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array_view_unittest.cc (19819B)


      1 /*
      2 *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
      3 *
      4 *  Use of this source code is governed by a BSD-style license
      5 *  that can be found in the LICENSE file in the root of the source
      6 *  tree. An additional intellectual property rights grant can be found
      7 *  in the file PATENTS.  All contributing project authors may
      8 *  be found in the AUTHORS file in the root of the source tree.
      9 */
     10 
     11 #include "api/array_view.h"
     12 
     13 #include <array>
     14 #include <cstddef>
     15 #include <cstdint>
     16 #include <string>
     17 #include <utility>
     18 #include <vector>
     19 
     20 #include "rtc_base/buffer.h"
     21 #include "rtc_base/checks.h"
     22 #include "test/gmock.h"
     23 #include "test/gtest.h"
     24 
     25 namespace webrtc {
     26 
     27 namespace {
     28 
     29 using ::testing::ElementsAre;
     30 using ::testing::IsEmpty;
     31 
     32 template <typename T>
     33 size_t Call(ArrayView<T> av) {
     34  return av.size();
     35 }
     36 
     37 template <typename T, size_t N>
     38 void CallFixed(ArrayView<T, N> /* av */) {}
     39 
     40 }  // namespace
     41 
     42 TEST(ArrayViewDeathTest, TestConstructFromPtrAndArray) {
     43  char arr[] = "Arrr!";
     44  const char carr[] = "Carrr!";
     45  EXPECT_EQ(6u, Call<const char>(arr));
     46  EXPECT_EQ(7u, Call<const char>(carr));
     47  EXPECT_EQ(6u, Call<char>(arr));
     48  // Call<char>(carr);  // Compile error, because can't drop const.
     49  // Call<int>(arr);  // Compile error, because incompatible types.
     50  ArrayView<int*> x;
     51  EXPECT_EQ(0u, x.size());
     52  EXPECT_EQ(nullptr, x.data());
     53  ArrayView<char> y = arr;
     54  EXPECT_EQ(6u, y.size());
     55  EXPECT_EQ(arr, y.data());
     56  ArrayView<char, 6> yf = arr;
     57  static_assert(yf.size() == 6, "");
     58  EXPECT_EQ(arr, yf.data());
     59  ArrayView<const char> z(arr + 1, 3);
     60  EXPECT_EQ(3u, z.size());
     61  EXPECT_EQ(arr + 1, z.data());
     62  ArrayView<const char, 3> zf(arr + 1, 3);
     63  static_assert(zf.size() == 3, "");
     64  EXPECT_EQ(arr + 1, zf.data());
     65  ArrayView<const char> w(arr, 2);
     66  EXPECT_EQ(2u, w.size());
     67  EXPECT_EQ(arr, w.data());
     68  ArrayView<const char, 2> wf(arr, 2);
     69  static_assert(wf.size() == 2, "");
     70  EXPECT_EQ(arr, wf.data());
     71  ArrayView<char> q(arr, 0);
     72  EXPECT_EQ(0u, q.size());
     73  EXPECT_EQ(nullptr, q.data());
     74  ArrayView<char, 0> qf(arr, 0);
     75  static_assert(qf.size() == 0, "");
     76  EXPECT_EQ(nullptr, qf.data());
     77 #if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
     78  // DCHECK error (nullptr with nonzero size).
     79  EXPECT_DEATH(ArrayView<int>(static_cast<int*>(nullptr), 5), "");
     80 #endif
     81  // These are compile errors, because incompatible types.
