/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <folly/Range.h>

#include <array>
#include <deque>
#include <iterator>
#include <limits>
#include <random>
#include <string>
#include <type_traits>
#include <vector>

#include <boost/algorithm/string/trim.hpp>
#include <boost/range/concepts.hpp>

#include <folly/CppAttributes.h>
#include <folly/Memory.h>
#include <folly/portability/GMock.h>
#include <folly/portability/GTest.h>
#include <folly/portability/SysMman.h>
#include <folly/portability/Unistd.h>

#if __has_include(<range/v3/range/concepts.hpp>)
#include <range/v3/range/concepts.hpp>

// Check conformance with the C++20 range concepts as specified
// by the range-v3 library.
CPP_assert(ranges::range<folly::StringPiece>);
CPP_assert(ranges::view_<folly::StringPiece>);
#endif

using namespace folly;
using namespace std;

static_assert(folly::detail::range_is_char_type_v_<char*>, "");
static_assert(folly::detail::range_is_byte_type_v_<unsigned char*>, "");

static_assert(std::is_same_v<char, typename Range<char*>::value_type>);

BOOST_CONCEPT_ASSERT((boost::RandomAccessRangeConcept<StringPiece>));

#define EXPECT_CMP_(op, a_, b_, eq, ne, lt, le, gt, ge)  \
  ::std::invoke(                                         \
      [](auto const& a, auto const& b) {                 \
        EXPECT_##op(a, b);                               \
        EXPECT_THAT(a, ::testing::eq(::testing::Eq(b))); \
        EXPECT_THAT(a, ::testing::ne(::testing::Ne(b))); \
        EXPECT_THAT(a, ::testing::lt(::testing::Lt(b))); \
        EXPECT_THAT(a, ::testing::le(::testing::Le(b))); \
        EXPECT_THAT(a, ::testing::gt(::testing::Gt(b))); \
        EXPECT_THAT(a, ::testing::ge(::testing::Ge(b))); \
      },                                                 \
      (a_),                                              \
      (b_));

#define EXPECT_CMP_EQ(a_, b_) \
  EXPECT_CMP_(EQ, a_, b_, AllArgs, Not, Not, AllArgs, Not, AllArgs)
#define EXPECT_CMP_LT(a_, b_) \
  EXPECT_CMP_(LT, a_, b_, Not, AllArgs, AllArgs, AllArgs, Not, Not)
#define EXPECT_CMP_GT(a_, b_) \
  EXPECT_CMP_(GT, a_, b_, Not, AllArgs, Not, Not, AllArgs, AllArgs)

TEST(StringPiece, All) {
  const char* foo = "foo";
  const char* foo2 = "foo";
  string fooStr(foo);
  string foo2Str(foo2);

  // we expect the compiler to optimize things so that there's only one copy
  // of the string literal "foo", even though we've got it in multiple places
  EXPECT_EQ(foo, foo2); // remember, this uses ==, not strcmp, so it's a ptr
                        // comparison rather than lexical

  // the string object creates copies though, so the c_str of these should be
  // distinct
  EXPECT_NE(fooStr.c_str(), foo2Str.c_str());

  // test the basic StringPiece functionality
  StringPiece s(foo);
  EXPECT_EQ(s.size(), 3);

  EXPECT_EQ(s.start(), foo); // ptr comparison
  EXPECT_NE(s.start(), fooStr.c_str()); // ptr comparison
  EXPECT_NE(s.start(), foo2Str.c_str()); // ptr comparison

  EXPECT_EQ(s.toString(), foo); // lexical comparison
  EXPECT_EQ(s.toString(), fooStr.c_str()); // lexical comparison
  EXPECT_EQ(s.toString(), foo2Str.c_str()); // lexical comparison

  EXPECT_EQ(s, foo); // lexical comparison
  EXPECT_EQ(s, fooStr); // lexical comparison
  EXPECT_EQ(s, foo2Str); // lexical comparison
  EXPECT_EQ(foo, s);

  // check using StringPiece to reference substrings
  const char* foobarbaz = "foobarbaz";

  // the full "foobarbaz"
  s.reset(foobarbaz, strlen(foobarbaz));
  EXPECT_EQ(s.size(), 9);
  EXPECT_EQ(s.start(), foobarbaz);
  EXPECT_EQ(s, "foobarbaz");

  // only the 'foo'
  s.assign(foobarbaz, foobarbaz + 3);
  EXPECT_EQ(s.size(), 3);
  EXPECT_EQ(s.start(), foobarbaz);
  EXPECT_EQ(s, "foo");

  // find
  s.reset(foobarbaz, strlen(foobarbaz));
  EXPECT_EQ(s.find("bar"), 3);
  EXPECT_EQ(s.find("ba", 3), 3);
  EXPECT_EQ(s.find("ba", 4), 6);
  EXPECT_EQ(s.find("notfound"), StringPiece::npos);
  EXPECT_EQ(s.find("notfound", 1), StringPiece::npos);
  EXPECT_EQ(s.find("bar", 4), StringPiece::npos); // starting position too far
  // starting pos that is obviously past the end -- This works for std::string
  EXPECT_EQ(s.toString().find("notfound", 55), StringPiece::npos);
  EXPECT_EQ(s.find("z", s.size()), StringPiece::npos);
  EXPECT_EQ(s.find("z", 55), StringPiece::npos);
  // empty needle
  EXPECT_EQ(s.find(""), std::string().find(""));
  EXPECT_EQ(s.find(""), 0);

  // single char finds
  EXPECT_EQ(s.find('b'), 3);
  EXPECT_EQ(s.find('b', 3), 3);
  EXPECT_EQ(s.find('b', 4), 6);
  EXPECT_EQ(s.find('o', 2), 2);
  EXPECT_EQ(s.find('y'), StringPiece::npos);
  EXPECT_EQ(s.find('y', 1), StringPiece::npos);
  EXPECT_EQ(s.find('o', 4), StringPiece::npos); // starting position too far
  EXPECT_TRUE(s.contains('z'));
  // starting pos that is obviously past the end -- This works for std::string
  EXPECT_EQ(s.toString().find('y', 55), StringPiece::npos);
  EXPECT_EQ(s.find('z', s.size()), StringPiece::npos);
  EXPECT_EQ(s.find('z', 55), StringPiece::npos);
  // null char
  EXPECT_EQ(s.find('\0'), std::string().find('\0'));
  EXPECT_EQ(s.find('\0'), StringPiece::npos);
  EXPECT_FALSE(s.contains('\0'));

  // single char rfinds
  EXPECT_EQ(s.rfind('b'), 6);
  EXPECT_EQ(s.rfind('y'), StringPiece::npos);
  EXPECT_EQ(s.str().rfind('y'), StringPiece::npos);
  EXPECT_EQ(ByteRange(s).rfind('b'), 6);
  EXPECT_EQ(ByteRange(s).rfind('y'), StringPiece::npos);
  // null char
  EXPECT_EQ(s.rfind('\0'), s.str().rfind('\0'));
  EXPECT_EQ(s.rfind('\0'), StringPiece::npos);

  // find_first_of
  s.reset(foobarbaz, strlen(foobarbaz));
  EXPECT_EQ(s.find_first_of("bar"), 3);
  EXPECT_EQ(s.find_first_of("ba", 3), 3);
  EXPECT_EQ(s.find_first_of("ba", 4), 4);
  EXPECT_TRUE(s.contains("bar"));
  EXPECT_EQ(s.find_first_of("xyxy"), StringPiece::npos);
  EXPECT_EQ(s.find_first_of("xyxy", 1), StringPiece::npos);
  EXPECT_FALSE(s.contains("xyxy"));
  // starting position too far
  EXPECT_EQ(s.find_first_of("foo", 4), StringPiece::npos);
  // starting pos that is obviously past the end -- This works for std::string
  EXPECT_EQ(s.toString().find_first_of("xyxy", 55), StringPiece::npos);
  EXPECT_EQ(s.find_first_of("z", s.size()), StringPiece::npos);
  EXPECT_EQ(s.find_first_of("z", 55), StringPiece::npos);
  // empty needle. Note that this returns npos, while find() returns 0!
  EXPECT_EQ(s.find_first_of(""), std::string().find_first_of(""));
  EXPECT_EQ(s.find_first_of(""), StringPiece::npos);

