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Diffstat (limited to 'contrib/libstdc++/include/bits/stl_alloc.h')
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1 files changed, 941 insertions, 0 deletions
diff --git a/contrib/libstdc++/include/bits/stl_alloc.h b/contrib/libstdc++/include/bits/stl_alloc.h new file mode 100644 index 0000000..7c34000 --- /dev/null +++ b/contrib/libstdc++/include/bits/stl_alloc.h @@ -0,0 +1,941 @@ +// Allocators -*- C++ -*- + +// Copyright (C) 2001, 2002 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 2, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING. If not, write to the Free +// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, +// USA. + +// As a special exception, you may use this file as part of a free software +// library without restriction. Specifically, if other files instantiate +// templates or use macros or inline functions from this file, or you compile +// this file and link it with other files to produce an executable, this +// file does not by itself cause the resulting executable to be covered by +// the GNU General Public License. This exception does not however +// invalidate any other reasons why the executable file might be covered by +// the GNU General Public License. + +/* + * Copyright (c) 1996-1997 + * 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. + */ + +/** @file stl_alloc.h + * This is an internal header file, included by other library headers. + * You should not attempt to use it directly. + */ + +#ifndef __GLIBCPP_INTERNAL_ALLOC_H +#define __GLIBCPP_INTERNAL_ALLOC_H + +/** + * @defgroup Allocators Memory Allocators + * @if maint + * stl_alloc.h implements some node allocators. These are NOT the same as + * allocators in the C++ standard, nor in the original H-P STL. They do not + * encapsulate different pointer types; we assume that there is only one + * pointer type. The C++ standard allocators are intended to allocate + * individual objects, not pools or arenas. + * + * In this file allocators are of two different styles: "standard" and + * "SGI" (quotes included). "Standard" allocators conform to 20.4. "SGI" + * allocators differ in AT LEAST the following ways (add to this list as you + * discover them): + * + * - "Standard" allocate() takes two parameters (n_count,hint=0) but "SGI" + * allocate() takes one paramter (n_size). + * - Likewise, "standard" deallocate()'s argument is a count, but in "SGI" + * is a byte size. + * - max_size(), construct(), and destroy() are missing in "SGI" allocators. + * - reallocate(p,oldsz,newsz) is added in "SGI", and behaves as + * if p=realloc(p,newsz). + * + * "SGI" allocators may be wrapped in __allocator to convert the interface + * into a "standard" one. + * @endif + * + * The canonical description of these classes is in docs/html/ext/howto.html + * or online at http://gcc.gnu.org/onlinedocs/libstdc++/ext/howto.html#3 +*/ + +#include <cstddef> +#include <cstdlib> +#include <cstring> +#include <cassert> +#include <bits/functexcept.h> // For __throw_bad_alloc +#include <bits/stl_threads.h> + +namespace std +{ + /** + * @if maint + * A new-based allocator, as required by the standard. Allocation and + * deallocation forward to global new and delete. "SGI" style, minus + * reallocate(). + * @endif + * (See @link Allocators allocators info @endlink for more.) + */ + class __new_alloc + { + public: + static void* + allocate(size_t __n) + { return ::operator new(__n); } + + static void + deallocate(void* __p, size_t) + { ::operator delete(__p); } + }; + + + /** + * @if maint + * A malloc-based allocator. Typically slower than the + * __default_alloc_template (below). Typically thread-safe and more + * storage efficient. The template argument is unused and is only present + * to permit multiple instantiations (but see __default_alloc_template + * for caveats). "SGI" style, plus __set_malloc_handler for OOM conditions. + * @endif + * (See @link Allocators allocators info @endlink for more.) + */ + template <int __inst> + class __malloc_alloc_template + { + private: + static void* _S_oom_malloc(size_t); + static void* _S_oom_realloc(void*, size_t); + static void (* __malloc_alloc_oom_handler)(); + + public: + static void* + allocate(size_t __n) + { + void* __result = malloc(__n); + if (0 == __result) __result = _S_oom_malloc(__n); + return __result; + } + + static void + deallocate(void* __p, size_t /* __n */) + { free(__p); } + + static void* + reallocate(void* __p, size_t /* old_sz */, size_t __new_sz) + { + void* __result = realloc(__p, __new_sz); + if (0 == __result) __result = _S_oom_realloc(__p, __new_sz); + return __result; + } + + static void (* __set_malloc_handler(void (*__f)()))() + { + void (* __old)() = __malloc_alloc_oom_handler; + __malloc_alloc_oom_handler = __f; + return(__old); + } + }; + + // malloc_alloc out-of-memory handling + template <int __inst> + void (* __malloc_alloc_template<__inst>::__malloc_alloc_oom_handler)() = 0; + + template <int __inst> + void* + __malloc_alloc_template<__inst>::_S_oom_malloc(size_t __n) + { + void (* __my_malloc_handler)(); + void* __result; + + for (;;) + { + __my_malloc_handler = __malloc_alloc_oom_handler; + if (0 == __my_malloc_handler) + std::__throw_bad_alloc(); + (*__my_malloc_handler)(); + __result = malloc(__n); + if (__result) + return(__result); + } + } + + template <int __inst> + void* + __malloc_alloc_template<__inst>::_S_oom_realloc(void* __p, size_t __n) + { + void (* __my_malloc_handler)(); + void* __result; + + for (;;) + { + __my_malloc_handler = __malloc_alloc_oom_handler; + if (0 == __my_malloc_handler) + std::__throw_bad_alloc(); + (*__my_malloc_handler)(); + __result = realloc(__p, __n); + if (__result) + return(__result); + } + } + + +// Determines the underlying allocator choice for the node allocator. +#ifdef __USE_MALLOC + typedef __malloc_alloc_template<0> __mem_interface; +#else + typedef __new_alloc __mem_interface; +#endif + + + /** + * @if maint + * This is used primarily (only?) in _Alloc_traits and other places to + * help provide the _Alloc_type typedef. + * + * This is neither "standard"-conforming nor "SGI". The _Alloc parameter + * must be "SGI" style. + * @endif + * (See @link Allocators allocators info @endlink for more.) + */ + template<class _Tp, class _Alloc> + class __simple_alloc + { + public: + static _Tp* allocate(size_t __n) + { return 0 == __n ? 0 : (_Tp*) _Alloc::allocate(__n * sizeof (_Tp)); } + + static _Tp* allocate() + { return (_Tp*) _Alloc::allocate(sizeof (_Tp)); } + + static void deallocate(_Tp* __p, size_t __n) + { if (0 != __n) _Alloc::deallocate(__p, __n * sizeof (_Tp)); } + + static void deallocate(_Tp* __p) + { _Alloc::deallocate(__p, sizeof (_Tp)); } + }; + + + /** + * @if maint + * An adaptor for an underlying allocator (_Alloc) to check the size + * arguments for debugging. Errors are reported using assert; these + * checks can be disabled via NDEBUG, but the space penalty is still + * paid, therefore it is far better to just use the underlying allocator + * by itelf when no checking is desired. + * + * "There is some evidence that this can confuse Purify." - SGI comment + * + * This adaptor is "SGI" style. The _Alloc parameter must also be "SGI". + * @endif + * (See @link Allocators allocators info @endlink for more.) + */ + template <class _Alloc> + class __debug_alloc + { + private: + enum {_S_extra = 8}; // Size of space used to store size. Note that this + // must be large enough to preserve alignment. + + public: + + static void* allocate(size_t __n) + { + char* __result = (char*)_Alloc::allocate(__n + (int) _S_extra); + *(size_t*)__result = __n; + return __result + (int) _S_extra; + } + + static void deallocate(void* __p, size_t __n) + { + char* __real_p = (char*)__p - (int) _S_extra; + assert(*(size_t*)__real_p == __n); + _Alloc::deallocate(__real_p, __n + (int) _S_extra); + } + + static void* reallocate(void* __p, size_t __old_sz, size_t __new_sz) + { + char* __real_p = (char*)__p - (int) _S_extra; + assert(*(size_t*)__real_p == __old_sz); + char* __result = (char*) + _Alloc::reallocate(__real_p, __old_sz + (int) _S_extra, + __new_sz + (int) _S_extra); + *(size_t*)__result = __new_sz; + return __result + (int) _S_extra; + } + }; + + +#ifdef __USE_MALLOC + +typedef __mem_interface __alloc; +typedef __mem_interface __single_client_alloc; + +#else + + +/** + * @if maint + * Default node allocator. "SGI" style. Uses __mem_interface for its + * underlying requests (and makes as few requests as possible). + * **** Currently __mem_interface is always __new_alloc, never __malloc*. + * + * Important implementation properties: + * 1. If the clients request an object of size > _MAX_BYTES, the resulting + * object will be obtained directly from the underlying __mem_interface. + * 2. In all other cases, we allocate an object of size exactly + * _S_round_up(requested_size). Thus the client has enough size + * information that we can return the object to the proper free list + * without permanently losing part of the object. + * + * The first template parameter specifies whether more than one thread may + * use this allocator. It is safe to allocate an object from one instance + * of a default_alloc and deallocate it with another one. This effectively + * transfers its ownership to the second one. This may have undesirable + * effects on reference locality. + * + * The second parameter is unused and serves only to allow the creation of + * multiple default_alloc instances. Note that containers built on different + * allocator instances have different types, limiting the utility of this + * approach. If you do not wish to share the free lists with the main + * default_alloc instance, instantiate this with a non-zero __inst. + * + * @endif + * (See @link Allocators allocators info @endlink for more.) +*/ +template<bool __threads, int __inst> + class __default_alloc_template + { + private: + enum {_ALIGN = 8}; + enum {_MAX_BYTES = 128}; + enum {_NFREELISTS = _MAX_BYTES / _ALIGN}; + + union _Obj + { + union _Obj* _M_free_list_link; + char _M_client_data[1]; // The client sees this. + }; + + static _Obj* volatile _S_free_list[_NFREELISTS]; + + // Chunk allocation state. + static char* _S_start_free; + static char* _S_end_free; + static size_t _S_heap_size; + + static _STL_mutex_lock _S_node_allocator_lock; + + static size_t + _S_round_up(size_t __bytes) + { return (((__bytes) + (size_t) _ALIGN-1) & ~((size_t) _ALIGN - 1)); } + + static size_t + _S_freelist_index(size_t __bytes) + { return (((__bytes) + (size_t)_ALIGN-1)/(size_t)_ALIGN - 1); } + + // Returns an object of size __n, and optionally adds to size __n + // free list. + static void* + _S_refill(size_t __n); + + // Allocates a chunk for nobjs of size size. nobjs may be reduced + // if it is inconvenient to allocate the requested number. + static char* + _S_chunk_alloc(size_t __size, int& __nobjs); + + // It would be nice to use _STL_auto_lock here. But we need a + // test whether threads are in use. + class _Lock + { + public: + _Lock() { if (__threads) _S_node_allocator_lock._M_acquire_lock(); } + ~_Lock() { if (__threads) _S_node_allocator_lock._M_release_lock(); } + } __attribute__ ((__unused__)); + friend class _Lock; + + public: + // __n must be > 0 + static void* + allocate(size_t __n) + { + void* __ret = 0; + + if (__n > (size_t) _MAX_BYTES) + __ret = __mem_interface::allocate(__n); + else + { + _Obj* volatile* __my_free_list = _S_free_list + + _S_freelist_index(__n); + // Acquire the lock here with a constructor call. This + // ensures that it is released in exit or during stack + // unwinding. + _Lock __lock_instance; + _Obj* __restrict__ __result = *__my_free_list; + if (__result == 0) + __ret = _S_refill(_S_round_up(__n)); + else + { + *__my_free_list = __result -> _M_free_list_link; + __ret = __result; + } + } + return __ret; + }; + + // __p may not be 0 + static void + deallocate(void* __p, size_t __n) + { + if (__n > (size_t) _MAX_BYTES) + __mem_interface::deallocate(__p, __n); + else + { + _Obj* volatile* __my_free_list + = _S_free_list + _S_freelist_index(__n); + _Obj* __q = (_Obj*)__p; + + // Acquire the lock here with a constructor call. This ensures that + // it is released in exit or during stack unwinding. + _Lock __lock_instance; + __q -> _M_free_list_link = *__my_free_list; + *__my_free_list = __q; + } + } + + static void* + reallocate(void* __p, size_t __old_sz, size_t __new_sz); + }; + + + template<bool __threads, int __inst> + inline bool + operator==(const __default_alloc_template<__threads, __inst>&, + const __default_alloc_template<__threads, __inst>&) + { return true; } + + template<bool __threads, int __inst> + inline bool + operator!