palemoon-dev/platform/mfbt/TextUtils.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Character/text operations. */

#ifndef mozilla_TextUtils_h
#define mozilla_TextUtils_h

#include "mozilla/TypeTraits.h"

namespace mozilla {

namespace detail {

template<typename Char>
class MakeUnsignedChar
  : public MakeUnsigned<Char>
{};

template<>
class MakeUnsignedChar<char16_t>
{
public:
  using Type = char16_t;
};

template<>
class MakeUnsignedChar<char32_t>
{
public:
  using Type = char32_t;
};

} // namespace detail

/**
 * Returns true iff |aChar| matches [a-zA-Z].
 *
 * This function is basically what you thought isalpha was, except its behavior
 * doesn't depend on the user's current locale.
 */
template<typename Char>
constexpr bool
IsAsciiAlpha(Char aChar)
{
  using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
  return ('a' <= static_cast<UnsignedChar>(aChar) &&
          static_cast<UnsignedChar>(aChar) <= 'z') ||
         ('A' <= static_cast<UnsignedChar>(aChar) &&
          static_cast<UnsignedChar>(aChar) <= 'Z');
}

} // namespace mozilla

#endif /* mozilla_TextUtils_h */