folly/test/OptionalTest.cpp

   1 /*
   2  * Copyright 2014 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
  19 #include <memory>
  20 #include <vector>
  21 #include <algorithm>
  22 #include <iomanip>
  23 #include <string>
  24
  25 #include <glog/logging.h>
  26 #include <gtest/gtest.h>
  27 #include <boost/optional.hpp>
  28
  29 using std::unique_ptr;
  30 using std::shared_ptr;
  31
  32 namespace folly {
  33
  34 template<class V>
  35 std::ostream& operator<<(std::ostream& os, const Optional<V>& v) {
  36   if (v) {
  37     os << "Optional(" << v.value() << ')';
  38   } else {
  39     os << "None";
  40   }
  41   return os;
  42 }
  43
  44 struct NoDefault {
  45   NoDefault(int, int) {}
  46   char a, b, c;
  47 };
  48
  49 static_assert(sizeof(Optional<char>) == 2, "");
  50 static_assert(sizeof(Optional<int>) == 8, "");
  51 static_assert(sizeof(Optional<NoDefault>) == 4, "");
  52 static_assert(sizeof(Optional<char>) == sizeof(boost::optional<char>), "");
  53 static_assert(sizeof(Optional<short>) == sizeof(boost::optional<short>), "");
  54 static_assert(sizeof(Optional<int>) == sizeof(boost::optional<int>), "");
  55 static_assert(sizeof(Optional<double>) == sizeof(boost::optional<double>), "");
  56
  57 TEST(Optional, NoDefault) {
  58   Optional<NoDefault> x;
  59   EXPECT_FALSE(x);
  60   x.emplace(4, 5);
  61   EXPECT_TRUE(bool(x));
  62   x.clear();
  63   EXPECT_FALSE(x);
  64 }
  65
  66 TEST(Optional, String) {
  67   Optional<std::string> maybeString;
  68   EXPECT_FALSE(maybeString);
  69   maybeString = "hello";
  70   EXPECT_TRUE(bool(maybeString));
  71 }
  72
  73 TEST(Optional, Const) {
  74   { // default construct
  75     Optional<const int> opt;
  76     EXPECT_FALSE(bool(opt));
  77     opt.emplace(4);
  78     EXPECT_EQ(*opt, 4);
  79     opt.emplace(5);
  80     EXPECT_EQ(*opt, 5);
  81     opt.clear();
  82     EXPECT_FALSE(bool(opt));
  83   }
  84   { // copy-constructed
  85     const int x = 6;
  86     Optional<const int> opt(x);
  87     EXPECT_EQ(*opt, 6);
  88   }
  89   { // move-constructed
  90     const int x = 7;
  91     Optional<const int> opt(std::move(x));
  92     EXPECT_EQ(*opt, 7);
  93   }
  94   // no assignment allowed
  95 }
  96
  97 TEST(Optional, Simple) {
  98   Optional<int> opt;
  99   EXPECT_FALSE(bool(opt));
 100   opt = 4;
 101   EXPECT_TRUE(bool(opt));
 102   EXPECT_EQ(4, *opt);
 103   opt = 5;
 104   EXPECT_EQ(5, *opt);
 105   opt.clear();
 106   EXPECT_FALSE(bool(opt));
 107 }
 108
 109 TEST(Optional, EmptyConstruct) {
 110   Optional<int> opt;
 111   EXPECT_FALSE(bool(opt));
 112   Optional<int> test1(opt);
 113   EXPECT_FALSE(bool(test1));