     82  // ArrayView<int> m = arr;
     83  // ArrayView<float> n(arr + 2, 2);
     84 }
     85 
     86 TEST(ArrayViewTest, TestCopyConstructorVariableLvalue) {
     87  char arr[] = "Arrr!";
     88  ArrayView<char> x = arr;
     89  EXPECT_EQ(6u, x.size());
     90  EXPECT_EQ(arr, x.data());
     91  ArrayView<char> y = x;  // Copy non-const -> non-const.
     92  EXPECT_EQ(6u, y.size());
     93  EXPECT_EQ(arr, y.data());
     94  ArrayView<const char> z = x;  // Copy non-const -> const.
     95  EXPECT_EQ(6u, z.size());
     96  EXPECT_EQ(arr, z.data());
     97  ArrayView<const char> w = z;  // Copy const -> const.
     98  EXPECT_EQ(6u, w.size());
     99  EXPECT_EQ(arr, w.data());
    100  // ArrayView<char> v = z;  // Compile error, because can't drop const.
    101 }
    102 
    103 TEST(ArrayViewTest, TestCopyConstructorVariableRvalue) {
    104  char arr[] = "Arrr!";
    105  ArrayView<char> x = arr;
    106  EXPECT_EQ(6u, x.size());
    107  EXPECT_EQ(arr, x.data());
    108  ArrayView<char> y = std::move(x);  // Copy non-const -> non-const.
    109  EXPECT_EQ(6u, y.size());
    110  EXPECT_EQ(arr, y.data());
    111  ArrayView<const char> z = std::move(x);  // Copy non-const -> const.
    112  EXPECT_EQ(6u, z.size());
    113  EXPECT_EQ(arr, z.data());
    114  ArrayView<const char> w = std::move(z);  // Copy const -> const.
    115  EXPECT_EQ(6u, w.size());
    116  EXPECT_EQ(arr, w.data());
    117  // ArrayView<char> v = std::move(z);  // Error, because can't drop const.
    118 }
    119 
    120 TEST(ArrayViewTest, TestCopyConstructorFixedLvalue) {
    121  char arr[] = "Arrr!";
    122  ArrayView<char, 6> x = arr;
    123  static_assert(x.size() == 6, "");
    124  EXPECT_EQ(arr, x.data());
    125 
    126  // Copy fixed -> fixed.
    127  ArrayView<char, 6> y = x;  // Copy non-const -> non-const.
    128  static_assert(y.size() == 6, "");
    129  EXPECT_EQ(arr, y.data());
    130  ArrayView<const char, 6> z = x;  // Copy non-const -> const.
    131  static_assert(z.size() == 6, "");
    132  EXPECT_EQ(arr, z.data());
    133  ArrayView<const char, 6> w = z;  // Copy const -> const.
    134  static_assert(w.size() == 6, "");
    135  EXPECT_EQ(arr, w.data());
    136  // ArrayView<char, 6> v = z;  // Compile error, because can't drop const.
    137 
    138  // Copy fixed -> variable.
    139  ArrayView<char> yv = x;  // Copy non-const -> non-const.
    140  EXPECT_EQ(6u, yv.size());
    141  EXPECT_EQ(arr, yv.data());
    142  ArrayView<const char> zv = x;  // Copy non-const -> const.
    143  EXPECT_EQ(6u, zv.size());
    144  EXPECT_EQ(arr, zv.data());
    145  ArrayView<const char> wv = z;  // Copy const -> const.
    146  EXPECT_EQ(6u, wv.size());
    147  EXPECT_EQ(arr, wv.data());
    148  // ArrayView<char> vv = z;  // Compile error, because can't drop const.
    149 }
    150 
    151 TEST(ArrayViewTest, TestCopyConstructorFixedRvalue) {
    152  char arr[] = "Arrr!";
    153  ArrayView<char, 6> x = arr;
    154  static_assert(x.size() == 6, "");
    155  EXPECT_EQ(arr, x.data());
    156 
    157  // Copy fixed -> fixed.
    158  ArrayView<char, 6> y = std::move(x);  // Copy non-const -> non-const.
    159  static_assert(y.size() == 6, "");
    160  EXPECT_EQ(arr, y.data());
    161  ArrayView<const char, 6> z = std::move(x);  // Copy non-const -> const.
    162  static_assert(z.size() == 6, "");
    163  EXPECT_EQ(arr, z.data());
    164  ArrayView<const char, 6> w = std::move(z);  // Copy const -> const.
    165  static_assert(w.size() == 6, "");
    166  EXPECT_EQ(arr, w.data());
    167  // ArrayView<char, 6> v = std::move(z);  // Error, because can't drop const.
