folly/test/OptionalTest.cpp

   1 /*
   2  * Copyright 2017 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/GTest.h>
  19
  20 #include <algorithm>
  21 #include <iomanip>
  22 #include <memory>
  23 #include <string>
  24 #include <type_traits>
  25 #include <unordered_map>
  26 #include <vector>
  27
  28 #include <boost/optional.hpp>
  29
  30 using std::unique_ptr;
  31 using std::shared_ptr;
  32
  33 namespace folly {
  34
  35 template<class V>
  36 std::ostream& operator<<(std::ostream& os, const Optional<V>& v) {
  37   if (v) {
  38     os << "Optional(" << v.value() << ')';
  39   } else {
  40     os << "None";
  41   }
  42   return os;
  43 }
  44
  45 struct NoDefault {
  46   NoDefault(int, int) {}
  47   char a, b, c;
  48 };
  49
  50 static_assert(sizeof(Optional<char>) == 2, "");
  51 static_assert(sizeof(Optional<int>) == 8, "");
  52 static_assert(sizeof(Optional<NoDefault>) == 4, "");
  53 static_assert(sizeof(Optional<char>) == sizeof(boost::optional<char>), "");
  54 static_assert(sizeof(Optional<short>) == sizeof(boost::optional<short>), "");
  55 static_assert(sizeof(Optional<int>) == sizeof(boost::optional<int>), "");
  56 static_assert(sizeof(Optional<double>) == sizeof(boost::optional<double>), "");
  57
  58 TEST(Optional, NoDefault) {
  59   Optional<NoDefault> x;
  60   EXPECT_FALSE(x);
  61   x.emplace(4, 5);
  62   EXPECT_TRUE(bool(x));
  63   x.clear();
  64   EXPECT_FALSE(x);
  65 }
  66
  67 TEST(Optional, String) {
  68   Optional<std::string> maybeString;
  69   EXPECT_FALSE(maybeString);
  70   maybeString = "hello";
  71   EXPECT_TRUE(bool(maybeString));
  72 }
  73
  74 TEST(Optional, Const) {
  75   { // default construct
  76     Optional<const int> opt;
  77     EXPECT_FALSE(bool(opt));
  78     opt.emplace(4);
  79     EXPECT_EQ(*opt, 4);
  80     opt.emplace(5);
  81     EXPECT_EQ(*opt, 5);
  82     opt.clear();
  83     EXPECT_FALSE(bool(opt));
  84   }
  85   { // copy-constructed
  86     const int x = 6;
  87     Optional<const int> opt(x);
  88     EXPECT_EQ(*opt, 6);
  89   }
  90   { // move-constructed
  91     const int x = 7;
  92     Optional<const int> opt(std::move(x));
  93     EXPECT_EQ(*opt, 7);
  94   }
  95   // no assignment allowed
  96 }
  97
  98 TEST(Optional, Simple) {
  99   Optional<int> opt;
 100   EXPECT_FALSE(bool(opt));
 101   EXPECT_EQ(42, opt.value_or(42));
 102   opt = 4;
 103   EXPECT_TRUE(bool(opt));
 104   EXPECT_EQ(4, *opt);
 105   EXPECT_EQ(4, opt.value_or(42));
 106   opt = 5;
 107   EXPECT_EQ(5, *opt);
 108   opt.clear();
 109   EXPECT_FALSE(bool(opt));
 110 }
 111
 112 class MoveTester {
 113 public:
 114   /* implicit */ MoveTester(const char* s) : s_(s) {}
 115   MoveTester(const MoveTester&) = default;
 116   MoveTester(MoveTester&& other) noexcept {
 117     s_ = std::move(other.s_);
 118     other.s_ = "";
 119   }
 120   MoveTester& operator=(const MoveTester&) = default;
