/* -*- 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 nsCharTraits_h___

#define nsCharTraits_h___

#include <ctype.h> // for |EOF|, |WEOF|

#include <string.h> // for |memcpy|, et al

#include "mozilla/MemoryChecking.h"

// This file may be used (through nsUTF8Utils.h) from non-XPCOM code, in

// particular the standalone software updater. In that case stub out

// the macros provided by nsDebug.h which are only usable when linking XPCOM

#ifdef NS_NO_XPCOM

#define NS_WARNING(msg)

#define NS_ASSERTION(cond, msg)

#define NS_ERROR(msg)

#else

#include "nsDebug.h"  // for NS_ASSERTION

#endif

/*

 * Some macros for converting char16_t (UTF-16) to and from Unicode scalar

 * values.

 *

 * Note that UTF-16 represents all Unicode scalar values up to U+10FFFF by

 * using "surrogate pairs". These consist of a high surrogate, i.e. a code

 * point in the range U+D800 - U+DBFF, and a low surrogate, i.e. a code point

 * in the range U+DC00 - U+DFFF, like this:

 *

 *  U+D800 U+DC00 =  U+10000

 *  U+D800 U+DC01 =  U+10001

 *  ...

 *  U+DBFF U+DFFE = U+10FFFE

 *  U+DBFF U+DFFF = U+10FFFF

 *

 * These surrogate code points U+D800 - U+DFFF are not themselves valid Unicode

 * scalar values and are not well-formed UTF-16 except as high-surrogate /

 * low-surrogate pairs.

 */

#define PLANE1_BASE          uint32_t(0x00010000)

// High surrogates are in the range 0xD800 -- OxDBFF

#define NS_IS_HIGH_SURROGATE(u) ((uint32_t(u) & 0xFFFFFC00) == 0xD800)

// Low surrogates are in the range 0xDC00 -- 0xDFFF

#define NS_IS_LOW_SURROGATE(u)  ((uint32_t(u) & 0xFFFFFC00) == 0xDC00)

// Faster than testing NS_IS_HIGH_SURROGATE || NS_IS_LOW_SURROGATE

#define IS_SURROGATE(u)      ((uint32_t(u) & 0xFFFFF800) == 0xD800)

// Everything else is not a surrogate: 0x000 -- 0xD7FF, 0xE000 -- 0xFFFF

// N = (H - 0xD800) * 0x400 + 0x10000 + (L - 0xDC00)

// I wonder whether we could somehow assert that H is a high surrogate

// and L is a low surrogate

#define SURROGATE_TO_UCS4(h, l) (((uint32_t(h) & 0x03FF) << 10) + \

                                 (uint32_t(l) & 0x03FF) + PLANE1_BASE)

// Extract surrogates from a UCS4 char

// Reference: the Unicode standard 4.0, section 3.9

// Since (c - 0x10000) >> 10 == (c >> 10) - 0x0080 and

// 0xD7C0 == 0xD800 - 0x0080,

// ((c - 0x10000) >> 10) + 0xD800 can be simplified to

#define H_SURROGATE(c) char16_t(char16_t(uint32_t(c) >> 10) + \

                                char16_t(0xD7C0))

// where it's to be noted that 0xD7C0 is not bitwise-OR'd

// but added.

// Since 0x10000 & 0x03FF == 0,

// (c - 0x10000) & 0x03FF == c & 0x03FF so that

// ((c - 0x10000) & 0x03FF) | 0xDC00 is equivalent to

#define L_SURROGATE(c) char16_t(char16_t(uint32_t(c) & uint32_t(0x03FF)) | \

                                 char16_t(0xDC00))

#define IS_IN_BMP(ucs) (uint32_t(ucs) < PLANE1_BASE)

#define UCS2_REPLACEMENT_CHAR char16_t(0xFFFD)

#define UCS_END uint32_t(0x00110000)