  // single char find_first_ofs
  EXPECT_EQ(s.find_first_of('b'), 3);
  EXPECT_EQ(s.find_first_of('b', 3), 3);
  EXPECT_EQ(s.find_first_of('b', 4), 6);
  EXPECT_EQ(s.find_first_of('o', 2), 2);
  EXPECT_EQ(s.find_first_of('y'), StringPiece::npos);
  EXPECT_EQ(s.find_first_of('y', 1), StringPiece::npos);
  // starting position too far
  EXPECT_EQ(s.find_first_of('o', 4), StringPiece::npos);
  // starting pos that is obviously past the end -- This works for std::string
  EXPECT_EQ(s.toString().find_first_of('y', 55), StringPiece::npos);
  EXPECT_EQ(s.find_first_of('z', s.size()), StringPiece::npos);
  EXPECT_EQ(s.find_first_of('z', 55), StringPiece::npos);
  // null char
  EXPECT_EQ(s.find_first_of('\0'), std::string().find_first_of('\0'));
  EXPECT_EQ(s.find_first_of('\0'), StringPiece::npos);

  // just "barbaz"
  s.reset(foobarbaz + 3, strlen(foobarbaz + 3));
  EXPECT_EQ(s.size(), 6);
  EXPECT_EQ(s.start(), foobarbaz + 3);
  EXPECT_EQ(s, "barbaz");

  // just "bar"
  s.reset(foobarbaz + 3, 3);
  EXPECT_EQ(s.size(), 3);
  EXPECT_EQ(s, "bar");

  // clear
  s.clear();
  EXPECT_EQ(s.toString(), "");

  // test an empty StringPiece
  StringPiece s2;
  EXPECT_EQ(s2.size(), 0);

  // Test comparison operators
  foo = "";
  EXPECT_LE(s, foo);
  EXPECT_LE(foo, s);
  EXPECT_GE(s, foo);
  EXPECT_GE(foo, s);
  EXPECT_EQ(s, foo);
  EXPECT_EQ(foo, s);

  foo = "abc";
  EXPECT_LE(s, foo);
  EXPECT_LT(s, foo);
  EXPECT_GE(foo, s);
  EXPECT_GT(foo, s);
  EXPECT_NE(s, foo);

  EXPECT_LE(s, s);
  EXPECT_LE(s, s);
  EXPECT_GE(s, s);
  EXPECT_GE(s, s);
  EXPECT_EQ(s, s);
  EXPECT_EQ(s, s);

  s = "abc";
  s2 = "abc";
  EXPECT_LE(s, s2);
  EXPECT_LE(s2, s);
  EXPECT_GE(s, s2);
  EXPECT_GE(s2, s);
  EXPECT_EQ(s, s2);
  EXPECT_EQ(s2, s);
}

#if !defined(__GLIBCXX__) || _GLIBCXX_USE_CXX11_ABI
TEST(StringPiece, CustomAllocator) {
  using Alloc = AlignedSysAllocator<char>;
  Alloc const alloc{32};
  char const* const text = "foo bar baz";
  std::basic_string<char, std::char_traits<char>, Alloc> str{text, alloc};
  EXPECT_EQ("foo", StringPiece(str).subpiece(0, 3));
  EXPECT_EQ("bar", StringPiece(str, 4).subpiece(0, 3));
  EXPECT_EQ("baz", StringPiece(str, 8, 3));
  StringPiece piece;
  piece.reset(str);
  EXPECT_EQ("foo", piece.subpiece(0, 3));
}
#endif

template <class T>
void expectLT(const T& a, const T& b) {
  EXPECT_TRUE(a < b);
  EXPECT_TRUE(a <= b);
  EXPECT_FALSE(a == b);
  EXPECT_FALSE(a >= b);
  EXPECT_FALSE(a > b);

  EXPECT_FALSE(b < a);
  EXPECT_FALSE(b <= a);
  EXPECT_TRUE(b >= a);
  EXPECT_TRUE(b > a);
}

template <class T>
void expectEQ(const T& a, const T& b) {
  EXPECT_FALSE(a < b);
  EXPECT_TRUE(a <= b);
  EXPECT_TRUE(a == b);
  EXPECT_TRUE(a >= b);
  EXPECT_FALSE(a > b);
}

TEST(StringPiece, EightBitComparisons) {
  char values[] = {'\x00', '\x20', '\x40', '\x7f', '\x80', '\xc0', '\xff'};
  constexpr size_t count = sizeof(values) / sizeof(values[0]);
  for (size_t i = 0; i < count; ++i) {
    std::string a(1, values[i]);
    // Defeat copy-on-write
    std::string aCopy(a.data(), a.size());
    expectEQ(a, aCopy);
    expectEQ(StringPiece(a), StringPiece(aCopy));

    for (size_t j = i + 1; j < count; ++j) {
      std::string b(1, values[j]);
      expectLT(a, b);
      expectLT(StringPiece(a), StringPiece(b));
    }
  }
}

TEST(StringPiece, ToByteRange) {
  StringPiece a("hello");
  ByteRange b(a);
  EXPECT_EQ(
      static_cast<const void*>(a.begin()), static_cast<const void*>(b.begin()));
  EXPECT_EQ(
      static_cast<const void*>(a.end()), static_cast<const void*>(b.end()));

  // and convert back again
  StringPiece c(b);
  EXPECT_EQ(a.begin(), c.begin());
  EXPECT_EQ(a.end(), c.end());
}

TEST(ByteRange, FromString) {
  std::string s("hello");
  ByteRange b(s);
  EXPECT_EQ(
      static_cast<const void*>(s.data()), static_cast<const void*>(b.begin()));
  EXPECT_EQ(s.size(), b.size());

  std::string_view sv(s);
  ByteRange b2(sv);
  EXPECT_EQ(
      static_cast<const void*>(s.data()), static_cast<const void*>(b2.begin()));
  EXPECT_EQ(s.size(), b2.size());
}

TEST(StringPiece, InvalidRange) {
  StringPiece a("hello");
  EXPECT_EQ(a, a.subpiece(0, 10));
  EXPECT_EQ(StringPiece("ello"), a.subpiece(1));
  EXPECT_EQ(StringPiece("ello"), a.subpiece(1, std::string::npos));
  EXPECT_EQ(StringPiece("ell"), a.subpiece(1, 3));
  EXPECT_THROW(a.subpiece(6, 7), std::out_of_range);
  EXPECT_THROW(a.subpiece(6), std::out_of_range);

  std::string b("hello");
  EXPECT_EQ(a, StringPiece(b, 0, 10));
  EXPECT_EQ("ello", a.subpiece(1));
  EXPECT_EQ("ello", a.subpiece(1, std::string::npos));
  EXPECT_EQ("ell", a.subpiece(1, 3));
  EXPECT_THROW(a.subpiece(6, 7), std::out_of_range);
  EXPECT_THROW(a.subpiece(6), std::out_of_range);
}

TEST(StringPiece, Constexpr) {
  constexpr const char* helloArray = "hello";

  constexpr StringPiece hello1("hello");
  EXPECT_EQ("hello", hello1);
  static_assert(hello1.size() == 5, "hello size should be 5 at compile time");

  constexpr StringPiece hello2(helloArray);
  EXPECT_EQ("hello", hello2);
  static_assert(hello2.size() == 5, "hello size should be 5 at compile time");
}

TEST(StringPiece, Prefix) {
  StringPiece a("hello");
  EXPECT_TRUE(a.starts_with(""));
  EXPECT_TRUE(a.starts_with("h"));
  EXPECT_TRUE(a.starts_with('h'));
  EXPECT_TRUE(a.starts_with("hello"));
  EXPECT_FALSE(a.starts_with("hellox"));
  EXPECT_FALSE(a.starts_with('x'));
  EXPECT_FALSE(a.starts_with("x"));

  EXPECT_TRUE(a.startsWith("", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.startsWith("hello", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.startsWith("hellO", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.startsWith("HELL", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.startsWith("H", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.startsWith("HELLOX", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.startsWith("x", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.startsWith("X", folly::AsciiCaseInsensitive()));

