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/*
* Copyright (C) 2004 Peter Harvey <pah06@uow.edu.au>
*
* 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.
*
* $Id$
*/
#include "config.h"
#include "ephy-nodes-cover.h"
/* Count the number of node entries which are children of parent. */
gint
ephy_nodes_count_covered (EphyNode *parent, const GPtrArray *children)
{
guint i, len = 0;
EphyNode *child;
for(i = 0; i < children->len; i++)
{
child = g_ptr_array_index (children, i);
if (ephy_node_has_child (parent, child))
{
len++;
}
}
return len;
}
/* Removes from the array of children those which are children of the given parent. */
gint
ephy_nodes_remove_covered (EphyNode *parent, GPtrArray *children)
{
guint i, len = children->len;
EphyNode *child;
for(i = 0; i < children->len; i++)
{
child = g_ptr_array_index (children, i);
if (ephy_node_has_child (parent, child))
{
g_ptr_array_remove_index_fast (children, i);
i--;
}
}
return len - children->len;
}
/* Removes from the array of children those which are children of the given parent. */
gint
ephy_nodes_remove_not_covered (EphyNode *parent, GPtrArray *children)
{
guint i, len = children->len;
EphyNode *child;
for(i = 0; i < children->len; i++)
{
child = g_ptr_array_index (children, i);
if (!ephy_node_has_child (parent, child))
{
g_ptr_array_remove_index_fast (children, i);
i--;
}
}
return len - children->len;
}
/* Returns the subset of children which are childs of the given parent.
* Stores the result in the given _covered array if non-null. */
GPtrArray *
ephy_nodes_get_covered (EphyNode *parent, const GPtrArray *children, GPtrArray *_covered)
{
GPtrArray *covered = _covered?_covered:g_ptr_array_sized_new (children->len);
EphyNode *child;
guint i;
covered->len = 0;
for (i = 0; i < children->len; i++)
{
child = g_ptr_array_index (children, i);
if (ephy_node_has_child (parent, child))
{
g_ptr_array_add (covered, child);
}
}
return covered;
}
/* Returns true if the parent covers all the children. */
gboolean
ephy_nodes_covered (EphyNode *parent, const GPtrArray *children)
{
EphyNode *child;
guint i;
for (i = 0; i < children->len; i++)
{
child = g_ptr_array_index (children, i);
if (!ephy_node_has_child (parent, child))
{
return FALSE;
}
}
return TRUE;
}
static gint
compare_chosen (const guint *a, const guint *b, guint *count_c)
{
return (count_c[*b] - count_c[*a]);
}
/* Returns the subset of parents which provide a covering of children.
* Arguments other than parents and children arguments are only used if non-null.
* Uses the _covering array to store the subset of parents.
* Uses the _uncovered array to store those children which couldn't be covered.
* Uses the _sizes array to store the number of children covered by each parent. */
GPtrArray *
ephy_nodes_get_covering (const GPtrArray *parents, const GPtrArray *children,
GPtrArray *_covering, GPtrArray *_uncovered, GArray *_sizes)
{
GPtrArray *uncovered = _uncovered?_uncovered:g_ptr_array_sized_new (children->len);
GPtrArray *covering = _covering?_covering:g_ptr_array_sized_new (parents->len);
GArray *chosen = g_array_sized_new (FALSE, FALSE, sizeof(guint), parents->len);
GArray *sizes = _sizes;
/* Create arrays to store the number of children each parent has which
* are currently not covered, and the number of children it has total. */
guint *count_u = g_malloc (sizeof(guint) * parents->len);
guint *count_c = g_malloc (sizeof(guint) * parents->len);
EphyNode *parent;
guint i, p;
/* Empty all the returning arrays. */
uncovered->len = 0;
covering->len = 0;
if (sizes) sizes->len = 0;
/* Initialise the array of uncovered bookmarks. */
for (i = 0; i < children->len; i++)
{
g_ptr_array_add (uncovered, g_ptr_array_index (children, i));
}
/* Initialise the count_u and count_c arrays.
* NB: count_u[0] is set to 0 if the parent node
covers the entire set of children. */
for (i = 0, p = 0; i < parents->len; i++)
{
parent = g_ptr_array_index (parents, i);
count_c[i] = ephy_nodes_count_covered (parent, children);
count_u[i] = (count_c[i]<children->len) ? count_c[i] : 0;
if (count_u[i] > count_u[p]) p = i;
}
/* While there are more suitable topics... */
while (p < parents->len && count_u[p])
{
/* Update the arrays of uncovered bookmarks and covering topics. */
parent = g_ptr_array_index (parents, p);
ephy_nodes_remove_covered (parent, uncovered);
g_array_append_val (chosen, p);
/* Find the next most suitable topic. */
count_u[p] = 0;
for (i = 0; i < parents->len; i++)
{
/* Lazy update the count_u[i] array. */
if (count_u[i] > count_u[p] || (count_u[i] == count_u[p] && count_c[i] < count_c[p]))
{
parent = g_ptr_array_index (parents, i);
count_u[i] = ephy_nodes_count_covered (parent, uncovered);
}
if (count_u[i] > count_u[p] || (count_u[i] == count_u[p] && count_c[i] < count_c[p]))
{
p = i;
}
}
}
g_array_sort_with_data (chosen, (GCompareDataFunc)compare_chosen, count_c);
for (i = 0; i < chosen->len; i++)
{
p = g_array_index (chosen, guint, i);
g_ptr_array_add (covering, g_ptr_array_index (parents, p));
if (sizes) g_array_append_val (sizes, count_c[p]);
}
if (_uncovered != uncovered) g_ptr_array_free (uncovered, TRUE);
g_array_free (chosen, TRUE);
g_free (count_u);
g_free (count_c);
return covering;
}
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