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Remove assertion. Return TRUE if the iter doesn't have a parent. Fix

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Fri Feb  9 17:46:18 2007  Søren Sandmann  <sandmann@redhat.com>

       * glib/gsequence.c (g_sequence_get_end_iter): Remove assertion.
       * glib/gsequence.c (is_end): Return TRUE if the iter doesn't have
       a parent.
       * glib/gsequence.c: Fix grammar of comment. 
       * glib/gsequence.c (node_update_fields): Use a temporary variable
       for the n_nodes.



svn path=/trunk/; revision=5331
This commit is contained in:
Søren Sandmann 2007-02-09 22:53:42 +00:00 committed by Søren Sandmann Pedersen
parent 5fa8f600f5
commit 49eaf7a69b
2 changed files with 38 additions and 25 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
Fri Feb 9 17:46:18 2007 Søren Sandmann <sandmann@redhat.com>
* glib/gsequence.c (g_sequence_get_end_iter): Remove assertion.
* glib/gsequence.c (is_end): Return TRUE if the iter doesn't have
a parent.
* glib/gsequence.c: Fix grammar of comment.
* glib/gsequence.c (node_update_fields): Use a temporary variable
for the n_nodes.
2007-02-07 Soren Sandmann <sandmann@daimi.au.dk>
* tests/sequence-test.c (compare_items): Force an arbitrary order

54
glib/gsequence.c
View File

@ -116,9 +116,12 @@ is_end (GSequenceIter *iter)
if (iter->right)
return FALSE;
if (iter->parent && iter->parent->right != iter)
if (!iter->parent)
return TRUE;
if (iter->parent->right != iter)
return FALSE;
seq = get_sequence (iter);
return seq->end_node == iter;
@ -1035,8 +1038,6 @@ g_sequence_get_end_iter (GSequence *seq)
{
g_return_val_if_fail (seq != NULL, NULL);
g_assert (is_end (seq->end_node));
return seq->end_node;
}
@ -1305,31 +1306,32 @@ g_sequence_swap (GSequenceIter *a,
*
* Advantages of splay trees
*
* - They are very simple to implement, especially things like move_range() or concatenate()
* are very easy to do for splay trees. The algorithm to split a red/black tree, while still,
* O(log n) is much more involved.
* - They are very simple to implement, especially things like move_range or concatenate
* are easy to do for splay trees. The algorithm to split a red/black tree, while still O(log n),
* is much more complicated
*
* - If we add aggregates at one point, splay trees make it really easy to compute the aggregate
* for an arbitrary range of the tree. In a red/black tree you would have to pick out the correct
* subtrees, then call out to the aggregator function to compute them.
* - If we add aggregates at some point, splay trees make it easy to compute the aggregate
* for an arbitrary range of the tree. In a red/black tree you would have to pick out
* the correct subtrees, then call out to the aggregator function to compute them.
* On the other hand, for a splay tree, aggregates would be invalidated on lookups, so you
* would call the aggregator much more often. In both cases, the aggregator function would be
* called O(log n) times as a side-effect of asking for the aggregate of a range.
* would call the aggregator much more often. The aggregates could be invalidated lazily though.
* In both cases, the aggregator function would be called O(log n) times as a side-effect of
* asking for the aggregate of a range.
*
* - If you are only using the list API and never the insert_sorted(), the operations on a
* splay tree will actually be O(1) rather than O(log n). But this is most likely one
* for the "who cares" department, since the O(log n) of a red/black tree really is quite
* fast and if what you need is a queue you can just use GQueue.
* splay tree will actually be O(1) rather than O(log n). But this is most likely just
* not that interesting in practice since the O(log n) of a BTree is actually very fast.
*
* The disadvantages
*
* - Splay trees are only amortized O(log n) which means individual operations could take a long
* time, which is undesirable in GUI applications
*
* - Red/black trees are mode widely known since they are tought in CS101 courses.
* - Red/black trees are more widely known since they are tought in CS101 courses.
*
* - Red/black trees or btrees are more efficient. In particular, splay trees write to the
* nodes on lookup, which causes dirty pages that the VM system will have to launder.
* - Red/black trees or btrees are more efficient. Not only is the red/black algorithm faster
* in itself, the splaying writes to nodes on lookup which causes dirty pages that the VM
* system will have to launder.
*
* - Splay trees are not necessarily balanced at all which means straight-forward recursive
* algorithms can use lots of stack.
@ -1337,21 +1339,23 @@ g_sequence_swap (GSequenceIter *a,
* It is likely worth investigating whether a BTree would be a better choice, in particular the
* algorithm to split a BTree may not be all that complicated given that split/join for nodes
* will have to be implemented anyway.
*
*
*/
static void
node_update_fields (GSequenceNode *node)
{
int n_nodes = 1;
g_assert (node != NULL);
node->n_nodes = 1;
if (node->left)
node->n_nodes += node->left->n_nodes;
n_nodes += node->left->n_nodes;
if (node->right)
node->n_nodes += node->right->n_nodes;
n_nodes += node->right->n_nodes;
node->n_nodes = n_nodes;
}
#define NODE_LEFT_CHILD(n) (((n)->parent) && ((n)->parent->left) == (n))