4.1 Queues, Lists, FIFOs etc.

This data structure is based on circular buffer, and can be used both like a FIFO and a Stack.

Following functions are available for use in C:

typedef ... CdsFifo;
An opaque data type representing a queue of void* pointers.

CdsFifo CdsFifo_Create(void);
Creates a queue in memory and returns its pointer.

CdsFifo CdsFifo_Create_len(int len);
Creates a queue in memory with the initial buffer size of len entries and returns its pointer.

void CdsFifo_Enqueue(CdsFifo q, void *elt);
Appends elt at the end of q.

void *CdsFifo_Dequeue(CdsFifo q);
Removes an element from the front of the q, and returns it. Returns 0 if the queue is empty.

void *CdsFifo_Pop(CdsFifo q);
Removes an element from the front of the q, and returns it. Returns 0 if the queue is empty. An alias for the dequeue function.

void CdsFifo_Push(CdsFifo q, void *elt);
Inserts elt in the beginning of q.

int CdsFifo_Empty(CdsFifo q);
Returns 1 if the q is empty, 0 otherwise.

int CdsFifo_Length(CdsFifo q);
Returns the length of the q.

int CdsFifo_Peek(CdsFifo q);
Returns the element from the front of the q without removing it.

void CdsFifo_Destroy(CdsFifo q);
Releases memory used by q.

Following Templates are available for use in C++:

template<class T>
class CkQ {
  CkQ();  // default constructor
  CkQ(int initial_size); // constructor with initial buffer size
  ~CkQ(); // destructor
  int length(void); // returns length of the q
  CmiBool isEmpty(void); // returns CmiTrue if q is empty, CmiFalse otherwise
  T deq(void); // removes and returns the front element
  void enq(const T&); // appends at the end of the list
  void push(const T&); // inserts in the beginning of the list
  T& operator[](size_t n); // returns the n'th element
};