## Trash Stacks

Trash Stacks — maintain a stack of unused allocated memory chunks

## Synopsis

    #include <glib.h>

                        GTrashStack;
    void                g_trash_stack_push                  (GTrashStack **stack_p,
                                                             gpointer data_p);
    gpointer            g_trash_stack_pop                   (GTrashStack **stack_p);
    gpointer            g_trash_stack_peek                  (GTrashStack **stack_p);
    guint               g_trash_stack_height                (GTrashStack **stack_p);

## Description

A GTrashStack is an efficient way to keep a stack of unused allocated memory chunks. Each memory chunk is required to be large enough to hold a gpointer. This allows the stack to be maintained without any space overhead, since the stack pointers can be stored inside the memory chunks.

There is no function to create a GTrashStack. A `NULL` GTrashStack* is a perfectly valid empty stack.

## Details

### GTrashStack

    typedef struct {
      GTrashStack *next;
    } GTrashStack;

Each piece of memory that is pushed onto the stack is cast to a GTrashStack*.

GTrashStack *`next`; | pointer to the previous element of the stack, gets stored in the first `sizeof (gpointer)` bytes of the element.

### g_trash_stack_push ()

    void                g_trash_stack_push                  (GTrashStack **stack_p,
                                                             gpointer data_p);

Pushes a piece of memory onto a GTrashStack.

`stack_p` : | a pointer to a GTrashStack.
`data_p` : | the piece of memory to push on the stack.

### g_trash_stack_pop ()

    gpointer            g_trash_stack_pop                   (GTrashStack **stack_p);

Pops a piece of memory off a GTrashStack.

`stack_p` : | a pointer to a GTrashStack.
Returns : | the element at the top of the stack.

### g_trash_stack_peek ()

    gpointer            g_trash_stack_peek                  (GTrashStack **stack_p);

Returns the element at the top of a GTrashStack which may be `NULL`.

`stack_p` : | a pointer to a GTrashStack.
Returns : | the element at the top of the stack.

### g_trash_stack_height ()

    guint               g_trash_stack_height                (GTrashStack **stack_p);

Returns the height of a GTrashStack. Note that execution of this function is of O(N) complexity where N denotes the number of items on the stack.

`stack_p` : | a pointer to a GTrashStack.
Returns : | the height of the stack.