 114   Optional<int> test2(std::move(opt));
 115   EXPECT_FALSE(bool(test2));
 116 }
 117
 118 TEST(Optional, Unique) {
 119   Optional<unique_ptr<int>> opt;
 120
 121   opt.clear();
 122   EXPECT_FALSE(bool(opt));
 123   // empty->emplaced
 124   opt.emplace(new int(5));
 125   EXPECT_TRUE(bool(opt));
 126   EXPECT_EQ(5, **opt);
 127
 128   opt.clear();
 129   // empty->moved
 130   opt = unique_ptr<int>(new int(6));
 131   EXPECT_EQ(6, **opt);
 132   // full->moved
 133   opt = unique_ptr<int>(new int(7));
 134   EXPECT_EQ(7, **opt);
 135
 136   // move it out by move construct
 137   Optional<unique_ptr<int>> moved(std::move(opt));
 138   EXPECT_TRUE(bool(moved));
 139   EXPECT_FALSE(bool(opt));
 140   EXPECT_EQ(7, **moved);
 141
 142   EXPECT_TRUE(bool(moved));
 143   opt = std::move(moved); // move it back by move assign
 144   EXPECT_FALSE(bool(moved));
 145   EXPECT_TRUE(bool(opt));
 146   EXPECT_EQ(7, **opt);
 147 }
 148
 149 TEST(Optional, Shared) {
 150   shared_ptr<int> ptr;
 151   Optional<shared_ptr<int>> opt;
 152   EXPECT_FALSE(bool(opt));
 153   // empty->emplaced
 154   opt.emplace(new int(5));
 155   EXPECT_TRUE(bool(opt));
 156   ptr = opt.value();
 157   EXPECT_EQ(ptr.get(), opt->get());
 158   EXPECT_EQ(2, ptr.use_count());
 159   opt.clear();
 160   EXPECT_EQ(1, ptr.use_count());
 161   // full->copied
 162   opt = ptr;
 163   EXPECT_EQ(2, ptr.use_count());
 164   EXPECT_EQ(ptr.get(), opt->get());
 165   opt.clear();
 166   EXPECT_EQ(1, ptr.use_count());
 167   // full->moved
 168   opt = std::move(ptr);
 169   EXPECT_EQ(1, opt->use_count());
 170   EXPECT_EQ(nullptr, ptr.get());
 171   {
 172     Optional<shared_ptr<int>> copied(opt);
 173     EXPECT_EQ(2, opt->use_count());
 174     Optional<shared_ptr<int>> moved(std::move(opt));
 175     EXPECT_EQ(2, moved->use_count());
 176     moved.emplace(new int(6));
 177     EXPECT_EQ(1, moved->use_count());
 178     copied = moved;
 179     EXPECT_EQ(2, moved->use_count());
 180   }
 181 }
 182
 183 TEST(Optional, Order) {
 184   std::vector<Optional<int>> vect{
 185     { none },
 186     { 3 },
 187     { 1 },
 188     { none },
 189     { 2 },
 190   };
 191   std::vector<Optional<int>> expected {
 192     { none },
 193     { none },
 194     { 1 },
 195     { 2 },
 196     { 3 },
 197   };
 198   std::sort(vect.begin(), vect.end());
 199   EXPECT_EQ(vect, expected);
 200 }
 201
 202 TEST(Optional, Swap) {
 203   Optional<std::string> a;
 204   Optional<std::string> b;
 205
 206   swap(a, b);
 207   EXPECT_FALSE(a.hasValue());
 208   EXPECT_FALSE(b.hasValue());
 209
 210   a = "hello";
 211   EXPECT_TRUE(a.hasValue());
 212   EXPECT_FALSE(b.hasValue());
 213   EXPECT_EQ("hello", a.value());
