506 lines
13 KiB
C++
506 lines
13 KiB
C++
// =====================================================================================================================
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// Copyright 2024 Medusa Slockbower
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// =====================================================================================================================
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#ifndef OPEN_CPP_UTILS_DIRECTED_TREE_H
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#define OPEN_CPP_UTILS_DIRECTED_TREE_H
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#include <vector>
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#include <deque>
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#include <algorithm>
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namespace open_cpp_utils
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{
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/**
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* \brief Class for creating a directed tree
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* \tparam T Type of the data associated with each node
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*
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* The tree is a series of child nodes in forward linked lists.
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*
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*/
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template<typename T>
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class directed_tree
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{
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// Forward Definitions =================================================================================================
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public:
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class breadth_first;
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class pre_order;
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class in_order;
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class post_order;
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class unordered;
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private:
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struct Node_;
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// Typedefs ============================================================================================================
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public:
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using data_type = T;
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using node = uint32_t;
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using node_queue = std::deque<node>;
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private:
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using hierarchy = std::vector<Node_>;
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using storage = std::vector<data_type>;
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// Constants ===========================================================================================================
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public:
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static constexpr std::integral_constant<node, 0> root{};
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// Data Structures =====================================================================================================
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private:
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struct Node_
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{
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enum flags
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{
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VALID = 0x0001
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};
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node parent, child, prev_sibling, next_sibling;
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uint32_t flags, depth;
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Node_() : parent(0), child(0), prev_sibling(0), next_sibling(0), flags(VALID), depth(0) { }
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};
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// Functions ===========================================================================================================
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public:
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// Constructors & Destructor -------------------------------------------------------------------------------------------
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/**
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* \brief Default constructor, creates tree with empty root
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*/
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directed_tree() : graph_{ Node_() }, data_{ data_type() }, freed_{ } { }
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directed_tree(data_type&& data) : graph_{ Node_() }, data_(data), freed_{} { }
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directed_tree(const data_type& data) : graph_{ Node_() }, data_(data), freed_{} { }
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~directed_tree() = default;
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// Tree Navigation -----------------------------------------------------------------------------------------------------
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/**
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* \brief Check whether a node is valid. O(1)
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* \param id Node id to reference
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* \return Whether the valid flag is true in the node
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*/
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[[nodiscard]] bool valid(node id) const { return graph_[id].flags & Node_::VALID; }
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/**
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* \brief Get the parent of a node. O(1)
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* \param id Node id to reference
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* \return Node id of the parent
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*/
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[[nodiscard]] node parent(node id) const { return graph_[id].parent; }
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/**
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* \brief Get the first child of a node. O(1)
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* \param id Node id to reference
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* \return Node id of the first child
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*/
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[[nodiscard]] node first_child(node id) const { return graph_[id].child; }
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/**
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* \brief Get the first child of a node. O(1)
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* \param id Node id to reference
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* \return Node id of the first child
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*/
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[[nodiscard]] node last_child(node id) const
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{
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node c = first_child(id);
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while(c != 0) { if(graph_[c].next_sibling == 0) break; c = graph_[c].next_sibling; }
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return c;
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}
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[[nodiscard]] int child_index(node id)
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{
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if(id == root) return -1;
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int i = 0;
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while(id != root) { id = prev_sibling(id); ++i; }
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return i;
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}
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/**
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* \brief Get the previous sibling of a node. O(1)
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* \param id Node id to reference
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* \return Node id of the next sibling in the linked list
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*/
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[[nodiscard]] node prev_sibling(node id) const { return graph_[id].prev_sibling; }
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/**
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* \brief Get the next sibling of a node. O(1)
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* \param id Node id to reference
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* \return Node id of the next sibling in the linked list
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*/
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[[nodiscard]] node next_sibling(node id) const { return graph_[id].next_sibling; }
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/**
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* \brief Get the left most child of a node. O(log(n))
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* \param id Node id to reference
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* \return Node id of the left most child
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*/
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[[nodiscard]] node left_most(node id) const