  {
    auto b = a;
    EXPECT_TRUE(b.removePrefix(""));
    EXPECT_EQ("hello", b);
  }
  {
    auto b = a;
    EXPECT_TRUE(b.removePrefix("h"));
    EXPECT_EQ("ello", b);
  }
  {
    auto b = a;
    EXPECT_TRUE(b.removePrefix('h'));
    EXPECT_EQ("ello", b);
  }
  {
    auto b = a;
    EXPECT_TRUE(b.removePrefix("hello"));
    EXPECT_EQ("", b);
  }
  {
    auto b = a;
    EXPECT_FALSE(b.removePrefix("hellox"));
    EXPECT_EQ("hello", b);
  }
  {
    auto b = a;
    EXPECT_FALSE(b.removePrefix("x"));
    EXPECT_EQ("hello", b);
  }
  {
    auto b = a;
    EXPECT_FALSE(b.removePrefix('x'));
    EXPECT_EQ("hello", b);
  }
}

TEST(StringPiece, Suffix) {
  StringPiece a("hello");
  EXPECT_TRUE(a.ends_with(""));
  EXPECT_TRUE(a.ends_with("o"));
  EXPECT_TRUE(a.ends_with('o'));
  EXPECT_TRUE(a.ends_with("hello"));
  EXPECT_FALSE(a.ends_with("xhello"));
  EXPECT_FALSE(a.ends_with("x"));
  EXPECT_FALSE(a.ends_with('x'));

  EXPECT_TRUE(a.endsWith("", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.endsWith("o", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.endsWith("O", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.endsWith("hello", folly::AsciiCaseInsensitive()));
  EXPECT_TRUE(a.endsWith("hellO", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.endsWith("xhello", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.endsWith("Xhello", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.endsWith("x", folly::AsciiCaseInsensitive()));
  EXPECT_FALSE(a.endsWith("X", folly::AsciiCaseInsensitive()));

  {
    auto b = a;
    EXPECT_TRUE(b.removeSuffix(""));
    EXPECT_EQ("hello", b);
  }
  {
    auto b = a;
    EXPECT_TRUE(b.removeSuffix("o"));
    EXPECT_EQ("hell", b);
  }
  {
    auto b = a;
    EXPECT_TRUE(b.removeSuffix('o'));
    EXPECT_EQ("hell", b);
  }
  {
    auto b = a;
    EXPECT_TRUE(b.removeSuffix("hello"));
    EXPECT_EQ("", b);
  }
  {
    auto b = a;
    EXPECT_FALSE(b.removeSuffix("xhello"));
    EXPECT_EQ("hello", b);
  }
  {
    auto b = a;
    EXPECT_FALSE(b.removeSuffix("x"));
    EXPECT_EQ("hello", b);
  }
  {
    auto b = a;
    EXPECT_FALSE(b.removeSuffix('x'));
    EXPECT_EQ("hello", b);
  }
}

TEST(StringPiece, Equals) {
  StringPiece a("hello");

  EXPECT_TRUE(a.equals("HELLO", AsciiCaseInsensitive()));
  EXPECT_FALSE(a.equals("HELLOX", AsciiCaseInsensitive()));
}

TEST(StringPiece, PrefixEmpty) {
  StringPiece a;
  EXPECT_TRUE(a.startsWith(""));
  EXPECT_FALSE(a.startsWith("a"));
  EXPECT_FALSE(a.startsWith('a'));
  EXPECT_TRUE(a.removePrefix(""));
  EXPECT_EQ("", a);
  EXPECT_FALSE(a.removePrefix("a"));
  EXPECT_EQ("", a);
  EXPECT_FALSE(a.removePrefix('a'));
  EXPECT_EQ("", a);
}

TEST(StringPiece, SuffixEmpty) {
  StringPiece a;
  EXPECT_TRUE(a.endsWith(""));
  EXPECT_FALSE(a.endsWith("a"));
  EXPECT_FALSE(a.endsWith('a'));
  EXPECT_TRUE(a.removeSuffix(""));
  EXPECT_EQ("", a);
  EXPECT_FALSE(a.removeSuffix("a"));
  EXPECT_EQ("", a);
  EXPECT_FALSE(a.removeSuffix('a'));
  EXPECT_EQ("", a);
}

TEST(StringPiece, erase) {
  StringPiece a("hello");
  auto b = a.begin();
  auto e = b + 1;
  a.erase(b, e);
  EXPECT_EQ("ello", a);

  e = a.end();
  b = e - 1;
  a.erase(b, e);
  EXPECT_EQ("ell", a);

  b = a.end() - 1;
  e = a.end() - 1;
  EXPECT_THROW(a.erase(b, e), std::out_of_range);

  b = a.begin();
  e = a.end();
  a.erase(b, e);
  EXPECT_EQ("", a);

  a = "hello";
  b = a.begin();
  e = b + 2;
  a.erase(b, e);
  EXPECT_EQ("llo", a);

  b = a.end() - 2;
  e = a.end();
  a.erase(b, e);
  EXPECT_EQ("l", a);

  a = "      hello  ";
  boost::algorithm::trim(a);
  EXPECT_EQ(a, "hello");
}

TEST(StringPiece, splitStepCharDelimiter) {
  //              0         1         2
  //              012345678901234567890123456
  auto const s = "this is just  a test string";
  auto const e = std::next(s, std::strlen(s));
  EXPECT_EQ('\0', *e);

  folly::StringPiece p(s);
  EXPECT_EQ(s, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(s, p);

  auto x = p.split_step(' ');
  EXPECT_EQ(std::next(s, 5), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("this", x);

  x = p.split_step(' ');
  EXPECT_EQ(std::next(s, 8), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("is", x);

  x = p.split_step('u');
  EXPECT_EQ(std::next(s, 10), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("j", x);

  x = p.split_step(' ');
  EXPECT_EQ(std::next(s, 13), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("st", x);

  x = p.split_step(' ');
  EXPECT_EQ(std::next(s, 14), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("", x);

  x = p.split_step(' ');
  EXPECT_EQ(std::next(s, 16), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("a", x);

  x = p.split_step(' ');
  EXPECT_EQ(std::next(s, 21), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("test", x);

  x = p.split_step(' ');
  EXPECT_EQ(e, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("string", x);

  x = p.split_step(' ');
  EXPECT_EQ(e, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("", x);
}

TEST(StringPiece, splitStepRangeDelimiter) {
  //              0         1         2         3
  //              0123456789012345678901234567890123
  auto const s = "this  is  just    a   test  string";
  auto const e = std::next(s, std::strlen(s));
  EXPECT_EQ('\0', *e);

  folly::StringPiece p(s);
  EXPECT_EQ(s, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(s, p);

  auto x = p.split_step("  ");
  EXPECT_EQ(std::next(s, 6), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("this", x);

  x = p.split_step("  ");
  EXPECT_EQ(std::next(s, 10), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("is", x);

  x = p.split_step("u");
  EXPECT_EQ(std::next(s, 12), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("j", x);

  x = p.split_step("  ");
  EXPECT_EQ(std::next(s, 16), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("st", x);

  x = p.split_step("  ");
  EXPECT_EQ(std::next(s, 18), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("", x);

  x = p.split_step("  ");
  EXPECT_EQ(std::next(s, 21), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("a", x);

  x = p.split_step("  ");
  EXPECT_EQ(std::next(s, 28), p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(" test", x);

  x = p.split_step("  ");
  EXPECT_EQ(e, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("string", x);

  x = p.split_step("  ");
  EXPECT_EQ(e, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("", x);

  x = p.split_step(" ");
  EXPECT_EQ(e, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ("", x);
}

void split_step_with_process_noop(folly::StringPiece) {}

TEST(StringPiece, splitStepWithProcessCharDelimiter) {
  //              0         1         2
  //              012345678901234567890123456
  auto const s = "this is just  a test string";
  auto const e = std::next(s, std::strlen(s));
  EXPECT_EQ('\0', *e);

  folly::StringPiece p(s);
  EXPECT_EQ(s, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(s, p);

  EXPECT_EQ(1, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 5), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("this", x);
              return 1;
            })));