 121   MoveTester& operator=(MoveTester&& other) noexcept {
 122     s_ = std::move(other.s_);
 123     other.s_ = "";
 124     return *this;
 125   }
 126 private:
 127   friend bool operator==(const MoveTester& o1, const MoveTester& o2);
 128   std::string s_;
 129 };
 130
 131 bool operator==(const MoveTester& o1, const MoveTester& o2) {
 132   return o1.s_ == o2.s_;
 133 }
 134
 135 TEST(Optional, value_or_rvalue_arg) {
 136   Optional<MoveTester> opt;
 137   MoveTester dflt = "hello";
 138   EXPECT_EQ("hello", opt.value_or(dflt));
 139   EXPECT_EQ("hello", dflt);
 140   EXPECT_EQ("hello", opt.value_or(std::move(dflt)));
 141   EXPECT_EQ("", dflt);
 142   EXPECT_EQ("world", opt.value_or("world"));
 143
 144   dflt = "hello";
 145   // Make sure that the const overload works on const objects
 146   const auto& optc = opt;
 147   EXPECT_EQ("hello", optc.value_or(dflt));
 148   EXPECT_EQ("hello", dflt);
 149   EXPECT_EQ("hello", optc.value_or(std::move(dflt)));
 150   EXPECT_EQ("", dflt);
 151   EXPECT_EQ("world", optc.value_or("world"));
 152
 153   dflt = "hello";
 154   opt = "meow";
 155   EXPECT_EQ("meow", opt.value_or(dflt));
 156   EXPECT_EQ("hello", dflt);
 157   EXPECT_EQ("meow", opt.value_or(std::move(dflt)));
 158   EXPECT_EQ("hello", dflt);  // only moved if used
 159 }
 160
 161 TEST(Optional, value_or_noncopyable) {
 162   Optional<std::unique_ptr<int>> opt;
 163   std::unique_ptr<int> dflt(new int(42));
 164   EXPECT_EQ(42, *std::move(opt).value_or(std::move(dflt)));
 165 }
 166
 167 struct ExpectingDeleter {
 168   explicit ExpectingDeleter(int expected) : expected(expected) { }
 169   int expected;
 170   void operator()(const int* ptr) {
 171     EXPECT_EQ(*ptr, expected);
 172     delete ptr;
 173   }
 174 };
 175
 176 TEST(Optional, value_move) {
 177   auto ptr = Optional<std::unique_ptr<int, ExpectingDeleter>>(
 178       {new int(42), ExpectingDeleter{1337}}).value();
 179   *ptr = 1337;
 180 }
 181
 182 TEST(Optional, dereference_move) {
 183   auto ptr = *Optional<std::unique_ptr<int, ExpectingDeleter>>(
 184       {new int(42), ExpectingDeleter{1337}});
 185   *ptr = 1337;
 186 }
 187
 188 TEST(Optional, EmptyConstruct) {
 189   Optional<int> opt;
 190   EXPECT_FALSE(bool(opt));
 191   Optional<int> test1(opt);
 192   EXPECT_FALSE(bool(test1));
 193   Optional<int> test2(std::move(opt));
 194   EXPECT_FALSE(bool(test2));
 195 }
 196
 197 TEST(Optional, Unique) {
 198   Optional<unique_ptr<int>> opt;
 199
 200   opt.clear();
 201   EXPECT_FALSE(bool(opt));
 202   // empty->emplaced
 203   opt.emplace(new int(5));
 204   EXPECT_TRUE(bool(opt));
 205   EXPECT_EQ(5, **opt);
 206
 207   opt.clear();
 208   // empty->moved
 209   opt = unique_ptr<int>(new int(6));
 210   EXPECT_EQ(6, **opt);
 211   // full->moved
 212   opt = unique_ptr<int>(new int(7));
 213   EXPECT_EQ(7, **opt);
 214
 215   // move it out by move construct
 216   Optional<unique_ptr<int>> moved(std::move(opt));
