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Optimized the comparison for non-element nodes in xmlXPathCmpNodesExt();

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* xpath.c: Optimized the comparison for non-element nodes
  in xmlXPathCmpNodesExt(); the comparison is used for sorting
  of node-sets. This enhancement is related to bug #165547.
  There are other places where the old comparison function
  xmlXPathCmpNodes() is still called, but I currently don't
  know exactly what those calls are for; thus if they can be
  substituted (if it makes sense) for the new function.
This commit is contained in:
Kasimier T. Buchcik 2006-05-19 11:26:15 +00:00
parent 6ed2eb47fc
commit 2bdabbd711
2 changed files with 306 additions and 1 deletions
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10
ChangeLog
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@ -1,3 +1,13 @@
Fri May 19 13:16:58 CEST 2006 Kasimier Buchcik <libxml2-cvs@cazic.net>
* xpath.c: Optimized the comparison for non-element nodes
in xmlXPathCmpNodesExt(); the comparison is used for sorting
of node-sets. This enhancement is related to bug #165547.
There are other places where the old comparison function
xmlXPathCmpNodes() is still called, but I currently don't
know exactly what those calls are for; thus if they can be
substituted (if it makes sense) for the new function.
Tue May 16 16:55:13 CEST 2006 Kasimier Buchcik <libxml2-cvs@cazic.net>
* xpath.c: Applied patch from Rob Richards, fixing a potential

297
xpath.c
View File

@ -75,6 +75,17 @@
* only element-nodes and the document node.
*/
#define XP_PATTERN_TO_ANY_NODE_ENABLED
/*
* XP_FAST_NON_ELEM_COMPARISON:
* If defined, this will use xmlXPathCmpNodesExt() instead of
* xmlXPathCmpNodes(). The new function is optimized comparison of
* non-element nodes; actually it will speed up comparison only if
* xmlXPathOrderDocElems() was called in order to index the elements of
* a tree in document order; Libxslt does such an indexing, thus it will
* benefit from this optimization.
*/
#define XP_FAST_NON_ELEM_COMPARISON
/*
* TODO:
* There are a few spots where some tests are done which depend upon ascii
@ -1691,6 +1702,284 @@ xmlXPathCmpNodes(xmlNodePtr node1, xmlNodePtr node2) {
return(-1); /* assume there is no sibling list corruption */
}
#ifdef XP_FAST_NON_ELEM_COMPARISON
/**
* xmlXPathCmpNodesExt:
* @node1: the first node
* @node2: the second node
*
* Compare two nodes w.r.t document order.
* This one is optimized for handling of non-element nodes.
*
* Returns -2 in case of error 1 if first point < second point, 0 if
* it's the same node, -1 otherwise
*/
static int
xmlXPathCmpNodesExt(xmlNodePtr node1, xmlNodePtr node2) {
int depth1, depth2;
int misc = 0, precedence1 = 0, precedence2 = 0;
xmlNodePtr miscNode1 = NULL, miscNode2 = NULL;
xmlNodePtr cur, root;
if ((node1 == NULL) || (node2 == NULL))
return(-2);
if (node1 == node2)
return(0);
/*
* a couple of optimizations which will avoid computations in most cases
*/
switch (node1->type) {
case XML_ELEMENT_NODE:
break;
case XML_ATTRIBUTE_NODE:
precedence1 = 1; /* element is owner */
miscNode1 = node1;
node1 = node1->parent;
misc = 1;
break;
case XML_TEXT_NODE:
case XML_CDATA_SECTION_NODE:
case XML_COMMENT_NODE:
case XML_PI_NODE: {
miscNode1 = node1;
/*
* Find nearest element node.
*/
if (node1->prev != NULL) {
do {
node1 = node1->prev;
if (node1->type == XML_ELEMENT_NODE) {
precedence1 = 3; /* element in prev-sibl axis */
break;
}
if (node1->prev == NULL) {
precedence1 = 2; /* element is parent */
/*
* URGENT TODO: Are there any cases, where the
* parent of such a node is not an element node?
*/
node1 = node1->parent;
break;
}
} while (1);
} else {
precedence1 = 2; /* element is parent */
node1 = node1->parent;
}
if ((node1 == NULL) || (node1->type != XML_ELEMENT_NODE)) {
/*
* Fallback for whatever case.
*/
node1 = miscNode1;
precedence1 = 0;
} else
misc = 1;
}
break;
case XML_NAMESPACE_DECL:
/*
* TODO: why do we return 1 for namespace nodes?
*/
return(1);
default:
break;
}
switch (node2->type) {
case XML_ELEMENT_NODE:
break;
case XML_ATTRIBUTE_NODE:
precedence2 = 1; /* element is owner */
miscNode2 = node2;
node2 = node2->parent;
misc = 1;
break;
case XML_TEXT_NODE:
case XML_CDATA_SECTION_NODE:
case XML_COMMENT_NODE:
case XML_PI_NODE: {
miscNode2 = node2;
if (node2->prev != NULL) {
do {
node2 = node2->prev;
if (node2->type == XML_ELEMENT_NODE) {
precedence2 = 3; /* element in prev-sibl axis */
break;
}
if (node2->prev == NULL) {
precedence2 = 2; /* element is parent */
node2 = node2->parent;
break;
}
} while (1);
} else {
precedence2 = 2; /* element is parent */
node2 = node2->parent;
}
if ((node2 == NULL) || (node2->type != XML_ELEMENT_NODE) ||
(0 <= (long) node1->content))
{
node2 = miscNode2;
precedence2 = 0;
} else
misc = 1;
}
break;
case XML_NAMESPACE_DECL:
return(1);
default:
break;
}
if (misc) {
if (node1 == node2) {
if (precedence1 == precedence2) {
/*
* The ugly case; but normally there aren't many
* adjacent non-element nodes around.
*/
cur = miscNode2->prev;
while (cur != NULL) {
if (cur == miscNode1)
return(1);
if (cur->type == XML_ELEMENT_NODE)
return(-1);
cur = cur->prev;
}
return (-1);
} else {
/*
* Evaluate based on higher precedence wrt to the element.
* TODO: This assumes attributes are sorted before content.
* Is this 100% correct?
*/
if (precedence1 < precedence2)
return(1);
else
return(-1);
}
}
/*
* Special case: One of the helper-elements is contained by the other.
* <foo>
* <node2>
* <node1>Text-1(precedence1 == 2)</node1>
* </node2>
* Text-6(precedence2 == 3)
* </foo>
*/
if ((precedence2 == 3) && (precedence1 > 1)) {
cur = node1->parent;
while (cur) {
if (cur == node2)
return(1);
cur = cur->parent;
}
}
if ((precedence1 == 3) && (precedence2 > 1)) {
cur = node2->parent;
while (cur) {
if (cur == node1)
return(-1);
cur = cur->parent;
}
}
}
if (node1 == node2->prev)
return(1);
if (node1 == node2->next)
return(-1);
/*
* Speedup using document order if availble.
*/
if ((node1->type == XML_ELEMENT_NODE) &&
(node2->type == XML_ELEMENT_NODE) &&
(0 > (long) node1->content) &&
(0 > (long) node2->content) &&
(node1->doc == node2->doc)) {
long l1, l2;
l1 = -((long) node1->content);
l2 = -((long) node2->content);
if (l1 < l2)
return(1);
if (l1 > l2)
return(-1);
}
/*
* compute depth to root
*/
for (depth2 = 0, cur = node2;cur->parent != NULL;cur = cur->parent) {
if (cur == node1)
return(1);
depth2++;
}
root = cur;
for (depth1 = 0, cur = node1;cur->parent != NULL;cur = cur->parent) {
if (cur == node2)
return(-1);
depth1++;
}
/*
* Distinct document (or distinct entities :-( ) case.
*/
if (root != cur) {
return(-2);
}
/*
* get the nearest common ancestor.
*/
while (depth1 > depth2) {
depth1--;
node1 = node1->parent;
}
while (depth2 > depth1) {
depth2--;
node2 = node2->parent;
}
while (node1->parent != node2->parent) {
node1 = node1->parent;
node2 = node2->parent;
/* should not happen but just in case ... */
if ((node1 == NULL) || (node2 == NULL))
return(-2);
}
/*
* Find who's first.
*/
if (node1 == node2->prev)
return(1);
if (node1 == node2->next)
return(-1);
/*
* Speedup using document order if availble.
*/
if ((node1->type == XML_ELEMENT_NODE) &&
(node2->type == XML_ELEMENT_NODE) &&
(0 > (long) node1->content) &&
(0 > (long) node2->content) &&
(node1->doc == node2->doc)) {
long l1, l2;
l1 = -((long) node1->content);
l2 = -((long) node2->content);
if (l1 < l2)
return(1);
if (l1 > l2)
return(-1);
}
for (cur = node1->next;cur != NULL;cur = cur->next)
if (cur == node2)
return(1);
return(-1); /* assume there is no sibling list corruption */
}
#endif /* XP_FAST_NON_ELEM_COMPARISON */
/**
* xmlXPathNodeSetSort:
* @set: the node set
@ -1711,8 +2000,14 @@ xmlXPathNodeSetSort(xmlNodeSetPtr set) {
for (i = incr; i < len; i++) {
j = i - incr;
while (j >= 0) {
#ifdef XP_FAST_NON_ELEM_COMPARISON
if (xmlXPathCmpNodesExt(set->nodeTab[j],
set->nodeTab[j + incr]) == -1)
#else
if (xmlXPathCmpNodes(set->nodeTab[j],
set->nodeTab[j + incr]) == -1) {
set->nodeTab[j + incr]) == -1)
#endif
{
tmp = set->nodeTab[j];
set->nodeTab[j] = set->nodeTab[j + incr];
set->nodeTab[j + incr] = tmp;