#define IS_VALID_CHAR(c) ((uint32_t(c) < UCS_END) && !IS_SURROGATE(c))

#define ENSURE_VALID_CHAR(c) (IS_VALID_CHAR(c) ? (c) : UCS2_REPLACEMENT_CHAR)

template <class CharT>

struct nsCharTraits

{

};

template <>

struct nsCharTraits<char16_t>

{

  typedef char16_t char_type;

  typedef uint16_t  unsigned_char_type;

  typedef char      incompatible_char_type;

  static char_type* const sEmptyBuffer;

  // integer representation of characters:

  typedef int int_type;

  static char_type

  to_char_type(int_type aChar)

  {

    return char_type(aChar);

  }

  static int_type

  to_int_type(char_type aChar)

  {

    return int_type(static_cast<unsigned_char_type>(aChar));

  }

  static bool

  eq_int_type(int_type aLhs, int_type aRhs)

  {

    return aLhs == aRhs;

  }

  // |char_type| comparisons:

  static bool

  eq(char_type aLhs, char_type aRhs)

  {

    return aLhs == aRhs;

  }

  static bool

  lt(char_type aLhs, char_type aRhs)

  {

    return aLhs < aRhs;

  }

  // operations on s[n] arrays:

  static char_type*

  move(char_type* aStr1, const char_type* aStr2, size_t aN)

  {

    return static_cast<char_type*>(memmove(aStr1, aStr2,

                                           aN * sizeof(char_type)));

  }

  static char_type*

  copy(char_type* aStr1, const char_type* aStr2, size_t aN)

  {

    return static_cast<char_type*>(memcpy(aStr1, aStr2,

                                          aN * sizeof(char_type)));

  }

  static void uninitialize(char_type* aStr, size_t aN)

  {

#ifdef DEBUG

    memset(aStr, 0xE4, aN * sizeof(char_type));

#endif

    MOZ_MAKE_MEM_UNDEFINED(aStr, aN * sizeof(char_type));

  }

  static char_type*

  copyASCII(char_type* aStr1, const char* aStr2, size_t aN)

  {

    for (char_type* s = aStr1; aN--; ++s, ++aStr2) {

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      *s = static_cast<char_type>(*aStr2);

    }

    return aStr1;

  }

  static int

  compare(const char_type* aStr1, const char_type* aStr2, size_t aN)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      if (!eq(*aStr1, *aStr2)) {

        return to_int_type(*aStr1) - to_int_type(*aStr2);

      }

    }

    return 0;

  }

  static int

  compareASCII(const char_type* aStr1, const char* aStr2, size_t aN)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      if (!eq_int_type(to_int_type(*aStr1),

                       to_int_type(static_cast<char_type>(*aStr2)))) {

        return to_int_type(*aStr1) -

               to_int_type(static_cast<char_type>(*aStr2));

      }

    }

    return 0;

  }

  // this version assumes that s2 is null-terminated and s1 has length n.

  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,

  // we return 1.

  static int

  compareASCIINullTerminated(const char_type* aStr1, size_t aN,

                             const char* aStr2)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      if (!*aStr2) {

        return 1;

      }

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      if (!eq_int_type(to_int_type(*aStr1),

                       to_int_type(static_cast<char_type>(*aStr2)))) {

        return to_int_type(*aStr1) -

               to_int_type(static_cast<char_type>(*aStr2));

      }

    }

    if (*aStr2) {

      return -1;

    }

    return 0;

  }

  /**

   * Convert c to its lower-case form, but only if c is in the ASCII

   * range. Otherwise leave it alone.