    168 
    169  // Copy fixed -> variable.
    170  ArrayView<char> yv = std::move(x);  // Copy non-const -> non-const.
    171  EXPECT_EQ(6u, yv.size());
    172  EXPECT_EQ(arr, yv.data());
    173  ArrayView<const char> zv = std::move(x);  // Copy non-const -> const.
    174  EXPECT_EQ(6u, zv.size());
    175  EXPECT_EQ(arr, zv.data());
    176  ArrayView<const char> wv = std::move(z);  // Copy const -> const.
    177  EXPECT_EQ(6u, wv.size());
    178  EXPECT_EQ(arr, wv.data());
    179  // ArrayView<char> vv = std::move(z);  // Error, because can't drop const.
    180 }
    181 
    182 TEST(ArrayViewTest, TestCopyAssignmentVariableLvalue) {
    183  char arr[] = "Arrr!";
    184  ArrayView<char> x(arr);
    185  EXPECT_EQ(6u, x.size());
    186  EXPECT_EQ(arr, x.data());
    187  ArrayView<char> y;
    188  y = x;  // Copy non-const -> non-const.
    189  EXPECT_EQ(6u, y.size());
    190  EXPECT_EQ(arr, y.data());
    191  ArrayView<const char> z;
    192  z = x;  // Copy non-const -> const.
    193  EXPECT_EQ(6u, z.size());
    194  EXPECT_EQ(arr, z.data());
    195  ArrayView<const char> w;
    196  w = z;  // Copy const -> const.
    197  EXPECT_EQ(6u, w.size());
    198  EXPECT_EQ(arr, w.data());
    199  // ArrayView<char> v;
    200  // v = z;  // Compile error, because can't drop const.
    201 }
    202 
    203 TEST(ArrayViewTest, TestCopyAssignmentVariableRvalue) {
    204  char arr[] = "Arrr!";
    205  ArrayView<char> x(arr);
    206  EXPECT_EQ(6u, x.size());
    207  EXPECT_EQ(arr, x.data());
    208  ArrayView<char> y;
    209  y = std::move(x);  // Copy non-const -> non-const.
    210  EXPECT_EQ(6u, y.size());
    211  EXPECT_EQ(arr, y.data());
    212  ArrayView<const char> z;
    213  z = std::move(x);  // Copy non-const -> const.
    214  EXPECT_EQ(6u, z.size());
    215  EXPECT_EQ(arr, z.data());
    216  ArrayView<const char> w;
    217  w = std::move(z);  // Copy const -> const.
    218  EXPECT_EQ(6u, w.size());
    219  EXPECT_EQ(arr, w.data());
    220  // ArrayView<char> v;
    221  // v = std::move(z);  // Compile error, because can't drop const.
    222 }
    223 
    224 TEST(ArrayViewTest, TestCopyAssignmentFixedLvalue) {
    225  char arr[] = "Arrr!";
    226  char init[] = "Init!";
    227  ArrayView<char, 6> x(arr);
    228  EXPECT_EQ(arr, x.data());
    229 
    230  // Copy fixed -> fixed.
    231  ArrayView<char, 6> y(init);
    232  y = x;  // Copy non-const -> non-const.
    233  EXPECT_EQ(arr, y.data());
    234  ArrayView<const char, 6> z(init);
    235  z = x;  // Copy non-const -> const.
    236  EXPECT_EQ(arr, z.data());
    237  ArrayView<const char, 6> w(init);
    238  w = z;  // Copy const -> const.
    239  EXPECT_EQ(arr, w.data());
    240  // ArrayView<char, 6> v(init);
    241  // v = z;  // Compile error, because can't drop const.
    242 
    243  // Copy fixed -> variable.
