template_util_unittest.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/template_util.h"

#include <string>

#include "base/containers/flat_tree.h"
#include "base/test/move_only_int.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {
namespace {

enum SimpleEnum { SIMPLE_ENUM };
enum EnumWithExplicitType : uint64_t { ENUM_WITH_EXPLICIT_TYPE };
enum class ScopedEnum { SCOPED_ENUM };
enum class ScopedEnumWithOperator { SCOPED_ENUM_WITH_OPERATOR };
std::ostream& operator<<(std::ostream& os, ScopedEnumWithOperator v) {
  return os;
}
struct SimpleStruct {};
struct StructWithOperator {};
std::ostream& operator<<(std::ostream& os, const StructWithOperator& v) {
  return os;
}
struct StructWithToString {
  std::string ToString() const { return ""; }
};

// is_non_const_reference<Type>
static_assert(!is_non_const_reference<int>::value, "IsNonConstReference");
static_assert(!is_non_const_reference<const int&>::value,
              "IsNonConstReference");
static_assert(is_non_const_reference<int&>::value, "IsNonConstReference");

// A few standard types that definitely support printing.
static_assert(internal::SupportsOstreamOperator<int>::value,
              "ints should be printable");
static_assert(internal::SupportsOstreamOperator<const char*>::value,
              "C strings should be printable");
static_assert(internal::SupportsOstreamOperator<std::string>::value,
              "std::string should be printable");

// Various kinds of enums operator<< support.
static_assert(internal::SupportsOstreamOperator<SimpleEnum>::value,
              "simple enum should be printable by value");
static_assert(internal::SupportsOstreamOperator<const SimpleEnum&>::value,
              "simple enum should be printable by const ref");
static_assert(internal::SupportsOstreamOperator<EnumWithExplicitType>::value,
              "enum with explicit type should be printable by value");
static_assert(
    internal::SupportsOstreamOperator<const EnumWithExplicitType&>::value,
    "enum with explicit type should be printable by const ref");
static_assert(!internal::SupportsOstreamOperator<ScopedEnum>::value,
              "scoped enum should not be printable by value");
static_assert(!internal::SupportsOstreamOperator<const ScopedEnum&>::value,
              "simple enum should not be printable by const ref");
static_assert(internal::SupportsOstreamOperator<ScopedEnumWithOperator>::value,
              "scoped enum with operator<< should be printable by value");
static_assert(
    internal::SupportsOstreamOperator<const ScopedEnumWithOperator&>::value,
    "scoped enum with operator<< should be printable by const ref");

// operator<< support on structs.
static_assert(!internal::SupportsOstreamOperator<SimpleStruct>::value,
              "simple struct should not be printable by value");
static_assert(!internal::SupportsOstreamOperator<const SimpleStruct&>::value,
              "simple struct should not be printable by const ref");
static_assert(internal::SupportsOstreamOperator<StructWithOperator>::value,
              "struct with operator<< should be printable by value");
static_assert(
    internal::SupportsOstreamOperator<const StructWithOperator&>::value,
    "struct with operator<< should be printable by const ref");

// .ToString() support on structs.
static_assert(!internal::SupportsToString<SimpleStruct>::value,
              "simple struct value doesn't support .ToString()");
static_assert(!internal::SupportsToString<const SimpleStruct&>::value,
              "simple struct const ref doesn't support .ToString()");
static_assert(internal::SupportsToString<StructWithToString>::value,
              "struct with .ToString() should be printable by value");
static_assert(internal::SupportsToString<const StructWithToString&>::value,
              "struct with .ToString() should be printable by const ref");

// base::is_trivially_copyable
class TrivialCopy {
 public:
  TrivialCopy(int d) : data_(d) {}

 protected:
  int data_;
};

class TrivialCopyButWithDestructor : public TrivialCopy {
 public:
  TrivialCopyButWithDestructor(int d) : TrivialCopy(d) {}
  ~TrivialCopyButWithDestructor() { data_ = 0; }
};

static_assert(base::is_trivially_copyable<TrivialCopy>::value,
              "TrivialCopy should be detected as trivially copyable");
static_assert(!base::is_trivially_copyable<TrivialCopyButWithDestructor>::value,
              "TrivialCopyButWithDestructor should not be detected as "
              "trivially copyable");

class NoCopy {
 public:
  NoCopy(const NoCopy&) = delete;
};

static_assert(
    !base::is_trivially_copy_constructible<std::vector<NoCopy>>::value,
    "is_trivially_copy_constructible<std::vector<T>> must be compiled.");

}  // namespace

}  // namespace base