  EXPECT_EQ(2, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 8), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("is", x);
              return 2;
            })));

  EXPECT_EQ(3, (p.split_step('u', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 10), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("j", x);
              return 3;
            })));

  EXPECT_EQ(4, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 13), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("st", x);
              return 4;
            })));

  EXPECT_EQ(5, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 14), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("", x);
              return 5;
            })));

  EXPECT_EQ(6, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 16), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("a", x);
              return 6;
            })));

  EXPECT_EQ(7, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 21), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("test", x);
              return 7;
            })));

  EXPECT_EQ(8, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(e, p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("string", x);
              return 8;
            })));

  EXPECT_EQ(9, (p.split_step(' ', [&](folly::StringPiece x) {
              EXPECT_EQ(e, p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("", x);
              return 9;
            })));

  EXPECT_TRUE(
      (std::is_same<
          void,
          decltype(p.split_step(' ', split_step_with_process_noop))>::value));

  EXPECT_NO_THROW(p.split_step(' ', split_step_with_process_noop));
}

TEST(StringPiece, splitStepWithProcessRangeDelimiter) {
  //              0         1         2         3
  //              0123456789012345678901234567890123
  auto const s = "this  is  just    a   test  string";
  auto const e = std::next(s, std::strlen(s));
  EXPECT_EQ('\0', *e);

  folly::StringPiece p(s);
  EXPECT_EQ(s, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(s, p);

  EXPECT_EQ(1, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 6), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("this", x);
              return 1;
            })));

  EXPECT_EQ(2, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 10), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("is", x);
              return 2;
            })));

  EXPECT_EQ(3, (p.split_step("u", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 12), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("j", x);
              return 3;
            })));

  EXPECT_EQ(4, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 16), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("st", x);
              return 4;
            })));

  EXPECT_EQ(5, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 18), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("", x);
              return 5;
            })));

  EXPECT_EQ(6, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 21), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("a", x);
              return 6;
            })));

  EXPECT_EQ(7, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(std::next(s, 28), p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ(" test", x);
              return 7;
            })));

  EXPECT_EQ(8, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(e, p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("string", x);
              return 8;
            })));

  EXPECT_EQ(9, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(e, p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("", x);
              return 9;
            })));

  EXPECT_EQ(10, (p.split_step("  ", [&](folly::StringPiece x) {
              EXPECT_EQ(e, p.begin());
              EXPECT_EQ(e, p.end());
              EXPECT_EQ("", x);
              return 10;
            })));

  EXPECT_TRUE(
      (std::is_same<
          void,
          decltype(p.split_step(' ', split_step_with_process_noop))>::value));

  EXPECT_NO_THROW(p.split_step(' ', split_step_with_process_noop));
}

TEST(StringPiece, splitStepWithProcessCharDelimiterAdditionalArgs) {
  //              0         1         2
  //              012345678901234567890123456
  auto const s = "this is just  a test string";
  auto const e = std::next(s, std::strlen(s));
  auto const delimiter = ' ';
  EXPECT_EQ('\0', *e);

  folly::StringPiece p(s);
  EXPECT_EQ(s, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(s, p);

  auto const functor = [](folly::StringPiece s_, folly::StringPiece expected) {
    EXPECT_EQ(expected, s_);
    return expected;
  };

  auto const checker = [&](folly::StringPiece expected) {
    EXPECT_EQ(expected, p.split_step(delimiter, functor, expected));
  };

  checker("this");
  checker("is");
  checker("just");
  checker("");
  checker("a");
  checker("test");
  checker("string");
  checker("");
  checker("");

  EXPECT_TRUE(p.empty());
}

TEST(StringPiece, splitStepWithProcessRangeDelimiterAdditionalArgs) {
  //              0         1         2         3
  //              0123456789012345678901234567890123
  auto const s = "this  is  just    a   test  string";
  auto const e = std::next(s, std::strlen(s));
  auto const delimiter = "  ";
  EXPECT_EQ('\0', *e);

  folly::StringPiece p(s);
  EXPECT_EQ(s, p.begin());
  EXPECT_EQ(e, p.end());
  EXPECT_EQ(s, p);

  auto const functor = [](folly::StringPiece s_, folly::StringPiece expected) {
    EXPECT_EQ(expected, s_);
    return expected;
  };

  auto const checker = [&](folly::StringPiece expected) {
    EXPECT_EQ(expected, p.split_step(delimiter, functor, expected));
  };

  checker("this");
  checker("is");
  checker("just");
  checker("");
  checker("a");
  checker(" test");
  checker("string");
  checker("");
  checker("");

  EXPECT_TRUE(p.empty());
}

TEST(StringPiece, NoInvalidImplicitConversions) {
  struct IsString {
    bool operator()(folly::Range<int*>) { return false; }
    bool operator()(folly::StringPiece) { return true; }
  };

  std::string s = "hello";
  EXPECT_TRUE(IsString()(s));
}

TEST(qfind, UInt32Ranges) {
  vector<uint32_t> a({1, 2, 3, 260, 5});
  vector<uint32_t> b({2, 3, 4});

  auto a_range = folly::Range<const uint32_t*>(&a[0], a.size());
  auto b_range = folly::Range<const uint32_t*>(&b[0], b.size());

  EXPECT_EQ(qfind(a_range, b_range), string::npos);

  a[3] = 4;
  EXPECT_EQ(qfind(a_range, b_range), 1);
}

template <typename NeedleFinder>
class NeedleFinderTest : public ::testing::Test {
 public:
  static size_t find_first_byte_of(StringPiece haystack, StringPiece needles) {
    return NeedleFinder::find_first_byte_of(haystack, needles);
  }
};

struct SseNeedleFinder {
  static size_t find_first_byte_of(StringPiece haystack, StringPiece needles) {
    // This will only use the SSE version if it is supported on this CPU
    // (selected using ifunc).
    return detail::qfind_first_byte_of(haystack, needles);
  }
};

struct NoSseNeedleFinder {
  static size_t find_first_byte_of(StringPiece haystack, StringPiece needles) {
    return detail::qfind_first_byte_of_nosse(haystack, needles);
  }
};

struct ByteSetNeedleFinder {
  static size_t find_first_byte_of(StringPiece haystack, StringPiece needles) {
    return detail::qfind_first_byte_of_byteset(haystack, needles);
  }
};

using NeedleFinders =
    ::testing::Types<SseNeedleFinder, NoSseNeedleFinder, ByteSetNeedleFinder>;
TYPED_TEST_SUITE(NeedleFinderTest, NeedleFinders);

TYPED_TEST(NeedleFinderTest, Null) {
  { // null characters in the string
    string s(10, char(0));
    s[5] = 'b';
    string delims("abc");
    EXPECT_EQ(5, this->find_first_byte_of(s, delims));
  }
  { // null characters in delim
    string s("abc");
    string delims(10, char(0));
    delims[3] = 'c';
    delims[7] = 'b';
    EXPECT_EQ(1, this->find_first_byte_of(s, delims));
  }
  { // range not terminated by null character
    string buf = "abcdefghijklmnopqrstuvwxyz";
    StringPiece s(buf.data() + 5, 3);
    StringPiece delims("z");
    EXPECT_EQ(string::npos, this->find_first_byte_of(s, delims));
  }
}

TYPED_TEST(NeedleFinderTest, DelimDuplicates) {
  string delims(1000, 'b');
  EXPECT_EQ(1, this->find_first_byte_of("abc", delims));
  EXPECT_EQ(string::npos, this->find_first_byte_of("ac", delims));
}

TYPED_TEST(NeedleFinderTest, Empty) {
  string a = "abc";
  string b = "";
  EXPECT_EQ(string::npos, this->find_first_byte_of(a, b));
  EXPECT_EQ(string::npos, this->find_first_byte_of(b, a));
  EXPECT_EQ(string::npos, this->find_first_byte_of(b, b));
}

TYPED_TEST(NeedleFinderTest, Unaligned) {
  // works correctly even if input buffers are not 16-byte aligned
  string s = "0123456789ABCDEFGH";
  for (size_t i = 0; i < s.size(); ++i) {
    StringPiece a(s.c_str() + i);
    for (size_t j = 0; j < s.size(); ++j) {
      StringPiece b(s.c_str() + j);
      EXPECT_EQ((i > j) ? 0 : j - i, this->find_first_byte_of(a, b));
    }
  }
}

