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
  20 #include <memory>
  21 #include <vector>
  22 #include <algorithm>
  23 #include <iomanip>
  24 #include <string>
  25 #include <type_traits>
  26
  27 #include <glog/logging.h>
  28 #include <gtest/gtest.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_life_extention) {
 178   // Extends the life of the value.
 179   const auto& ptr = Optional<std::unique_ptr<int, ExpectingDeleter>>(
 180       {new int(42), ExpectingDeleter{1337}}).value();
 181   *ptr = 1337;
 182 }
 183
 184 TEST(Optional, value_move) {
 185   auto ptr = Optional<std::unique_ptr<int, ExpectingDeleter>>(
 186       {new int(42), ExpectingDeleter{1337}}).value();
 187   *ptr = 1337;
 188 }
 189
 190 TEST(Optional, dereference_life_extention) {
 191   // Extends the life of the value.
 192   const auto& ptr = *Optional<std::unique_ptr<int, ExpectingDeleter>>(
 193       {new int(42), ExpectingDeleter{1337}});
 194   *ptr = 1337;
 195 }
 196
 197 TEST(Optional, dereference_move) {
 198   auto ptr = *Optional<std::unique_ptr<int, ExpectingDeleter>>(
 199       {new int(42), ExpectingDeleter{1337}});
 200   *ptr = 1337;
 201 }
 202
 203 TEST(Optional, EmptyConstruct) {
 204   Optional<int> opt;
 205   EXPECT_FALSE(bool(opt));
 206   Optional<int> test1(opt);
 207   EXPECT_FALSE(bool(test1));
 208   Optional<int> test2(std::move(opt));
 209   EXPECT_FALSE(bool(test2));
 210 }
 211
 212 TEST(Optional, Unique) {
 213   Optional<unique_ptr<int>> opt;
 214
 215   opt.clear();
 216   EXPECT_FALSE(bool(opt));
 217   // empty->emplaced
 218   opt.emplace(new int(5));
 219   EXPECT_TRUE(bool(opt));
 220   EXPECT_EQ(5, **opt);
 221
 222   opt.clear();
 223   // empty->moved
 224   opt = unique_ptr<int>(new int(6));
 225   EXPECT_EQ(6, **opt);
 226   // full->moved
 227   opt = unique_ptr<int>(new int(7));
 228   EXPECT_EQ(7, **opt);
 229
 230   // move it out by move construct
 231   Optional<unique_ptr<int>> moved(std::move(opt));
 232   EXPECT_TRUE(bool(moved));
 233   EXPECT_FALSE(bool(opt));
 234   EXPECT_EQ(7, **moved);
 235
 236   EXPECT_TRUE(bool(moved));
 237   opt = std::move(moved); // move it back by move assign
 238   EXPECT_FALSE(bool(moved));
 239   EXPECT_TRUE(bool(opt));
 240   EXPECT_EQ(7, **opt);
 241 }
 242
 243 TEST(Optional, Shared) {
 244   shared_ptr<int> ptr;
 245   Optional<shared_ptr<int>> opt;
 246   EXPECT_FALSE(bool(opt));
 247   // empty->emplaced
 248   opt.emplace(new int(5));
 249   EXPECT_TRUE(bool(opt));
 250   ptr = opt.value();
 251   EXPECT_EQ(ptr.get(), opt->get());
 252   EXPECT_EQ(2, ptr.use_count());
 253   opt.clear();
 254   EXPECT_EQ(1, ptr.use_count());
 255   // full->copied
 256   opt = ptr;
 257   EXPECT_EQ(2, ptr.use_count());
 258   EXPECT_EQ(ptr.get(), opt->get());
 259   opt.clear();
 260   EXPECT_EQ(1, ptr.use_count());
 261   // full->moved
 262   opt = std::move(ptr);
 263   EXPECT_EQ(1, opt->use_count());
 264   EXPECT_EQ(nullptr, ptr.get());
 265   {
 266     Optional<shared_ptr<int>> copied(opt);
 267     EXPECT_EQ(2, opt->use_count());
 268     Optional<shared_ptr<int>> moved(std::move(opt));
 269     EXPECT_EQ(2, moved->use_count());
 270     moved.emplace(new int(6));
 271     EXPECT_EQ(1, moved->use_count());
 272     copied = moved;
 273     EXPECT_EQ(2, moved->use_count());
 274   }
 275 }
 276
 277 TEST(Optional, Order) {
