Function node_copy_tree

lib/pugixml/src/pugixml.cpp:4426–4478

	}

	PUGI__FN void node_copy_tree(xml_node_struct* dn, xml_node_struct* sn)
	{
		xml_allocator& alloc = get_allocator(dn);
		xml_allocator* shared_alloc = (&alloc == &get_allocator(sn)) ? &alloc : 0;

		node_copy_contents(dn, sn, shared_alloc);

		xml_node_struct* dit = dn;
		xml_node_struct* sit = sn->first_child;

		while (sit && sit != sn)
		{
			// loop invariant: dit is inside the subtree rooted at dn
			assert(dit);

			// when a tree is copied into one of the descendants, we need to skip that subtree to avoid an infinite loop
			if (sit != dn)
			{
				xml_node_struct* copy = append_new_node(dit, alloc, PUGI__NODETYPE(sit));

				if (copy)
				{
					node_copy_contents(copy, sit, shared_alloc);

					if (sit->first_child)
					{
						dit = copy;
						sit = sit->first_child;
						continue;
					}
				}
			}

			// continue to the next node
			do
			{
				if (sit->next_sibling)
				{
					sit = sit->next_sibling;
					break;
				}

				sit = sit->parent;
				dit = dit->parent;

				// loop invariant: dit is inside the subtree rooted at dn while sit is inside sn
				assert(sit == sn || dit);
			}
			while (sit != sn);
		}

		assert(!sit || dit == dn->parent);
	}

	PUGI__FN void node_copy_attribute(xml_attribute_struct* da, xml_attribute_struct* sa)
	{