From 9a066ce16f666fe20a5f374c593e3e14b66b6da1 Mon Sep 17 00:00:00 2001
From: Pagwin <pgp2024@pagwin.xyz>
Date: Sat, 23 Nov 2024 19:25:26 -0500
Subject: [PATCH] most of red-black insert done debugging it atm

---
 Map.hpp     | 146 ++++++++--
 Map.hpp.old | 768 ----------------------------------------------------
 2 files changed, 123 insertions(+), 791 deletions(-)
 delete mode 100644 Map.hpp.old

diff --git a/Map.hpp b/Map.hpp
index 78cd5a8..6f9a943 100644
--- a/Map.hpp
+++ b/Map.hpp
@@ -35,23 +35,32 @@ template <typename Key_T, typename Mapped_T> class Map {
     Color color;
     Node *prev;
     Node *next;
-    Node(internal_ValueType val)
+    Map *map;
+    Node(internal_ValueType val, Map *map)
         : parent{nullptr}, val{val}, left{}, right{}, color{Color::Red},
-          prev{nullptr}, next{nullptr} {}
+          prev{nullptr}, next{nullptr}, map{map} {}
     Node(const Node &rhs)
         : parent{nullptr}, val{rhs.val},
           left{std::make_unique<Node>(*rhs.left)},
           right{std::make_unique<Node>(*rhs.right)}, color{rhs.color},
-          prev{nullptr}, next{nullptr} {
-      this->left->parent = this;
-      this->right->parent = this;
+          prev{nullptr}, next{nullptr}, map{rhs.map} {
+      if (this->left) {
+        this->left->parent = this;
+      }
+      if (this->right) {
+        this->right->parent = this;
+      }
     }
     Node(Node &&rhs)
         : parent{nullptr}, val{std::move(rhs.val)}, left{std::move(rhs.left)},
           right{std::move(rhs.right)}, color{rhs.color}, prev{nullptr},
-          next{nullptr} {
-      this->left->parent = this;
-      this->right->parent = this;
+          next{nullptr}, map{rhs.map} {
+      if (this->left) {
+        this->left->parent = this;
+      }
+      if (this->right) {
+        this->right->parent = this;
+      }
     }
     Node &operator=(const Node &rhs) {
       // retain parent as is, common case is the copy or move is happening due
@@ -61,10 +70,16 @@ template <typename Key_T, typename Mapped_T> class Map {
       this->left = std::make_unique<Node>(*rhs.left);
       this->right = std::make_unique<Node>(*rhs.right);
 
-      this->left->parent = this;
-      this->right->parent = this;
-      this->left->restore_ordering();
-      this->right->restore_ordering();
+      if (this->left) {
+        this->left->parent = this;
+        this->left->restore_ordering();
+      }
+      if (this->right) {
+        this->right->parent = this;
+        this->right->restore_ordering();
+      }
+
+      this->map = rhs.map;
       return *this;
     }
     Node &operator=(Node &&rhs) {
@@ -74,10 +89,15 @@ template <typename Key_T, typename Mapped_T> class Map {
       this->val = rhs.val;
       this->left = std::move(rhs.left);
       this->right = std::move(rhs.right);
-      this->left->parent = this;
-      this->right->parent = this;
-      this->left->restore_ordering();
-      this->right->restore_ordering();
+      if (this->left) {
+        this->left->parent = this;
+        this->left->restore_ordering();
+      }
+      if (this->right) {
+        this->right->parent = this;
+        this->right->restore_ordering();
+      }
+      this->map = rhs.map;
       return *this;
     }
     Node *child(Direction dir) {
@@ -150,8 +170,12 @@ template <typename Key_T, typename Mapped_T> class Map {
     void restore_ordering() {
       this->prev = this->calc_pred();
       this->next = this->calc_succ();
-      this->prev->next = this;
-      this->next->prev = this;
+      if (this->prev) {
+        this->prev->next = this;
+      }
+      if (this->next) {
+        this->next->prev = this;
+      }
     }
     Node *calc_pred() {
       if (this->left) {
@@ -216,7 +240,67 @@ template <typename Key_T, typename Mapped_T> class Map {
       this->parent->child(!dir)->set_child(dir, std::move(self));
     }
     // TODO:
-    void restore_red_black_insert() {}