=(const __default_alloc_template<__threads, __inst>&, + const __default_alloc_template<__threads, __inst>&) + { return false; } + + + // We allocate memory in large chunks in order to avoid fragmenting the + // malloc heap (or whatever __mem_interface is using) too much. We assume + // that __size is properly aligned. We hold the allocation lock. + template<bool __threads, int __inst> + char* + __default_alloc_template<__threads, __inst>::_S_chunk_alloc(size_t __size, + int& __nobjs) + { + char* __result; + size_t __total_bytes = __size * __nobjs; + size_t __bytes_left = _S_end_free - _S_start_free; + + if (__bytes_left >= __total_bytes) + { + __result = _S_start_free; + _S_start_free += __total_bytes; + return(__result); + } + else if (__bytes_left >= __size) + { + __nobjs = (int)(__bytes_left/__size); + __total_bytes = __size * __nobjs; + __result = _S_start_free; + _S_start_free += __total_bytes; + return(__result); + } + else + { + size_t __bytes_to_get = + 2 * __total_bytes + _S_round_up(_S_heap_size >> 4); + // Try to make use of the left-over piece. + if (__bytes_left > 0) + { + _Obj* volatile* __my_free_list = + _S_free_list + _S_freelist_index(__bytes_left); + + ((_Obj*)_S_start_free) -> _M_free_list_link = *__my_free_list; + *__my_free_list = (_Obj*)_S_start_free; + } + _S_start_free = (char*) __mem_interface::allocate(__bytes_to_get); + if (0 == _S_start_free) + { + size_t __i; + _Obj* volatile* __my_free_list; + _Obj* __p; + // Try to make do with what we have. That can't hurt. We + // do not try smaller requests, since that tends to result + // in disaster on multi-process machines. + __i = __size; + for (; __i <= (size_t) _MAX_BYTES; __i += (size_t) _ALIGN) + { + __my_free_list = _S_free_list + _S_freelist_index(__i); + __p = *__my_free_list; + if (0 != __p) + { + *__my_free_list = __p -> _M_free_list_link; + _S_start_free = (char*)__p; + _S_end_free = _S_start_free + __i; + return(_S_chunk_alloc(__size, __nobjs)); + // Any leftover piece will eventually make it to the + // right free list. + } + } + _S_end_free = 0; // In case of exception. + _S_start_free = (char*)__mem_interface::allocate(__bytes_to_get); + // This should either throw an exception or remedy the situation. + // Thus we assume it succeeded. + } + _S_heap_size += __bytes_to_get; + _S_end_free = _S_start_free + __bytes_to_get; + return(_S_chunk_alloc(__size, __nobjs)); + } + } + + + // Returns an object of size __n, and optionally adds to "size + // __n"'s free list. We assume that __n is properly aligned. We + // hold the allocation lock. + template<bool __threads, int __inst> + void* + __default_alloc_template<__threads, __inst>::_S_refill(size_t __n) + { + int __nobjs = 20; + char* __chunk = _S_chunk_alloc(__n, __nobjs); + _Obj* volatile* __my_free_list; + _Obj* __result; + _Obj* __current_obj; + _Obj* __next_obj; + int __i; + + if (1 == __nobjs) return(__chunk); + __my_free_list = _S_free_list + _S_freelist_index(__n); + + /* Build free list in chunk */ + __result = (_Obj*)__chunk; + *__my_free_list = __next_obj = (_Obj*)(__chunk + __n); + for (__i = 1; ; __i++) { + __current_obj = __next_obj; + __next_obj = (_Obj*)((char*)__next_obj + __n); + if (__nobjs - 1 == __i) { + __current_obj -> _M_free_list_link = 0; + break; + } else { + __current_obj -> _M_free_list_link = __next_obj; + } + } + return(__result); + } + + + template<bool threads, int inst> + void* + __default_alloc_template<threads, inst>::reallocate(void* __p, + size_t __old_sz, + size_t __new_sz) + { + void* __result; + size_t __copy_sz; + + if (__old_sz > (size_t) _MAX_BYTES && __new_sz > (size_t) _MAX_BYTES) { + return(realloc(__p, __new_sz)); + } + if (_S_round_up(__old_sz) == _S_round_up(__new_sz)) return(__p); + __result = allocate(__new_sz); + __copy_sz = __new_sz > __old_sz? __old_sz : __new_sz; + memcpy(__result, __p, __copy_sz); + deallocate(__p, __old_sz); + return(__result); + } + + template<bool __threads, int __inst> + _STL_mutex_lock + __default_alloc_template<__threads, __inst>::_S_node_allocator_lock + __STL_MUTEX_INITIALIZER; + + template<bool __threads, int __inst> + char* __default_alloc_template<__threads, __inst>::_S_start_free = 0; + + template<bool __threads, int __inst> + char* __default_alloc_template<__threads, __inst>::_S_end_free = 0; + + template<bool __threads, int __inst> + size_t __default_alloc_template<__threads, __inst>::_S_heap_size = 0; + + template<bool __threads, int __inst> + typename __default_alloc_template<__threads, __inst>::_Obj* volatile + __default_alloc_template<__threads, __inst>::_S_free_list[_NFREELISTS]; + + typedef __default_alloc_template<true, 0> __alloc; + typedef __default_alloc_template<false, 0> __single_client_alloc; + + +#endif /* ! __USE_MALLOC */ + + +/** + * This is a "standard" allocator, as per [20.4]. The private _Alloc is + * "SGI" style. (See comments at the top of stl_alloc.h.) + * + * The underlying allocator behaves as follows. + * - if __USE_MALLOC then + * - thread safety depends on malloc and is entirely out of our hands + * - __malloc_alloc_template is used for memory requests + * - else (the default) + * - __default_alloc_template is used via two typedefs + * - "__single_client_alloc" typedef does no locking for threads + * - "__alloc" typedef is threadsafe via the locks + * - __new_alloc is used for memory requests + * + * (See @link Allocators allocators info @endlink for more.) +*/ +template <class _Tp> +class allocator +{ + typedef __alloc _Alloc; // The underlying allocator. +public: + typedef size_t size_type; + typedef ptrdiff_t difference_type; + typedef _Tp* pointer; + typedef const _Tp* const_pointer; + typedef _Tp& reference; + typedef const _Tp& const_reference; + typedef _Tp value_type; + + template <class _Tp1> struct rebind { + typedef allocator<_Tp1> other; + }; + + allocator() throw() {} + allocator(const allocator&) throw() {} + template <class _Tp1> allocator(const allocator<_Tp1>&) throw() {} + ~allocator() throw() {} + + pointer address(reference __x) const { return &__x; } + const_pointer address(const_reference __x) const { return &__x; } + + // __n is permitted to be 0. The C++ standard says nothing about what + // the return value is when __n == 0. + _Tp* allocate(size_type __n, const void* = 0) { + return __n != 0 ? static_cast<_Tp*>(_Alloc::allocate(__n * sizeof(_Tp))) + : 0; + } + + // __p is not permitted to be a null pointer. + void deallocate(pointer __p, size_type __n) + { _Alloc::deallocate(__p, __n * sizeof(_Tp)); } + + size_type max_size() const throw() + { return size_t(-1) / sizeof(_Tp); } + + void construct(pointer __p, const _Tp& __val) { new(__p) _Tp(__val); } + void destroy(pointer __p) { __p->~_Tp(); } +}; + +template<> +class allocator<void> { +public: + typedef size_t size_type; + typedef ptrdiff_t difference_type; + typedef void* pointer; + typedef const void* const_pointer; + typedef void value_type; + + template <class _Tp1> struct rebind { + typedef allocator<_Tp1> other; + }; +}; + + +template <class _T1, class _T2> +inline bool operator==(const allocator<_T1>&, const allocator<_T2>&) +{ + return true; +} + +template <class _T1, class _T2> +inline bool operator!