Merge branch 'maint'

[pacman-ng.git] / lib / libalpm / alpm_list.c

/*
 *  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 = calloc(1, 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 = calloc(1, 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;

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

        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;
        }
        else if(right != NULL) {
                lp->next = right;
                right->prev = lp;
        }

        /* Find our tail pointer
         * TODO maintain this in the algorithm itself */
        lp = newlist;
        while(lp && lp->next) {
                lp = lp->next;
        }
        newlist->prev = lp;

        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) {
                alpm_list_t *left = list;
                alpm_list_t *lastleft = alpm_list_nth(list, n/2 - 1);
                alpm_list_t *right = lastleft->next;
                /* terminate first list */
                lastleft->next = NULL;

                left = alpm_list_msort(left, n/2, fn);
                right = alpm_list_msort(right, n - (n/2), 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 = calloc(1, 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 Get the first element of a list.
 *
 * @param list the list
 *
 * @return the first element in the list
 */
inline alpm_list_t SYMEXPORT *alpm_list_first(const alpm_list_t *list)
{
        if(list) {
                return (alpm_list_t *)list;
        } else {
                return NULL;
        }
}

/**
 * @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 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;
        }
}

/**
 * @brief Get the data member of a list node.
 *
 * @param node the list node
 *
 * @return the contained data, or NULL if none
 */
void SYMEXPORT *alpm_list_getdata(const alpm_list_t *node)
{
        if(node == NULL) return NULL;
        return node->data;
}

/* 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;
}

/** @} */

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