// for some algorithms (specifically those that create a set of needles),
// we check for the edge-case of _all_ possible needles being sought.
TYPED_TEST(NeedleFinderTest, Needles256) {
  string needles;
  const auto minValue = std::numeric_limits<StringPiece::value_type>::min();
  const auto maxValue = std::numeric_limits<StringPiece::value_type>::max();
  // make the size ~big to avoid any edge-case branches for tiny haystacks
  const int haystackSize = 50;
  for (int i = minValue; i <= maxValue; i++) { // <=
    needles.push_back(i);
  }
  EXPECT_EQ(StringPiece::npos, this->find_first_byte_of("", needles));
  for (int i = minValue; i <= maxValue; i++) {
    EXPECT_EQ(0, this->find_first_byte_of(string(haystackSize, i), needles));
  }

  needles.append("these are redundant characters");
  EXPECT_EQ(StringPiece::npos, this->find_first_byte_of("", needles));
  for (int i = minValue; i <= maxValue; i++) {
    EXPECT_EQ(0, this->find_first_byte_of(string(haystackSize, i), needles));
  }
}

TYPED_TEST(NeedleFinderTest, Base) {
  for (size_t i = 0; i < 32; ++i) {
    for (int j = 0; j < 32; ++j) {
      string s = string(i, 'X') + "abca" + string(i, 'X');
      string delims = string(j, 'Y') + "a" + string(j, 'Y');
      EXPECT_EQ(i, this->find_first_byte_of(s, delims));
    }
  }
}

const size_t kPageSize = sysconf(_SC_PAGESIZE);
// Updates contents so that any read accesses past the last byte will
// cause a SIGSEGV.  It accomplishes this by changing access to the page that
// begins immediately after the end of the contents (as allocators and mmap()
// all operate on page boundaries, this is a reasonable assumption).
// This function will also initialize buf, which caller must free().
void createProtectedBuf(StringPiece& contents, char** buf) {
  ASSERT_LE(contents.size(), kPageSize);
  char* pageAlignedBuf = (char*)aligned_malloc(2 * kPageSize, kPageSize);
  if (pageAlignedBuf == nullptr) {
    FAIL();
  }
  // Protect the page after the first full page-aligned region of the
  // malloc'ed buffer
  mprotect(pageAlignedBuf + kPageSize, kPageSize, PROT_NONE);
  size_t newBegin = kPageSize - contents.size();
  memcpy(pageAlignedBuf + newBegin, contents.data(), contents.size());
  contents.reset(pageAlignedBuf + newBegin, contents.size());
  *buf = pageAlignedBuf;
}

void freeProtectedBuf(char* buf) {
  mprotect(buf + kPageSize, kPageSize, PROT_READ | PROT_WRITE);
  aligned_free(buf);
}

TYPED_TEST(NeedleFinderTest, NoSegFault) {
  const string base = string(32, 'a') + string("b");
  const string delims = string(32, 'c') + string("b");
  for (int i = 0; i <= 32; i++) {
    for (int j = 0; j <= 33; j++) {
      for (int shouldFind = 0; shouldFind <= 1; ++shouldFind) {
        StringPiece s1(base);
        s1.advance(i);
        ASSERT_TRUE(!s1.empty());
        if (!shouldFind) {
          s1.pop_back();
        }
        StringPiece s2(delims);
        s2.advance(j);
        char* buf1;
        char* buf2;
        createProtectedBuf(s1, &buf1);
        createProtectedBuf(s2, &buf2);
        // printf("s1: '%s' (%ld) \ts2: '%s' (%ld)\n",
        //        string(s1.data(), s1.size()).c_str(), s1.size(),
        //        string(s2.data(), s2.size()).c_str(), s2.size());
        auto r1 = this->find_first_byte_of(s1, s2);
        auto f1 =
            std::find_first_of(s1.begin(), s1.end(), s2.begin(), s2.end());
        auto e1 = (f1 == s1.end()) ? StringPiece::npos : f1 - s1.begin();
        EXPECT_EQ(r1, e1);
        auto r2 = this->find_first_byte_of(s2, s1);
        auto f2 =
            std::find_first_of(s2.begin(), s2.end(), s1.begin(), s1.end());
        auto e2 = (f2 == s2.end()) ? StringPiece::npos : f2 - s2.begin();
        EXPECT_EQ(r2, e2);
        freeProtectedBuf(buf1);
        freeProtectedBuf(buf2);
      }
    }
  }
}

TEST(NonConstTest, StringPiece) {
  std::string hello("hello");
  MutableStringPiece sp(&hello.front(), hello.size());
  sp[0] = 'x';
  EXPECT_EQ("xello", hello);
  {
    StringPiece s(sp);
    EXPECT_EQ("xello", s);
  }
  {
    ByteRange r1(sp);
    MutableByteRange r2(sp);
  }
}

// Similar to the begin() template functions, but instread of returing
// an iterator, return a pointer to data.
template <class Container>
typename Container::value_type* dataPtr(Container& cont) {
  // NOTE: &cont[0] is undefined if cont is empty (it creates a
  // reference to nullptr - which is not dereferenced, but still UBSAN).
  return cont.data();
}
template <class T, size_t N>
constexpr T* dataPtr(T (&arr)[N]) noexcept {
  return &arr[0];
}

template <class C>
void testRangeFunc(C&& x, size_t n) {
  const auto& cx = x;
  // type, conversion checks
  using R1Iter =
      std::conditional_t<_t<std::is_reference<C>>::value, int*, int const*>;
  Range<R1Iter> r1 = range(std::forward<C>(x));
  Range<const int*> r2 = range(std::forward<C>(x));
  Range<const int*> r3 = range(cx);
  Range<const int*> r5 = range(std::move(cx));
  EXPECT_EQ(r1.begin(), dataPtr(x));
  EXPECT_EQ(r1.end(), dataPtr(x) + n);
  EXPECT_EQ(n, r1.size());
  EXPECT_EQ(n, r2.size());
  EXPECT_EQ(n, r3.size());
  EXPECT_EQ(n, r5.size());
}

TEST(RangeFunc, Vector) {
  std::vector<int> x;
  testRangeFunc(x, 0);
  x.push_back(2);
  testRangeFunc(x, 1);
  testRangeFunc(std::vector<int>{1, 2}, 2);
}

TEST(RangeFunc, Array) {
  std::array<int, 3> x;
  testRangeFunc(x, 3);
}

TEST(RangeFunc, CArray) {
  int x[]{1, 2, 3, 4};
  testRangeFunc(x, 4);
}

TEST(RangeFunc, ConstexprCArray) {
  static constexpr const int numArray[4] = {3, 17, 1, 9};
  constexpr const auto numArrayRange = range(numArray);
  EXPECT_EQ(17, numArrayRange[1]);
  constexpr const auto numArrayRangeSize = numArrayRange.size();
  EXPECT_EQ(4, numArrayRangeSize);
}

TEST(RangeFunc, ConstexprStdArray) {
  static constexpr const std::array<int, 4> numArray = {{3, 17, 1, 9}};
  constexpr const auto numArrayRange = range(numArray);
  EXPECT_EQ(17, numArrayRange[1]);
  constexpr const auto numArrayRangeSize = numArrayRange.size();
  EXPECT_EQ(4, numArrayRangeSize);
}

TEST(RangeFunc, ConstexprStdArrayZero) {
  static constexpr const std::array<int, 0> numArray = {};
  constexpr const auto numArrayRange = range(numArray);
  constexpr const auto numArrayRangeSize = numArrayRange.size();
  EXPECT_EQ(0, numArrayRangeSize);
}

TEST(RangeFunc, ConstexprIteratorPair) {
  static constexpr const int numArray[4] = {3, 17, 1, 9};
  constexpr const auto numPtr = static_cast<const int*>(numArray);
  constexpr const auto numIterRange = range(numPtr + 1, numPtr + 3);
  EXPECT_EQ(1, numIterRange[1]);
  constexpr const auto numIterRangeSize = numIterRange.size();
  EXPECT_EQ(2, numIterRangeSize);
}