+    // Referencing
+    // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Notes_to_the_insert_diagrams
+    void restore_red_black_insert(Direction dir) {
+      Node *self = this;
+
+      // infinite loop for case 2's sake, if tail recursion optimization was
+      // guaranteed I'd use tail recursion
+      while (true) {
+        Node *parent = self->parent;
+        // we're root, no-op (case 3)
+        if (!parent) {
+          return;
+        }
+
+        // if this is violated it's a bug
+        assert(parent->child(dir) == self);
+
+        // parent is black so no violation no-op (case 1)
+        if (parent->color == Color::Black) {
+          return;
+        }
+
+        Node *grandparent = parent->parent;
+
+        // parent is root (case 4)
+        if (!grandparent) {
+          parent->color = Color::Black;
+          return;
+        }
+
+        // table showing transforms on wikipedia doesn't have this so if it
+        // happens it's probably a bug
+        assert(grandparent->color == Color::Black);
+
+        Node *uncle = grandparent->child(!grandparent->which_child(parent));
+        if (uncle == nullptr || uncle->color == Color::Black) {
+          if (parent->which_child(self) != grandparent->which_child(parent)) {
+            // we're an inner child
+            // case 5
+            parent->rotate(dir);
+            self = parent;
+            parent = self->parent;
+          }
+          // case 6
+          if (grandparent->parent == nullptr) {
+            map->rotate_root(!dir);
+          } else {
+            grandparent->rotate(!dir);
+          }
+          parent->color = Color::Black;
+          grandparent->color = Color::Red;
+          return;
+        }
+
+        // case 2 (by process of elimination)
+        parent->color = Color::Black;
+        uncle->color = Color::Black;
+        grandparent->color = Color::Red;
+        self = grandparent;
+      }
+    }
     // TODO:
     void restore_red_black_erase() {}
   };
@@ -228,6 +312,7 @@ template <typename Key_T, typename Mapped_T> class Map {
   Node *max;
 
 public:
+  friend Node;
   // public type definitions
   class Iterator {
     Node *underlying;
@@ -255,6 +340,21 @@ public:
   std::size_t size() { return this->_size; }
 
 private:
+  // private helpers
+  void rotate_root(Direction dir) {
+    assert(root.has_value());
+
+    std::unique_ptr<Node> new_root = root.value().uchild(!dir);
+    // can't make null the new root
+    assert(new_root);
+
+    std::unique_ptr<Node> old_root =
+        std::make_unique<Node>(std::move(root.value()));
+
+    root.value() = std::move(*new_root);
+
+    root.value().set_child(dir, std::move(old_root));
+  }
   template <bool trace = false>
   std::pair<Node *, Direction> locate(const Key_T &key) {
     Node *ret_parent;
@@ -349,21 +449,21 @@ public:
       if (this->root.has_value()) {
         return std::make_pair(Iterator{&root.value()}, false);
       } else {
-        this->root = Node{val};
+        this->root = Node{val, this};
         return std::make_pair(Iterator{&root.value()}, true);
       }
     }
 
     // non-root node
-    if (!parent->child(dir)) {
+    if (parent->child(dir)) {
       // node already present
       return std::make_pair(Iterator{parent->child(dir)}, false);
     }
 
     // need to insert non-root node
     Node *new_node =
-        parent->set_child(dir, std::make_unique<Node>(Node{val})).get();
-    new_node->restore_red_black_insert();
+        parent->set_child(dir, std::make_unique<Node>(Node{val, this})).get();
+    new_node->restore_red_black_insert(dir);
     new_node->restore_ordering();
     return std::make_pair(Iterator{new_node}, true);
   }
diff --git a/Map.hpp.old b/Map.hpp.old
deleted file mode 100644
index 1f87b01..0000000
--- a/Map.hpp.old
+++ /dev/null
@@ -1,768 +0,0 @@
-#include <algorithm>
-#include <cassert>
-#include <cstddef>
