alpm_list.c

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/*
 *  alpm_list.c
 *
 *  Copyright (c) 2006-2011 Pacman Development Team <pacman-dev@archlinux.org>
 *  Copyright (c) 2002-2006 by Judd Vinet <jvinet@zeroflux.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <string.h>

/* libalpm */
#include "alpm_list.h"

/* check exported library symbols with: nm -C -D <lib> */
#define SYMEXPORT __attribute__((visibility("default")))
#define SYMHIDDEN __attribute__((visibility("internal")))

/**
 * @addtogroup alpm_list List Functions
 * @brief Functions to manipulate alpm_list_t lists.
 *
 * These functions are designed to create, destroy, and modify lists of
 * type alpm_list_t. This is an internal list type used by libalpm that is
 * publicly exposed for use by frontends if desired.
 *
 * @{ */

/* Allocation */

/**
 * @brief Free a list, but not the contained data.
 *
 * @param list the list to free
 */
void SYMEXPORT alpm_list_free(alpm_list_t *list)
{
    alpm_list_t *it = list;

    while(it) {
        alpm_list_t *tmp = it->next;
        free(it);
        it = tmp;
    }
}

/**
 * @brief Free the internal data of a list structure.
 *
 * @param list the list to free
 * @param fn   a free function for the internal data
 */
void SYMEXPORT alpm_list_free_inner(alpm_list_t *list, alpm_list_fn_free fn)
{
    alpm_list_t *it = list;

    while(it) {
        if(fn && it->data) {
            fn(it->data);
        }
        it = it->next;
    }
}


/* Mutators */

/**
 * @brief Add a new item to the end of the list.
 *
 * @param list the list to add to
 * @param data the new item to be added to the list
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_add(alpm_list_t *list, void *data)
{
    alpm_list_t *ptr, *lp;

    ptr = malloc(sizeof(alpm_list_t));
    if(ptr == NULL) {
        return list;
    }

    ptr->data = data;
    ptr->next = NULL;

    /* Special case: the input list is empty */
    if(list == NULL) {
        ptr->prev = ptr;
        return ptr;
    }

    lp = alpm_list_last(list);
    lp->next = ptr;
    ptr->prev = lp;
    list->prev = ptr;

    return list;
}

/**
 * @brief Add items to a list in sorted order.
 *
 * @param list the list to add to
 * @param data the new item to be added to the list
 * @param fn   the comparison function to use to determine order
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_add_sorted(alpm_list_t *list, void *data, alpm_list_fn_cmp fn)
{
    if(!fn || !list) {
        return alpm_list_add(list, data);
    } else {
        alpm_list_t *add = NULL, *prev = NULL, *next = list;

        add = malloc(sizeof(alpm_list_t));
        if(add == NULL) {
            return list;
        }
        add->data = data;

        /* Find insertion point. */
        while(next) {
            if(fn(add->data, next->data) <= 0) break;
            prev = next;
            next = next->next;
        }

        /* Insert the add node to the list */
        if(prev == NULL) { /* special case: we insert add as the first element */
            add->prev = list->prev; /* list != NULL */
            add->next = list;
            list->prev = add;
            return add;
        } else if(next == NULL) { /* another special case: add last element */
            add->prev = prev;
            add->next = NULL;
            prev->next = add;
            list->prev = add;
            return list;
        } else {
            add->prev = prev;
            add->next = next;
            next->prev = add;
            prev->next = add;
            return list;
        }
    }
}

/**
 * @brief Join two lists.
 * The two lists must be independent. Do not free the original lists after
 * calling this function, as this is not a copy operation. The list pointers
 * passed in should be considered invalid after calling this function.
 *
 * @param first  the first list
 * @param second the second list
 *
 * @return the resultant joined list
 */
alpm_list_t SYMEXPORT *alpm_list_join(alpm_list_t *first, alpm_list_t *second)
{
    alpm_list_t *tmp;

    if(first == NULL) {
        return second;
    }
    if(second == NULL) {
        return first;
    }
    /* tmp is the last element of the first list */
    tmp = first->prev;
    /* link the first list to the second */
    tmp->next = second;
    /* link the second list to the first */
    first->prev = second->prev;
    /* set the back reference to the tail */
    second->prev = tmp;

    return first;
}

/**
 * @brief Merge the two sorted sublists into one sorted list.
 *
 * @param left  the first list
 * @param right the second list
 * @param fn    comparison function for determining merge order
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right,
        alpm_list_fn_cmp fn)
{
    alpm_list_t *newlist, *lp, *tail_ptr, *left_tail_ptr, *right_tail_ptr;

    if(left == NULL) {
        return right;
    }
    if(right == NULL) {
        return left;
    }