=(const allocator<_T1>&, const allocator<_T2>&) +{ + return false; +} + + +/** + * @if maint + * Allocator adaptor to turn an "SGI" style allocator (e.g., __alloc, + * __malloc_alloc_template) into a "standard" conforming allocator. Note + * that this adaptor does *not* assume that all objects of the underlying + * alloc class are identical, nor does it assume that all of the underlying + * alloc's member functions are static member functions. Note, also, that + * __allocator<_Tp, __alloc> is essentially the same thing as allocator<_Tp>. + * @endif + * (See @link Allocators allocators info @endlink for more.) +*/ +template <class _Tp, class _Alloc> +struct __allocator +{ + _Alloc __underlying_alloc; + + typedef size_t size_type; + typedef ptrdiff_t difference_type; + typedef _Tp* pointer; + typedef const _Tp* const_pointer; + typedef _Tp& reference; + typedef const _Tp& const_reference; + typedef _Tp value_type; + + template <class _Tp1> struct rebind { + typedef __allocator<_Tp1, _Alloc> other; + }; + + __allocator() throw() {} + __allocator(const __allocator& __a) throw() + : __underlying_alloc(__a.__underlying_alloc) {} + template <class _Tp1> + __allocator(const __allocator<_Tp1, _Alloc>& __a) throw() + : __underlying_alloc(__a.__underlying_alloc) {} + ~__allocator() throw() {} + + pointer address(reference __x) const { return &__x; } + const_pointer address(const_reference __x) const { return &__x; } + + // __n is permitted to be 0. + _Tp* allocate(size_type __n, const void* = 0) { + return __n != 0 + ? static_cast<_Tp*>(__underlying_alloc.allocate(__n * sizeof(_Tp))) + : 0; + } + + // __p is not permitted to be a null pointer. + void deallocate(pointer __p, size_type __n) + { __underlying_alloc.deallocate(__p, __n * sizeof(_Tp)); } + + size_type max_size() const throw() + { return size_t(-1) / sizeof(_Tp); } + + void construct(pointer __p, const _Tp& __val) { new(__p) _Tp(__val); } + void destroy(pointer __p) { __p->~_Tp(); } +}; + +template <class _Alloc> +class __allocator<void, _Alloc> { + typedef size_t size_type; + typedef ptrdiff_t difference_type; + typedef void* pointer; + typedef const void* const_pointer; + typedef void value_type; + + template <class _Tp1> struct rebind { + typedef __allocator<_Tp1, _Alloc> other; + }; +}; + +template <class _Tp, class _Alloc> +inline bool operator==(const __allocator<_Tp, _Alloc>& __a1, + const __allocator<_Tp, _Alloc>& __a2) +{ + return __a1.__underlying_alloc == __a2.__underlying_alloc; +} + +template <class _Tp, class _Alloc> +inline bool operator!=(const __allocator<_Tp, _Alloc>& __a1, + const __allocator<_Tp, _Alloc>& __a2) +{ + return __a1.__underlying_alloc != __a2.__underlying_alloc; +} + + +//@{ +/** Comparison operators for all of the predifined SGI-style allocators. + * This ensures that __allocator<malloc_alloc> (for example) will work + * correctly. As required, all allocators compare equal. +*/ +template <int inst> +inline bool operator==(const __malloc_alloc_template<inst>&, + const __malloc_alloc_template<inst>&) +{ + return true; +} + +template <int __inst> +inline bool operator!=(const __malloc_alloc_template<__inst>&, + const __malloc_alloc_template<__inst>&) +{ + return false; +} + +template <class _Alloc> +inline bool operator==(const __debug_alloc<_Alloc>&, + const __debug_alloc<_Alloc>&) { + return true; +} + +template <class _Alloc> +inline bool operator!=(const __debug_alloc<_Alloc>&, + const __debug_alloc<_Alloc>&) { + return false; +} +//@} + + +/** + * @if maint + * Another allocator adaptor: _Alloc_traits. This serves two purposes. + * First, make it possible to write containers that can use either "SGI" + * style allocators or "standard" allocators. Second, provide a mechanism + * so that containers can query whether or not the allocator has distinct + * instances. If not, the container can avoid wasting a word of memory to + * store an empty object. For examples of use, see stl_vector.h, etc, or + * any of the other classes derived from this one. + * + * This adaptor uses partial specialization. The general case of + * _Alloc_traits<_Tp, _Alloc> assumes that _Alloc is a + * standard-conforming allocator, possibly with non-equal instances and + * non-static members. (It still behaves correctly even if _Alloc has + * static member and if all instances are equal. Refinements affect + * performance, not