pop.c

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/* ************************************************************************** */
/*      ____    _    _____ ____     _    _   _   _____ _  _   ____  ____      */
/*     / ___|  / \  |  ___|  _ \   / \  | \ | | |_   _| || | |  _ \/ ___|     */
/*     \___ \ / _ \ | |_  | |_) | / _ \ |  \| |   | | | || |_| | | \___ \     */
/*      ___) / ___ \|  _| |  _ < / ___ \| |\  |   | | |__   _| |_| |___) |    */
/*     |____/_/   \_|_|   |_| \_/_/   \_|_| \_|   |_|    |_| |____/|____/     */
/*                                                                            */
/* ************************************************************************** */
 
#include "private.h"
 
#include "o2s/deque.h"
#include "o2s/preprocessing.h" // min
 
#include <string.h>            // memcpy

bool deque_pop_front(deque_t* self, void* destination)
{
    if (deque_is_empty(self))
        return false;
    if (destination != NULL)
        memcpy(destination, self->front, deque_offset(self, 1));
    self->front = deque_pointer_after(self, self->front);
    self->count -= 1;
    return true;
}

bool deque_pop_front_n(deque_t* self, void* destination, size_t count)
{
    size_t first_pass;
    size_t first_pass_size;
 
    if (count == 0)
        return true;
    if (deque_count(self) < count)
        return false;
 
    first_pass = min(count, deque_distance(self, self->front, deque_end(self)));
    first_pass_size = deque_offset(self, first_pass);
    if (destination != NULL)
    {
        memcpy(destination, self->front, first_pass_size);
        destination += first_pass_size;
    }
    self->front += first_pass_size;
    self->count -= first_pass;
 
    if (self->front == deque_end(self))
        self->front = deque_begin(self);
    if (first_pass < count)
        return deque_pop_front_n(self, destination, count - first_pass);
    return true;
}

bool deque_pop_back(deque_t* self, void* destination)
{
    if (deque_is_empty(self))
        return false;
    self->back = deque_pointer_before(self, self->back);
    if (destination != NULL)
        memcpy(destination, self->back, deque_offset(self, 1));
    self->count -= 1;
    return true;
}

bool deque_pop_back_n(deque_t* self, void* destination, size_t count)
{
    if (deque_count(self) < count)
        return false;
    while (count-- > 0)
    {
        deque_pop_back(self, destination);
        destination += deque_offset(self, 1);
    }
    return true;
}