1 /* Copyright (c) 2008-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/mc/explo/odpor/WakeupTreeIterator.hpp"
7 #include "src/mc/explo/odpor/WakeupTree.hpp"
8 #include "xbt/asserts.h"
10 namespace simgrid::mc::odpor {
12 WakeupTreeIterator::WakeupTreeIterator(const WakeupTree& tree) : root_list{tree.root_}
14 post_order_iteration.push(root_list.begin());
15 push_until_left_most_found();
18 void WakeupTreeIterator::push_until_left_most_found()
20 // INVARIANT: Since we are traversing over a tree,
21 // there are no cycles. This means that at least
22 // one node in the tree won't have any children,
23 // so the loop will eventually terminate
24 WakeupTreeNode* cur_top_node = *post_order_iteration.top();
25 while (not cur_top_node->is_leaf()) {
26 // INVARIANT: Since we push children in
27 // reverse order (right-most to left-most),
28 // we ensure that we'll always process left-most
30 auto& children = cur_top_node->children_;
31 for (auto iter = children.rbegin(); iter != children.rend(); ++iter) {
32 // iter.base() points one element past where we seek; that is,
33 // we want the value one position forward
34 post_order_iteration.push(std::prev(iter.base()));
36 has_added_children.push(cur_top_node);
37 cur_top_node = *post_order_iteration.top();
41 void WakeupTreeIterator::increment()
43 // If there are no nodes in the stack, we've
44 // completed the traversal: there's nothing left
46 if (post_order_iteration.empty()) {
50 post_order_iteration.pop();
52 // If there are now no longer any nodes left,
53 // we know that `prev_top` must be the original
54 // root; that is, we were *just* pointing at the
55 // original root, so we're done
56 if (post_order_iteration.empty()) {
60 xbt_assert(not has_added_children.empty(), "Invariant violated: There are more "
61 "nodes in the iteration that we must search "
62 "yet nobody has claimed to have added these nodes. "
63 "This implies that the algorithm is not iterating over "
64 "the wakeup tree is not following the post-fix order "
67 // Otherwise, look at what is the new, current top node.
68 // We're traversing the tree in
70 // If we've already added our children, we want
71 // to be sure not to add them again; but we ALSO
72 // want to be sure that we now start checking against
73 // the the node that's next in line as "finished"
75 // INVARIANT: Since we're searching in post-fix order,
76 // it always suffices to compare the current node
77 // with the top of the stack of nodes which have added their
79 if (*post_order_iteration.top() == has_added_children.top()) {
80 has_added_children.pop();
82 push_until_left_most_found();
86 } // namespace simgrid::mc::odpor