 217   EXPECT_TRUE(bool(moved));
 218   EXPECT_FALSE(bool(opt));
 219   EXPECT_EQ(7, **moved);
 220
 221   EXPECT_TRUE(bool(moved));
 222   opt = std::move(moved); // move it back by move assign
 223   EXPECT_FALSE(bool(moved));
 224   EXPECT_TRUE(bool(opt));
 225   EXPECT_EQ(7, **opt);
 226 }
 227
 228 TEST(Optional, Shared) {
 229   shared_ptr<int> ptr;
 230   Optional<shared_ptr<int>> opt;
 231   EXPECT_FALSE(bool(opt));
 232   // empty->emplaced
 233   opt.emplace(new int(5));
 234   EXPECT_TRUE(bool(opt));
 235   ptr = opt.value();
 236   EXPECT_EQ(ptr.get(), opt->get());
 237   EXPECT_EQ(2, ptr.use_count());
 238   opt.clear();
 239   EXPECT_EQ(1, ptr.use_count());
 240   // full->copied
 241   opt = ptr;
 242   EXPECT_EQ(2, ptr.use_count());
 243   EXPECT_EQ(ptr.get(), opt->get());
 244   opt.clear();
 245   EXPECT_EQ(1, ptr.use_count());
 246   // full->moved
 247   opt = std::move(ptr);
 248   EXPECT_EQ(1, opt->use_count());
 249   EXPECT_EQ(nullptr, ptr.get());
 250   {
 251     Optional<shared_ptr<int>> copied(opt);
 252     EXPECT_EQ(2, opt->use_count());
 253     Optional<shared_ptr<int>> moved(std::move(opt));
 254     EXPECT_EQ(2, moved->use_count());
 255     moved.emplace(new int(6));
 256     EXPECT_EQ(1, moved->use_count());
 257     copied = moved;
 258     EXPECT_EQ(2, moved->use_count());
 259   }
 260 }
 261
 262 TEST(Optional, Order) {
 263   std::vector<Optional<int>> vect{
 264     { none },
 265     { 3 },
 266     { 1 },
 267     { none },
 268     { 2 },
 269   };
 270   std::vector<Optional<int>> expected {
 271     { none },
 272     { none },
 273     { 1 },
 274     { 2 },
 275     { 3 },
 276   };
 277   std::sort(vect.begin(), vect.end());
 278   EXPECT_EQ(vect, expected);
 279 }
 280
 281 TEST(Optional, Swap) {
 282   Optional<std::string> a;
 283   Optional<std::string> b;
 284
 285   swap(a, b);
 286   EXPECT_FALSE(a.hasValue());
 287   EXPECT_FALSE(b.hasValue());
 288
 289   a = "hello";
 290   EXPECT_TRUE(a.hasValue());
 291   EXPECT_FALSE(b.hasValue());
 292   EXPECT_EQ("hello", a.value());
 293
 294   swap(a, b);
 295   EXPECT_FALSE(a.hasValue());
 296   EXPECT_TRUE(b.hasValue());
 297   EXPECT_EQ("hello", b.value());
 298
 299   a = "bye";
 300   EXPECT_TRUE(a.hasValue());
 301   EXPECT_EQ("bye", a.value());
 302
 303   swap(a, b);
 304 }
 305
 306 TEST(Optional, Comparisons) {
 307   Optional<int> o_;
 308   Optional<int> o1(1);
 309   Optional<int> o2(2);
 310
 311   EXPECT_TRUE(o_ <= (o_));
 312   EXPECT_TRUE(o_ == (o_));
 313   EXPECT_TRUE(o_ >= (o_));
 314
 315   EXPECT_TRUE(o1 < o2);
 316   EXPECT_TRUE(o1 <= o2);
 317   EXPECT_TRUE(o1 <= (o1));
 318   EXPECT_TRUE(o1 == (o1));
 319   EXPECT_TRUE(o1 != o2);
 320   EXPECT_TRUE(o1 >= (o1));
 321   EXPECT_TRUE(o2 >= o1);
 322   EXPECT_TRUE(o2 > o1);
 323
 324   EXPECT_FALSE(o2 < o1);
 325   EXPECT_FALSE(o2 <= o1);
 326   EXPECT_FALSE(o2 <= o1);
 327   EXPECT_FALSE(o2 == o1);
 328   EXPECT_FALSE(o1 != (o1));