-#include <initializer_list>
-#include <optional>
-#include <stdexcept>
-#include <utility>
-#include <vector>
-
-// everything is super interconnected so some forward declarations are needed at
-// various points
-namespace cs440 {
-
-template <typename Key_T, typename Mapped_T> class Map;
-
-namespace {
-enum class Color { Red, Black };
-enum class Direction { Left, Right };
-Direction operator!(Direction dir) {
-  switch (dir) {
-  case Direction::Left:
-    return Direction::Right;
-  case Direction::Right:
-    return Direction::Left;
-  default:
-    // unreachable the only directions are left and right
-    assert(false);
-  }
-}
-template <typename Key_T, typename Mapped_T> struct BookKeeping {
-  using Self = BookKeeping<Key_T, Mapped_T>;
-  using ValueType = std::pair<Key_T, Mapped_T>;
-  using Ptr = typename std::vector<Self>::iterator;
-  friend class Map<Key_T, Mapped_T>;
-  Map<Key_T, Mapped_T> &container;
-  ValueType value;
-  // Ptr self;
-  Color color;
-  // nullptr indicates empty
-  std::optional<std::size_t> parent;
-  std::optional<std::size_t> left;
-  std::optional<std::size_t> right;
-  std::optional<std::size_t> prev;
-  std::optional<std::size_t> next;
-  BookKeeping(Map<Key_T, Mapped_T> &container) : container{container} {}
-  BookKeeping(BookKeeping const &rhs)
-      : container{rhs.container}, value{rhs.value}, // self{rhs.self},
-        color{rhs.color}, parent{rhs.parent}, left{rhs.left}, right{rhs.right},
-        prev{rhs.prev}, next{rhs.next} {}
-  // if pointing to different containers throws
-  BookKeeping &operator=(BookKeeping const &rhs) {
-    if (&this->container != &rhs.container) {
-      throw std::invalid_argument{"can only reassign Bookkeeping "
-                                  "values/iterators from the same map object"};
-    }
-    this->value = rhs.value;
-    // this->self = rhs.self;
-    this->color = rhs.color;
-    this->parent = rhs.parent;
-    this->left = rhs.left;
-    this->right = rhs.right;
-    this->prev = rhs.prev;
-    this->next = rhs.next;
-    return *this;
-  }
-  // reference to a pointer because the alternatives were worse
-  inline Self *child(Direction dir) {
-    auto ret = c_select(dir);
-    return ret.has_value() ? &container.nodes[ret.value()] : nullptr;
-  }
-  inline std::optional<std::size_t> c_select(Direction dir) {
-    switch (dir) {
-    case Direction::Left:
-      return left;
-      break;
-    case Direction::Right:
-      return right;
-      break;
-    default:
-      assert(false);
-    }
-  }
-  inline void c_trans(Direction dir, Self *v) {
-    switch (dir) {
-    case Direction::Left:
-      this->set_l(v);
-      break;
-    case Direction::Right:
-      this->set_r(v);
-      break;
-    default:
-      assert(false);
-    }
-  }
-
-  inline Self *n() {
-    return next.has_value() ? &container.nodes[next.value()] : nullptr;
-  }
-  inline void set_n(Self *ptr) {
-    this->next = ptr == nullptr
-                     ? std::nullopt
-                     : std::optional<std::size_t>{static_cast<std::size_t>(
-                           ptr - &this->container.nodes[0])};
-  }
-  inline Self *p() {
-    return prev.has_value() ? &container.nodes[prev.value()] : nullptr;
-  }
-  inline void set_p(Self *ptr) {
-    this->prev = ptr == nullptr
-                     ? std::nullopt
-                     : std::optional<std::size_t>{static_cast<std::size_t>(
-                           ptr - &this->container.nodes[0])};
-  }
-  inline Self *r() {
-    return right.has_value() ? &container.nodes[right.value()] : nullptr;
-  }
-  inline void set_r(Self *ptr) {
-    this->right = ptr == nullptr
-                      ? std::nullopt
-                      : std::optional<std::size_t>{static_cast<std::size_t>(
-                            ptr - &this->container.nodes[0])};
-  }
-  inline Self *l() {
-    return left.has_value() ? &container.nodes[left.value()] : nullptr;