    244  ArrayView<char> yv;
    245  yv = x;  // Copy non-const -> non-const.
    246  EXPECT_EQ(6u, yv.size());
    247  EXPECT_EQ(arr, yv.data());
    248  ArrayView<const char> zv;
    249  zv = x;  // Copy non-const -> const.
    250  EXPECT_EQ(6u, zv.size());
    251  EXPECT_EQ(arr, zv.data());
    252  ArrayView<const char> wv;
    253  wv = z;  // Copy const -> const.
    254  EXPECT_EQ(6u, wv.size());
    255  EXPECT_EQ(arr, wv.data());
    256  // ArrayView<char> v;
    257  // v = z;  // Compile error, because can't drop const.
    258 }
    259 
    260 TEST(ArrayViewTest, TestCopyAssignmentFixedRvalue) {
    261  char arr[] = "Arrr!";
    262  char init[] = "Init!";
    263  ArrayView<char, 6> x(arr);
    264  EXPECT_EQ(arr, x.data());
    265 
    266  // Copy fixed -> fixed.
    267  ArrayView<char, 6> y(init);
    268  y = std::move(x);  // Copy non-const -> non-const.
    269  EXPECT_EQ(arr, y.data());
    270  ArrayView<const char, 6> z(init);
    271  z = std::move(x);  // Copy non-const -> const.
    272  EXPECT_EQ(arr, z.data());
    273  ArrayView<const char, 6> w(init);
    274  w = std::move(z);  // Copy const -> const.
    275  EXPECT_EQ(arr, w.data());
    276  // ArrayView<char, 6> v(init);
    277  // v = std::move(z);  // Compile error, because can't drop const.
    278 
    279  // Copy fixed -> variable.
    280  ArrayView<char> yv;
    281  yv = std::move(x);  // Copy non-const -> non-const.
    282  EXPECT_EQ(6u, yv.size());
    283  EXPECT_EQ(arr, yv.data());
    284  ArrayView<const char> zv;
    285  zv = std::move(x);  // Copy non-const -> const.
    286  EXPECT_EQ(6u, zv.size());
    287  EXPECT_EQ(arr, zv.data());
    288  ArrayView<const char> wv;
    289  wv = std::move(z);  // Copy const -> const.
    290  EXPECT_EQ(6u, wv.size());
    291  EXPECT_EQ(arr, wv.data());
    292  // ArrayView<char> v;
    293  // v = std::move(z);  // Compile error, because can't drop const.
    294 }
    295 
    296 TEST(ArrayViewTest, TestStdArray) {
    297  EXPECT_EQ(4u, Call<const int>(std::array<int, 4>{1, 2, 3, 4}));
    298  CallFixed<const int, 3>(std::array<int, 3>{2, 3, 4});
    299  constexpr size_t size = 5;
    300  std::array<float, size> arr{};
    301  // Fixed size view.
    302  ArrayView<float, size> arr_view_fixed(arr);
    303  EXPECT_EQ(arr.data(), arr_view_fixed.data());
    304  static_assert(size == arr_view_fixed.size(), "");
    305  // Variable size view.
