stl_algobase.h

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1996-1998
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/* NOTE: This is an internal header file, included by other STL headers.
 *   You should not attempt to use it directly.
 */


#ifndef __SGI_STL_INTERNAL_ALGOBASE_H
#define __SGI_STL_INTERNAL_ALGOBASE_H

#ifndef __STL_CONFIG_H
#include <stl_config.h>
#endif

#ifndef __SGI_STL_INTERNAL_RELOPS
#include <stl_relops.h>
#endif

#ifndef __SGI_STL_INTERNAL_PAIR_H
#include <stl_pair.h>
#endif

#ifndef __TYPE_TRAITS_H_
#include <type_traits.h>
#endif

#include <string.h>
#include <limits.h>
#include <stdlib.h>
#include <stddef.h>
#include <new.h>

#ifdef __STL_USE_NEW_IOSTREAMS 
#include <iosfwd>
#else /* __STL_USE_NEW_IOSTREAMS */
#include <iostream.h>
#endif /* __STL_USE_NEW_IOSTREAMS */

#ifndef __SGI_STL_INTERNAL_ITERATOR_H
#include <stl_iterator_base.h>
#include <stl_iterator.h>
#endif

__STL_BEGIN_NAMESPACE

// swap and iter_swap

template <class _ForwardIter1, class _ForwardIter2, class _Tp>
inline void __iter_swap(_ForwardIter1 __a, _ForwardIter2 __b, _Tp*) {
  _Tp __tmp = *__a;
  *__a = *__b;
  *__b = __tmp;
}

template <class _ForwardIter1, class _ForwardIter2>
inline void iter_swap(_ForwardIter1 __a, _ForwardIter2 __b) {
  __iter_swap(__a, __b, __VALUE_TYPE(__a));
}

template <class _Tp>
inline void swap(_Tp& __a, _Tp& __b) {
  _Tp __tmp = __a;
  __a = __b;
  __b = __tmp;
}

//--------------------------------------------------
// min and max

#ifndef __BORLANDC__

#undef min
#undef max

template <class _Tp>
inline const _Tp& min(const _Tp& __a, const _Tp& __b) {
  return __b < __a ? __b : __a;
}

template <class _Tp>
inline const _Tp& max(const _Tp& __a, const _Tp& __b) {
  return  __a < __b ? __b : __a;
}

#endif /* __BORLANDC__ */

template <class _Tp, class _Compare>
inline const _Tp& min(const _Tp& __a, const _Tp& __b, _Compare __comp) {
  return __comp(__b, __a) ? __b : __a;
}

template <class _Tp, class _Compare>
inline const _Tp& max(const _Tp& __a, const _Tp& __b, _Compare __comp) {
  return __comp(__a, __b) ? __b : __a;
}

//--------------------------------------------------
// copy

// All of these auxiliary functions serve two purposes.  (1) Replace
// calls to copy with memmove whenever possible.  (Memmove, not memcpy,
// because the input and output ranges are permitted to overlap.)
// (2) If we're using random access iterators, then write the loop as
// a for loop with an explicit count.

//对三个函数模板进行重载：通过迭代器的型别;
//输入迭代器版本;
template <class _InputIter, class _OutputIter, class _Distance>
inline _OutputIter __copy(_InputIter __first, _InputIter __last,
                          _OutputIter __result,
                          input_iterator_tag, _Distance*)
{
  for ( ; __first != __last; ++__result, ++__first)//以迭代器是否相等来决定是否结束，速度稍慢；
    *__result = *__first;
  return __result;
}
//随机存取迭代器版本;
template <class _RandomAccessIter, class _OutputIter, class _Distance>
inline _OutputIter
__copy(_RandomAccessIter __first, _RandomAccessIter __last,
       _OutputIter __result, random_access_iterator_tag, _Distance*)
{
  for (_Distance __n = __last - __first; __n > 0; --__n) {//以__n是否为0来决定是否结束，速度很快；
    *__result = *__first;
    ++__first;
    ++__result;
  }
  return __result;
}

//对于POD类型的数据，转调memmove函数，速度极快；
template <class _Tp>
inline _Tp*
__copy_trivial(const _Tp* __first, const _Tp* __last, _Tp* __result) {
  memmove(__result, __first, sizeof(_Tp) * (__last - __first));
  return __result + (__last - __first);
}