-  }
-  inline void set_l(Self *ptr) {
-    this->left = ptr == nullptr
-                     ? std::nullopt
-                     : std::optional<std::size_t>{static_cast<std::size_t>(
-                           ptr - &this->container.nodes[0])};
-  }
-  inline Self *par() {
-    return parent.has_value() ? &container.nodes[parent.value()] : nullptr;
-  }
-  inline void set_par(Self *ptr) {
-    this->parent = ptr == nullptr
-                       ? std::nullopt
-                       : std::optional<std::size_t>{static_cast<std::size_t>(
-                             ptr - &this->container.nodes[0])};
-  }
-  // this is root/P for this method
-  // copying from wikipedia RotateDirRoot with translation into my own idioms
-  // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Operations
-  inline void rotate(Direction dir) {
-    // wikipedia version uses alphabet soup, might fix later
-    Self *P = this;
-    auto &T = container;
-    Self *G = P->par();
-    Self *S = P->child(!dir);
-    Self *C;
-
-    // this tidbit is wrong and wikipedia is wrong to have this assert it seems
-    // this method shouldn't be called in cases where this assert will trip
-    // assert(S != nullptr);
-
-    C = S->child(dir);
-    P->c_trans(!dir, C);
-
-    if (C != nullptr) {
-      C->set_par(P);
-    }
-    S->c_trans(dir, P);
-    P->set_par(S);
-    S->set_par(G);
-    if (G != nullptr) {
-      if (P == G->r()) {
-        G->set_r(S);
-      } else {
-        G->set_l(S);
-      }
-    } else {
-      T.root = S - &T.nodes[0];
-    }
-  }
-};
-} // namespace
-// https://en.wikipedia.org/wiki/Red%E2%80%93black_tree
-template <typename Key_T, typename Mapped_T> class Map {
-private:
-  using ValueType = std::pair<Key_T, Mapped_T>;
-  using Node = BookKeeping<Key_T, Mapped_T>;
-  using Map_T = Map<Key_T, Mapped_T>;
-
-public:
-  class Iterator;
-  class ConstIterator;
-  class ReverseIterator;
-
-  friend class Iterator;
-  friend class ConstIterator;
-  friend class ReverseIterator;
-  friend Node;
-  class Iterator {
-    friend Map_T;
-    friend Node;
-
-  private:
-    using Ref_T = std::optional<std::size_t>;
-    Map<Key_T, Mapped_T> &parent;
-    Ref_T ref;
-    Ref_T escape;
-    Iterator(Map<Key_T, Mapped_T> &parent, Ref_T ref,
-             Ref_T escape = std::nullopt)
-        : parent{parent}, ref{ref}, escape{escape} {}
-
-  public:
-    Iterator() = delete;
-    Iterator &operator++() {
-      if (ref == std::nullopt) {
-        ref = escape;
-        return *this;
-      }
-      if (parent.nodes[ref.value()].next == std::nullopt) {
-        escape = ref;
-      }
-      ref = parent.nodes[ref.value()].next;
-      return *this;
-    }
-    Iterator operator++(int) {
-      Iterator tmp = *this;
-      ++(*this);
-      return tmp;
-    }
-    Iterator &operator--() {
-      if (ref == std::nullopt) {
-        ref = escape;
-        return *this;
-      }
-      if (parent.nodes[ref.value()].prev == std::nullopt) {
-        escape = ref;
-      }
-      ref = parent.nodes[ref.value()].prev;
-      return *this;
-    }
-    Iterator operator--(int) {
-      Iterator tmp = *this;
-      --(*this);
-      return tmp;
-    }
-    ValueType &operator*() const {
-      return this->parent.nodes[this->ref.value()].value;
-    }
-    ValueType *operator->() const { return &this->operator*(); }
-    friend bool operator==(Iterator const &lhs, Iterator const &rhs) {
-      return lhs.ref == rhs.ref;
-    }
-    friend bool operator!=(Iterator const &lhs, Iterator const &rhs) {
-      return lhs.ref != rhs.ref;
-    }
-    friend bool operator==(ConstIterator const &lhs, Iterator const &rhs) {
-      return lhs.store_iter.ref == rhs.ref;
-    }
-    friend bool operator!=(ConstIterator const &lhs, Iterator const &rhs) {
-      return lhs.store_iter.ref != rhs.ref;
-    }
-    friend bool operator==(Iterator const &lhs, ConstIterator const &rhs) {