   */

  static char_type

  ASCIIToLower(char_type aChar)

  {

    if (aChar >= 'A' && aChar <= 'Z') {

      return char_type(aChar + ('a' - 'A'));

    }

    return aChar;

  }

  static int

  compareLowerCaseToASCII(const char_type* aStr1, const char* aStr2, size_t aN)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),

                   "Unexpected uppercase character");

      char_type lower_s1 = ASCIIToLower(*aStr1);

      if (lower_s1 != static_cast<char_type>(*aStr2)) {

        return to_int_type(lower_s1) -

               to_int_type(static_cast<char_type>(*aStr2));

      }

    }

    return 0;

  }

  // this version assumes that s2 is null-terminated and s1 has length n.

  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,

  // we return 1.

  static int

  compareLowerCaseToASCIINullTerminated(const char_type* aStr1,

                                        size_t aN, const char* aStr2)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      if (!*aStr2) {

        return 1;

      }

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),

                   "Unexpected uppercase character");

      char_type lower_s1 = ASCIIToLower(*aStr1);

      if (lower_s1 != static_cast<char_type>(*aStr2)) {

        return to_int_type(lower_s1) -

               to_int_type(static_cast<char_type>(*aStr2));

      }

    }

    if (*aStr2) {

      return -1;

    }

    return 0;

  }

  static size_t

  length(const char_type* aStr)

  {

    size_t result = 0;

    while (!eq(*aStr++, char_type(0))) {

      ++result;

    }

    return result;

  }

  static const char_type*

  find(const char_type* aStr, size_t aN, char_type aChar)

  {

    while (aN--) {

      if (eq(*aStr, aChar)) {

        return aStr;

      }

      ++aStr;

    }

    return 0;

  }

};

template <>

struct nsCharTraits<char>

{

  typedef char           char_type;

  typedef unsigned char  unsigned_char_type;

  typedef char16_t      incompatible_char_type;

  static char_type* const sEmptyBuffer;

  // integer representation of characters:

  typedef int int_type;

  static char_type

  to_char_type(int_type aChar)

  {

    return char_type(aChar);

  }

  static int_type

  to_int_type(char_type aChar)

  {

    return int_type(static_cast<unsigned_char_type>(aChar));

  }

  static bool

  eq_int_type(int_type aLhs, int_type aRhs)

  {

    return aLhs == aRhs;

  }

  // |char_type| comparisons:

  static bool eq(char_type aLhs, char_type aRhs)

  {

    return aLhs == aRhs;

  }

  static bool

  lt(char_type aLhs, char_type aRhs)

  {

    return aLhs < aRhs;

  }

  // operations on s[n] arrays:

  static char_type*

  move(char_type* aStr1, const char_type* aStr2, size_t aN)

  {

    return static_cast<char_type*>(memmove(aStr1, aStr2,

                                           aN * sizeof(char_type)));

  }

  static char_type*

  copy(char_type* aStr1, const char_type* aStr2, size_t aN)

  {

    return static_cast<char_type*>(memcpy(aStr1, aStr2,

                                          aN * sizeof(char_type)));

  }

  static void uninitialize(char_type* aStr, size_t aN)

  {

#ifdef DEBUG

    memset(aStr, 0xE4, aN * sizeof(char_type));

#endif

    MOZ_MAKE_MEM_UNDEFINED(aStr, aN * sizeof(char_type));

  }

  static char_type*

  copyASCII(char_type* aStr1, const char* aStr2, size_t aN)

  {

    return copy(aStr1, aStr2, aN);

  }

  static int

  compare(const char_type* aStr1, const char_type* aStr2, size_t aN)

  {

    return memcmp(aStr1, aStr2, aN);

  }

  static int

  compareASCII(const char_type* aStr1, const char* aStr2, size_t aN)

  {

#ifdef DEBUG

    for (size_t i = 0; i < aN; ++i) {

      NS_ASSERTION(!(aStr2[i] & ~0x7F), "Unexpected non-ASCII character");

    }

#endif

    return compare(aStr1, aStr2, aN);

  }

  // this version assumes that s2 is null-terminated and s1 has length n.