#if defined(__STL_FUNCTION_TMPL_PARTIAL_ORDER)
//第一种情况：用函数偏特化技术来实现copy函数的分派;
//两个完全泛化函数,根据迭代器的型别进行调用;
template <class _InputIter, class _OutputIter>
inline _OutputIter __copy_aux2(_InputIter __first, _InputIter __last,
                               _OutputIter __result, __false_type) {
  return __copy(__first, __last, __result,
                __ITERATOR_CATEGORY(__first),
                __DISTANCE_TYPE(__first));
}
template <class _InputIter, class _OutputIter>
inline _OutputIter __copy_aux2(_InputIter __first, _InputIter __last,
                               _OutputIter __result, __true_type) {
  return __copy(__first, __last, __result,
                __ITERATOR_CATEGORY(__first),
                __DISTANCE_TYPE(__first));
}
//一个偏特化版本：三个参数都是_Tp*类型;
template <class _Tp>
inline _Tp* __copy_aux2(_Tp* __first, _Tp* __last, _Tp* __result,
                        __true_type) {
  return __copy_trivial(__first, __last, __result);
}
//另外一个偏特化版本：前两个参数是const _Tp*类型，后一个参数_Tp*类型;
template <class _Tp>
inline _Tp* __copy_aux2(const _Tp* __first, const _Tp* __last, _Tp* __result,
                        __true_type) {
  return __copy_trivial(__first, __last, __result);
}


template <class _InputIter, class _OutputIter, class _Tp>
inline _OutputIter __copy_aux(_InputIter __first, _InputIter __last,
                              _OutputIter __result, _Tp*) {
  typedef typename __type_traits<_Tp>::has_trivial_assignment_operator
          _Trivial;
  return __copy_aux2(__first, __last, __result, _Trivial());//根据是否为POD类型进行分派调用;
}

template <class _InputIter, class _OutputIter>
inline _OutputIter copy(_InputIter __first, _InputIter __last,
                        _OutputIter __result) {
  return __copy_aux(__first, __last, __result, __VALUE_TYPE(__first));//增加了一层间接调用，以使得__copy_aux函数可以
}                                                                     //在另外的地方被调用;

// Hack for compilers that don't have partial ordering of function templates
// but do have partial specialization of class templates.
#elif defined(__STL_CLASS_PARTIAL_SPECIALIZATION)
//第二种情况：用类的偏特化技术来实现copy的分派调用；

//完全泛化版本;
template <class _InputIter, class _OutputIter, class _BoolType>
struct __copy_dispatch {
  static _OutputIter copy(_InputIter __first, _InputIter __last,
                          _OutputIter __result) {
    typedef typename iterator_traits<_InputIter>::iterator_category _Category;
    typedef typename iterator_traits<_InputIter>::difference_type _Distance;
    return __copy(__first, __last, __result, _Category(), (_Distance*) 0);//根据迭代器的型别来区分调用相应的版本;
  }
};
//一个偏特化版本：两个参数都是_Tp*类型;
template <class _Tp>
struct __copy_dispatch<_Tp*, _Tp*, __true_type>
{
  static _Tp* copy(const _Tp* __first, const _Tp* __last, _Tp* __result) {
    return __copy_trivial(__first, __last, __result);
  }
};
//另外一个偏特化版本：第一个参数是cosnt _Tp*类型，第二个参数是_Tp*类型;
template <class _Tp>
struct __copy_dispatch<const _Tp*, _Tp*, __true_type>
{
  static _Tp* copy(const _Tp* __first, const _Tp* __last, _Tp* __result) {
    return __copy_trivial(__first, __last, __result);
  }
};
//接口函数;
template <class _InputIter, class _OutputIter>
inline _OutputIter copy(_InputIter __first, _InputIter __last,
                        _OutputIter __result) {
  typedef typename iterator_traits<_InputIter>::value_type _Tp;
  typedef typename __type_traits<_Tp>::has_trivial_assignment_operator
          _Trivial;
  return __copy_dispatch<_InputIter, _OutputIter, _Trivial>
    ::copy(__first, __last, __result);
}

// Fallback for compilers with neither partial ordering nor partial
// specialization.  Define the faster version for the basic builtin
// types.
#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */

template <class _InputIter, class _OutputIter>
inline _OutputIter copy(_InputIter __first, _InputIter __last,
                        _OutputIter __result)
{
  return __copy(__first, __last, __result,
                __ITERATOR_CATEGORY(__first),
                __DISTANCE_TYPE(__first));
}
//第三种情况：通过带参数的宏定义来实现多个版本的完全特化;
#define __SGI_STL_DECLARE_COPY_TRIVIAL(_Tp)                                \
  inline _Tp* copy(const _Tp* __first, const _Tp* __last, _Tp* __result) { \
    return __copy_trivial(__first, __last, __result);                      \
  }

