// Compare two positions, taking into account the possibility that one or both
// could be inside a shadow tree. Only works for non-null values.
int comparePositions(const Position& a, const Position& b)
{
TreeScope* commonScope = commonTreeScope(a.containerNode(), b.containerNode());
ASSERT(commonScope);
if (!commonScope)
return 0;
Node* nodeA = commonScope->ancestorInThisScope(a.containerNode());
ASSERT(nodeA);
bool hasDescendentA = nodeA != a.containerNode();
int offsetA = hasDescendentA ? 0 : a.computeOffsetInContainerNode();
Node* nodeB = commonScope->ancestorInThisScope(b.containerNode());
ASSERT(nodeB);
bool hasDescendentB = nodeB != b.containerNode();
int offsetB = hasDescendentB ? 0 : b.computeOffsetInContainerNode();
int bias = 0;
if (nodeA == nodeB) {
if (hasDescendentA)
bias = -1;
else if (hasDescendentB)
bias = 1;
}
int result = Range::compareBoundaryPoints(nodeA, offsetA, nodeB, offsetB, IGNORE_EXCEPTION);
return result ? result : bias;
}
static Position adjustPositionForStart(const Position& currentPosition, Node* endContainerNode)
{
TreeScope* treeScope = endContainerNode->treeScope();
ASSERT(currentPosition.containerNode()->treeScope() != treeScope);
if (Node* ancestor = treeScope->ancestorInThisScope(currentPosition.containerNode())) {
if (ancestor->contains(endContainerNode))
return positionBeforeNode(ancestor);
return positionAfterNode(ancestor);
}
if (Node* firstChild = treeScope->rootNode()->firstChild())
return positionBeforeNode(firstChild);
return Position();
}