mirror of https://github.com/python/cpython
85 lines
2.0 KiB
C
85 lines
2.0 KiB
C
#ifndef Py_INTERNAL_OBJECT_STACK_H
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#define Py_INTERNAL_OBJECT_STACK_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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// _PyObjectStack is a stack of Python objects implemented as a linked list of
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// fixed size buffers.
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// Chosen so that _PyObjectStackChunk is a power-of-two size.
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#define _Py_OBJECT_STACK_CHUNK_SIZE 254
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typedef struct _PyObjectStackChunk {
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struct _PyObjectStackChunk *prev;
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Py_ssize_t n;
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PyObject *objs[_Py_OBJECT_STACK_CHUNK_SIZE];
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} _PyObjectStackChunk;
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typedef struct _PyObjectStack {
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_PyObjectStackChunk *head;
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} _PyObjectStack;
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extern _PyObjectStackChunk *
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_PyObjectStackChunk_New(void);
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extern void
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_PyObjectStackChunk_Free(_PyObjectStackChunk *);
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extern void
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_PyObjectStackChunk_ClearFreeList(_PyFreeListState *state, int is_finalization);
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// Push an item onto the stack. Return -1 on allocation failure, 0 on success.
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static inline int
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_PyObjectStack_Push(_PyObjectStack *stack, PyObject *obj)
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{
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_PyObjectStackChunk *buf = stack->head;
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if (buf == NULL || buf->n == _Py_OBJECT_STACK_CHUNK_SIZE) {
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buf = _PyObjectStackChunk_New();
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if (buf == NULL) {
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return -1;
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}
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buf->prev = stack->head;
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buf->n = 0;
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stack->head = buf;
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}
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assert(buf->n >= 0 && buf->n < _Py_OBJECT_STACK_CHUNK_SIZE);
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buf->objs[buf->n] = obj;
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buf->n++;
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return 0;
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}
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// Pop the top item from the stack. Return NULL if the stack is empty.
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static inline PyObject *
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_PyObjectStack_Pop(_PyObjectStack *stack)
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{
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_PyObjectStackChunk *buf = stack->head;
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if (buf == NULL) {
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return NULL;
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}
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assert(buf->n > 0 && buf->n <= _Py_OBJECT_STACK_CHUNK_SIZE);
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buf->n--;
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PyObject *obj = buf->objs[buf->n];
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if (buf->n == 0) {
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stack->head = buf->prev;
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_PyObjectStackChunk_Free(buf);
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}
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return obj;
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}
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// Remove all items from the stack
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extern void
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_PyObjectStack_Clear(_PyObjectStack *stack);
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#ifdef __cplusplus
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}
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#endif
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#endif // !Py_INTERNAL_OBJECT_STACK_H
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