__SGI_STL_DECLARE_COPY_TRIVIAL(char)
__SGI_STL_DECLARE_COPY_TRIVIAL(signed char)
__SGI_STL_DECLARE_COPY_TRIVIAL(unsigned char)
__SGI_STL_DECLARE_COPY_TRIVIAL(short)
__SGI_STL_DECLARE_COPY_TRIVIAL(unsigned short)
__SGI_STL_DECLARE_COPY_TRIVIAL(int)
__SGI_STL_DECLARE_COPY_TRIVIAL(unsigned int)
__SGI_STL_DECLARE_COPY_TRIVIAL(long)
__SGI_STL_DECLARE_COPY_TRIVIAL(unsigned long)
#ifdef __STL_HAS_WCHAR_T
__SGI_STL_DECLARE_COPY_TRIVIAL(wchar_t)
#endif
#ifdef _STL_LONG_LONG
__SGI_STL_DECLARE_COPY_TRIVIAL(long long)
__SGI_STL_DECLARE_COPY_TRIVIAL(unsigned long long)
#endif 
__SGI_STL_DECLARE_COPY_TRIVIAL(float)
__SGI_STL_DECLARE_COPY_TRIVIAL(double)
__SGI_STL_DECLARE_COPY_TRIVIAL(long double)

#undef __SGI_STL_DECLARE_COPY_TRIVIAL
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */


//memmove函数；
void* memmove(void* dest,void* src,size_t count)
{
  ASSERT(dest!=0||src!=0);
  if(dest<=src||src+count<dest){
    while(count--)//从头开始复制;
       *dest++=*src++;
  }
  else{//从尾开始复制;
    dest+=count-1;
    src+=count-1;
    while(count--)
      *dest--=*src--;
  }
  return dest;
}
//memcpy函数；
void* memcpy(void* dest,void*src,size_t count)
{
  ASSERT(dest!=0||src!=0);
  ASSERT(src<dest&&dest<src+count);
  while(count--)
     *dest++=*src++;
  return dest;
}
//--------------------------------------------------
// copy_backward
//两个函数重载;
template <class _BidirectionalIter1, class _BidirectionalIter2, 
          class _Distance>
inline _BidirectionalIter2 __copy_backward(_BidirectionalIter1 __first, 
                                           _BidirectionalIter1 __last, 
                                           _BidirectionalIter2 __result,
                                           bidirectional_iterator_tag,
                                           _Distance*)
{
  while (__first != __last)
    *--__result = *--__last;
  return __result;
}

template <class _RandomAccessIter, class _BidirectionalIter, class _Distance>
inline _BidirectionalIter __copy_backward(_RandomAccessIter __first, 
                                          _RandomAccessIter __last, 
                                          _BidirectionalIter __result,
                                          random_access_iterator_tag,
                                          _Distance*)
{
  for (_Distance __n = __last - __first; __n > 0; --__n)
    *--__result = *--__last;
  return __result;
}

#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION 

// This dispatch class is a workaround for compilers that do not 
// have partial ordering of function templates.  All we're doing is
// creating a specialization so that we can turn a call to copy_backward
// into a memmove whenever possible.

template <class _BidirectionalIter1, class _BidirectionalIter2,
          class _BoolType>
struct __copy_backward_dispatch
{
  typedef typename iterator_traits<_BidirectionalIter1>::iterator_category 
          _Cat;
  typedef typename iterator_traits<_BidirectionalIter1>::difference_type
          _Distance;

  static _BidirectionalIter2 copy(_BidirectionalIter1 __first, 
                                  _BidirectionalIter1 __last, 
                                  _BidirectionalIter2 __result) {
    return __copy_backward(__first, __last, __result, _Cat(), (_Distance*) 0);
  }
};

template <class _Tp>
struct __copy_backward_dispatch<_Tp*, _Tp*, __true_type>
{
  static _Tp* copy(const _Tp* __first, const _Tp* __last, _Tp* __result) {
    const ptrdiff_t _Num = __last - __first;
    memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
    return __result - _Num;
  }
};

