path: root/lib/libalpm/alpm_list.c

/*
 *  alpm_list.c
 *
 *  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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 *  USA.
 */

#include "config.h"

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

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

/**
 * @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 Allocate a new alpm_list_t.
 *
 * @return a new alpm_list_t item, or NULL on failure
 */
alpm_list_t SYMEXPORT *alpm_list_new()
{
  alpm_list_t *list = NULL;

  list = malloc(sizeof(alpm_list_t));
  if(list) {
    list->data = NULL;
    list->prev = list; /* maintain a back reference to the tail pointer */
    list->next = NULL;
  }

  return(list);
}

/**
 * @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 = list;
  if(ptr == NULL) {
    ptr = alpm_list_new();
    if(ptr == NULL) {
      return(NULL);
    }
  }

  lp = alpm_list_last(ptr);
  if(lp == ptr && lp->data == NULL) {
    /* nada */
  } else {
    lp->next = alpm_list_new();
    if(lp->next == NULL) {
      return(NULL);
    }
    lp->next->prev = lp;
    lp = lp->next;
    list->prev = lp;
  }

  lp->data = data;

  return(ptr);
}

/**
 * @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) {
    return alpm_list_add(list, data);
  } else {
    alpm_list_t *add = NULL, *prev = NULL, *next = list;

    add = alpm_list_new();
    add->data = data;

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

    /*  Insert node before insertion point. */
    add->prev = prev;
    add->next = next;

    if(next != NULL) {
      next->prev = add;   /*  Not at end.  */
    }

    if(prev != NULL) {
      prev->next = add;       /*  In middle.  */
    } else {
      list = add; /* At beginning, or new list */
    }

    if(next == NULL) {
      /* At end, adjust tail pointer on head node */
      list->prev = 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, int 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.
 *
 * @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, *tmp = NULL;

  if(data) {
    *data = NULL;
  }

  while(i) {
    if(i->data == NULL) {
      continue;
    }
    tmp = i->next;
    if(fn(needle, i->data) == 0) {
      /* we found a matching item */
      if(i == haystack) {
        /* Special case: removing the head node which has a back reference to
         * the tail node */
        haystack = i->next;
        if(haystack) {
          haystack->prev = i->prev;
        }
        i->prev = NULL;
      } else if(i == 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(i->prev) {
          /* i->next should always be null */
          i->prev->next = i->next;
          haystack->prev = i->prev;
          i->prev = NULL;
        }
      } else {
        /* Normal case, non-head and non-tail node */
        if(i->next) {
          i->next->prev = i->prev;
        }
        if(i->prev) {
          i->prev->next = i->next;
        }
      }

      if(data) {
        *data = i->data;
      }
      i->data = NULL;
      free(i);
      i = NULL;
    } else {
      i = tmp;
    }
  }

  return(haystack);
}

/**
 * @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;

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

  while(lp) {
    newlist = alpm_list_add(newlist, lp->data);
    lp = lp->prev;
  }
  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)
{
  return((alpm_list_t*)list);
}

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

/**
 * @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
 */
int SYMEXPORT alpm_list_count(const alpm_list_t *list)
{
  unsigned int 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 ptrcmp(const void *p, const void *q)
{
  return(p != q);
}

/**
 * @brief Find an item in a list.
 *
 * Search for the item whos 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, ptrcmp));
}

/**
 * @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 items in list `lhs` that are not present in list `rhs`.
 *
 * Entries are not duplicated. Operation is O(m*n). The first list is stepped
 * through one node at a time, and for each node in the first list, each node
 * in the second list is compared to it.
 *
 * @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)
{
  const alpm_list_t *i, *j;
  alpm_list_t *ret = NULL;
  for(i = lhs; i; i = i->next) {
    int found = 0;
    for(j = rhs; j; j = j->next) {
      if(fn(i->data, j->data) == 0) {
        found = 1;
        break;
      }
    }
    if(!found) {
      ret = alpm_list_add(ret, i->data);
    }
  }

  return(ret);
}

/** @} */

/* vim: set ts=2 sw=2 noet: */