 private:
 128   friend bool operator==(const MoveTester& o1, const MoveTester& o2);
 129   std::string s_;
 130 };
 131
 132 bool operator==(const MoveTester& o1, const MoveTester& o2) {
 133   return o1.s_ == o2.s_;
 134 }
 135
 136 TEST(Optional, value_or_rvalue_arg) {
 137   Optional<MoveTester> opt;
 138   MoveTester dflt = "hello";
 139   EXPECT_EQ("hello", opt.value_or(dflt));
 140   EXPECT_EQ("hello", dflt);
 141   EXPECT_EQ("hello", opt.value_or(std::move(dflt)));
 142   EXPECT_EQ("", dflt);
 143   EXPECT_EQ("world", opt.value_or("world"));
 144
 145   dflt = "hello";
 146   // Make sure that the const overload works on const objects
 147   const auto& optc = opt;
 148   EXPECT_EQ("hello", optc.value_or(dflt));
 149   EXPECT_EQ("hello", dflt);
 150   EXPECT_EQ("hello", optc.value_or(std::move(dflt)));
 151   EXPECT_EQ("", dflt);
 152   EXPECT_EQ("world", optc.value_or("world"));
 153
 154   dflt = "hello";
 155   opt = "meow";
 156   EXPECT_EQ("meow", opt.value_or(dflt));
 157   EXPECT_EQ("hello", dflt);
 158   EXPECT_EQ("meow", opt.value_or(std::move(dflt)));
 159   EXPECT_EQ("hello", dflt);  // only moved if used
 160 }
 161
 162 TEST(Optional, value_or_noncopyable) {
 163   Optional<std::unique_ptr<int>> opt;
 164   std::unique_ptr<int> dflt(new int(42));
 165   EXPECT_EQ(42, *std::move(opt).value_or(std::move(dflt)));
 166 }
 167
 168 struct ExpectingDeleter {
 169   explicit ExpectingDeleter(int expected) : expected(expected) { }
 170   int expected;
 171   void operator()(const int* ptr) {
 172     EXPECT_EQ(*ptr, expected);
 173     delete ptr;
 174   }
 175 };
 176
 177 TEST(Optional, value_move) {
 178   auto ptr = Optional<std::unique_ptr<int, ExpectingDeleter>>(
 179       {new int(42), ExpectingDeleter{1337}}).value();
 180   *ptr = 1337;
 181 }
 182
 183 TEST(Optional, dereference_move) {
 184   auto ptr = *Optional<std::unique_ptr<int, ExpectingDeleter>>(
 185       {new int(42), ExpectingDeleter{1337}});
 186   *ptr = 1337;
 187 }
 188
 189 TEST(Optional, EmptyConstruct) {
 190   Optional<int> opt;
 191   EXPECT_FALSE(bool(opt));
 192   Optional<int> test1(opt);
 193   EXPECT_FALSE(bool(test1));
 194   Optional<int> test2(std::move(opt));
 195   EXPECT_FALSE(bool(test2));
 196 }
 197
 198 TEST(Optional, Unique) {
 199   Optional<unique_ptr<int>> opt;
 200
 201   opt.clear();
 202   EXPECT_FALSE(bool(opt));
 203   // empty->emplaced
 204   opt.emplace(new int(5));
 205   EXPECT_TRUE(bool(opt));
 206   EXPECT_EQ(5, **opt);
 207
 208   opt.clear();
 209   // empty->moved
 210   opt = unique_ptr<int>(new int(6));
 211   EXPECT_EQ(6, **opt);
 212   // full->moved
 213   opt = unique_ptr<int>(new int(7));
 214   EXPECT_EQ(7, **opt);
 215
 216   // move it out by move construct
 217   Optional<unique_ptr<int>> moved(std::move(opt));
 218   EXPECT_TRUE(bool(moved));
 219   EXPECT_FALSE(bool(opt));
 220   EXPECT_EQ(7, **moved);
 221
 222   EXPECT_TRUE(bool(moved));
 223   opt = std::move(moved); // move it back by move assign
 224   EXPECT_FALSE(bool(moved));