 214
 215   swap(a, b);
 216   EXPECT_FALSE(a.hasValue());
 217   EXPECT_TRUE(b.hasValue());
 218   EXPECT_EQ("hello", b.value());
 219
 220   a = "bye";
 221   EXPECT_TRUE(a.hasValue());
 222   EXPECT_EQ("bye", a.value());
 223
 224   swap(a, b);
 225 }
 226
 227 TEST(Optional, Comparisons) {
 228   Optional<int> o_;
 229   Optional<int> o1(1);
 230   Optional<int> o2(2);
 231
 232   EXPECT_TRUE(o_ <= o_);
 233   EXPECT_TRUE(o_ == o_);
 234   EXPECT_TRUE(o_ >= o_);
 235
 236   EXPECT_TRUE(o1 < o2);
 237   EXPECT_TRUE(o1 <= o2);
 238   EXPECT_TRUE(o1 <= o1);
 239   EXPECT_TRUE(o1 == o1);
 240   EXPECT_TRUE(o1 != o2);
 241   EXPECT_TRUE(o1 >= o1);
 242   EXPECT_TRUE(o2 >= o1);
 243   EXPECT_TRUE(o2 > o1);
 244
 245   EXPECT_FALSE(o2 < o1);
 246   EXPECT_FALSE(o2 <= o1);
 247   EXPECT_FALSE(o2 <= o1);
 248   EXPECT_FALSE(o2 == o1);
 249   EXPECT_FALSE(o1 != o1);
 250   EXPECT_FALSE(o1 >= o2);
 251   EXPECT_FALSE(o1 >= o2);
 252   EXPECT_FALSE(o1 > o2);
 253
 254   /* folly::Optional explicitly doesn't support comparisons with contained value
 255   EXPECT_TRUE(1 < o2);
 256   EXPECT_TRUE(1 <= o2);
 257   EXPECT_TRUE(1 <= o1);
 258   EXPECT_TRUE(1 == o1);
 259   EXPECT_TRUE(2 != o1);
 260   EXPECT_TRUE(1 >= o1);
 261   EXPECT_TRUE(2 >= o1);
 262   EXPECT_TRUE(2 > o1);
 263
 264   EXPECT_FALSE(o2 < 1);
 265   EXPECT_FALSE(o2 <= 1);
 266   EXPECT_FALSE(o2 <= 1);
 267   EXPECT_FALSE(o2 == 1);
 268   EXPECT_FALSE(o2 != 2);
 269   EXPECT_FALSE(o1 >= 2);
 270   EXPECT_FALSE(o1 >= 2);
 271   EXPECT_FALSE(o1 > 2);
 272   */
 273
 274   // boost::optional does support comparison with contained value, which can
 275   // lead to confusion when a bool is contained
 276   boost::optional<int> boi(3);
 277   EXPECT_TRUE(boi < 5);
 278   EXPECT_TRUE(boi <= 4);
 279   EXPECT_TRUE(boi == 3);
 280   EXPECT_TRUE(boi != 2);
 281   EXPECT_TRUE(boi >= 1);
 282   EXPECT_TRUE(boi > 0);
 283   EXPECT_TRUE(1 <  boi);
 284   EXPECT_TRUE(2 <= boi);
 285   EXPECT_TRUE(3 == boi);
 286   EXPECT_TRUE(4 != boi);
 287   EXPECT_TRUE(5 >= boi);
 288   EXPECT_TRUE(6 >  boi);
 289
 290   boost::optional<bool> bob(false);
 291   EXPECT_TRUE(bob);
 292   EXPECT_TRUE(bob == false); // well that was confusing
 293   EXPECT_FALSE(bob != false);
 294 }
 295
 296 TEST(Optional, Conversions) {
 297   Optional<bool> mbool;
 298   Optional<short> mshort;
 299   Optional<char*> mstr;
 300   Optional<int> mint;
 301
 302   //These don't compile
 303   //bool b = mbool;
 304   //short s = mshort;
 305   //char* c = mstr;
 306   //int x = mint;
 307   //char* c(mstr);
 308   //short s(mshort);
 309   //int x(mint);
 310
 311   // intended explicit operator bool, for if (opt).