-      return lhs.ref == rhs.store_iter.ref;
-    }
-    friend bool operator!=(Iterator const &lhs, ConstIterator const &rhs) {
-      return lhs.ref != rhs.store_iter.ref;
-    }
-  };
-  class ConstIterator {
-  public:
-    friend class Map<Key_T, Mapped_T>;
-    friend class Iterator;
-    using underlying = Iterator;
-
-  private:
-    underlying store_iter;
-    ConstIterator(underlying iter) : store_iter{iter} {}
-
-  public:
-    ConstIterator() = delete;
-    friend bool operator==(ConstIterator const &lhs, ConstIterator const &rhs) {
-      return lhs.store_iter == rhs.store_iter;
-    }
-    ConstIterator &operator++() {
-      ++this->store_iter;
-      return *this;
-    }
-    ConstIterator operator++(int) {
-      ConstIterator tmp = *this;
-      this->store_iter++;
-      return tmp;
-    }
-    ConstIterator &operator--() {
-      --this->store_iter;
-      return *this;
-    }
-    ConstIterator operator--(int) {
-      ConstIterator tmp = *this;
-      this->store_iter--;
-      return tmp;
-    }
-    const ValueType &operator*() const { return *this->store_iter; }
-    const ValueType *operator->() const {
-      return this->store_iter.operator->();
-    }
-    friend bool operator!=(ConstIterator const &lhs, ConstIterator const &rhs) {
-      return lhs.store_iter != rhs.store_iter;
-    }
-  };
-  class ReverseIterator {
-  public:
-    friend class Map<Key_T, Mapped_T>;
-    friend class Iterator;
-    using underlying = Iterator;
-
-  private:
-    underlying store_iter;
-
-  public:
-    ReverseIterator() = delete;
-    ReverseIterator(underlying store_iter) : store_iter{store_iter} {}
-    ReverseIterator &operator++() {
-      --store_iter;
-      return *this;
-    }
-    ReverseIterator operator++(int) {
-      ReverseIterator ret = *this;
-      ++(*this);
-      return ret;
-    }
-    ReverseIterator &operator--() {
-      ++store_iter;
-      return *this;
-    }
-    ReverseIterator operator--(int) {
-      ReverseIterator ret = *this;
-      --(*this);
-      return ret;
-    }
-    ValueType &operator*() const { return this->store_iter.ref->value; }
-    ValueType *operator->() const { return &this->store_iter.ref->value; }
-    friend bool operator==(ReverseIterator const &lhs,
-                           ReverseIterator const &rhs) {
-      return lhs.store_iter == rhs.store_iter;
-    }
-    friend bool operator!=(ConstIterator const &lhs, ConstIterator const &rhs) {
-      return lhs.store_iter != rhs.store_iter;
-    }
-  };
-
-private:
-  std::optional<std::size_t> root;
-  std::optional<std::size_t> min;
-  std::optional<std::size_t> max;
-  std::vector<Node> nodes;
-  std::size_t size_diff;
-
-  std::optional<std::size_t> pred(std::size_t node) {
-    if (this->nodes[node].left.has_value()) {
-      std::size_t store = this->nodes[node].left.value();
-      while (this->nodes[store].right.has_value()) {
-        store = this->nodes[node].right.value();
-      }
-      return store;
-    } else {
-      if (!this->nodes[node].parent.has_value()) {
-        return std::nullopt;
-      }
-
-      std::size_t prev_store = node;
-      std::size_t store = this->nodes[node].parent.value();
-      while (this->nodes[store].parent.has_value()) {
-        if (this->nodes[store].right == prev_store) {
-          return store;
-        }
-        prev_store = store;
-        store = this->nodes[store].parent.value();
-      }
-      return std::nullopt;
-    }
-  }
-  std::optional<std::size_t> succ(std::size_t node) {
-    if (this->nodes[node].right.has_value()) {
-      std::size_t store = this->nodes[node].right.value();
-      while (this->nodes[store].left.has_value()) {
-        store = this->nodes[node].left.value();
-      }
-      return store;
-    } else {
-      if (!this->nodes[node].parent.has_value()) {
-        return std::nullopt;
-      }
-
-      std::size_t prev_store = node;
