faststack.h File Reference

Implementation of a fast stack with smart memory management. More...

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Data Structures
struct	stack_level
struct	stack_wrapper
Defines
#define	top_data(s)   (s->top->data)
#define	empty_stack(s)   (s->top == NULL)
Typedefs
typedef stack_level	stack_lvl_t
typedef stack_wrapper	faststack_t
Functions
faststack_t *	make_stack ()
void	destroy_stack (faststack_t *s)
faststack_t *	push (faststack_t *cur_stack, void *data)
stack_lvl_t *	pop (faststack_t *s)

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Detailed Description

Implementation of a fast stack with smart memory management.

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Define Documentation

#define empty_stack (  s   )     (s->top == NULL)

Given a stack s, check to see if the stack is empty or not. Value is boolean true or false.

#define top_data (  s   )     (s->top->data)

Given a stack s, examine the data pointer at the top.

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Typedef Documentation

typedef struct stack_wrapper faststack_t

Wrapper around the stack levels - keeps a pointer to the current top and bottom of the stack and a count of the current height. This allows the top to have non-null above pointer resulting from previously allocated stack levels that may be recycled later without malloc overhead.

typedef struct stack_level stack_lvl_t

Structure representing a single level in the stack. Has a pointer to the level above and below itself and a pointer to a generic blob of data associated with this level.

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Function Documentation

void destroy_stack (  faststack_t *  s  )

Given a stack structure, destroy it and free all of the stack levels. Important note : This function does not free the data pointed to from each level of the stack - the user is responsible for freeing this data themselves before calling this function to prevent memory leakage.

faststack_t* make_stack (   )

Return a pointer to an empty stack structure. If the return value is NULL, one should check sexp_errno to determine why.

stack_lvl_t* pop (  faststack_t *  s  )

Given a stack, pop a level off and return a pointer to that level. The user is responsible for extracting the data, but the stack_lvl_t structures pointed to from the level (above and below) should be left alone. If NULL is returned, either the stack contained nothing, or the incoming stack s was NULL. Consult sexp_errno to determine which was the case -- SEXP_ERR_BAD_STACK indicates a null stack was passed in.

faststack_t* push (  faststack_t *  cur_stack, void *  data )

Given a stack, push a new level on referring to the data pointer. If a new level cannot be allocated, NULL is returned and sexp_errno is set with the appropriate error condition. Memory allocation errors will result in SEXP_ERR_MEMORY, while a null stack will result in SEXP_ERR_BAD_STACK.

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