info2_uebungen/08_queue/namesarchive.c

#include "namesarchive.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

typedef struct queueElem
{
    char *name;
    struct queueElem *next;
} QueueElem;

static QueueElem *head = NULL;
static QueueElem *iter = NULL;

static QueueElem *createEmptyElem()
{
    return calloc(1, sizeof(QueueElem));
}

static QueueElem *createNameElem(const char *name)
{
    QueueElem *newElem = NULL;
    
    if(name != NULL)
    {
        newElem = createEmptyElem();

        if(newElem != NULL)
        {
            newElem->name = malloc(sizeof(char) * (strlen(name)+1));

            if(newElem->name != NULL)
                strcpy(newElem->name, name);
            else
            {
                free(newElem);
                newElem = NULL;
            }
        }
    }

    return newElem;
}

int addName(const char *name)
{
    int wasSuccessful = 0;

    if(head == NULL)
        head = createEmptyElem();

    if(head != NULL)
    {
        QueueElem *newElem = createNameElem(name);

        if(newElem != NULL)
        {
            QueueElem *currentElem = head;

            while(currentElem->next != NULL)
            {
                currentElem = currentElem->next;
            }

            currentElem->next = newElem;

            wasSuccessful = 1;
        }
    }

    return wasSuccessful;
}

int addNameSorted(const char *name)
{
    int wasSuccessful = 0;

    if(head == NULL)
        head = createEmptyElem();

    if(head != NULL)
    {
        QueueElem *newElem = createNameElem(name);

        if(newElem != NULL)
        {
            QueueElem *currentElem = head;

            while(currentElem->next != NULL && strcmp(name, currentElem->next->name) > 0)
            {
                currentElem = currentElem->next;
            }

            newElem->next = currentElem->next;
            currentElem->next = newElem;

            wasSuccessful = 1;
        }
    }

    return wasSuccessful;
}

void printNames()
{
    if(head != NULL)
    {
        QueueElem *elem = head->next;

        while(elem != NULL)
        {
            printf("%s\n", elem->name);
            elem = elem->next;
        }
    }
}

static QueueElem *getPreviousNode(const char *name)
{
    QueueElem *currentElem = head;

    while(currentElem != NULL && currentElem->next != NULL && strcmp(currentElem->next->name, name) != 0)
    {
        currentElem = currentElem->next;
    }

    if(currentElem == NULL || currentElem->next == NULL)
        return NULL;
    else
        return currentElem;
}

static void disposeElem(QueueElem *elem)
{
    if(elem != NULL)
        free(elem->name);
    free(elem);
}

int removeName(const char *name)
{
    QueueElem *prevElem = getPreviousNode(name);

    if(prevElem != NULL)
    {
        QueueElem *elemToRemove = prevElem->next;
        prevElem->next = prevElem->next->next;
        disposeElem(elemToRemove);
    }

    return prevElem != NULL;
}

void clearArchive()
{
    while(head != NULL)
    {
        QueueElem *oldHead = head;
        head = head->next;
        disposeElem(oldHead);
    }
}

const char *getNextName()
{
    const char *name = NULL;

    if(iter != NULL)
        iter = iter->next;
    
    if(iter != NULL)
        name = iter->name;

    return name;
}

void initIter()
{
    iter = head;
}