-      std::size_t store = this->nodes[prev_store].parent.value();
-      while (this->nodes[store].parent.has_value()) {
-        if (this->nodes[store].left == prev_store) {
-          return store;
-        }
-        prev_store = store;
-        store = this->nodes[store].parent.value();
-      }
-      return std::nullopt;
-    }
-  }
-
-public:
-  Map()
-      : root{std::nullopt}, min{std::nullopt}, max{std::nullopt}, nodes{},
-        size_diff{0} {}
-  Map(const Map &rhs)
-      : root{rhs.root}, min{rhs.min}, max{rhs.max}, nodes{rhs.nodes},
-        size_diff{0} {}
-  Map &operator=(const Map &rhs) {
-    this->root = rhs.root;
-    this->min = rhs.min;
-    this->max = rhs.max;
-    this->nodes = rhs.nodes;
-  }
-  Map(std::initializer_list<ValueType> elems)
-      : root{std::nullopt}, min{std::nullopt}, max{std::nullopt}, nodes{} {
-    this->insert(elems.begin(), elems.end());
-  }
-
-  ~Map() {}
-
-  size_t size() const { return this->nodes.size() - this->size_diff; }
-  bool empty() const { return this->size() == 0; }
-
-  Iterator begin() { return Iterator{*this, min}; }
-  Iterator end() { return Iterator{*this, std::nullopt, max}; }
-  ConstIterator begin() const { return ConstIterator{*this, this->begin()}; }
-  ConstIterator end() const { return ConstIterator{*this, this->end()}; }
-  ConstIterator cbegin() const { return this->begin(); }
-  ConstIterator cend() const { return this->end(); }
-  ReverseIterator rbegin() {
-    return ReverseIterator{Iterator{*this, this->max}};
-  }
-  ReverseIterator rend() {
-    return ReverseIterator{Iterator{*this, nullptr, min}};
-  }
-  Iterator find(const Key_T &key) {
-    // we need a locate slot function for insert regardless so might as well use
-    // it here
-    auto [parent, dir] = this->locate_slot(key);
-    if (!parent.has_value()) {
-      if (this->root.has_value() &&
-          this->nodes[this->root.value()].value.first == key) {
-        return Iterator{*this, root};
-      } else {
-        return this->end();
-      }
-    }
-    if (!this->nodes[parent.value()].c_select(dir).has_value()) {
-      return this->end();
-    }
-    return Iterator{*this, this->nodes[parent.value()].c_select(dir)};
-  }
-  // implicit cast to ConstIterator from Iterator
-  ConstIterator find(const Key_T &key) const { return this->find(key); }
-
-  Mapped_T &at(const Key_T &key) {
-    auto ret = this->find(key);
-    if (ret == this->end()) {
-      throw std::out_of_range{"Key not in map"};
-    }
-    return ret->second;
-  }
-  const Mapped_T &at(const Key_T &key) const {
-    auto ret = this->find(key);
-    if (ret == this->end()) {
-      throw std::out_of_range{"Key not in map"};
-    }
-    return ret->second;
-  }
-  Mapped_T &operator[](const Key_T &key) {
-    Mapped_T v;
-    auto insert_val = std::make_pair(key, v);
-    auto [iter, key_no_exist] = this->insert(insert_val);
-    return iter->second;
-  }
-
-private:
-  void handle_root_rotation(std::optional<std::size_t> g,
-                            std::optional<std::size_t> p,
-                            std::optional<std::size_t> i, Direction dir) {
-    handle_root_rotation(g.has_value() ? &this->nodes[g.value()] : nullptr,
-                         p.has_value() ? &this->nodes[p.value()] : nullptr,
-                         i.has_value() ? &this->nodes[i.value()] : nullptr,
-                         dir);
-  }
-  void handle_root_rotation(Node *grandparent, Node *parent, Node *inserting,
-                            Direction dir) {
-    // making inner grandchild into outer grandchild
-
-    if (inserting == parent->child(!dir)) {
-      parent->rotate(dir);
-      inserting = parent;
-      parent = grandparent->child(dir);
-    }
-    grandparent->rotate(!dir);
-
-    parent->color = Color::Black;
-    grandparent->color = Color::Red;
-  }
-  using Ref_T = std::optional<std::size_t>;
-  // heavily referencing the wikipedia implementation for this