 312   bool b(mbool);
 313
 314   // Truthy tests work and are not ambiguous
 315   if (mbool && mshort && mstr && mint) { // only checks not-empty
 316     if (*mbool && *mshort && *mstr && *mint) { // only checks value
 317       ;
 318     }
 319   }
 320
 321   mbool = false;
 322   EXPECT_TRUE(bool(mbool));
 323   EXPECT_FALSE(*mbool);
 324
 325   mbool = true;
 326   EXPECT_TRUE(bool(mbool));
 327   EXPECT_TRUE(*mbool);
 328
 329   mbool = none;
 330   EXPECT_FALSE(bool(mbool));
 331
 332   // No conversion allowed; does not compile
 333   // EXPECT_TRUE(mbool == false);
 334 }
 335
 336 TEST(Optional, Pointee) {
 337   Optional<int> x;
 338   EXPECT_FALSE(get_pointer(x));
 339   x = 1;
 340   EXPECT_TRUE(get_pointer(x));
 341   *get_pointer(x) = 2;
 342   EXPECT_TRUE(*x == 2);
 343   x = none;
 344   EXPECT_FALSE(get_pointer(x));
 345 }
 346
 347 TEST(Optional, MakeOptional) {
 348   // const L-value version
 349   const std::string s("abc");
 350   auto optStr = make_optional(s);
 351   ASSERT_TRUE(optStr.hasValue());
 352   EXPECT_EQ(*optStr, "abc");
 353   *optStr = "cde";
 354   EXPECT_EQ(s, "abc");
 355   EXPECT_EQ(*optStr, "cde");
 356
 357   // L-value version
 358   std::string s2("abc");
 359   auto optStr2 = make_optional(s2);
 360   ASSERT_TRUE(optStr2.hasValue());
 361   EXPECT_EQ(*optStr2, "abc");
 362   *optStr2 = "cde";
 363   // it's vital to check that s2 wasn't clobbered
 364   EXPECT_EQ(s2, "abc");
 365
 366   // L-value reference version
 367   std::string& s3(s2);
 368   auto optStr3 = make_optional(s3);
 369   ASSERT_TRUE(optStr3.hasValue());
 370   EXPECT_EQ(*optStr3, "abc");
 371   *optStr3 = "cde";
 372   EXPECT_EQ(s3, "abc");
 373
 374   // R-value ref version
 375   unique_ptr<int> pInt(new int(3));
 376   auto optIntPtr = make_optional(std::move(pInt));
 377   EXPECT_TRUE(pInt.get() == nullptr);
 378   ASSERT_TRUE(optIntPtr.hasValue());
 379   EXPECT_EQ(**optIntPtr, 3);
 380 }
 381
 382 class ContainsOptional {
 383  public:
 384   ContainsOptional() { }
 385   explicit ContainsOptional(int x) : opt_(x) { }
 386   bool hasValue() const { return opt_.hasValue(); }
 387   int value() const { return opt_.value(); }
 388
 389   ContainsOptional(const ContainsOptional &other) = default;
 390   ContainsOptional& operator=(const ContainsOptional &other) = default;
 391   ContainsOptional(ContainsOptional &&other) = default;
 392   ContainsOptional& operator=(ContainsOptional &&other) = default;
 393
 394  private:
 395   Optional<int> opt_;
 396 };
 397
 398 /**
 399  * Test that a class containing an Optional can be copy and move assigned.
 400  * This was broken under gcc 4.7 until assignment operators were explicitly
 401  * defined.
 402  */
 403 TEST(Optional, AssignmentContained) {
 404   {
 405     ContainsOptional source(5), target;
 406     target = source;
 407     EXPECT_TRUE(target.hasValue());
 408     EXPECT_EQ(5, target.value());
 409   }
 410
 411   {
 412     ContainsOptional source(5), target;
 413     target = std::move(source);
 414     EXPECT_TRUE(target.hasValue());
 415     EXPECT_EQ(5, target.value());
 416     EXPECT_FALSE(source.hasValue());
 417   }
 418
 419   {
 420     ContainsOptional opt_uninit, target(10);
 421     target = opt_uninit;
 422     EXPECT_FALSE(target.hasValue());
 423   }
 424 }
 425
 426 }