+/* Copyright (c) 2008-2023. The SimGrid Team. All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+#include "src/mc/explo/odpor/WakeupTree.hpp"
+#include "src/mc/explo/odpor/Execution.hpp"
+#include "xbt/asserts.h"
+
+#include <algorithm>
+#include <exception>
+#include <queue>
+
+namespace simgrid::mc::odpor {
+
+WakeupTree::WakeupTree() : WakeupTree(std::unique_ptr<WakeupTreeNode>(new WakeupTreeNode({}))) {}
+WakeupTree::WakeupTree(std::unique_ptr<WakeupTreeNode> root) : root_(root.get())
+{
+ this->insert_node(std::move(root));
+}
+
+WakeupTree WakeupTree::new_subtree_rooted_at(WakeupTreeNode* root)
+{
+ if (not root->is_single_process()) {
+ throw std::invalid_argument("Selecting subtrees is only defined for single-process nodes");
+ }
+
+ const aid_t p = (*(root->get_sequence().begin()))->aid_;
+
+ // Perform a BFS search to perform a deep copy of the portion
+ // of the tree underneath and including `root`. Note that `root`
+ // is contained within the context of a *different* wakeup tree;
+ // hence, we have to be careful to update each node's children
+ // appropriately
+ auto subtree = WakeupTree();
+ WakeupTreeNode* root_equivalent = subtree.make_node(root->get_sequence());
+
+ std::list<std::pair<WakeupTreeNode*, WakeupTreeNode*>> frontier{std::make_pair(root, root_equivalent)};
+ while (not frontier.empty()) {
+ auto [node_in_other_tree, subtree_equivalent] = frontier.front();
+ frontier.pop_front();
+
+ // For each child of the node corresponding to that in `subtree`,
+ // make clones of each of its children and add them to `frontier`
+ // to that their children are added, and so on. Note that the subtree
+ // **explicitly** removes the first process from each child
+ for (WakeupTreeNode* child_in_other_tree : node_in_other_tree->get_ordered_children()) {
+ auto p_w = child_in_other_tree->get_sequence();
+ const auto p_again = p_w.front()->aid_;
+
+ // INVARIANT: A nodes of a wakeup tree form a prefix-closed set;
+ // this means that any child node `c` of a node `n` must contain
+ // `n.get_sequence()` as a prefix of `c.get_sequence()`
+ xbt_assert(p_again == p,
+ "Invariant Violation: The wakeup tree from which a subtree with actor "
+ "`%ld` is being taken is not prefix free! The child node starts with "
+ "`%ld` while the parent is `%ld`! This indicates that there "
+ "is a bug in the insertion logic for the wakeup tree",
+ p, p_again, p);
+ p_w.pop_front();
+
+ WakeupTreeNode* child_equivalent = subtree.make_node(p_w);
+ subtree_equivalent->add_child(child_equivalent);
+ frontier.push_back(std::make_pair(child_in_other_tree, child_equivalent));
+ }
+ }
+ return subtree;
+}
+
+WakeupTreeNode* WakeupTree::make_node(const PartialExecution& u)
+{
+ auto node = std::unique_ptr<WakeupTreeNode>(new WakeupTreeNode(u));
+ auto* node_handle = node.get();
+ this->nodes_[node_handle] = std::move(node);
+ return node_handle;
+}
+
+void WakeupTree::insert_node(std::unique_ptr<WakeupTreeNode> node)
+{
+ auto* node_handle = node.get();
+ this->nodes_[node_handle] = std::move(node);
+}
+
+void WakeupTree::insert(const Execution& E, const PartialExecution& w)
+{
+ // See section 6.2 of Abdulla. et al.'s 2017 ODPOR paper for details
+
+ // Find the first node `v` in the tree such that
+ // `v ~_[E] w` and `v` is not a leaf node
+ for (WakeupTreeNode* node : *this) {
+ if (const auto shortest_sequence = E.get_shortest_odpor_sq_subset_insertion(node->get_sequence(), w);
+ shortest_sequence.has_value()) {
+ // Insert the sequence as a child of `node`, but only
+ // if the node is not already a leaf
+ if (not node->is_leaf()) {
+ WakeupTreeNode* new_node = this->make_node(shortest_sequence.value());
+ node->add_child(new_node);
+ }
+ // Since we're following the post-order traversal of the tree,
+ // the first such node we see is the smallest w.r.t "<"
+ return;
+ }
+ }
+}
+
+} // namespace simgrid::mc::odpor
\ No newline at end of file