    306  ArrayView<float> arr_view(arr);
    307  EXPECT_EQ(arr.data(), arr_view.data());
    308  EXPECT_EQ(size, arr_view.size());
    309 }
    310 
    311 TEST(ArrayViewTest, TestConstStdArray) {
    312  constexpr size_t size = 5;
    313 
    314  constexpr std::array<float, size> constexpr_arr{};
    315  ArrayView<const float, size> constexpr_arr_view(constexpr_arr);
    316  EXPECT_EQ(constexpr_arr.data(), constexpr_arr_view.data());
    317  static_assert(constexpr_arr.size() == constexpr_arr_view.size(), "");
    318 
    319  const std::array<float, size> const_arr{};
    320  ArrayView<const float, size> const_arr_view(const_arr);
    321  EXPECT_EQ(const_arr.data(), const_arr_view.data());
    322  static_assert(const_arr.size() == const_arr_view.size(), "");
    323 
    324  std::array<float, size> non_const_arr{};
    325  ArrayView<const float, size> non_const_arr_view(non_const_arr);
    326  EXPECT_EQ(non_const_arr.data(), non_const_arr_view.data());
    327  static_assert(non_const_arr.size() == non_const_arr_view.size(), "");
    328 }
    329 
    330 TEST(ArrayViewTest, TestStdVector) {
    331  EXPECT_EQ(3u, Call<const int>(std::vector<int>{4, 5, 6}));
    332  std::vector<int> v;
    333  v.push_back(3);
    334  v.push_back(11);
    335  EXPECT_EQ(2u, Call<const int>(v));
    336  EXPECT_EQ(2u, Call<int>(v));
    337  // Call<unsigned int>(v);  // Compile error, because incompatible types.
    338  ArrayView<int> x = v;
    339  EXPECT_EQ(2u, x.size());
    340  EXPECT_EQ(v.data(), x.data());
    341  ArrayView<const int> y;
    342  y = v;
    343  EXPECT_EQ(2u, y.size());
    344  EXPECT_EQ(v.data(), y.data());
    345  // ArrayView<double> d = v;  // Compile error, because incompatible types.
    346  const std::vector<int> cv;
    347  EXPECT_EQ(0u, Call<const int>(cv));
    348  // Call<int>(cv);  // Compile error, because can't drop const.
    349  ArrayView<const int> z = cv;
    350  EXPECT_EQ(0u, z.size());
    351  EXPECT_EQ(nullptr, z.data());
    352  // ArrayView<int> w = cv;  // Compile error, because can't drop const.
    353 }
    354 
    355 TEST(ArrayViewTest, TestRtcBuffer) {
    356  Buffer b = "so buffer";
    357  EXPECT_EQ(10u, Call<const uint8_t>(b));
    358  EXPECT_EQ(10u, Call<uint8_t>(b));
    359  // Call<int8_t>(b);  // Compile error, because incompatible types.
    360  ArrayView<uint8_t> x = b;
    361  EXPECT_EQ(10u, x.size());
    362  EXPECT_EQ(b.data(), x.data());
    363  ArrayView<const uint8_t> y;
    364  y = b;
    365  EXPECT_EQ(10u, y.size());
    366  EXPECT_EQ(b.data(), y.data());
    367  // ArrayView<char> d = b;  // Compile error, because incompatible types.
    368  const Buffer cb = "very const";
    369  EXPECT_EQ(11u, Call<const uint8_t>(cb));
    370  // Call<uint8_t>(cb);  // Compile error, because can't drop const.
    371  ArrayView<const uint8_t> z = cb;
    372  EXPECT_EQ(11u, z.size());
    373  EXPECT_EQ(cb.data(), z.data());
    374  // ArrayView<uint8_t> w = cb;  // Compile error, because can't drop const.
    375 }
    376 
    377 TEST(ArrayViewTest, TestSwapVariable) {
    378  const char arr[] = "Arrr!";
    379  const char aye[] = "Aye, Cap'n!";
    380  ArrayView<const char> x(arr);
    381  EXPECT_EQ(6u, x.size());
    382  EXPECT_EQ(arr, x.data());
    383  ArrayView<const char> y(aye);
    384  EXPECT_EQ(12u, y.size());
    385  EXPECT_EQ(aye, y.data());
    386  using std::swap;
    387  swap(x, y);
    388  EXPECT_EQ(12u, x.size());
    389  EXPECT_EQ(aye, x.data());
    390  EXPECT_EQ(6u, y.size());
    391  EXPECT_EQ(arr, y.data());
    392  // ArrayView<char> z;
    393  // swap(x, z);  // Compile error, because can't drop const.