 225   EXPECT_TRUE(bool(opt));
 226   EXPECT_EQ(7, **opt);
 227 }
 228
 229 TEST(Optional, Shared) {
 230   shared_ptr<int> ptr;
 231   Optional<shared_ptr<int>> opt;
 232   EXPECT_FALSE(bool(opt));
 233   // empty->emplaced
 234   opt.emplace(new int(5));
 235   EXPECT_TRUE(bool(opt));
 236   ptr = opt.value();
 237   EXPECT_EQ(ptr.get(), opt->get());
 238   EXPECT_EQ(2, ptr.use_count());
 239   opt.clear();
 240   EXPECT_EQ(1, ptr.use_count());
 241   // full->copied
 242   opt = ptr;
 243   EXPECT_EQ(2, ptr.use_count());
 244   EXPECT_EQ(ptr.get(), opt->get());
 245   opt.clear();
 246   EXPECT_EQ(1, ptr.use_count());
 247   // full->moved
 248   opt = std::move(ptr);
 249   EXPECT_EQ(1, opt->use_count());
 250   EXPECT_EQ(nullptr, ptr.get());
 251   {
 252     Optional<shared_ptr<int>> copied(opt);
 253     EXPECT_EQ(2, opt->use_count());
 254     Optional<shared_ptr<int>> moved(std::move(opt));
 255     EXPECT_EQ(2, moved->use_count());
 256     moved.emplace(new int(6));
 257     EXPECT_EQ(1, moved->use_count());
 258     copied = moved;
 259     EXPECT_EQ(2, moved->use_count());
 260   }
 261 }
 262
 263 TEST(Optional, Order) {
 264   std::vector<Optional<int>> vect{
 265     { none },
 266     { 3 },
 267     { 1 },
 268     { none },
 269     { 2 },
 270   };
 271   std::vector<Optional<int>> expected {
 272     { none },
 273     { none },
 274     { 1 },
 275     { 2 },
 276     { 3 },
 277   };
 278   std::sort(vect.begin(), vect.end());
 279   EXPECT_EQ(vect, expected);
 280 }
 281
 282 TEST(Optional, Swap) {
 283   Optional<std::string> a;
 284   Optional<std::string> b;
 285
 286   swap(a, b);
 287   EXPECT_FALSE(a.hasValue());
 288   EXPECT_FALSE(b.hasValue());
 289
 290   a = "hello";
 291   EXPECT_TRUE(a.hasValue());
 292   EXPECT_FALSE(b.hasValue());
 293   EXPECT_EQ("hello", a.value());
 294
 295   swap(a, b);
 296   EXPECT_FALSE(a.hasValue());
 297   EXPECT_TRUE(b.hasValue());
 298   EXPECT_EQ("hello", b.value());
 299
 300   a = "bye";
 301   EXPECT_TRUE(a.hasValue());
 302   EXPECT_EQ("bye", a.value());
 303
 304   swap(a, b);
 305 }
 306
 307 TEST(Optional, Comparisons) {
 308   Optional<int> o_;
 309   Optional<int> o1(1);
 310   Optional<int> o2(2);
 311
 312   EXPECT_TRUE(o_ <= (o_));
 313   EXPECT_TRUE(o_ == (o_));
 314   EXPECT_TRUE(o_ >= (o_));
 315
 316   EXPECT_TRUE(o1 < o2);
 317   EXPECT_TRUE(o1 <= o2);
 318   EXPECT_TRUE(o1 <= (o1));
 319   EXPECT_TRUE(o1 == (o1));
 320   EXPECT_TRUE(o1 != o2);
 321   EXPECT_TRUE(o1 >= (o1));
 322   EXPECT_TRUE(o2 >= o1);
 323   EXPECT_TRUE(o2 > o1);
 324
 325   EXPECT_FALSE(o2 < o1);
 326   EXPECT_FALSE(o2 <= o1);
 327   EXPECT_FALSE(o2 <= o1);
 328   EXPECT_FALSE(o2 == o1);
 329   EXPECT_FALSE(o1 != (o1));
 330   EXPECT_FALSE(o1 >= o2);
 331   EXPECT_FALSE(o1 >= o2);
 332   EXPECT_FALSE(o1 > o2);
 333
 334   /* folly::Optional explicitly doesn't support comparisons with contained value
 335   EXPECT_TRUE(1 < o2);
 336   EXPECT_TRUE(1 <= o2);
 337   EXPECT_TRUE(1 <= o1);
 338   EXPECT_TRUE(1 == o1);
 339   EXPECT_TRUE(2 != o1);