-  // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Insertion
-  void insert_helper(Ref_T to_insert, Ref_T parent, Direction dir) {
-    // initialize the element we're inserting
-    this->nodes[to_insert.value()].color = Color::Red;
-    this->nodes[to_insert.value()].left = std::nullopt;
-    this->nodes[to_insert.value()].right = std::nullopt;
-    this->nodes[to_insert.value()].next = std::nullopt;
-    this->nodes[to_insert.value()].prev = std::nullopt;
-    this->nodes[to_insert.value()].parent = parent;
-
-    // if this is the first element to be inserted it's root
-    if (!this->nodes[to_insert.value()].parent.has_value()) {
-      this->root = to_insert;
-      this->nodes[to_insert.value()].color = Color::Black;
-      return;
-    }
-
-    switch (dir) {
-    case Direction::Left:
-      this->nodes[parent.value()].left = to_insert;
-      break;
-    case Direction::Right:
-      this->nodes[parent.value()].right = to_insert;
-      break;
-    }
-
-    do {
-      // don't need to keep track of these in between loops they get
-      // recalculated
-      std::optional<std::size_t> grandparent;
-      std::optional<std::size_t> uncle;
-      if (this->nodes[parent.value()].color == Color::Black) {
-        // black parent means invariants definitely hold
-        return;
-      }
-
-      grandparent = this->nodes[parent.value()].parent;
-
-      if (!grandparent.has_value()) {
-        // parent is root, just need to recolor it to black
-        this->nodes[parent.value()].color = Color::Black;
-        return;
-      }
-
-      Direction parent_direction;
-      if (this->nodes[grandparent.value()].left == parent) {
-        parent_direction = Direction::Left;
-        uncle = this->nodes[grandparent.value()].right;
-      } else {
-        parent_direction = Direction::Right;
-        uncle = this->nodes[grandparent.value()].left;
-      }
-
-      if (!uncle.has_value() ||
-          this->nodes[uncle.value()].color == Color::Black) {
-        if (to_insert == this->nodes[parent.value()].c_select(!dir)) {
-          // case 5
-          this->nodes[parent.value()].rotate(dir);
-          to_insert = parent;
-          parent = this->nodes[grandparent.value()].c_select(dir);
-        }
-        // case 6
-        this->handle_root_rotation(grandparent, parent, to_insert,
-                                   parent_direction);
-        return;
-      }
-
-      // now we know parent and uncle are both red so red-black coloring can be
-      // pushed down from grandparent
-      this->nodes[parent.value()].color = Color::Black;
-      this->nodes[uncle.value()].color = Color::Black;
-      this->nodes[grandparent.value()].color = Color::Red;
-
-      to_insert = grandparent;
-      parent = this->nodes[to_insert.value()].parent;
-    } while (parent.has_value());
-
-    // case 3: current node is red root so we're done
-  }
-  // returns nullptr iff map is empty
-  std::pair<std::optional<std::size_t>, Direction>
-  locate_slot(const Key_T &key) {
-    using Ref_T = std::optional<std::size_t>;
-    Ref_T current = this->root;
-    Ref_T parent = std::nullopt;
-    Direction dir;
-    while (current.has_value() &&
-           this->nodes[current.value()].value.first != key) {
-      parent = current;
-      if (key < this->nodes[current.value()].value.first) {
-        dir = Direction::Left;
-        current = this->nodes[current.value()].left;
-      } else {
-        dir = Direction::Right;
-        current = this->nodes[current.value()].right;
-      }
-    }
-    return std::make_pair(parent, dir);
-  }
-
-public:
-  // If the key does not already exist in the map, it returns an iterator
-  // pointing to the new element, and true. If the key already exists, no
-  // insertion is performed nor is the mapped object changed, and it returns
-  // an iterator pointing to the element with the same key, and false.
