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realloc(). This is achieved by tracking the overallocation size in a new field and using that information to skip calls to realloc() whenever possible. * Simplified and tightened the amount of overallocation. For larger lists, this overallocates by 1/8th (compared to the previous scheme which ranged between 1/4th to 1/32nd over-allocation). For smaller lists (n<6), the maximum overallocation is one byte (formerly it could be upto eight bytes). This saves memory in applications with large numbers of small lists. * Eliminated the NRESIZE macro in favor of a new, static list_resize function that encapsulates the resizing logic. Coverting this back to macro would give a small (under 1%) speed-up. This was too small to warrant the loss of readability, maintainability, and de-coupling. * Some functions using NRESIZE had grown unnecessarily complex in their efforts to bend to the macro's calling pattern. With the new list_resize function in place, those other functions could be simplified. That is being saved for a separate patch. * The ob_item==NULL check could be eliminated from the new list_resize function. This would entail finding each piece of code that sets ob_item to NULL and adding a new line to invalidate the overallocation tracking field. Rather than impose a new requirement on other pieces of list code, it was preferred to leave the NULL check in place and retain the benefits of decoupling, maintainability and information hiding (only PyList_New() and list_sort() need to know about the new field). This approach also reduces the odds of breaking an extension module. (Collaborative effort by Raymond Hettinger, Hye-Shik Chang, Tim Peters, and Armin Rigo.)
53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
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/* List object interface */
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/*
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Another generally useful object type is an list of object pointers.
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This is a mutable type: the list items can be changed, and items can be
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added or removed. Out-of-range indices or non-list objects are ignored.
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*** WARNING *** PyList_SetItem does not increment the new item's reference
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count, but does decrement the reference count of the item it replaces,
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if not nil. It does *decrement* the reference count if it is *not*
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inserted in the list. Similarly, PyList_GetItem does not increment the
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returned item's reference count.
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*/
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#ifndef Py_LISTOBJECT_H
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#define Py_LISTOBJECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct {
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PyObject_VAR_HEAD
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PyObject **ob_item;
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int allocated;
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} PyListObject;
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PyAPI_DATA(PyTypeObject) PyList_Type;
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#define PyList_Check(op) PyObject_TypeCheck(op, &PyList_Type)
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#define PyList_CheckExact(op) ((op)->ob_type == &PyList_Type)
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PyAPI_FUNC(PyObject *) PyList_New(int size);
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PyAPI_FUNC(int) PyList_Size(PyObject *);
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PyAPI_FUNC(PyObject *) PyList_GetItem(PyObject *, int);
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PyAPI_FUNC(int) PyList_SetItem(PyObject *, int, PyObject *);
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PyAPI_FUNC(int) PyList_Insert(PyObject *, int, PyObject *);
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PyAPI_FUNC(int) PyList_Append(PyObject *, PyObject *);
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PyAPI_FUNC(PyObject *) PyList_GetSlice(PyObject *, int, int);
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PyAPI_FUNC(int) PyList_SetSlice(PyObject *, int, int, PyObject *);
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PyAPI_FUNC(int) PyList_Sort(PyObject *);
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PyAPI_FUNC(int) PyList_Reverse(PyObject *);
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PyAPI_FUNC(PyObject *) PyList_AsTuple(PyObject *);
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/* Macro, trading safety for speed */
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#define PyList_GET_ITEM(op, i) (((PyListObject *)(op))->ob_item[i])
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#define PyList_SET_ITEM(op, i, v) (((PyListObject *)(op))->ob_item[i] = (v))
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#define PyList_GET_SIZE(op) (((PyListObject *)(op))->ob_size)
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_LISTOBJECT_H */
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