learning_stl/stl_tempbuf.h at master · hiddaorear/learning_stl · GitHub

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#include "stl_iterator_base.h"
#include "stl_pair.h"
#include "stl_uninitialized.h"

#ifndef LEARNING_STL_STL_TEMPBUF_H
#define LEARNING_STL_STL_TEMPBUF_H
template <class _Tp>
pair<_Tp*, ptrdiff_t>
__get_temporary_buffer(ptrdiff_t __len, _Tp*)
{
    if (__len > ptrdiff_t(INT_MAX / sizeof(_Tp)))
        __len = INT_MAX / sizeof(_Tp);

    while (__len > 0) {
        _Tp* __tmp = (_Tp*) malloc((size_t)__len * sizeof(_Tp));
        if (__tmp != 0)
            return pair<_Tp*, ptrdiff_t>(__tmp, __len);
        __len /= 2;
    }

    return pair<_Tp*, ptrdiff_t>((_Tp*)0, 0);
}

#ifdef __STL_EXPLICIT_FUNCTION_TMPL_ARGS

template <class _Tp>
inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len) {
  return __get_temporary_buffer(__len, (_Tp*) 0);
}

#endif /* __STL_EXPLICIT_FUNCTION_TMPL_ARGS */

// This overload is not required by the standard; it is an extension.
// It is supported for backward compatibility with the HP STL, and
// because not all compilers support the language feature (explicit
// function template arguments) that is required for the standard
// version of get_temporary_buffer.
template <class _Tp>
inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len, _Tp*) {
    return __get_temporary_buffer(__len, (_Tp*) 0);
}

template <class _Tp>
void return_temporary_buffer(_Tp* __p) {
    free(__p);
}

template <class _ForwardIterator, class _Tp>
class _Temporary_buffer {
private:
    ptrdiff_t  _M_original_len;
    ptrdiff_t  _M_len;
    _Tp*       _M_buffer;

    void _M_allocate_buffer() {
        _M_original_len = _M_len;
        _M_buffer = 0;

        if (_M_len > (ptrdiff_t)(INT_MAX / sizeof(_Tp)))
            _M_len = INT_MAX / sizeof(_Tp);

        while (_M_len > 0) {
            _M_buffer = (_Tp*) malloc(_M_len * sizeof(_Tp));
            if (_M_buffer)
                break;
            _M_len /= 2;
        }
    }

    void _M_initialize_buffer(const _Tp&, SGI::__true_type) {}
    void _M_initialize_buffer(const _Tp& val, SGI::__false_type) {
        uninitialized_fill_n(_M_buffer, _M_len, val);
    }

public:
    ptrdiff_t size() const { return _M_len; }
    ptrdiff_t requested_size() const { return _M_original_len; }
    _Tp* begin() { return _M_buffer; }
    _Tp* end() { return _M_buffer + _M_len; }

    _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) {
        // Workaround for a __type_traits bug in the pre-7.3 compiler.
#   if defined(__sgi) && !defined(__GNUC__) && _COMPILER_VERSION < 730
        typedef typename __type_traits<_Tp>::is_POD_type _Trivial;
#   else
        typedef typename SGI::__type_traits<_Tp>::has_trivial_default_constructor
                _Trivial;
#   endif

        __STL_TRY {
                _M_len = 0;
            _M_len = SGI::distance(__first, __last);
                _M_allocate_buffer();
                if (_M_len > 0)
                _M_initialize_buffer(*__first, _Trivial());
        }
        __STL_UNWIND(free(_M_buffer); _M_buffer = 0; _M_len = 0);
    }

    ~_Temporary_buffer() {
        destroy(_M_buffer, _M_buffer + _M_len);
        free(_M_buffer);
    }

private:
    // Disable copy constructor and assignment operator.
    _Temporary_buffer(const _Temporary_buffer&) {}
    void operator=(const _Temporary_buffer&) {}
};

// Class temporary_buffer is not part of the standard.  It is an extension.

template <class _ForwardIterator,
        class _Tp
#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION
        = typename iterator_traits<_ForwardIterator>::value_type
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */
>
struct temporary_buffer : public _Temporary_buffer<_ForwardIterator, _Tp>
{
    temporary_buffer(_ForwardIterator __first, _ForwardIterator __last)
            : _Temporary_buffer<_ForwardIterator, _Tp>(__first, __last) {}
    ~temporary_buffer() {}
};
#endif //LEARNING_STL_STL_TEMPBUF_H