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Binary heap - type agnostic

Introduction

This is a preprocessor-only implementation of a type agnostic binary heap data structure. Inserting ordered elements is O(logN), peeking the first element is O(1).

For its properties, this data structure is indicated to implement timers.

Usage

Create a data type you want to order, like:

        typedef struct potato {
            /* some fields ... */
            uint32_t weight;    /* Field used for sorting */
            /* more fields ... */
        } potato_t;

Use the macro DECLARE_HEAP to automatically generate the functions tailored on your type and ordering fields. For the structure above this will be:

DECLARE_HEAP(potato_t, weight);

There is now a new type heap_potato_t that describes the binary heap itself. You can create a new binary heap by calling:

heap_potato_t *pHeap = heap_init();

The macro will also create the following inline functions:
- void heap_destroy(heap_type *h) : dealloc the binary heap and all its content.
- int heap_insert(heap_type *heap, element_type *element) : insert a new element of the given type into the heap. Return value is the new element id which is automatically created. A negative return value indicates an error. errno is set accordingly.
- int heap_first(heap_type *heap) : fetch the first element of the heap, without removing it from the structure. Useful to look inside the first element before deciding if it is time to peek.
- int heap_peek(heap_type *heap, element_type *element) : fetch the first element of the heap, and removes it from the structure. Returns 0 in case of success, and the result is put in the element pointed by element. Returns -1 on error and errno is set accordingly.
- int heap_delete(heap_type *heap, int id) : deletes the element with id id from the heap. id is the id number returned by heap_insert. Returns 0 in case of success, -1 on error, and errno is set accordingly.

License

See COPYING.