 329   EXPECT_FALSE(o1 >= o2);
 330   EXPECT_FALSE(o1 >= o2);
 331   EXPECT_FALSE(o1 > o2);
 332
 333   /* folly::Optional explicitly doesn't support comparisons with contained value
 334   EXPECT_TRUE(1 < o2);
 335   EXPECT_TRUE(1 <= o2);
 336   EXPECT_TRUE(1 <= o1);
 337   EXPECT_TRUE(1 == o1);
 338   EXPECT_TRUE(2 != o1);
 339   EXPECT_TRUE(1 >= o1);
 340   EXPECT_TRUE(2 >= o1);
 341   EXPECT_TRUE(2 > o1);
 342
 343   EXPECT_FALSE(o2 < 1);
 344   EXPECT_FALSE(o2 <= 1);
 345   EXPECT_FALSE(o2 <= 1);
 346   EXPECT_FALSE(o2 == 1);
 347   EXPECT_FALSE(o2 != 2);
 348   EXPECT_FALSE(o1 >= 2);
 349   EXPECT_FALSE(o1 >= 2);
 350   EXPECT_FALSE(o1 > 2);
 351   */
 352
 353   // boost::optional does support comparison with contained value, which can
 354   // lead to confusion when a bool is contained
 355   boost::optional<int> boi(3);
 356   EXPECT_TRUE(boi < 5);
 357   EXPECT_TRUE(boi <= 4);
 358   EXPECT_TRUE(boi == 3);
 359   EXPECT_TRUE(boi != 2);
 360   EXPECT_TRUE(boi >= 1);
 361   EXPECT_TRUE(boi > 0);
 362   EXPECT_TRUE(1 <  boi);
 363   EXPECT_TRUE(2 <= boi);
 364   EXPECT_TRUE(3 == boi);
 365   EXPECT_TRUE(4 != boi);
 366   EXPECT_TRUE(5 >= boi);
 367   EXPECT_TRUE(6 >  boi);
 368
 369   boost::optional<bool> bob(false);
 370   EXPECT_TRUE((bool)bob);
 371   EXPECT_TRUE(bob == false); // well that was confusing
 372   EXPECT_FALSE(bob != false);
 373 }
 374
 375 TEST(Optional, HeterogeneousComparisons) {
 376   using opt8 = Optional<uint8_t>;
 377   using opt64 = Optional<uint64_t>;
 378
 379   EXPECT_TRUE(opt8(4) == uint64_t(4));
 380   EXPECT_FALSE(opt8(8) == uint64_t(4));
 381   EXPECT_FALSE(opt8() == uint64_t(4));
 382
 383   EXPECT_TRUE(uint64_t(4) == opt8(4));
 384   EXPECT_FALSE(uint64_t(4) == opt8(8));
 385   EXPECT_FALSE(uint64_t(4) == opt8());
 386
 387   EXPECT_FALSE(opt8(4) != uint64_t(4));
 388   EXPECT_TRUE(opt8(8) != uint64_t(4));
 389   EXPECT_TRUE(opt8() != uint64_t(4));
 390
 391   EXPECT_FALSE(uint64_t(4) != opt8(4));
 392   EXPECT_TRUE(uint64_t(4) != opt8(8));
 393   EXPECT_TRUE(uint64_t(4) != opt8());
 394
 395   EXPECT_TRUE(opt8() == opt64());
 396   EXPECT_TRUE(opt8(4) == opt64(4));
 397   EXPECT_FALSE(opt8(8) == opt64(4));
 398   EXPECT_FALSE(opt8() == opt64(4));
 399   EXPECT_FALSE(opt8(4) == opt64());
 400
 401   EXPECT_FALSE(opt8() != opt64());
 402   EXPECT_FALSE(opt8(4) != opt64(4));
 403   EXPECT_TRUE(opt8(8) != opt64(4));
 404   EXPECT_TRUE(opt8() != opt64(4));
 405   EXPECT_TRUE(opt8(4) != opt64());
 406
 407   EXPECT_TRUE(opt8() < opt64(4));
 408   EXPECT_TRUE(opt8(4) < opt64(8));
 409   EXPECT_FALSE(opt8() < opt64());
 410   EXPECT_FALSE(opt8(4) < opt64(4));
 411   EXPECT_FALSE(opt8(8) < opt64(4));
 412   EXPECT_FALSE(opt8(4) < opt64());
 413
 414   EXPECT_FALSE(opt8() > opt64(4));
 415   EXPECT_FALSE(opt8(4) > opt64(8));
 416   EXPECT_FALSE(opt8() > opt64());
 417   EXPECT_FALSE(opt8(4) > opt64(4));
 418   EXPECT_TRUE(opt8(8) > opt64(4));
