moved to std::reference_wrapper>

Author: Владимир Чиж

srcbpatch/trie.cpp

@@ -2,32 +2,35 @@
 
 void Trie::insert(std::string_view key, std::string_view value)
 {
-    TrieNode* node = &root;
+    std::reference_wrapper<TrieNode> node = root;
     for (char character : key)
     {
-        auto [it, inserted] = node->children.try_emplace(character, std::make_unique<TrieNode>());
-        node = it->second.get();
+        if (!node.get().children.contains(character)) [[unlikely]] {
+            nodes.emplace_back();
+            node.get().children.emplace(character, nodes.back());
+        }
+        node = node.get().children.at(character);
     }
-    node->target = value;
+    node.get().target = value;
 }
 
-[[nodiscard]] std::pair<std::string_view, bool> Trie::searchFullMatch(const std::span<const char>& cachedData)
+[[nodiscard]] std::pair<std::string_view, bool> Trie::searchFullMatch(const std::span<const char>& cachedData) const
 {
-    TrieNode* node = &root;
+    std::reference_wrapper<const TrieNode> node = root;
     for (char c: cachedData)
     {
-        auto res = node->children.find(c);
-        if (res == node->children.end())
+        auto res = node.get().children.find(c);
+        if (res == node.get().children.end())
         {
             return std::make_pair(std::string_view(), false);
         }
         node = res->second.get();
     }
 
     // full match
-    if (node->target)
+    if (node.get().target)
     {
-        return std::make_pair(node->target.value(), true);
+        return std::make_pair(node.get().target.value(), true);
     }
 
     return std::make_pair(std::string_view(), false);

srcbpatch/trie.h

@@ -2,14 +2,18 @@
 
 #include <string_view>
 
+/// @brief A node of prefix Trie, each node contains current target (if exist) and child nodes in children.
+/// And doesn't contain a char of current node
 class TrieNode {
     public:
-        std::unordered_map<char, std::unique_ptr<TrieNode>> children;
+        /// a list of child nodes of current node.
+        std::unordered_map<char, std::reference_wrapper<TrieNode>> children;
+        /// target of curretn node (if there are node target at this node in our lexemmePairs --> target is std::nullopt)
         std::optional<std::string_view> target;
-    };
+};
 
 /// @brief Frefix tree class to speed up UniformLexemeReplacer::DoReplace
-class Trie {
+class Trie final{
 public:
     /// <summary>
     ///  Adds a new key-value pair in prefix tree
@@ -23,8 +27,11 @@ class Trie {
     /// </summary>
     /// <param name="cachedData"> key to find </param>
     /// <returns>string_view: target, bool: FullMatch</returns>
-    [[nodiscard]] std::pair<std::string_view, bool> searchFullMatch(const std::span<const char>& cachedData);
+    [[nodiscard]] std::pair<std::string_view, bool> searchFullMatch(const std::span<const char>& cachedData) const;
 
 private:
+    /// a root node, doesn't contains target value
     TrieNode root;
+    /// holds all the nodes of Trie. While default Trie uses pointers, we are going to user reference_wrapper to this deque elements
+    std::deque<TrieNode> nodes;
 };