template <class _Tp>
struct __copy_backward_dispatch<const _Tp*, _Tp*, __true_type>
{
  static _Tp* copy(const _Tp* __first, const _Tp* __last, _Tp* __result) {
    return  __copy_backward_dispatch<_Tp*, _Tp*, __true_type>
      ::copy(__first, __last, __result);
  }
};

template <class _BI1, class _BI2>
inline _BI2 copy_backward(_BI1 __first, _BI1 __last, _BI2 __result) {
  typedef typename __type_traits<typename iterator_traits<_BI2>::value_type>
                        ::has_trivial_assignment_operator
          _Trivial;
  return __copy_backward_dispatch<_BI1, _BI2, _Trivial>
              ::copy(__first, __last, __result);
}

#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */

template <class _BI1, class _BI2>
inline _BI2 copy_backward(_BI1 __first, _BI1 __last, _BI2 __result) {
  return __copy_backward(__first, __last, __result,
                         __ITERATOR_CATEGORY(__first),
                         __DISTANCE_TYPE(__first));
}

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

//--------------------------------------------------
// copy_n (not part of the C++ standard)

template <class _InputIter, class _Size, class _OutputIter>
pair<_InputIter, _OutputIter> __copy_n(_InputIter __first, _Size __count,
                                       _OutputIter __result,
                                       input_iterator_tag) {
  for ( ; __count > 0; --__count) {
    *__result = *__first;
    ++__first;
    ++__result;
  }
  return pair<_InputIter, _OutputIter>(__first, __result);
}

template <class _RAIter, class _Size, class _OutputIter>
inline pair<_RAIter, _OutputIter>
__copy_n(_RAIter __first, _Size __count,
         _OutputIter __result,
         random_access_iterator_tag) {
  _RAIter __last = __first + __count;
  return pair<_RAIter, _OutputIter>(__last, copy(__first, __last, __result));
}

template <class _InputIter, class _Size, class _OutputIter>
inline pair<_InputIter, _OutputIter>
__copy_n(_InputIter __first, _Size __count, _OutputIter __result) {
  return __copy_n(__first, __count, __result,
                  __ITERATOR_CATEGORY(__first));
}

template <class _InputIter, class _Size, class _OutputIter>
inline pair<_InputIter, _OutputIter>
copy_n(_InputIter __first, _Size __count, _OutputIter __result) {
  return __copy_n(__first, __count, __result);
}

//--------------------------------------------------
// fill and fill_n


template <class _ForwardIter, class _Tp>
void fill(_ForwardIter __first, _ForwardIter __last, const _Tp& __value) {
  for ( ; __first != __last; ++__first)
    *__first = __value;
}

template <class _OutputIter, class _Size, class _Tp>
_OutputIter fill_n(_OutputIter __first, _Size __n, const _Tp& __value) {
  for ( ; __n > 0; --__n, ++__first)
    *__first = __value;
  return __first;
}

//--------------------------------------------------
// equal and mismatch

template <class _InputIter1, class _InputIter2>
pair<_InputIter1, _InputIter2> mismatch(_InputIter1 __first1,
                                        _InputIter1 __last1,
                                        _InputIter2 __first2) {
  while (__first1 != __last1 && *__first1 == *__first2) {
    ++__first1;
    ++__first2;
  }
  return pair<_InputIter1, _InputIter2>(__first1, __first2);
}

template <class _InputIter1, class _InputIter2, class _BinaryPredicate>
pair<_InputIter1, _InputIter2> mismatch(_InputIter1 __first1,
                                        _InputIter1 __last1,
                                        _InputIter2 __first2,
                                        _BinaryPredicate __binary_pred) {
  while (__first1 != __last1 && __binary_pred(*__first1, *__first2)) {
    ++__first1;
    ++__first2;
  }
  return pair<_InputIter1, _InputIter2>(__first1, __first2);
}

template <class _InputIter1, class _InputIter2>
inline bool equal(_InputIter1 __first1, _InputIter1 __last1,
                  _InputIter2 __first2) {
  for ( ; __first1 != __last1; ++__first1, ++__first2)
    if (*__first1 != *__first2)
      return false;
  return true;
}

template <class _InputIter1, class _InputIter2, class _BinaryPredicate>
inline bool equal(_InputIter1 __first1, _InputIter1 __last1,
                  _InputIter2 __first2, _BinaryPredicate __binary_pred) {
  for ( ; __first1 != __last1; ++__first1, ++__first2)
    if (!__binary_pred(*__first1, *__first2))
      return false;
  return true;
}