 419   EXPECT_TRUE(opt8(4) > opt64());
 420
 421   EXPECT_TRUE(opt8() <= opt64(4));
 422   EXPECT_TRUE(opt8(4) <= opt64(8));
 423   EXPECT_TRUE(opt8() <= opt64());
 424   EXPECT_TRUE(opt8(4) <= opt64(4));
 425   EXPECT_FALSE(opt8(8) <= opt64(4));
 426   EXPECT_FALSE(opt8(4) <= opt64());
 427
 428   EXPECT_FALSE(opt8() >= opt64(4));
 429   EXPECT_FALSE(opt8(4) >= opt64(8));
 430   EXPECT_TRUE(opt8() >= opt64());
 431   EXPECT_TRUE(opt8(4) >= opt64(4));
 432   EXPECT_TRUE(opt8(8) >= opt64(4));
 433   EXPECT_TRUE(opt8(4) >= opt64());
 434 }
 435
 436 TEST(Optional, Conversions) {
 437   Optional<bool> mbool;
 438   Optional<short> mshort;
 439   Optional<char*> mstr;
 440   Optional<int> mint;
 441
 442   //These don't compile
 443   //bool b = mbool;
 444   //short s = mshort;
 445   //char* c = mstr;
 446   //int x = mint;
 447   //char* c(mstr);
 448   //short s(mshort);
 449   //int x(mint);
 450
 451   // intended explicit operator bool, for if (opt).
 452   bool b(mbool);
 453   EXPECT_FALSE(b);
 454
 455   // Truthy tests work and are not ambiguous
 456   if (mbool && mshort && mstr && mint) { // only checks not-empty
 457     if (*mbool && *mshort && *mstr && *mint) { // only checks value
 458       ;
 459     }
 460   }
 461
 462   mbool = false;
 463   EXPECT_TRUE(bool(mbool));
 464   EXPECT_FALSE(*mbool);
 465
 466   mbool = true;
 467   EXPECT_TRUE(bool(mbool));
 468   EXPECT_TRUE(*mbool);
 469
 470   mbool = none;
 471   EXPECT_FALSE(bool(mbool));
 472
 473   // No conversion allowed; does not compile
 474   // EXPECT_TRUE(mbool == false);
 475 }
 476
 477 TEST(Optional, Pointee) {
 478   Optional<int> x;
 479   EXPECT_FALSE(get_pointer(x));
 480   x = 1;
 481   EXPECT_TRUE(get_pointer(x));
 482   *get_pointer(x) = 2;
 483   EXPECT_TRUE(*x == 2);
 484   x = none;
 485   EXPECT_FALSE(get_pointer(x));
 486 }
 487
 488 TEST(Optional, MakeOptional) {
 489   // const L-value version
 490   const std::string s("abc");
 491   auto optStr = make_optional(s);
 492   ASSERT_TRUE(optStr.hasValue());
 493   EXPECT_EQ(*optStr, "abc");
 494   *optStr = "cde";
 495   EXPECT_EQ(s, "abc");
 496   EXPECT_EQ(*optStr, "cde");
 497
 498   // L-value version
 499   std::string s2("abc");
 500   auto optStr2 = make_optional(s2);
 501   ASSERT_TRUE(optStr2.hasValue());
 502   EXPECT_EQ(*optStr2, "abc");
 503   *optStr2 = "cde";
 504   // it's vital to check that s2 wasn't clobbered
 505   EXPECT_EQ(s2, "abc");
 506
 507   // L-value reference version
 508   std::string& s3(s2);
 509   auto optStr3 = make_optional(s3);
 510   ASSERT_TRUE(optStr3.hasValue());
 511   EXPECT_EQ(*optStr3, "abc");
 512   *optStr3 = "cde";
 513   EXPECT_EQ(s3, "abc");
 514
 515   // R-value ref version
 516   unique_ptr<int> pInt(new int(3));
 517   auto optIntPtr = make_optional(std::move(pInt));
 518   EXPECT_TRUE(pInt.get() == nullptr);
 519   ASSERT_TRUE(optIntPtr.hasValue());
 520   EXPECT_EQ(**optIntPtr, 3);
 521 }
 522