correctness.) + * + * There are always two members: allocator_type, which is a standard- + * conforming allocator type for allocating objects of type _Tp, and + * _S_instanceless, a static const member of type bool. If + * _S_instanceless is true, this means that there is no difference + * between any two instances of type allocator_type. Furthermore, if + * _S_instanceless is true, then _Alloc_traits has one additional + * member: _Alloc_type. This type encapsulates allocation and + * deallocation of objects of type _Tp through a static interface; it + * has two member functions, whose signatures are + * + * - static _Tp* allocate(size_t) + * - static void deallocate(_Tp*, size_t) + * + * The size_t parameters are "standard" style (see top of stl_alloc.h) in + * that they take counts, not sizes. + * + * @endif + * (See @link Allocators allocators info @endlink for more.) +*/ +//@{ +// The fully general version. +template <class _Tp, class _Allocator> +struct _Alloc_traits +{ + static const bool _S_instanceless = false; + typedef typename _Allocator::template rebind<_Tp>::other allocator_type; +}; + +template <class _Tp, class _Allocator> +const bool _Alloc_traits<_Tp, _Allocator>::_S_instanceless; + +/// The version for the default allocator. +template <class _Tp, class _Tp1> +struct _Alloc_traits<_Tp, allocator<_Tp1> > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __alloc> _Alloc_type; + typedef allocator<_Tp> allocator_type; +}; +//@} + +//@{ +/// Versions for the predefined "SGI" style allocators. +template <class _Tp, int __inst> +struct _Alloc_traits<_Tp, __malloc_alloc_template<__inst> > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __malloc_alloc_template<__inst> > _Alloc_type; + typedef __allocator<_Tp, __malloc_alloc_template<__inst> > allocator_type; +}; + +#ifndef __USE_MALLOC +template <class _Tp, bool __threads, int __inst> +struct _Alloc_traits<_Tp, __default_alloc_template<__threads, __inst> > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __default_alloc_template<__threads, __inst> > + _Alloc_type; + typedef __allocator<_Tp, __default_alloc_template<__threads, __inst> > + allocator_type; +}; +#endif + +template <class _Tp, class _Alloc> +struct _Alloc_traits<_Tp, __debug_alloc<_Alloc> > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __debug_alloc<_Alloc> > _Alloc_type; + typedef __allocator<_Tp, __debug_alloc<_Alloc> > allocator_type; +}; +//@} + +//@{ +/// Versions for the __allocator adaptor used with the predefined "SGI" style allocators. +template <class _Tp, class _Tp1, int __inst> +struct _Alloc_traits<_Tp, + __allocator<_Tp1, __malloc_alloc_template<__inst> > > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __malloc_alloc_template<__inst> > _Alloc_type; + typedef __allocator<_Tp, __malloc_alloc_template<__inst> > allocator_type; +}; + +#ifndef __USE_MALLOC +template <class _Tp, class _Tp1, bool __thr, int __inst> +struct _Alloc_traits<_Tp, + __allocator<_Tp1, + __default_alloc_template<__thr, __inst> > > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __default_alloc_template<__thr,__inst> > + _Alloc_type; + typedef __allocator<_Tp, __default_alloc_template<__thr,__inst> > + allocator_type; +}; +#endif + +template <class _Tp, class _Tp1, class _Alloc> +struct _Alloc_traits<_Tp, __allocator<_Tp1, __debug_alloc<_Alloc> > > +{ + static const bool _S_instanceless = true; + typedef __simple_alloc<_Tp, __debug_alloc<_Alloc> > _Alloc_type; + typedef __allocator<_Tp, __debug_alloc<_Alloc> > allocator_type; +}; +//@} + + // Inhibit implicit instantiations for required instantiations, + // which are defined via explicit instantiations elsewhere. + // NB: This syntax is a GNU extension. + extern template class allocator<char>; + extern template class allocator<wchar_t>; +#ifdef __USE_MALLOC + extern template class __malloc_alloc_template<0>; +#else + extern template class __default_alloc_template<true, 0>; +#endif +} // namespace std + +#endif /* __GLIBCPP_INTERNAL_ALLOC_H */ + +// Local Variables: +// mode:C++ +// End: |