    /* Save tail node pointers for future use */
    left_tail_ptr = left->prev;
    right_tail_ptr = right->prev;

    if(fn(left->data, right->data) <= 0) {
        newlist = left;
        left = left->next;
    }
    else {
        newlist = right;
        right = right->next;
    }
    newlist->prev = NULL;
    newlist->next = NULL;
    lp = newlist;

    while((left != NULL) && (right != NULL)) {
        if(fn(left->data, right->data) <= 0) {
            lp->next = left;
            left->prev = lp;
            left = left->next;
        }
        else {
            lp->next = right;
            right->prev = lp;
            right = right->next;
        }
        lp = lp->next;
        lp->next = NULL;
    }
    if(left != NULL) {
        lp->next = left;
        left->prev = lp;
        tail_ptr = left_tail_ptr;
    }
    else if(right != NULL) {
        lp->next = right;
        right->prev = lp;
        tail_ptr = right_tail_ptr;
    }
    else {
        tail_ptr = lp;
    }

    newlist->prev = tail_ptr;

    return newlist;
}

/**
 * @brief Sort a list of size `n` using mergesort algorithm.
 *
 * @param list the list to sort
 * @param n    the size of the list
 * @param fn   the comparison function for determining order
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_msort(alpm_list_t *list, size_t n,
        alpm_list_fn_cmp fn)
{
    if(n > 1) {
        size_t half = n / 2;
        size_t i = half - 1;
        alpm_list_t *left = list, *lastleft = list, *right;

        while(i--) {
            lastleft = lastleft->next;
        }
        right = lastleft->next;
        /* terminate first list */
        lastleft->next = NULL;

        left = alpm_list_msort(left, half, fn);
        right = alpm_list_msort(right, n - half, fn);
        list = alpm_list_mmerge(left, right, fn);
    }
    return list;
}

/**
 * @brief Remove an item from the list.
 * item is not freed; this is the responsibility of the caller.
 *
 * @param haystack the list to remove the item from
 * @param item the item to remove from the list
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_remove_item(alpm_list_t *haystack,
        alpm_list_t *item)
{
    if(haystack == NULL || item == NULL) {
        return haystack;
    }

    if(item == haystack) {
        /* Special case: removing the head node which has a back reference to
         * the tail node */
        haystack = item->next;
        if(haystack) {
            haystack->prev = item->prev;
        }
        item->prev = NULL;
    } else if(item == haystack->prev) {
        /* Special case: removing the tail node, so we need to fix the back
         * reference on the head node. We also know tail != head. */
        if(item->prev) {
            /* i->next should always be null */
            item->prev->next = item->next;
            haystack->prev = item->prev;
            item->prev = NULL;
        }
    } else {
        /* Normal case, non-head and non-tail node */
        if(item->next) {
            item->next->prev = item->prev;
        }
        if(item->prev) {
            item->prev->next = item->next;
        }
    }

    return haystack;
}


/**
 * @brief Remove an item from the list.
 *
 * @param haystack the list to remove the item from
 * @param needle   the data member of the item we're removing
 * @param fn       the comparison function for searching
 * @param data     output parameter containing data of the removed item
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_remove(alpm_list_t *haystack,
        const void *needle, alpm_list_fn_cmp fn, void **data)
{
    alpm_list_t *i = haystack;

    if(data) {
        *data = NULL;
    }

    if(needle == NULL) {
        return haystack;
    }

    while(i) {
        if(i->data == NULL) {
            i = i->next;
            continue;
        }
        if(fn(i->data, needle) == 0) {
            haystack = alpm_list_remove_item(haystack, i);

            if(data) {
                *data = i->data;
            }
            free(i);
            break;
        } else {
            i = i->next;
        }
    }

    return haystack;
}

/**
 * @brief Remove a string from a list.
 *
 * @param haystack the list to remove the item from
 * @param needle   the data member of the item we're removing
 * @param data     output parameter containing data of the removed item
 *
 * @return the resultant list
 */
alpm_list_t SYMEXPORT *alpm_list_remove_str(alpm_list_t *haystack,
        const char *needle, char **data)
{
    return alpm_list_remove(haystack, (const void *)needle,
            (alpm_list_fn_cmp)strcmp, (void **)data);
}

/**
 * @brief Create a new list without any duplicates.
 *
 * This does NOT copy data members.
 *
 * @param list the list to copy
 *
 * @return a new list containing non-duplicate items
 */
alpm_list_t SYMEXPORT *alpm_list_remove_dupes(const alpm_list_t *list)
{
    const alpm_list_t *lp = list;
    alpm_list_t *newlist = NULL;
    while(lp) {
        if(!alpm_list_find_ptr(newlist, lp->data)) {
            newlist = alpm_list_add(newlist, lp->data);
        }
        lp = lp->next;
    }
    return newlist;
}