 523 #if __clang__
 524 # pragma clang diagnostic push
 525 # pragma clang diagnostic ignored "-Wself-move"
 526 #endif
 527
 528 TEST(Optional, SelfAssignment) {
 529   Optional<int> a = 42;
 530   a = a;
 531   ASSERT_TRUE(a.hasValue() && a.value() == 42);
 532
 533   Optional<int> b = 23333333;
 534   b = std::move(b);
 535   ASSERT_TRUE(b.hasValue() && b.value() == 23333333);
 536 }
 537
 538 #if __clang__
 539 # pragma clang diagnostic pop
 540 #endif
 541
 542 class ContainsOptional {
 543  public:
 544   ContainsOptional() { }
 545   explicit ContainsOptional(int x) : opt_(x) { }
 546   bool hasValue() const { return opt_.hasValue(); }
 547   int value() const { return opt_.value(); }
 548
 549   ContainsOptional(const ContainsOptional &other) = default;
 550   ContainsOptional& operator=(const ContainsOptional &other) = default;
 551   ContainsOptional(ContainsOptional &&other) = default;
 552   ContainsOptional& operator=(ContainsOptional &&other) = default;
 553
 554  private:
 555   Optional<int> opt_;
 556 };
 557
 558 /**
 559  * Test that a class containing an Optional can be copy and move assigned.
 560  * This was broken under gcc 4.7 until assignment operators were explicitly
 561  * defined.
 562  */
 563 TEST(Optional, AssignmentContained) {
 564   {
 565     ContainsOptional source(5), target;
 566     target = source;
 567     EXPECT_TRUE(target.hasValue());
 568     EXPECT_EQ(5, target.value());
 569   }
 570
 571   {
 572     ContainsOptional source(5), target;
 573     target = std::move(source);
 574     EXPECT_TRUE(target.hasValue());
 575     EXPECT_EQ(5, target.value());
 576     EXPECT_FALSE(source.hasValue());
 577   }
 578
 579   {
 580     ContainsOptional opt_uninit, target(10);
 581     target = opt_uninit;
 582     EXPECT_FALSE(target.hasValue());
 583   }
 584 }
 585
 586 TEST(Optional, Exceptions) {
 587   Optional<int> empty;
 588   EXPECT_THROW(empty.value(), OptionalEmptyException);
 589 }
 590
 591 TEST(Optional, NoThrowDefaultConstructible) {
 592   EXPECT_TRUE(std::is_nothrow_default_constructible<Optional<bool>>::value);
 593 }
 594
 595 struct NoDestructor {};
 596
 597 struct WithDestructor {
 598   ~WithDestructor();
 599 };
 600
 601 TEST(Optional, TriviallyDestructible) {
 602   // These could all be static_asserts but EXPECT_* give much nicer output on
 603   // failure.
 604   EXPECT_TRUE(std::is_trivially_destructible<Optional<NoDestructor>>::value);
 605   EXPECT_TRUE(std::is_trivially_destructible<Optional<int>>::value);
 606   EXPECT_FALSE(std::is_trivially_destructible<Optional<WithDestructor>>::value);
 607 }
 608
 609 TEST(Optional, Hash) {
 610   // Test it's usable in std::unordered map (compile time check)
 611   std::unordered_map<Optional<int>, Optional<int>> obj;
 612   // Also check the std::hash template can be instantiated by the compiler
 613   std::hash<Optional<int>>()(none);
 614   std::hash<Optional<int>>()(3);
 615 }
 616 }