 340   EXPECT_TRUE(1 >= o1);
 341   EXPECT_TRUE(2 >= o1);
 342   EXPECT_TRUE(2 > o1);
 343
 344   EXPECT_FALSE(o2 < 1);
 345   EXPECT_FALSE(o2 <= 1);
 346   EXPECT_FALSE(o2 <= 1);
 347   EXPECT_FALSE(o2 == 1);
 348   EXPECT_FALSE(o2 != 2);
 349   EXPECT_FALSE(o1 >= 2);
 350   EXPECT_FALSE(o1 >= 2);
 351   EXPECT_FALSE(o1 > 2);
 352   */
 353
 354   // boost::optional does support comparison with contained value, which can
 355   // lead to confusion when a bool is contained
 356   boost::optional<int> boi(3);
 357   EXPECT_TRUE(boi < 5);
 358   EXPECT_TRUE(boi <= 4);
 359   EXPECT_TRUE(boi == 3);
 360   EXPECT_TRUE(boi != 2);
 361   EXPECT_TRUE(boi >= 1);
 362   EXPECT_TRUE(boi > 0);
 363   EXPECT_TRUE(1 <  boi);
 364   EXPECT_TRUE(2 <= boi);
 365   EXPECT_TRUE(3 == boi);
 366   EXPECT_TRUE(4 != boi);
 367   EXPECT_TRUE(5 >= boi);
 368   EXPECT_TRUE(6 >  boi);
 369
 370   boost::optional<bool> bob(false);
 371   EXPECT_TRUE((bool)bob);
 372   EXPECT_TRUE(bob == false); // well that was confusing
 373   EXPECT_FALSE(bob != false);
 374 }
 375
 376 TEST(Optional, Conversions) {
 377   Optional<bool> mbool;
 378   Optional<short> mshort;
 379   Optional<char*> mstr;
 380   Optional<int> mint;
 381
 382   //These don't compile
 383   //bool b = mbool;
 384   //short s = mshort;
 385   //char* c = mstr;
 386   //int x = mint;
 387   //char* c(mstr);
 388   //short s(mshort);
 389   //int x(mint);
 390
 391   // intended explicit operator bool, for if (opt).
 392   bool b(mbool);
 393   EXPECT_FALSE(b);
 394
 395   // Truthy tests work and are not ambiguous
 396   if (mbool && mshort && mstr && mint) { // only checks not-empty
 397     if (*mbool && *mshort && *mstr && *mint) { // only checks value
 398       ;
 399     }
 400   }
 401
 402   mbool = false;
 403   EXPECT_TRUE(bool(mbool));
 404   EXPECT_FALSE(*mbool);
 405
 406   mbool = true;
 407   EXPECT_TRUE(bool(mbool));
 408   EXPECT_TRUE(*mbool);
 409
 410   mbool = none;
 411   EXPECT_FALSE(bool(mbool));
 412
 413   // No conversion allowed; does not compile
 414   // EXPECT_TRUE(mbool == false);
 415 }
 416
 417 TEST(Optional, Pointee) {
 418   Optional<int> x;
 419   EXPECT_FALSE(get_pointer(x));
 420   x = 1;
 421   EXPECT_TRUE(get_pointer(x));
 422   *get_pointer(x) = 2;
 423   EXPECT_TRUE(*x == 2);
 424   x = none;
 425   EXPECT_FALSE(get_pointer(x));
 426 }
 427
 428 TEST(Optional, MakeOptional) {
 429   // const L-value version
 430   const std::string s("abc");
 431   auto optStr = make_optional(s);
 432   ASSERT_TRUE(optStr.hasValue());
 433   EXPECT_EQ(*optStr, "abc");
 434   *optStr = "cde";
 435   EXPECT_EQ(s, "abc");
 436   EXPECT_EQ(*optStr, "cde");
 437
 438   // L-value version
 439   std::string s2("abc");
 440   auto optStr2 = make_optional(s2);
 441   ASSERT_TRUE(optStr2.hasValue());
 442   EXPECT_EQ(*optStr2, "abc");
 443   *optStr2 = "cde";
 444   // it's vital to check that s2 wasn't clobbered
 445   EXPECT_EQ(s2, "abc");
 446
 447   // L-value reference version
 448   std::string& s3(s2);
 449   auto optStr3 = make_optional(s3);