/**
 * @brief Copy a string list, including data.
 *
 * @param list the list to copy
 *
 * @return a copy of the original list
 */
alpm_list_t SYMEXPORT *alpm_list_strdup(const alpm_list_t *list)
{
    const alpm_list_t *lp = list;
    alpm_list_t *newlist = NULL;
    while(lp) {
        newlist = alpm_list_add(newlist, strdup(lp->data));
        lp = lp->next;
    }
    return newlist;
}

/**
 * @brief Copy a list, without copying data.
 *
 * @param list the list to copy
 *
 * @return a copy of the original list
 */
alpm_list_t SYMEXPORT *alpm_list_copy(const alpm_list_t *list)
{
    const alpm_list_t *lp = list;
    alpm_list_t *newlist = NULL;
    while(lp) {
        newlist = alpm_list_add(newlist, lp->data);
        lp = lp->next;
    }
    return newlist;
}

/**
 * @brief Copy a list and copy the data.
 * Note that the data elements to be copied should not contain pointers
 * and should also be of constant size.
 *
 * @param list the list to copy
 * @param size the size of each data element
 *
 * @return a copy of the original list, data copied as well
 */
alpm_list_t SYMEXPORT *alpm_list_copy_data(const alpm_list_t *list,
        size_t size)
{
    const alpm_list_t *lp = list;
    alpm_list_t *newlist = NULL;
    while(lp) {
        void *newdata = malloc(size);
        if(newdata) {
            memcpy(newdata, lp->data, size);
            newlist = alpm_list_add(newlist, newdata);
            lp = lp->next;
        }
    }
    return newlist;
}

/**
 * @brief Create a new list in reverse order.
 *
 * @param list the list to copy
 *
 * @return a new list in reverse order
 */
alpm_list_t SYMEXPORT *alpm_list_reverse(alpm_list_t *list)
{
    const alpm_list_t *lp;
    alpm_list_t *newlist = NULL, *backup;

    if(list == NULL) {
        return NULL;
    }

    lp = alpm_list_last(list);
    /* break our reverse circular list */
    backup = list->prev;
    list->prev = NULL;

    while(lp) {
        newlist = alpm_list_add(newlist, lp->data);
        lp = lp->prev;
    }
    list->prev = backup; /* restore tail pointer */
    return newlist;
}

/* Accessors */

/**
 * @brief Return nth element from list (starting from 0).
 *
 * @param list the list
 * @param n    the index of the item to find (n < alpm_list_count(list) IS needed)
 *
 * @return an alpm_list_t node for index `n`
 */
alpm_list_t SYMEXPORT *alpm_list_nth(const alpm_list_t *list, size_t n)
{
    const alpm_list_t *i = list;
    while(n--) {
        i = i->next;
    }
    return (alpm_list_t *)i;
}

/**
 * @brief Get the next element of a list.
 *
 * @param node the list node
 *
 * @return the next element, or NULL when no more elements exist
 */
inline alpm_list_t SYMEXPORT *alpm_list_next(const alpm_list_t *node)
{
    if(node) {
        return node->next;
    } else {
        return NULL;
    }
}

/**
 * @brief Get the previous element of a list.
 *
 * @param list the list head
 *
 * @return the previous element, or NULL when no previous element exist
 */
inline alpm_list_t SYMEXPORT *alpm_list_previous(const alpm_list_t *list)
{
    if(list && list->prev->next) {
        return list->prev;
    } else {
        return NULL;
    }
}

/**
 * @brief Get the last item in the list.
 *
 * @param list the list
 *
 * @return the last element in the list
 */
alpm_list_t SYMEXPORT *alpm_list_last(const alpm_list_t *list)
{
    if(list) {
        return list->prev;
    } else {
        return NULL;
    }
}

/* Misc */

/**
 * @brief Get the number of items in a list.
 *
 * @param list the list
 *
 * @return the number of list items
 */
size_t SYMEXPORT alpm_list_count(const alpm_list_t *list)
{
    size_t i = 0;
    const alpm_list_t *lp = list;
    while(lp) {
        ++i;
        lp = lp->next;
    }
    return i;
}