    394 }
    395 
    396 TEST(FixArrayViewTest, TestSwapFixed) {
    397  const char arr[] = "Arr!";
    398  char aye[] = "Aye!";
    399  ArrayView<const char, 5> x(arr);
    400  EXPECT_EQ(arr, x.data());
    401  ArrayView<const char, 5> y(aye);
    402  EXPECT_EQ(aye, y.data());
    403  using std::swap;
    404  swap(x, y);
    405  EXPECT_EQ(aye, x.data());
    406  EXPECT_EQ(arr, y.data());
    407  // ArrayView<char, 5> z(aye);
    408  // swap(x, z);  // Compile error, because can't drop const.
    409  // ArrayView<const char, 4> w(aye, 4);
    410  // swap(x, w);  // Compile error, because different sizes.
    411 }
    412 
    413 TEST(ArrayViewDeathTest, TestIndexing) {
    414  char arr[] = "abcdefg";
    415  ArrayView<char> x(arr);
    416  const ArrayView<char> y(arr);
    417  ArrayView<const char, 8> z(arr);
    418  EXPECT_EQ(8u, x.size());
    419  EXPECT_EQ(8u, y.size());
    420  EXPECT_EQ(8u, z.size());
    421  EXPECT_EQ('b', x[1]);
    422  EXPECT_EQ('c', y[2]);
    423  EXPECT_EQ('d', z[3]);
    424  x[3] = 'X';
    425  y[2] = 'Y';
    426  // z[1] = 'Z';  // Compile error, because z's element type is const char.
    427  EXPECT_EQ('b', x[1]);
    428  EXPECT_EQ('Y', y[2]);
    429  EXPECT_EQ('X', z[3]);
    430 #if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
    431  EXPECT_DEATH(z[8], "");  // DCHECK error (index out of bounds).
    432 #endif
    433 }
    434 
    435 TEST(ArrayViewTest, TestIterationEmpty) {
    436  // Variable-size.
    437  ArrayView<std::vector<std::vector<std::vector<std::string>>>> av;
    438  EXPECT_EQ(av.begin(), av.end());
    439  EXPECT_EQ(av.cbegin(), av.cend());
    440  for (auto& e : av) {
    441    EXPECT_TRUE(false);
    442    EXPECT_EQ(42u, e.size());  // Dummy use of e to prevent unused var warning.
    443  }
    444 
    445  // Fixed-size.
    446  ArrayView<std::vector<std::vector<std::vector<std::string>>>, 0> af;
    447  EXPECT_EQ(af.begin(), af.end());
    448  EXPECT_EQ(af.cbegin(), af.cend());
    449  for (auto& e : af) {
    450    EXPECT_TRUE(false);
    451    EXPECT_EQ(42u, e.size());  // Dummy use of e to prevent unused var warning.
    452  }
    453 }
    454 
    455 TEST(ArrayViewTest, TestReverseIterationEmpty) {
    456  // Variable-size.
    457  ArrayView<std::vector<std::vector<std::vector<std::string>>>> av;
    458  EXPECT_EQ(av.rbegin(), av.rend());
    459  EXPECT_EQ(av.crbegin(), av.crend());
    460  EXPECT_TRUE(av.empty());
    461 
    462  // Fixed-size.
    463  ArrayView<std::vector<std::vector<std::vector<std::string>>>, 0> af;
    464  EXPECT_EQ(af.begin(), af.end());
    465  EXPECT_EQ(af.cbegin(), af.cend());
    466  EXPECT_TRUE(af.empty());
    467 }
    468 
    469 TEST(ArrayViewTest, TestIterationVariable) {
    470  char arr[] = "Arrr!";
    471  ArrayView<char> av(arr);
    472  EXPECT_EQ('A', *av.begin());
    473  EXPECT_EQ('A', *av.cbegin());
    474  EXPECT_EQ('\0', *(av.end() - 1));
    475  EXPECT_EQ('\0', *(av.cend() - 1));
    476  char i = 0;
    477  for (auto& e : av) {
    478    EXPECT_EQ(arr + i, &e);
    479    e = 's' + i;
    480    ++i;
    481  }
    482  i = 0;
    483  for (auto& e : ArrayView<const char>(av)) {
    484    EXPECT_EQ(arr + i, &e);
    485    // e = 'q' + i;  // Compile error, because e is a const char&.