TEST(RangeFunc, ConstexprCollection) {
  class IntCollection {
   public:
    constexpr IntCollection(const int* d, size_t s) : data_(d), size_(s) {}
    constexpr const int* data() const { return data_; }
    constexpr size_t size() const { return size_; }

   private:
    const int* data_;
    size_t size_;
  };
  static constexpr const int numArray[4] = {3, 17, 1, 9};
  constexpr const auto numPtr = static_cast<const int*>(numArray);
  constexpr const auto numColl = IntCollection(numPtr + 1, 2);
  constexpr const auto numCollRange = range(numColl);
  EXPECT_EQ(1, numCollRange[1]);
  constexpr const auto numCollRangeSize = numCollRange.size();
  EXPECT_EQ(2, numCollRangeSize);
}

TEST(CRangeFunc, CArray) {
  int numArray[4] = {3, 17, 1, 9};
  auto const numArrayRange = crange(numArray);
  EXPECT_TRUE(
      (std::is_same<int const*, decltype(numArrayRange)::iterator>::value));
  EXPECT_THAT(numArrayRange, testing::ElementsAreArray(numArray));
}

TEST(CRangeFunc, StdArray) {
  std::array<int, 4> numArray = {{3, 17, 1, 9}};
  auto const numArrayRange = crange(numArray);
  EXPECT_TRUE(
      (std::is_same<int const*, decltype(numArrayRange)::iterator>::value));
  EXPECT_THAT(numArrayRange, testing::ElementsAreArray(numArray));
}

TEST(CRangeFunc, StdArrayZero) {
  std::array<int, 0> numArray = {};
  auto const numArrayRange = crange(numArray);
  EXPECT_TRUE(
      (std::is_same<int const*, decltype(numArrayRange)::iterator>::value));
  EXPECT_THAT(numArrayRange, testing::IsEmpty());
}

TEST(CRangeFunc, Collection) {
  class IntCollection {
   public:
    constexpr IntCollection(int* d, size_t s) : data_(d), size_(s) {}
    constexpr int const* data() const { return data_; }
    constexpr size_t size() const { return size_; }

   private:
    int* data_;
    size_t size_;
  };
  int numArray[4] = {3, 17, 1, 9};
  auto numPtr = static_cast<int*>(numArray);
  auto numColl = IntCollection(numPtr + 1, 2);
  auto const numCollRange = crange(numColl);
  EXPECT_TRUE(
      (std::is_same<int const*, decltype(numCollRange)::iterator>::value));
  EXPECT_THAT(numCollRange, testing::ElementsAreArray({17, 1}));
}

TEST(Range, CompareChar) {
  EXPECT_EQ(""_sp, ""_sp);
  EXPECT_LT(""_sp, "world"_sp);
  EXPECT_GT("world"_sp, ""_sp);
  EXPECT_EQ("hello"_sp, "hello"_sp);
  EXPECT_LT("hello"_sp, "world"_sp);
  EXPECT_LT("hello"_sp, "helloworld"_sp);
  EXPECT_GT("world"_sp, "hello"_sp);
  EXPECT_GT("helloworld"_sp, "hello"_sp);
}

TEST(Range, CompareByte) {
  auto br = [](auto sp) { return ByteRange(sp); };
  EXPECT_CMP_EQ(br(""_sp), br(""_sp));
  EXPECT_CMP_LT(br(""_sp), br("world"_sp));
  EXPECT_CMP_GT(br("world"_sp), br(""_sp));
  EXPECT_CMP_EQ(br("hello"_sp), br("hello"_sp));
  EXPECT_CMP_LT(br("hello"_sp), br("world"_sp));
  EXPECT_CMP_LT(br("hello"_sp), br("helloworld"_sp));
  EXPECT_CMP_GT(br("world"_sp), br("hello"_sp));
  EXPECT_CMP_GT(br("helloworld"_sp), br("hello"_sp));
}

TEST(Range, CompareFbck) {
  auto vr = [](std::vector<int> const& _) { return folly::range(_); };
  EXPECT_CMP_EQ(vr({}), vr({}));
  EXPECT_CMP_LT(vr({}), vr({1}));
  EXPECT_CMP_GT(vr({1}), vr({}));
  EXPECT_CMP_EQ(vr({1}), vr({1}));
  EXPECT_CMP_LT(vr({1}), vr({2}));
  EXPECT_CMP_LT(vr({1}), vr({1, 2}));
  EXPECT_CMP_GT(vr({2}), vr({1}));
  EXPECT_CMP_GT(vr({1, 1}), vr({1}));
  EXPECT_CMP_EQ(vr({2, 3, 4}), vr({2, 3, 4}));
  EXPECT_CMP_LT(vr({2, 3, 4}), vr({2, 3, 5}));
  EXPECT_CMP_GT(vr({2, 3, 5}), vr({2, 3, 4}));
}

TEST(Range, CompareDouble) {
  auto vr = [](std::vector<float> const& _) { return folly::range(_); };
  EXPECT_CMP_EQ(vr({}), vr({}));
  EXPECT_CMP_LT(vr({}), vr({1.}));
  EXPECT_CMP_GT(vr({1.}), vr({}));
  EXPECT_CMP_EQ(vr({1.}), vr({1.}));
  EXPECT_CMP_LT(vr({1.}), vr({2.}));
  EXPECT_CMP_LT(vr({1.}), vr({1., 2.}));
  EXPECT_CMP_GT(vr({2.}), vr({1.}));
  EXPECT_CMP_GT(vr({1., 1.}), vr({1.}));
  EXPECT_CMP_EQ(vr({2., 3., 4.}), vr({2., 3., 4.}));
  EXPECT_CMP_LT(vr({2., 3., 4.}), vr({2., 3., 5.}));
  EXPECT_CMP_GT(vr({2., 3., 5.}), vr({2., 3., 4.}));
}

std::string get_rand_str(
    size_t size, std::uniform_int_distribution<>& dist, std::mt19937& gen) {
  std::string ret(size, '\0');
  for (size_t i = 0; i < size; ++i) {
    ret[i] = static_cast<char>(dist(gen));
  }

  return ret;
}

namespace folly {
bool operator==(MutableStringPiece mp, StringPiece sp) {
  return mp.compare(sp) == 0;
}

bool operator==(StringPiece sp, MutableStringPiece mp) {
  return mp.compare(sp) == 0;
}
} // namespace folly

TEST(ReplaceAt, exhaustiveTest) {
  char input[] = "this is nice and long input";
  auto msp = MutableStringPiece(input);
  auto str = std::string(input);
  std::random_device rd;
  std::mt19937 gen(rd());
  std::uniform_int_distribution<> dist('a', 'z');

  for (int i = 0; i < 100; ++i) {
    for (size_t j = 1; j <= msp.size(); ++j) {
      auto replacement = get_rand_str(j, dist, gen);
      for (size_t pos = 0; pos < msp.size() - j; ++pos) {
        msp.replaceAt(pos, replacement);
        str.replace(pos, replacement.size(), replacement);
        EXPECT_EQ(msp.compare(str), 0);
      }
    }
  }

  // too far
  EXPECT_EQ(msp.replaceAt(msp.size() - 2, StringPiece("meh")), false);
}

TEST(ReplaceAll, basicTest) {
  char input[] = "this is nice and long input";
  auto orig = std::string(input);
  auto msp = MutableStringPiece(input);

  EXPECT_EQ(msp.replaceAll("is", "si"), 2);
  EXPECT_EQ("thsi si nice and long input", msp);
  EXPECT_EQ(msp.replaceAll("si", "is"), 2);
  EXPECT_EQ(msp, orig);

  EXPECT_EQ(msp.replaceAll("abcd", "efgh"), 0); // nothing to replace
  EXPECT_EQ(msp, orig);

  // at the very beginning
  EXPECT_EQ(msp.replaceAll("this", "siht"), 1);
  EXPECT_EQ("siht is nice and long input", msp);
  EXPECT_EQ(msp.replaceAll("siht", "this"), 1);
  EXPECT_EQ(msp, orig);