//--------------------------------------------------
// lexicographical_compare and lexicographical_compare_3way.
// (the latter is not part of the C++ standard.)

template <class _InputIter1, class _InputIter2>
bool lexicographical_compare(_InputIter1 __first1, _InputIter1 __last1,
                             _InputIter2 __first2, _InputIter2 __last2) {
  for ( ; __first1 != __last1 && __first2 != __last2
        ; ++__first1, ++__first2) {
    if (*__first1 < *__first2)
      return true;
    if (*__first2 < *__first1)
      return false;
  }
  return __first1 == __last1 && __first2 != __last2;
}

template <class _InputIter1, class _InputIter2, class _Compare>
bool lexicographical_compare(_InputIter1 __first1, _InputIter1 __last1,
                             _InputIter2 __first2, _InputIter2 __last2,
                             _Compare __comp) {
  for ( ; __first1 != __last1 && __first2 != __last2
        ; ++__first1, ++__first2) {
    if (__comp(*__first1, *__first2))
      return true;
    if (__comp(*__first2, *__first1))
      return false;
  }
  return __first1 == __last1 && __first2 != __last2;
}

inline bool 
lexicographical_compare(const unsigned char* __first1,
                        const unsigned char* __last1,
                        const unsigned char* __first2,
                        const unsigned char* __last2)
{
  const size_t __len1 = __last1 - __first1;
  const size_t __len2 = __last2 - __first2;
  const int __result = memcmp(__first1, __first2, min(__len1, __len2));
  return __result != 0 ? __result < 0 : __len1 < __len2;
}

inline bool lexicographical_compare(const char* __first1, const char* __last1,
                                    const char* __first2, const char* __last2)
{
#if CHAR_MAX == SCHAR_MAX
  return lexicographical_compare((const signed char*) __first1,
                                 (const signed char*) __last1,
                                 (const signed char*) __first2,
                                 (const signed char*) __last2);
#else /* CHAR_MAX == SCHAR_MAX */
  return lexicographical_compare((const unsigned char*) __first1,
                                 (const unsigned char*) __last1,
                                 (const unsigned char*) __first2,
                                 (const unsigned char*) __last2);
#endif /* CHAR_MAX == SCHAR_MAX */
}

template <class _InputIter1, class _InputIter2>
int __lexicographical_compare_3way(_InputIter1 __first1, _InputIter1 __last1,
                                   _InputIter2 __first2, _InputIter2 __last2)
{
  while (__first1 != __last1 && __first2 != __last2) {
    if (*__first1 < *__first2)
      return -1;
    if (*__first2 < *__first1)
      return 1;
    ++__first1;
    ++__first2;
  }
  if (__first2 == __last2) {
    return !(__first1 == __last1);
  }
  else {
    return -1;
  }
}

inline int
__lexicographical_compare_3way(const unsigned char* __first1,
                               const unsigned char* __last1,
                               const unsigned char* __first2,
                               const unsigned char* __last2)
{
  const ptrdiff_t __len1 = __last1 - __first1;
  const ptrdiff_t __len2 = __last2 - __first2;
  const int __result = memcmp(__first1, __first2, min(__len1, __len2));
  return __result != 0 ? __result 
                       : (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1));
}

inline int 
__lexicographical_compare_3way(const char* __first1, const char* __last1,
                               const char* __first2, const char* __last2)
{
#if CHAR_MAX == SCHAR_MAX
  return __lexicographical_compare_3way(
                                (const signed char*) __first1,
                                (const signed char*) __last1,
                                (const signed char*) __first2,
                                (const signed char*) __last2);
#else
  return __lexicographical_compare_3way((const unsigned char*) __first1,
                                        (const unsigned char*) __last1,
                                        (const unsigned char*) __first2,
                                        (const unsigned char*) __last2);
#endif
}

template <class _InputIter1, class _InputIter2>
int lexicographical_compare_3way(_InputIter1 __first1, _InputIter1 __last1,
                                 _InputIter2 __first2, _InputIter2 __last2)
{
  return __lexicographical_compare_3way(__first1, __last1, __first2, __last2);
}

__STL_END_NAMESPACE

#endif /* __SGI_STL_INTERNAL_ALGOBASE_H */

// Local Variables:
// mode:C++
// End: