void Path::moveLeft(unsigned Level) {
assert(Level != 0 && "Cannot move the root node");
// Go up the tree until we can go left.
unsigned l = 0;
if (valid()) {
l = Level - 1;
while (path[l].offset == 0) {
assert(l != 0 && "Cannot move beyond begin()");
--l;
}
} else if (height() < Level)
// end() may have created a height=0 path.
path.resize(Level + 1, Entry(nullptr, 0, 0));
// NR is the subtree containing our left sibling.
--path[l].offset;
NodeRef NR = subtree(l);
// Get the rightmost node in the subtree.
for (++l; l != Level; ++l) {
path[l] = Entry(NR, NR.size() - 1);
NR = NR.subtree(NR.size() - 1);
}
path[l] = Entry(NR, NR.size() - 1);
}
NodeRef Path::getLeftSibling(unsigned Level) const {
// The root has no siblings.
if (Level == 0)
return NodeRef();
// Go up the tree until we can go left.
unsigned l = Level - 1;
while (l && path[l].offset == 0)
--l;
// We can't go left.
if (path[l].offset == 0)
return NodeRef();
// NR is the subtree containing our left sibling.
NodeRef NR = path[l].subtree(path[l].offset - 1);
// Keep right all the way down.
for (++l; l != Level; ++l)
NR = NR.subtree(NR.size() - 1);
return NR;
}