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{
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node current = id;
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while(id = first_child(current)) current = id;
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return current;
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}
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/**
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* \brief Get the depth of a node
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* \param id
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* \return
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*/
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[[nodiscard]] uint32_t depth(node id) const { return graph_[id].depth; }
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// Tree Modification ---------------------------------------------------------------------------------------------------
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/**
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* \brief Get the next id that would be used if insert() were called
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* \return Next node id
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*/
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node next_id() const
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{
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if(freed_.empty()) return static_cast<node>(graph_.size());
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return freed_.front();
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}
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/**
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* \brief Insert a node into the tree as a child of the provided node
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* \param data Value to insert
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* \param p_id Id of the parent node
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* \param last Whether to insert at the back of the array
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* \return Id of the inserted node
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*/
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node insert(const data_type& data, node p_id, int child = 0)
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{
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// If there are no freed nodes, create a new node and mark it as freed
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if(freed_.empty())
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{
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freed_.push_back(static_cast<node>(graph_.size()));
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graph_.push_back(Node_()); data_.push_back(data);
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}
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// Pop a freed node from the stack
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node id = freed_.front(); freed_.pop_front();
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node s_id = first_child(p_id);
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Node_& node = graph_[id];
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Node_& parent = graph_[p_id];
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bool back = s_id == 0 ? false : child < 0;
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while(child > 0 && s_id != root)
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{
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s_id = next_sibling(s_id); --child;
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back |= (s_id == root);
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}
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Node_& sibling = graph_[s_id];
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if(s_id == parent.child && !back) parent.child = id;
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node.next_sibling = node.prev_sibling = 0;
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node.parent = p_id;
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node.depth = parent.depth + 1;
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node.flags = Node_::VALID;
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node.child = 0;
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if(s_id == 0) return id;
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if(back)
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{
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node.next_sibling = sibling.next_sibling;
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node.prev_sibling = s_id;
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sibling.next_sibling = id;
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}
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else
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{
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node.next_sibling = s_id;
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node.prev_sibling = sibling.prev_sibling;
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sibling.prev_sibling = id;
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}
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return id;
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}
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void swap(node a, node b)
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{
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Node_& A = graph_[a];
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Node_& B = graph_[b];
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std::swap(A, B);
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if(graph_[B.parent].child == a) graph_[B.parent].child = b;
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if(graph_[A.parent].child == b) graph_[A.parent].child = a;
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}
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/**
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* \brief Erase a node in the tree. O(n)
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* \param id Id of the node to erase
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*/
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void erase(node id)
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{
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if(id == root) return;
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// Mark node as invalid and push it to the freed list
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Node_& erased = graph_[id];
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erased.flags &= ~Node_::VALID;
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freed_.push_back(id);
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data_[id].~T();
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// Update the parent's child
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graph_[erased.parent].child = erased.next_sibling;
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// Update siblings
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if(erased.next_sibling) graph_[erased.next_sibling].prev_sibling = erased.prev_sibling;
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if(erased.prev_sibling) graph_[erased.prev_sibling].next_sibling = erased.next_sibling;
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// Erase children - essentially breadth first propagation down the tree
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node_queue stack{ erased.child };
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while(stack.empty() == false)
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{
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node next = stack.front(); stack.pop_front();
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Node_& child = graph_[next];
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child.flags &= ~Node_::VALID;
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freed_.push_back(next);
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data_[next].~T();
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if(child.next_sibling) stack.push_front(child.next_sibling);
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if(child.child) stack.push_front(child.child);
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}
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}
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// Tree Access ---------------------------------------------------------------------------------------------------------
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/**
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* \brief Getter for data associated with a node
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* \param id Id of the node to access
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* \return Reference to the node's data
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*/
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data_type& operator[](node id) { return data_[id]; }
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/**
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* \brief Constant getter for data associated with a node
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* \param node Id of the node to access
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* \return Reference to the node's data
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*/
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[[nodiscard]] const data_type& operator[](node id) const { return data_[id]; }
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// Visitor Pattern -----------------------------------------------------------------------------------------------------
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/**
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* \brief Traverser-Visitor pattern for accessing the tree
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* \tparam V Visitor type.
