/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* 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/. */

#ifndef nsASCIIMask_h_

#define nsASCIIMask_h_

#include <array>

#include <utility>

#include "mozilla/Attributes.h"

typedef std::array<bool, 128> ASCIIMaskArray;

namespace mozilla {

// Boolean arrays, fixed size and filled in at compile time, meant to

// record something about each of the (standard) ASCII characters.

// No extended ASCII for now, there has been no use case.

// If you have loops that go through a string character by character

// and test for equality to a certain set of characters before deciding

// on a course of action, chances are building up one of these arrays

// and using it is going to be faster, especially if the set of

// characters is more than one long, and known at compile time.

class ASCIIMask

{

public:

  // Preset masks for some common character groups

  // When testing, you must check if the index is < 128 or use IsMasked()

  //

  // if (someChar < 128 && MaskCRLF()[someChar]) this is \r or \n

  static const ASCIIMaskArray& MaskCRLF();

  static const ASCIIMaskArray& Mask0to9();

  static const ASCIIMaskArray& MaskCRLFTab();

  static const ASCIIMaskArray& MaskWhitespace();

  static MOZ_ALWAYS_INLINE bool IsMasked(const ASCIIMaskArray& aMask, uint32_t aChar)

  {

    return aChar < 128 && aMask[aChar];

  }

};

// Outside of the preset ones, use these templates to create more masks.

//

// The example creation will look like this:

//

// constexpr bool TestABC(char c) { return c == 'A' || c == 'B' || c == 'C'; }

// constexpr std::array<bool, 128> sABCMask = CreateASCIIMask(TestABC);

// ...

// if (someChar < 128 && sABCMask[someChar]) this is A or B or C

namespace details

{

template<typename F, size_t... Indices>

constexpr std::array<bool, 128> CreateASCIIMask(F fun, std::index_sequence<Indices...>)

{

  return {{ fun(Indices)... }};

}

} // namespace details

template<typename F>

constexpr std::array<bool, 128> CreateASCIIMask(F fun)

{

  return details::CreateASCIIMask(fun, std::make_index_sequence<128>{});

}

} // namespace mozilla

#endif // nsASCIIMask_h_