    486    ++i;
    487  }
    488 }
    489 
    490 TEST(ArrayViewTest, TestReverseIterationVariable) {
    491  char arr[] = "Arrr!";
    492  ArrayView<char> av(arr);
    493  EXPECT_EQ('\0', *av.rbegin());
    494  EXPECT_EQ('\0', *av.crbegin());
    495  EXPECT_EQ('A', *(av.rend() - 1));
    496  EXPECT_EQ('A', *(av.crend() - 1));
    497 
    498  const char* cit = av.cend() - 1;
    499  for (auto crit = av.crbegin(); crit != av.crend(); ++crit, --cit) {
    500    EXPECT_EQ(*cit, *crit);
    501  }
    502 
    503  char* it = av.end() - 1;
    504  for (auto rit = av.rbegin(); rit != av.rend(); ++rit, --it) {
    505    EXPECT_EQ(*it, *rit);
    506  }
    507 }
    508 
    509 TEST(ArrayViewTest, TestIterationFixed) {
    510  char arr[] = "Arrr!";
    511  ArrayView<char, 6> av(arr);
    512  EXPECT_EQ('A', *av.begin());
    513  EXPECT_EQ('A', *av.cbegin());
    514  EXPECT_EQ('\0', *(av.end() - 1));
    515  EXPECT_EQ('\0', *(av.cend() - 1));
    516  char i = 0;
    517  for (auto& e : av) {
    518    EXPECT_EQ(arr + i, &e);
    519    e = 's' + i;
    520    ++i;
    521  }
    522  i = 0;
    523  for (auto& e : ArrayView<const char, 6>(av)) {
    524    EXPECT_EQ(arr + i, &e);
    525    // e = 'q' + i;  // Compile error, because e is a const char&.
    526    ++i;
    527  }
    528 }
    529 
    530 TEST(ArrayViewTest, TestReverseIterationFixed) {
    531  char arr[] = "Arrr!";
    532  ArrayView<char, 6> av(arr);
    533  EXPECT_EQ('\0', *av.rbegin());
    534  EXPECT_EQ('\0', *av.crbegin());
    535  EXPECT_EQ('A', *(av.rend() - 1));
    536  EXPECT_EQ('A', *(av.crend() - 1));
    537 
    538  const char* cit = av.cend() - 1;
    539  for (auto crit = av.crbegin(); crit != av.crend(); ++crit, --cit) {
    540    EXPECT_EQ(*cit, *crit);
    541  }
    542 
    543  char* it = av.end() - 1;
    544  for (auto rit = av.rbegin(); rit != av.rend(); ++rit, --it) {
    545    EXPECT_EQ(*it, *rit);
    546  }
    547 }
    548 
    549 TEST(ArrayViewTest, TestEmpty) {
    550  EXPECT_TRUE(ArrayView<int>().empty());
    551  const int a[] = {1, 2, 3};
    552  EXPECT_FALSE(ArrayView<const int>(a).empty());
    553 
    554  static_assert(ArrayView<int, 0>::empty(), "");
    555  static_assert(!ArrayView<int, 3>::empty(), "");
    556 }
    557 
    558 TEST(ArrayViewTest, TestCompare) {
    559  int a[] = {1, 2, 3};
    560  int b[] = {1, 2, 3};
    561 
    562  EXPECT_EQ(ArrayView<int>(a), ArrayView<int>(a));
    563  EXPECT_EQ((ArrayView<int, 3>(a)), (ArrayView<int, 3>(a)));
    564  EXPECT_EQ(ArrayView<int>(a), (ArrayView<int, 3>(a)));
    565  EXPECT_EQ(ArrayView<int>(), ArrayView<int>());