  // at the very end
  EXPECT_EQ(msp.replaceAll("input", "soput"), 1);
  EXPECT_EQ("this is nice and long soput", msp);
  EXPECT_EQ(msp.replaceAll("soput", "input"), 1);
  EXPECT_EQ(msp, orig);

  // all spaces
  EXPECT_EQ(msp.replaceAll(" ", "@"), 5);
  EXPECT_EQ("this@is@nice@and@long@input", msp);
  EXPECT_EQ(msp.replaceAll("@", " "), 5);
  EXPECT_EQ(msp, orig);
}

TEST(ReplaceAll, randomTest) {
  char input[] = "abcdefghijklmnoprstuwqz"; // no pattern repeata inside
  auto orig = std::string(input);
  auto msp = MutableStringPiece(input);

  std::random_device rd;
  std::mt19937 gen(rd());
  std::uniform_int_distribution<> dist('A', 'Z');

  for (int i = 0; i < 100; ++i) {
    for (size_t j = 1; j <= orig.size(); ++j) {
      auto replacement = get_rand_str(j, dist, gen);
      for (size_t pos = 0; pos < msp.size() - j; ++pos) {
        auto piece = orig.substr(pos, j);
        EXPECT_EQ(msp.replaceAll(piece, replacement), 1);
        EXPECT_EQ(msp.find(replacement), pos);
        EXPECT_EQ(msp.replaceAll(replacement, piece), 1);
        EXPECT_EQ(msp, orig);
      }
    }
  }
}

TEST(ReplaceAll, BadArg) {
  int count = 0;
  auto fst = "longer";
  auto snd = "small";
  char input[] = "meh meh meh";
  auto all = MutableStringPiece(input);

  try {
    all.replaceAll(fst, snd);
  } catch (std::invalid_argument&) {
    ++count;
  }

  try {
    all.replaceAll(snd, fst);
  } catch (std::invalid_argument&) {
    ++count;
  }

  EXPECT_EQ(count, 2);
}

TEST(Range, Constructors) {
  vector<int> c = {1, 2, 3};
  typedef Range<vector<int>::iterator> RangeType;
  typedef Range<vector<int>::const_iterator> ConstRangeType;
  RangeType cr(c.begin(), c.end());
  auto subpiece1 = ConstRangeType(cr, 1, 5);
  auto subpiece2 = ConstRangeType(cr, 1);
  EXPECT_EQ(subpiece1.size(), 2);
  EXPECT_EQ(subpiece1.begin(), subpiece2.begin());
  EXPECT_EQ(subpiece1.end(), subpiece2.end());

  EXPECT_EQ(StringPiece("hello world").substr(5, 1), " ");
}

TEST(Range, ArrayConstructors) {
  auto charArray = std::array<char, 4>{{'t', 'e', 's', 't'}};
  auto constCharArray = std::array<char, 6>{{'f', 'o', 'o', 'b', 'a', 'r'}};
  auto emptyArray = std::array<char, 0>{};

  auto sp1 = StringPiece{charArray};
  EXPECT_EQ(4, sp1.size());
  EXPECT_EQ(charArray.data(), sp1.data());

  auto sp2 = StringPiece(constCharArray);
  EXPECT_EQ(6, sp2.size());
  EXPECT_EQ(constCharArray.data(), sp2.data());

  auto msp = MutableStringPiece(charArray);
  EXPECT_EQ(4, msp.size());
  EXPECT_EQ(charArray.data(), msp.data());

  auto esp = StringPiece(emptyArray);
  EXPECT_EQ(0, esp.size());
  EXPECT_EQ(nullptr, esp.data());

  auto emsp = MutableStringPiece(emptyArray);
  EXPECT_EQ(0, emsp.size());
  EXPECT_EQ(nullptr, emsp.data());

  static constexpr std::array<int, 4> numArray = {{3, 17, 1, 9}};
  constexpr auto numRange = Range<const int*>{numArray};
  EXPECT_EQ(17, numRange[1]);

  static constexpr std::array<int, 0> emptyNumArray{};
  constexpr auto emptyNumRange = Range<const int*>{emptyNumArray};
  EXPECT_EQ(0, emptyNumRange.size());
}

TEST(Range, ConstexprAccessors) {
  constexpr StringPiece piece = range("hello");
  static_assert(piece.size() == 6u, "");
  static_assert(piece.end() - piece.begin() == 6u, "");
  static_assert(piece.data() == piece.begin(), "");
  static_assert(piece.start() == piece.begin(), "");
  static_assert(piece.cbegin() == piece.begin(), "");
  static_assert(piece.cend() == piece.end(), "");
  static_assert(*piece.begin() == 'h', "");
  static_assert(*(piece.end() - 1) == '\0', "");
}

TEST(Range, LiteralSuffix) {
  constexpr auto literalPiece = "hello"_sp;
  constexpr StringPiece piece = "hello";
  EXPECT_EQ(literalPiece, piece);

#if __cplusplus <= 202001L
  constexpr auto literalPiece8 = u8"hello"_sp;
#if __cpp_char8_t >= 201811L
  constexpr Range<char8_t const*> piece8 = u8"hello";
#else
  constexpr Range<char const*> piece8 = u8"hello";
#endif
  EXPECT_EQ(literalPiece8, piece8);
#endif

  constexpr auto literalPiece16 = u"hello"_sp;
  constexpr Range<char16_t const*> piece16{u"hello", 5};
  EXPECT_EQ(literalPiece16, piece16);
  constexpr auto literalPiece32 = U"hello"_sp;
  constexpr Range<char32_t const*> piece32{U"hello", 5};
  EXPECT_EQ(literalPiece32, piece32);
  constexpr auto literalPieceW = L"hello"_sp;
  constexpr Range<wchar_t const*> pieceW{L"hello", 5};
  EXPECT_EQ(literalPieceW, pieceW);
}

TEST(Range, LiteralSuffixContainsNulBytes) {
  constexpr auto literalPiece = "\0foo\0"_sp;
  EXPECT_EQ(5u, literalPiece.size());
}

namespace {
class fake_tag {};
class fake_string_view {
 private:
  StringPiece piece_;

 public:
  using size_type = std::size_t;
  explicit fake_string_view(char const* s, size_type c, fake_tag = {})
      : piece_(s, c) {}
  /* implicit */ operator StringPiece() const { return piece_; }
  friend bool operator==(char const* rhs, fake_string_view lhs) {
    return rhs == lhs.piece_;
  }
};
} // namespace

TEST(Range, StringPieceExplicitConversionOperator) {
  using PieceM = StringPiece;
  using PieceC = StringPiece const;

  EXPECT_FALSE((std::is_convertible<PieceM, int>::value));
  EXPECT_FALSE((std::is_convertible<PieceM, std::string>::value));
  EXPECT_FALSE((std::is_convertible<PieceM, std::vector<char>>::value));
  EXPECT_FALSE((std::is_convertible<PieceM, fake_string_view>::value));
  EXPECT_FALSE((std::is_constructible<int, PieceM>::value));
  EXPECT_TRUE((std::is_constructible<std::string, PieceM>::value));
  EXPECT_TRUE((std::is_constructible<std::vector<char>, PieceM>::value));
  EXPECT_TRUE((std::is_constructible<fake_string_view, PieceM>::value));

  EXPECT_FALSE((std::is_convertible<PieceC, int>::value));
  EXPECT_FALSE((std::is_convertible<PieceC, std::string>::value));
  EXPECT_FALSE((std::is_convertible<PieceC, std::vector<char>>::value));
  EXPECT_FALSE((std::is_convertible<PieceC, fake_string_view>::value));
  EXPECT_FALSE((std::is_constructible<int, PieceC>::value));
  EXPECT_TRUE((std::is_constructible<std::string, PieceC>::value));
  EXPECT_TRUE((std::is_constructible<std::vector<char>, PieceC>::value));
  EXPECT_TRUE((std::is_constructible<fake_string_view, PieceC>::value));

  using testing::ElementsAreArray;
  std::array<char, 5> array = {{'h', 'e', 'l', 'l', 'o'}};
  PieceM piecem{array};
  PieceC piecec{array};
  std::allocator<char> alloc;