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* \tparam O Order type. Defaults to Pre-Order Traversal.
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* \param visitor
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*/
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template<typename O = pre_order, typename V>
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void traverse(V& visitor)
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{
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traverser<V, O> traverser(*this, visitor);
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traverser();
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}
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// Variables =======================================================================================================
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private:
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hierarchy graph_;
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storage data_;
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node_queue freed_;
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// Navigation ======================================================================================================
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public:
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class unordered
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{
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public:
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unordered(directed_tree& graph) : graph_(graph), current_(root) { }
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node operator()(node id)
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{
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while(!graph_.valid(current_) || current_ == root)
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{
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++current_;
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}
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id = current_;
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current_ ++;
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return id == graph_.graph_.size() ? 0 : id;
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}
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private:
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directed_tree& graph_;
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node current_;
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};
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/**
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* \brief Breadth first traversal
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*/
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class breadth_first
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{
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public:
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breadth_first(directed_tree& graph) : graph_(graph), visit_queue_(0) { }
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node operator()(node id)
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{
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id = visit_queue_.back(); visit_queue_.pop_back();
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Node_& current = graph_.graph_[id];
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if(current.next_sibling) visit_queue_.push_back(current.next_sibling);
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if(current.child) visit_queue_.push_front(current.child);
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if(visit_queue_.empty()) return 0;
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return id;
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}
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private:
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directed_tree& graph_;
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node_queue visit_queue_;
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};
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/**
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* \brief Pre-order traversal
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*/
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class pre_order
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{
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public:
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pre_order(directed_tree& graph) : graph_(graph) { }
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node operator()(node id)
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{
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Node_& current = graph_.graph_[id];
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if(current.next_sibling) visit_queue_.push_front(current.next_sibling);
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if(current.child) visit_queue_.push_front(current.child);
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if(visit_queue_.empty()) return 0;
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node next = visit_queue_.front(); visit_queue_.pop_front();
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return next;
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}
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private:
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directed_tree& graph_;
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node_queue visit_queue_;
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};
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/**
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* \brief In-order traversal
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*/
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class in_order
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{
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public:
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in_order(directed_tree& graph) : graph_(graph) { }
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node operator()(node id)
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{
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if(id == 0) visit_queue_.push_back(graph_.left_most(id));
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id = visit_queue_.front(); visit_queue_.pop_front();
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Node_& current = graph_.graph_[id];
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if(current.Sibling)
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{
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if(graph_.next_sibling(current.Sibling)) visit_queue_.push_back(current.parent);
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visit_queue_.push_back(graph_.left_most(current.Sibling));
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}
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return id;
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}
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private:
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directed_tree& graph_;
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node_queue visit_queue_;
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};
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/**
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* \brief Post-order traversal
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*/
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class post_order
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{
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public:
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post_order(directed_tree& graph) : graph_(graph) { }
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node operator()(node id)
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{
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if(visit_queue_.empty()) visit_queue_.push_back(graph_.left_most(id));
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id = visit_queue_.front(); visit_queue_.pop_front();
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if(id == 0) return id;
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Node_& current = graph_.graph_[id];
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visit_queue_.push_back(current.Sibling ? graph_.left_most(current.Sibling) : graph_.parent(id));
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return id;
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}
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private:
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directed_tree& graph_;
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node_queue visit_queue_;
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};
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/**
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* \brief Visitor pattern for traversing the tree
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*/
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template<typename V, typename O>
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class traverser
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{
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public:
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using visitor_type = V;
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using order_type = O;
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traverser(directed_tree& graph, visitor_type& visitor) : graph_(graph), visitor_(visitor), order_(graph) { }
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void operator()()
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{
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node id = 0;
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while(id = order_(id))
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{
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if(visitor_(graph_[id], id)) break;
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}
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}
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private:
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directed_tree& graph_;
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visitor_type& visitor_;
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order_type order_;
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};
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};
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}
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#endif // OPEN_CPP_UTILS_DIRECTED_TREE_H
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