    566  EXPECT_EQ(ArrayView<int>(), ArrayView<int>(a, 0));
    567  EXPECT_EQ(ArrayView<int>(a, 0), ArrayView<int>(b, 0));
    568  EXPECT_EQ((ArrayView<int, 0>(a, 0)), ArrayView<int>());
    569 
    570  EXPECT_NE(ArrayView<int>(a), ArrayView<int>(b));
    571  EXPECT_NE((ArrayView<int, 3>(a)), (ArrayView<int, 3>(b)));
    572  EXPECT_NE((ArrayView<int, 3>(a)), ArrayView<int>(b));
    573  EXPECT_NE(ArrayView<int>(a), ArrayView<int>());
    574  EXPECT_NE(ArrayView<int>(a), ArrayView<int>(a, 2));
    575  EXPECT_NE((ArrayView<int, 3>(a)), (ArrayView<int, 2>(a, 2)));
    576 }
    577 
    578 TEST(ArrayViewTest, TestSubViewVariable) {
    579  int a[] = {1, 2, 3};
    580  ArrayView<int> av(a);
    581 
    582  EXPECT_EQ(av.subview(0), av);
    583 
    584  EXPECT_THAT(av.subview(1), ElementsAre(2, 3));
    585  EXPECT_THAT(av.subview(2), ElementsAre(3));
    586  EXPECT_THAT(av.subview(3), IsEmpty());
    587  EXPECT_THAT(av.subview(4), IsEmpty());
    588 
    589  EXPECT_THAT(av.subview(1, 0), IsEmpty());
    590  EXPECT_THAT(av.subview(1, 1), ElementsAre(2));
    591  EXPECT_THAT(av.subview(1, 2), ElementsAre(2, 3));
    592  EXPECT_THAT(av.subview(1, 3), ElementsAre(2, 3));
    593 }
    594 
    595 TEST(ArrayViewTest, TestSubViewFixed) {
    596  int a[] = {1, 2, 3};
    597  ArrayView<int, 3> av(a);
    598 
    599  EXPECT_EQ(av.subview(0), av);
    600 
    601  EXPECT_THAT(av.subview(1), ElementsAre(2, 3));
    602  EXPECT_THAT(av.subview(2), ElementsAre(3));
    603  EXPECT_THAT(av.subview(3), IsEmpty());
    604  EXPECT_THAT(av.subview(4), IsEmpty());
    605 
    606  EXPECT_THAT(av.subview(1, 0), IsEmpty());
    607  EXPECT_THAT(av.subview(1, 1), ElementsAre(2));
    608  EXPECT_THAT(av.subview(1, 2), ElementsAre(2, 3));
    609  EXPECT_THAT(av.subview(1, 3), ElementsAre(2, 3));
    610 }
    611 
    612 TEST(ArrayViewTest, TestReinterpretCastFixedSize) {
    613  uint8_t bytes[] = {1, 2, 3};
    614  ArrayView<uint8_t, 3> uint8_av(bytes);
    615  ArrayView<int8_t, 3> int8_av = reinterpret_array_view<int8_t>(uint8_av);
    616  EXPECT_EQ(int8_av.size(), uint8_av.size());
    617  EXPECT_EQ(int8_av[0], 1);
    618  EXPECT_EQ(int8_av[1], 2);
    619  EXPECT_EQ(int8_av[2], 3);
    620 }
    621 
    622 TEST(ArrayViewTest, TestReinterpretCastVariableSize) {
    623  std::vector<int8_t> v = {1, 2, 3};
    624  ArrayView<int8_t> int8_av(v);
    625  ArrayView<uint8_t> uint8_av = reinterpret_array_view<uint8_t>(int8_av);
    626  EXPECT_EQ(int8_av.size(), uint8_av.size());
    627  EXPECT_EQ(uint8_av[0], 1);
    628  EXPECT_EQ(uint8_av[1], 2);
    629  EXPECT_EQ(uint8_av[2], 3);
    630 }
    631 }  // namespace webrtc