 278   std::vector<Optional<int>> vect{
 279     { none },
 280     { 3 },
 281     { 1 },
 282     { none },
 283     { 2 },
 284   };
 285   std::vector<Optional<int>> expected {
 286     { none },
 287     { none },
 288     { 1 },
 289     { 2 },
 290     { 3 },
 291   };
 292   std::sort(vect.begin(), vect.end());
 293   EXPECT_EQ(vect, expected);
 294 }
 295
 296 TEST(Optional, Swap) {
 297   Optional<std::string> a;
 298   Optional<std::string> b;
 299
 300   swap(a, b);
 301   EXPECT_FALSE(a.hasValue());
 302   EXPECT_FALSE(b.hasValue());
 303
 304   a = "hello";
 305   EXPECT_TRUE(a.hasValue());
 306   EXPECT_FALSE(b.hasValue());
 307   EXPECT_EQ("hello", a.value());
 308
 309   swap(a, b);
 310   EXPECT_FALSE(a.hasValue());
 311   EXPECT_TRUE(b.hasValue());
 312   EXPECT_EQ("hello", b.value());
 313
 314   a = "bye";
 315   EXPECT_TRUE(a.hasValue());
 316   EXPECT_EQ("bye", a.value());
 317
 318   swap(a, b);
 319 }
 320
 321 TEST(Optional, Comparisons) {
 322   Optional<int> o_;
 323   Optional<int> o1(1);
 324   Optional<int> o2(2);
 325
 326   EXPECT_TRUE(o_ <= (o_));
 327   EXPECT_TRUE(o_ == (o_));
 328   EXPECT_TRUE(o_ >= (o_));
 329
 330   EXPECT_TRUE(o1 < o2);
 331   EXPECT_TRUE(o1 <= o2);
 332   EXPECT_TRUE(o1 <= (o1));
 333   EXPECT_TRUE(o1 == (o1));
 334   EXPECT_TRUE(o1 != o2);
 335   EXPECT_TRUE(o1 >= (o1));
 336   EXPECT_TRUE(o2 >= o1);
 337   EXPECT_TRUE(o2 > o1);
 338
 339   EXPECT_FALSE(o2 < o1);
 340   EXPECT_FALSE(o2 <= o1);
 341   EXPECT_FALSE(o2 <= o1);
 342   EXPECT_FALSE(o2 == o1);
 343   EXPECT_FALSE(o1 != (o1));
 344   EXPECT_FALSE(o1 >= o2);
 345   EXPECT_FALSE(o1 >= o2);
 346   EXPECT_FALSE(o1 > o2);
 347
 348   /* folly::Optional explicitly doesn't support comparisons with contained value
 349   EXPECT_TRUE(1 < o2);
 350   EXPECT_TRUE(1 <= o2);
 351   EXPECT_TRUE(1 <= o1);
 352   EXPECT_TRUE(1 == o1);
 353   EXPECT_TRUE(2 != o1);
 354   EXPECT_TRUE(1 >= o1);
 355   EXPECT_TRUE(2 >= o1);
 356   EXPECT_TRUE(2 > o1);
 357
 358   EXPECT_FALSE(o2 < 1);
 359   EXPECT_FALSE(o2 <= 1);
 360   EXPECT_FALSE(o2 <= 1);
 361   EXPECT_FALSE(o2 == 1);
 362   EXPECT_FALSE(o2 != 2);
 363   EXPECT_FALSE(o1 >= 2);
 364   EXPECT_FALSE(o1 >= 2);
 365   EXPECT_FALSE(o1 > 2);
 366   */
 367
 368   // boost::optional does support comparison with contained value, which can
 369   // lead to confusion when a bool is contained
 370   boost::optional<int> boi(3);
 371   EXPECT_TRUE(boi < 5);
 372   EXPECT_TRUE(boi <= 4);
 373   EXPECT_TRUE(boi == 3);
 374   EXPECT_TRUE(boi != 2);
 375   EXPECT_TRUE(boi >= 1);
 376   EXPECT_TRUE(boi > 0);
 377   EXPECT_TRUE(1 <  boi);
 378   EXPECT_TRUE(2 <= boi);
 379   EXPECT_TRUE(3 == boi);
 380   EXPECT_TRUE(4 != boi);
 381   EXPECT_TRUE(5 >= boi);
 382   EXPECT_TRUE(6 >  boi);
 383
 384   boost::optional<bool> bob(false);
 385   EXPECT_TRUE((bool)bob);
 386   EXPECT_TRUE(bob == false); // well that was confusing
 387   EXPECT_FALSE(bob != false);
 388 }
 389
 390 TEST(Optional, Conversions) {
 391   Optional<bool> mbool;
 392   Optional<short> mshort;
 393   Optional<char*> mstr;
 394   Optional<int> mint;
 395
 396   //These don't compile
 397   //bool b = mbool;
 398   //short s = mshort;
 399   //char* c = mstr;
 400   //int x = mint;
 401   //char* c(mstr);
 402   //short s(mshort);
 403   //int x(mint);
 404
 405   // intended explicit operator bool, for if (opt).