/**
 * @brief Find an item in a list.
 *
 * @param needle   the item to search
 * @param haystack the list
 * @param fn       the comparison function for searching (!= NULL)
 *
 * @return `needle` if found, NULL otherwise
 */
void SYMEXPORT *alpm_list_find(const alpm_list_t *haystack, const void *needle,
        alpm_list_fn_cmp fn)
{
    const alpm_list_t *lp = haystack;
    while(lp) {
        if(lp->data && fn(lp->data, needle) == 0) {
            return lp->data;
        }
        lp = lp->next;
    }
    return NULL;
}

/* trivial helper function for alpm_list_find_ptr */
static int ptr_cmp(const void *p, const void *q)
{
    return (p != q);
}

/**
 * @brief Find an item in a list.
 *
 * Search for the item whose data matches that of the `needle`.
 *
 * @param needle   the data to search for (== comparison)
 * @param haystack the list
 *
 * @return `needle` if found, NULL otherwise
 */
void SYMEXPORT *alpm_list_find_ptr(const alpm_list_t *haystack,
        const void *needle)
{
    return alpm_list_find(haystack, needle, ptr_cmp);
}

/**
 * @brief Find a string in a list.
 *
 * @param needle   the string to search for
 * @param haystack the list
 *
 * @return `needle` if found, NULL otherwise
 */
char SYMEXPORT *alpm_list_find_str(const alpm_list_t *haystack,
        const char *needle)
{
    return (char *)alpm_list_find(haystack, (const void *)needle,
            (alpm_list_fn_cmp)strcmp);
}

/**
 * @brief Find the differences between list `left` and list `right`
 *
 * The two lists must be sorted. Items only in list `left` are added to the
 * `onlyleft` list. Items only in list `right` are added to the `onlyright`
 * list.
 *
 * @param left      the first list
 * @param right     the second list
 * @param fn        the comparison function
 * @param onlyleft  pointer to the first result list
 * @param onlyright pointer to the second result list
 *
 */
void SYMEXPORT alpm_list_diff_sorted(const alpm_list_t *left,
        const alpm_list_t *right, alpm_list_fn_cmp fn,
        alpm_list_t **onlyleft, alpm_list_t **onlyright)
{
    const alpm_list_t *l = left;
    const alpm_list_t *r = right;

    if(!onlyleft && !onlyright) {
        return;
    }

    while(l != NULL && r != NULL) {
        int cmp = fn(l->data, r->data);
        if(cmp < 0) {
            if(onlyleft) {
                *onlyleft = alpm_list_add(*onlyleft, l->data);
            }
            l = l->next;
        }
        else if(cmp > 0) {
            if(onlyright) {
                *onlyright = alpm_list_add(*onlyright, r->data);
            }
            r = r->next;
        } else {
            l = l->next;
            r = r->next;
        }
    }
    while(l != NULL) {
        if(onlyleft) {
            *onlyleft = alpm_list_add(*onlyleft, l->data);
        }
        l = l->next;
    }
    while(r != NULL) {
        if(onlyright) {
            *onlyright = alpm_list_add(*onlyright, r->data);
        }
        r = r->next;
    }
}


/**
 * @brief Find the items in list `lhs` that are not present in list `rhs`.
 *
 * @param lhs the first list
 * @param rhs the second list
 * @param fn  the comparison function
 *
 * @return a list containing all items in `lhs` not present in `rhs`
 */
alpm_list_t SYMEXPORT *alpm_list_diff(const alpm_list_t *lhs,
        const alpm_list_t *rhs, alpm_list_fn_cmp fn)
{
    alpm_list_t *left, *right;
    alpm_list_t *ret = NULL;

    left = alpm_list_copy(lhs);
    left = alpm_list_msort(left, alpm_list_count(left), fn);
    right = alpm_list_copy(rhs);
    right = alpm_list_msort(right, alpm_list_count(right), fn);

    alpm_list_diff_sorted(left, right, fn, &ret, NULL);

    alpm_list_free(left);
    alpm_list_free(right);
    return ret;
}

/**
 * @brief Copy a list and data into a standard C array of fixed length.
 * Note that the data elements are shallow copied so any contained pointers
 * will point to the original data.
 *
 * @param list the list to copy
 * @param n    the size of the list
 * @param size the size of each data element
 *
 * @return an array version of the original list, data copied as well
 */
void SYMEXPORT *alpm_list_to_array(const alpm_list_t *list, size_t n,
        size_t size)
{
    size_t i;
    const alpm_list_t *item;
    char *array;

    if(n == 0) {
        return NULL;
    }

    array = malloc(n * size);
    if(array == NULL) {
        return NULL;
    }
    for(i = 0, item = list; i < n && item; i++, item = item->next) {
        memcpy(array + i * size, item->data, size);
    }
    return array;
}

/** @} */

/* vim: set ts=2 sw=2 noet: */