/gecko_api/include/nsMemory.h

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 37
 38#ifndef nsMemory_h__
 39#define nsMemory_h__
 40
 41#include "nsXPCOM.h"
 42#include "nsIMemory.h"
 43
 44#define NS_MEMORY_CONTRACTID "@mozilla.org/xpcom/memory-service;1"
 45#define NS_MEMORY_CLASSNAME  "Global Memory Service"
 46#define NS_MEMORY_CID                                \
 47{ /* 30a04e40-38e7-11d4-8cf5-0060b0fc14a3 */         \
 48    0x30a04e40,                                      \
 49    0x38e7,                                          \
 50    0x11d4,                                          \
 51    {0x8c, 0xf5, 0x00, 0x60, 0xb0, 0xfc, 0x14, 0xa3} \
 52}
 53
 54
 55/**
 56 * Static helper routines to manage memory. These routines allow easy access
 57 * to xpcom's built-in (global) nsIMemory implementation, without needing
 58 * to go through the service manager to get it. However this requires clients
 59 * to link with the xpcom DLL. 
 60 *
 61 * This class is not threadsafe and is intented for use only on the main
 62 * thread.
 63 */
 64class nsMemory
 65{
 66public:
 67    static NS_HIDDEN_(void*) Alloc(size_t size)
 68        { return NS_Alloc(size); }
 69
 70    static NS_HIDDEN_(void*) Realloc(void* ptr, PRSize size)
 71        { return NS_Realloc(ptr, size); }
 72
 73    static NS_HIDDEN_(void) Free(void* ptr)
 74        { NS_Free(ptr); }
 75
 76    static NS_COM_GLUE nsresult   HeapMinimize(PRBool aImmediate);
 77    static NS_COM_GLUE void*      Clone(const void* ptr, PRSize size);
 78    static NS_COM_GLUE nsIMemory* GetGlobalMemoryService();       // AddRefs
 79};
 80
 81/** 
 82 * Macro to free all elements of an XPCOM array of a given size using
 83 * freeFunc, then frees the array itself using nsMemory::Free().  
 84 *
 85 * Note that this macro (and its wrappers) can be used to deallocate a
 86 * partially- or completely-built array while unwinding an error
 87 * condition inside the XPCOM routine that was going to return the
 88 * array.  For this to work on a partially-built array, your code
 89 * needs to be building the array from index 0 upwards, and simply
 90 * pass the number of elements that have already been built (and thus
 91 * need to be freed) as |size|.
 92 *
 93 * Thanks to <alecf@netscape.com> for suggesting this form, which
 94 * allows the macro to be used with NS_RELEASE / NS_RELEASE_IF in
 95 * addition to nsMemory::Free.
 96 * 
 97 * @param size      Number of elements in the array.  If not a constant, this 
 98 *                  should be a PRInt32.  Note that this means this macro 
 99 *                  will not work if size >= 2^31.
100 * @param array     The array to be freed.
101 * @param freeFunc  The function or macro to be used to free it. 
102 *                  For arrays of nsISupports (or any class derived
103 *                  from it), NS_IF_RELEASE (or NS_RELEASE) should be
104 *                  passed as freeFunc.  For most (all?) other pointer
105 *                  types (including XPCOM strings and wstrings),
106 *                  nsMemory::Free should be used, since the
107 *                  shared-allocator (nsMemory) is what will have been
108 *                  used to allocate the memory.  
109 */
110#define NS_FREE_XPCOM_POINTER_ARRAY(size, array, freeFunc)                    \
111    PR_BEGIN_MACRO                                                            \
112        PRInt32 iter_ = PRInt32(size);                                        \
113        while (--iter_ >= 0)                                                  \
114            freeFunc((array)[iter_]);                                         \
115        NS_Free((array));                                                     \
116    PR_END_MACRO
117
118// convenience macros for commonly used calls.  mmmmm.  syntactic sugar.
119
120/** 
121 * Macro to free arrays of non-refcounted objects allocated by the
122 * shared allocator (nsMemory) such as strings and wstrings.  A
123 * convenience wrapper around NS_FREE_XPCOM_POINTER_ARRAY.
124 *
125 * @param size      Number of elements in the array.  If not a constant, this 
126 *                  should be a PRInt32.  Note that this means this macro 
127 *                  will not work if size >= 2^31.
128 * @param array     The array to be freed.
129 */
130#define NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(size, array)                    \
131    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_Free)
132
133/**
134 * Macro to free an array of pointers to nsISupports (or classes
135 * derived from it).  A convenience wrapper around
136 * NS_FREE_XPCOM_POINTER_ARRAY.
137 *
138 * Note that if you know that none of your nsISupports pointers are
139 * going to be 0, you can gain a bit of speed by calling
140 * NS_FREE_XPCOM_POINTER_ARRAY directly and using NS_RELEASE as your
141 * free function.
142 *
143 * @param size      Number of elements in the array.  If not a constant, this 
144 *                  should be a PRInt32.  Note that this means this macro 
145 *                  will not work if size >= 2^31.
146 * @param array     The array to be freed.
147 */
148#define NS_FREE_XPCOM_ISUPPORTS_POINTER_ARRAY(size, array)                    \
149    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_IF_RELEASE)
150
151/**
152 * Helpful array length function for calculating the length of a
153 * statically declared array.
154 */
155
156#define NS_ARRAY_LENGTH(array_) \
157  (sizeof(array_)/sizeof(array_[0]))
158
159/**
160 * An enumeration type used to represent a method of assignment.
161 */
162enum nsAssignmentType {
163    NS_ASSIGNMENT_COPY,   // copy by value
164    NS_ASSIGNMENT_DEPEND, // copy by reference
165    NS_ASSIGNMENT_ADOPT   // copy by reference (take ownership of resource)
166};
167
168#endif // nsMemory_h__
169