  EXPECT_EQ("hello", std::string(piecem));
  EXPECT_EQ("hello", std::string(piecec));
  EXPECT_EQ("hello", std::string{piecem});
  EXPECT_EQ("hello", std::string{piecec});
  EXPECT_EQ("hello", piecem.to<std::string>());
  EXPECT_EQ("hello", piecec.to<std::string>());
  EXPECT_EQ("hello", piecem.to<std::string>(alloc));
  EXPECT_EQ("hello", piecec.to<std::string>(alloc));

  EXPECT_THAT(std::vector<char>(piecem), ElementsAreArray(array));
  EXPECT_THAT(std::vector<char>(piecec), ElementsAreArray(array));
  EXPECT_THAT(std::vector<char>{piecem}, ElementsAreArray(array));
  EXPECT_THAT(std::vector<char>{piecec}, ElementsAreArray(array));
  EXPECT_THAT(piecem.to<std::vector<char>>(), ElementsAreArray(array));
  EXPECT_THAT(piecec.to<std::vector<char>>(), ElementsAreArray(array));
  EXPECT_THAT(piecem.to<std::vector<char>>(alloc), ElementsAreArray(array));
  EXPECT_THAT(piecec.to<std::vector<char>>(alloc), ElementsAreArray(array));

  EXPECT_EQ("hello", fake_string_view(piecem));
  EXPECT_EQ("hello", fake_string_view(piecec));
  EXPECT_EQ("hello", fake_string_view{piecem});
  EXPECT_EQ("hello", fake_string_view{piecec});
  EXPECT_EQ("hello", piecem.to<fake_string_view>());
  EXPECT_EQ("hello", piecec.to<fake_string_view>());
  EXPECT_EQ("hello", piecem.to<fake_string_view>(fake_tag{}));
  EXPECT_EQ("hello", piecec.to<fake_string_view>(fake_tag{}));
}

TEST(Range, MutableStringPieceExplicitConversionOperator) {
  using PieceM = MutableStringPiece;
  using PieceC = MutableStringPiece const;

  EXPECT_FALSE((std::is_convertible<PieceM, int>::value));
  EXPECT_FALSE((std::is_convertible<PieceM, std::string>::value));
  EXPECT_FALSE((std::is_convertible<PieceM, std::vector<char>>::value));
  EXPECT_FALSE((std::is_convertible<PieceM, fake_string_view>::value));
  EXPECT_FALSE((std::is_constructible<int, PieceM>::value));
  EXPECT_TRUE((std::is_constructible<std::string, PieceM>::value));
  EXPECT_TRUE((std::is_constructible<std::vector<char>, PieceM>::value));
  EXPECT_TRUE((std::is_constructible<fake_string_view, PieceM>::value));

  EXPECT_FALSE((std::is_convertible<PieceC, int>::value));
  EXPECT_FALSE((std::is_convertible<PieceC, std::string>::value));
  EXPECT_FALSE((std::is_convertible<PieceC, std::vector<char>>::value));
  EXPECT_FALSE((std::is_convertible<PieceC, fake_string_view>::value));
  EXPECT_FALSE((std::is_constructible<int, PieceC>::value));
  EXPECT_TRUE((std::is_constructible<std::string, PieceC>::value));
  EXPECT_TRUE((std::is_constructible<std::vector<char>, PieceC>::value));
  EXPECT_TRUE((std::is_constructible<fake_string_view, PieceC>::value));

  using testing::ElementsAreArray;
  std::array<char, 5> array = {{'h', 'e', 'l', 'l', 'o'}};
  PieceM piecem{array};
  PieceC piecec{array};
  std::allocator<char> alloc;

  EXPECT_EQ("hello", std::string(piecem));
  EXPECT_EQ("hello", std::string(piecec));
  EXPECT_EQ("hello", std::string{piecem});
  EXPECT_EQ("hello", std::string{piecec});
  EXPECT_EQ("hello", piecem.to<std::string>());
  EXPECT_EQ("hello", piecec.to<std::string>());
  EXPECT_EQ("hello", piecem.to<std::string>(alloc));
  EXPECT_EQ("hello", piecec.to<std::string>(alloc));

  EXPECT_THAT(std::vector<char>(piecem), ElementsAreArray(array));
  EXPECT_THAT(std::vector<char>(piecec), ElementsAreArray(array));
  EXPECT_THAT(std::vector<char>{piecem}, ElementsAreArray(array));
  EXPECT_THAT(std::vector<char>{piecec}, ElementsAreArray(array));
  EXPECT_THAT(piecem.to<std::vector<char>>(), ElementsAreArray(array));
  EXPECT_THAT(piecec.to<std::vector<char>>(), ElementsAreArray(array));
  EXPECT_THAT(piecem.to<std::vector<char>>(alloc), ElementsAreArray(array));
  EXPECT_THAT(piecec.to<std::vector<char>>(alloc), ElementsAreArray(array));

  EXPECT_EQ("hello", fake_string_view(piecem));
  EXPECT_EQ("hello", fake_string_view(piecec));
  EXPECT_EQ("hello", fake_string_view{piecem});
  EXPECT_EQ("hello", fake_string_view{piecec});
  EXPECT_EQ("hello", piecem.to<fake_string_view>());
  EXPECT_EQ("hello", piecec.to<fake_string_view>());
  EXPECT_EQ("hello", piecem.to<fake_string_view>(fake_tag{}));
  EXPECT_EQ("hello", piecec.to<fake_string_view>(fake_tag{}));
}

TEST(Range, InitializerList) {
  auto check = [](Range<int const*> r) {
    ASSERT_EQ(r.size(), 3);
    EXPECT_EQ(*r.begin(), 1);
    EXPECT_EQ(*(r.begin() + 1), 2);
    EXPECT_EQ(*(r.begin() + 2), 3);
  };

  check(range({1, 2, 3}));
  check(crange({1, 2, 3}));

  static constexpr auto ilist = {1, 2, 3};
  check(range(ilist));
  check(crange(ilist));
}

namespace {
std::size_t stringViewSize(std::string_view s) {
  return s.size();
}

std::size_t stringPieceSize(StringPiece s) {
  return s.size();
}

struct TrickyTarget {
  TrickyTarget(char const*, char const*) : which{1} {}
  TrickyTarget(char const*, std::size_t) : which{2} {}
  TrickyTarget(std::string_view) : which{3} {}

  int which;
};

struct TrickierTarget {
  TrickierTarget(std::deque<char>::const_iterator, std::size_t) : which{1} {}
  TrickierTarget(std::string_view) : which{2} {}

  int which;
};
} // namespace

TEST(StringPiece, StringViewConversion) {
  StringPiece piece("foo");
  std::string str("bar");
  MutableStringPiece mut(str.data(), str.size());
  std::string_view view("baz");

  EXPECT_EQ(stringViewSize(piece), 3);
  EXPECT_EQ(stringViewSize(str), 3);
  EXPECT_EQ(stringViewSize(mut), 3);
  EXPECT_EQ(stringPieceSize(mut), 3);
  EXPECT_EQ(stringPieceSize(str), 3);
  EXPECT_EQ(stringPieceSize(view), 3);

  view = mut;
  piece = view;
  EXPECT_EQ(piece[2], 'r');
  piece = "quux";
  view = piece;
  EXPECT_EQ(view.size(), 4);

  TrickyTarget tt1(piece);
  EXPECT_EQ(tt1.which, 3);
  TrickyTarget tt2(view);
  EXPECT_EQ(tt2.which, 3);

  std::deque<char> deq;
  deq.push_back('a');
  deq.push_back('b');
  deq.push_back('c');
  Range<std::deque<char>::const_iterator> deqRange{deq.begin(), deq.end()};
  TrickierTarget tt3(deqRange);
  EXPECT_EQ(tt3.which, 1);
}

TEST(StringPiece, Format) {
  EXPECT_EQ("  foo", fmt::format("{:>5}", folly::StringPiece("foo")));
}

namespace {

// Range with non-pod value type should not cause compile errors.
class NonPOD {
 public:
  NonPOD() {}
};
[[maybe_unused]] void test_func(Range<const NonPOD*>) {}

} // anonymous namespace

namespace {
// Nested class should not cause compile errors due to incomplete parent
class Parent {
  struct Nested : Range<const Parent*> {};
};
} // namespace