  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,

  // we return 1.

  static int

  compareASCIINullTerminated(const char_type* aStr1, size_t aN,

                             const char* aStr2)

  {

    // can't use strcmp here because we don't want to stop when aStr1

    // contains a null

    for (; aN--; ++aStr1, ++aStr2) {

      if (!*aStr2) {

        return 1;

      }

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      if (*aStr1 != *aStr2) {

        return to_int_type(*aStr1) - to_int_type(*aStr2);

      }

    }

    if (*aStr2) {

      return -1;

    }

    return 0;

  }

  /**

   * Convert c to its lower-case form, but only if c is ASCII.

   */

  static char_type

  ASCIIToLower(char_type aChar)

  {

    if (aChar >= 'A' && aChar <= 'Z') {

      return char_type(aChar + ('a' - 'A'));

    }

    return aChar;

  }

  static int

  compareLowerCaseToASCII(const char_type* aStr1, const char* aStr2, size_t aN)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),

                   "Unexpected uppercase character");

      char_type lower_s1 = ASCIIToLower(*aStr1);

      if (lower_s1 != *aStr2) {

        return to_int_type(lower_s1) - to_int_type(*aStr2);

      }

    }

    return 0;

  }

  // this version assumes that s2 is null-terminated and s1 has length n.

  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,

  // we return 1.

  static int

  compareLowerCaseToASCIINullTerminated(const char_type* aStr1, size_t aN,

                                        const char* aStr2)

  {

    for (; aN--; ++aStr1, ++aStr2) {

      if (!*aStr2) {

        return 1;

      }

      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");

      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),

                   "Unexpected uppercase character");

      char_type lower_s1 = ASCIIToLower(*aStr1);

      if (lower_s1 != *aStr2) {

        return to_int_type(lower_s1) - to_int_type(*aStr2);

      }

    }

    if (*aStr2) {

      return -1;

    }

    return 0;

  }

  static size_t

  length(const char_type* aStr)

  {

    return strlen(aStr);

  }

  static const char_type*

  find(const char_type* aStr, size_t aN, char_type aChar)

  {

    return reinterpret_cast<const char_type*>(memchr(aStr, to_int_type(aChar),

                                                     aN));

  }

};

template <class InputIterator>

struct nsCharSourceTraits

{

  typedef typename InputIterator::difference_type difference_type;

  static uint32_t

  readable_distance(const InputIterator& aFirst, const InputIterator& aLast)

  {

    // assumes single fragment

    return uint32_t(aLast.get() - aFirst.get());

  }

  static const typename InputIterator::value_type*

  read(const InputIterator& aIter)

  {

    return aIter.get();

  }

  static void

  advance(InputIterator& aStr, difference_type aN)

  {

    aStr.advance(aN);

  }

};

template <class CharT>

struct nsCharSourceTraits<CharT*>

{

  typedef ptrdiff_t difference_type;

  static uint32_t

  readable_distance(CharT* aStr)

  {

    return uint32_t(nsCharTraits<CharT>::length(aStr));

    // return numeric_limits<uint32_t>::max();

  }

  static uint32_t

  readable_distance(CharT* aFirst, CharT* aLast)

  {

    return uint32_t(aLast - aFirst);

  }

  static const CharT*

  read(CharT* aStr)

  {

    return aStr;

  }

  static void

  advance(CharT*& aStr, difference_type aN)

  {

    aStr += aN;

  }

};

template <class OutputIterator>

struct nsCharSinkTraits

{

  static void

  write(OutputIterator& aIter, const typename OutputIterator::value_type* aStr,

        uint32_t aN)

  {

    aIter.write(aStr, aN);

  }

};

template <class CharT>

struct nsCharSinkTraits<CharT*>

{

  static void

  write(CharT*& aIter, const CharT* aStr, uint32_t aN)

  {

    nsCharTraits<CharT>::move(aIter, aStr, aN);

    aIter += aN;

  }

};

#endif // !defined(nsCharTraits_h___)