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, Conversions) {
 376   Optional<bool> mbool;
 377   Optional<short> mshort;
 378   Optional<char*> mstr;
 379   Optional<int> mint;
 380
 381   //These don't compile
 382   //bool b = mbool;
 383   //short s = mshort;
 384   //char* c = mstr;
 385   //int x = mint;
 386   //char* c(mstr);
 387   //short s(mshort);
 388   //int x(mint);
 389
 390   // intended explicit operator bool, for if (opt).
 391   bool b(mbool);
 392   EXPECT_FALSE(b);
 393
 394   // Truthy tests work and are not ambiguous
 395   if (mbool && mshort && mstr && mint) { // only checks not-empty
 396     if (*mbool && *mshort && *mstr && *mint) { // only checks value
 397       ;
 398     }
 399   }
 400
 401   mbool = false;
 402   EXPECT_TRUE(bool(mbool));
 403   EXPECT_FALSE(*mbool);
 404
 405   mbool = true;
 406   EXPECT_TRUE(bool(mbool));
 407   EXPECT_TRUE(*mbool);
 408
 409   mbool = none;
 410   EXPECT_FALSE(bool(mbool));
 411
 412   // No conversion allowed; does not compile
 413   // EXPECT_TRUE(mbool == false);
 414 }
 415
 416 TEST(Optional, Pointee) {
 417   Optional<int> x;
 418   EXPECT_FALSE(get_pointer(x));
 419   x = 1;
 420   EXPECT_TRUE(get_pointer(x));
 421   *get_pointer(x) = 2;
 422   EXPECT_TRUE(*x == 2);
 423   x = none;
 424   EXPECT_FALSE(get_pointer(x));
 425 }
 426
 427 TEST(Optional, MakeOptional) {
 428   // const L-value version
 429   const std::string s("abc");
 430   auto optStr = make_optional(s);
 431   ASSERT_TRUE(optStr.hasValue());
 432   EXPECT_EQ(*optStr, "abc");
 433   *optStr = "cde";
 434   EXPECT_EQ(s, "abc");
 435   EXPECT_EQ(*optStr, "cde");
 436
 437   // L-value version
 438   std::string s2("abc");
 439   auto optStr2 = make_optional(s2);
 440   ASSERT_TRUE(optStr2.hasValue());
 441   EXPECT_EQ(*optStr2, "abc");
 442   *optStr2 = "cde";
 443   // it's vital to check that s2 wasn't clobbered
 444   EXPECT_EQ(s2, "abc");
 445
 446   // L-value reference version
 447   std::string& s3(s2);
 448   auto optStr3 = make_optional(s3);
 449   ASSERT_TRUE(optStr3.hasValue());
 450   EXPECT_EQ(*optStr3, "abc");
 451   *optStr3 = "cde";
 452   EXPECT_EQ(s3, "abc");
 453
 454   // R-value ref version
 455   unique_ptr<int> pInt(new int(3));
 456   auto optIntPtr = make_optional(std::move(pInt));
 457   EXPECT_TRUE(pInt.get() == nullptr);
 458   ASSERT_TRUE(optIntPtr.hasValue());
 459   EXPECT_EQ(**optIntPtr, 3);
 460 }
 461
 462 #if __clang__
 463 # pragma clang diagnostic push
 464 # pragma clang diagnostic ignored "-Wself-move"
 465 #endif
 466
 467 TEST(Optional, SelfAssignment) {
 468   Optional<int> a = 42;
 469   a = a;
 470   ASSERT_TRUE(a.hasValue() && a.value() == 42);
 471
 472   Optional<int> b = 23333333;
 473   b = std::move(b);
 474   ASSERT_TRUE(b.hasValue() && b.value() == 23333333);
 475 }
 476
 477 #if __clang__
 478 # pragma clang diagnostic pop
 479 #endif
 480
 481 class ContainsOptional {
 482  public:
 483   ContainsOptional() { }
 484   explicit ContainsOptional(int x) : opt_(x) { }
 485   bool hasValue() const { return opt_.hasValue(); }
 486   int value() const { return opt_.value(); }
 487
 488   ContainsOptional(const ContainsOptional &other) = default;
 489   ContainsOptional& operator=(const ContainsOptional &other) = default;
 490   ContainsOptional(ContainsOptional &&other) = default;
 491   ContainsOptional& operator=(ContainsOptional &&other) = default;
 492
 493  private:
 494   Optional<int> opt_;
 495 };
 496
 497 /**
 498  * Test that a class containing an Optional can be copy and move assigned.
 499  * This was broken under gcc 4.7 until assignment operators were explicitly
 500  * defined.
 501  */
 502 TEST(Optional, AssignmentContained) {
 503   {
 504     ContainsOptional source(5), target;
 505     target = source;
 506     EXPECT_TRUE(target.hasValue());
 507     EXPECT_EQ(5, target.value());
 508   }
 509
 510   {
 511     ContainsOptional source(5), target;
 512     target = std::move(source);
 513     EXPECT_TRUE(target.hasValue());
 514     EXPECT_EQ(5, target.value());
 515     EXPECT_FALSE(source.hasValue());
 516   }
 517
 518   {
 519     ContainsOptional opt_uninit, target(10);
 520     target = opt_uninit;
 521     EXPECT_FALSE(target.hasValue());
 522   }
 523 }
 524
 525 TEST(Optional, Exceptions) {
 526   Optional<int> empty;
 527   EXPECT_THROW(empty.value(), OptionalEmptyException);
 528 }
 529
 530 TEST(Optional, NoThrowDefaultConstructible) {
 531   EXPECT_TRUE(std::is_nothrow_default_constructible<Optional<bool>>::value);
 532 }
 533
 534 struct NoDestructor {};
 535
 536 struct WithDestructor {
 537   ~WithDestructor();
 538 };
 539
 540 TEST(Optional, TriviallyDestructible) {
 541   // These could all be static_asserts but EXPECT_* give much nicer output on
 542   // failure.
 543   EXPECT_TRUE(std::is_trivially_destructible<Optional<NoDestructor>>::value);
 544   EXPECT_TRUE(std::is_trivially_destructible<Optional<int>>::value);
 545   EXPECT_FALSE(std::is_trivially_destructible<Optional<WithDestructor>>::value);
 546 }
 547
 548 TEST(Optional, Hash) {
 549   // Test it's usable in std::unordered map (compile time check)
 550   std::unordered_map<Optional<int>, Optional<int>> obj;
 551   // Also check the std::hash template can be instantiated by the compiler
 552   std::hash<Optional<int>>()(none);
 553   std::hash<Optional<int>>()(3);
 554 }
 555 }