 450   ASSERT_TRUE(optStr3.hasValue());
 451   EXPECT_EQ(*optStr3, "abc");
 452   *optStr3 = "cde";
 453   EXPECT_EQ(s3, "abc");
 454
 455   // R-value ref version
 456   unique_ptr<int> pInt(new int(3));
 457   auto optIntPtr = make_optional(std::move(pInt));
 458   EXPECT_TRUE(pInt.get() == nullptr);
 459   ASSERT_TRUE(optIntPtr.hasValue());
 460   EXPECT_EQ(**optIntPtr, 3);
 461 }
 462
 463 #if __CLANG_PREREQ(3, 6)
 464 # pragma clang diagnostic push
 465 # pragma clang diagnostic ignored "-Wself-move"
 466 #endif
 467
 468 TEST(Optional, SelfAssignment) {
 469   Optional<int> a = 42;
 470   a = a;
 471   ASSERT_TRUE(a.hasValue() && a.value() == 42);
 472
 473   Optional<int> b = 23333333;
 474   b = std::move(b);
 475   ASSERT_TRUE(b.hasValue() && b.value() == 23333333);
 476 }
 477
 478 #if __CLANG_PREREQ(3, 6)
 479 # pragma clang diagnostic pop
 480 #endif
 481
 482 class ContainsOptional {
 483  public:
 484   ContainsOptional() { }
 485   explicit ContainsOptional(int x) : opt_(x) { }
 486   bool hasValue() const { return opt_.hasValue(); }
 487   int value() const { return opt_.value(); }
 488
 489   ContainsOptional(const ContainsOptional &other) = default;
 490   ContainsOptional& operator=(const ContainsOptional &other) = default;
 491   ContainsOptional(ContainsOptional &&other) = default;
 492   ContainsOptional& operator=(ContainsOptional &&other) = default;
 493
 494  private:
 495   Optional<int> opt_;
 496 };
 497
 498 /**
 499  * Test that a class containing an Optional can be copy and move assigned.
 500  * This was broken under gcc 4.7 until assignment operators were explicitly
 501  * defined.
 502  */
 503 TEST(Optional, AssignmentContained) {
 504   {
 505     ContainsOptional source(5), target;
 506     target = source;
 507     EXPECT_TRUE(target.hasValue());
 508     EXPECT_EQ(5, target.value());
 509   }
 510
 511   {
 512     ContainsOptional source(5), target;
 513     target = std::move(source);
 514     EXPECT_TRUE(target.hasValue());
 515     EXPECT_EQ(5, target.value());
 516     EXPECT_FALSE(source.hasValue());
 517   }
 518
 519   {
 520     ContainsOptional opt_uninit, target(10);
 521     target = opt_uninit;
 522     EXPECT_FALSE(target.hasValue());
 523   }
 524 }
 525
 526 TEST(Optional, Exceptions) {
 527   Optional<int> empty;
 528   EXPECT_THROW(empty.value(), OptionalEmptyException);
 529 }
 530
 531 TEST(Optional, NoThrowDefaultConstructible) {
 532   EXPECT_TRUE(std::is_nothrow_default_constructible<Optional<bool>>::value);
 533 }
 534
 535 struct NoDestructor {};
 536
 537 struct WithDestructor {
 538   ~WithDestructor();
 539 };
 540
 541 TEST(Optional, TriviallyDestructible) {
 542   // These could all be static_asserts but EXPECT_* give much nicer output on
 543   // failure.
 544   EXPECT_TRUE(std::is_trivially_destructible<Optional<NoDestructor>>::value);
 545   EXPECT_TRUE(std::is_trivially_destructible<Optional<int>>::value);
 546   EXPECT_FALSE(std::is_trivially_destructible<Optional<WithDestructor>>::value);
 547 }
 548 }