 406   bool b(mbool);
 407   EXPECT_FALSE(b);
 408
 409   // Truthy tests work and are not ambiguous
 410   if (mbool && mshort && mstr && mint) { // only checks not-empty
 411     if (*mbool && *mshort && *mstr && *mint) { // only checks value
 412       ;
 413     }
 414   }
 415
 416   mbool = false;
 417   EXPECT_TRUE(bool(mbool));
 418   EXPECT_FALSE(*mbool);
 419
 420   mbool = true;
 421   EXPECT_TRUE(bool(mbool));
 422   EXPECT_TRUE(*mbool);
 423
 424   mbool = none;
 425   EXPECT_FALSE(bool(mbool));
 426
 427   // No conversion allowed; does not compile
 428   // EXPECT_TRUE(mbool == false);
 429 }
 430
 431 TEST(Optional, Pointee) {
 432   Optional<int> x;
 433   EXPECT_FALSE(get_pointer(x));
 434   x = 1;
 435   EXPECT_TRUE(get_pointer(x));
 436   *get_pointer(x) = 2;
 437   EXPECT_TRUE(*x == 2);
 438   x = none;
 439   EXPECT_FALSE(get_pointer(x));
 440 }
 441
 442 TEST(Optional, MakeOptional) {
 443   // const L-value version
 444   const std::string s("abc");
 445   auto optStr = make_optional(s);
 446   ASSERT_TRUE(optStr.hasValue());
 447   EXPECT_EQ(*optStr, "abc");
 448   *optStr = "cde";
 449   EXPECT_EQ(s, "abc");
 450   EXPECT_EQ(*optStr, "cde");
 451
 452   // L-value version
 453   std::string s2("abc");
 454   auto optStr2 = make_optional(s2);
 455   ASSERT_TRUE(optStr2.hasValue());
 456   EXPECT_EQ(*optStr2, "abc");
 457   *optStr2 = "cde";
 458   // it's vital to check that s2 wasn't clobbered
 459   EXPECT_EQ(s2, "abc");
 460
 461   // L-value reference version
 462   std::string& s3(s2);
 463   auto optStr3 = make_optional(s3);
 464   ASSERT_TRUE(optStr3.hasValue());
 465   EXPECT_EQ(*optStr3, "abc");
 466   *optStr3 = "cde";
 467   EXPECT_EQ(s3, "abc");
 468
 469   // R-value ref version
 470   unique_ptr<int> pInt(new int(3));
 471   auto optIntPtr = make_optional(std::move(pInt));
 472   EXPECT_TRUE(pInt.get() == nullptr);
 473   ASSERT_TRUE(optIntPtr.hasValue());
 474   EXPECT_EQ(**optIntPtr, 3);
 475 }
 476
 477 #if __CLANG_PREREQ(3, 6)
 478 # pragma clang diagnostic push
 479 # pragma clang diagnostic ignored "-Wself-move"
 480 #endif
 481
 482 TEST(Optional, SelfAssignment) {
 483   Optional<int> a = 42;
 484   a = a;
 485   ASSERT_TRUE(a.hasValue() && a.value() == 42);
 486
 487   Optional<int> b = 23333333;
 488   b = std::move(b);
 489   ASSERT_TRUE(b.hasValue() && b.value() == 23333333);
 490 }
 491
 492 #if __CLANG_PREREQ(3, 6)
 493 # pragma clang diagnostic pop
 494 #endif
 495
 496 class ContainsOptional {
 497  public:
 498   ContainsOptional() { }
 499   explicit ContainsOptional(int x) : opt_(x) { }
 500   bool hasValue() const { return opt_.hasValue(); }
 501   int value() const { return opt_.value(); }
 502
 503   ContainsOptional(const ContainsOptional &other) = default;
 504   ContainsOptional& operator=(const ContainsOptional &other) = default;
 505   ContainsOptional(ContainsOptional &&other) = default;
 506   ContainsOptional& operator=(ContainsOptional &&other) = default;
 507
 508  private:
 509   Optional<int> opt_;
 510 };
 511
 512 /**
 513  * Test that a class containing an Optional can be copy and move assigned.
 514  * This was broken under gcc 4.7 until assignment operators were explicitly
 515  * defined.
 516  */
 517 TEST(Optional, AssignmentContained) {
 518   {
 519     ContainsOptional source(5), target;
 520     target = source;
 521     EXPECT_TRUE(target.hasValue());
 522     EXPECT_EQ(5, target.value());
 523   }
 524
 525   {
 526     ContainsOptional source(5), target;
 527     target = std::move(source);
 528     EXPECT_TRUE(target.hasValue());
 529     EXPECT_EQ(5, target.value());
 530     EXPECT_FALSE(source.hasValue());
 531   }
 532
 533   {
 534     ContainsOptional opt_uninit, target(10);
 535     target = opt_uninit;
 536     EXPECT_FALSE(target.hasValue());
 537   }
 538 }
 539
 540 TEST(Optional, Exceptions) {
 541   Optional<int> empty;
 542   EXPECT_THROW(empty.value(), OptionalEmptyException);
 543 }
 544
 545 TEST(Optional, NoThrowDefaultConstructible) {
 546   EXPECT_TRUE(std::is_nothrow_default_constructible<Optional<bool>>::value);
 547 }
 548
 549 struct NoDestructor {};
 550
 551 struct WithDestructor {
 552   ~WithDestructor();
 553 };
 554
 555 TEST(Optional, TriviallyDestructible) {
 556   // These could all be static_asserts but EXPECT_* give much nicer output on
 557   // failure.
 558   EXPECT_TRUE(std::is_trivially_destructible<Optional<NoDestructor>>::value);
 559   EXPECT_TRUE(std::is_trivially_destructible<Optional<int>>::value);
 560   EXPECT_FALSE(std::is_trivially_destructible<Optional<WithDestructor>>::value);
 561 }
 562 }