-  std::pair<Iterator, bool> insert(const ValueType &val) {
-    auto [parent, dir] = locate_slot(val.first);
-    bool ret = !parent.has_value() ||
-               !this->nodes[parent.value()].c_select(dir).has_value();
-    if (!ret) {
-      return std::make_pair(
-          Iterator{*this, this->nodes[parent.value()].c_select(dir)}, ret);
-    }
-    Node to_insert{*this};
-    to_insert.value = val;
-    this->nodes.push_back(std::move(to_insert));
-    // this->nodes.back().self = (--this->nodes.end());
-    insert_helper(nodes.size() - 1, parent, dir);
-
-    if (min == std::nullopt ||
-        val.first < this->nodes[min.value()].value.first) {
-      min = nodes.size() - 1;
-    }
-    if (max == std::nullopt ||
-        val.first > this->nodes[max.value()].value.first) {
-      max = nodes.size() - 1;
-    }
-    Ref_T successor = this->succ(this->nodes.size() - 1);
-    Ref_T predessor = this->pred(this->nodes.size() - 1);
-    if (successor.has_value()) {
-      this->nodes[successor.value()].prev = this->nodes.size() - 1;
-    }
-    this->nodes[this->nodes.size() - 1].next = successor;
-    if (predessor.has_value()) {
-      this->nodes[predessor.value()].next = this->nodes.size() - 1;
-    }
-    this->nodes[this->nodes.size() - 1].prev = successor;
-    return std::make_pair(Iterator(*this, nodes.size() - 1), ret);
-  }
-  template <typename IT_T> void insert(IT_T range_beg, IT_T range_end) {
-    std::for_each(range_beg, range_end,
-                  [&](ValueType &val) { this->insert(val); });
-  }
-
-private:
-  void case5(Node *parent, Node *sibling, Node *close_nephew,
-             Node *distant_nephew, Direction dir) {
-    sibling->rotate(!dir);
-    sibling->color = Color::Red;
-    close_nephew->color = Color::Black;
-    distant_nephew = sibling;
-    sibling = close_nephew;
-    case6(parent, sibling, distant_nephew, dir);
-  }
-  void case6(Node *parent, Node *sibling, Node *distant_nephew, Direction dir) {
-    parent->rotate(dir);
-    sibling->color = parent->color;
-    parent->color = Color::Black;
-    distant_nephew->color = Color::Black;
-  }
-  // black leaf node with no kids
-  void complex_erase(Iterator pos) {}
-
-public:
-  void erase(Iterator pos) {
-    this->size_diff++;
-    // simple cases
-    Node *ref = &this->nodes[pos.ref.value()];
-    if (ref ==
-        (this->min.has_value() ? &this->nodes[this->min.value()] : nullptr)) {
-      this->min = ref->next;
-    }
-    if (ref ==
-        (this->max.has_value() ? &this->nodes[this->max.value()] : nullptr)) {
-      this->max = ref->prev;
-    }
-    // 2 children
-    if (ref->l() != nullptr && ref->r() != nullptr) {
-      Ref_T next = ref->next;
-      *ref = this->nodes[next.value()];
-      this->erase(Iterator{*this, next});
-    }
-    // single child which is left
-    else if (ref->l() != nullptr && ref->r() == nullptr) {
-      if (ref->par()->l() == ref) {
-        ref->par()->set_l(ref->l());
-      } else {
-        ref->par()->set_r(ref->l());
-      }
-      if (ref->color == Color::Black) {
-        ref->l()->color = Color::Black;
-      }
-    }
-    // single child which is right
-    else if (ref->l() == nullptr && ref->r() != nullptr) {
-      if (ref->par()->l() == ref) {
-        ref->par()->set_l(ref->r());
-      } else {
-        ref->par()->set_r(ref->r());
-      }
-      if (ref->color == Color::Black) {
-        ref->r()->color = Color::Black;
-      }
-    }
-    // no children and root
-    else if (this->root == pos.ref && ref->l() == nullptr &&
-             ref->r() == nullptr) {
-      this->root = std::nullopt;
-    }
-    // no children and red
-    else if (ref->color == Color::Red && ref->l() == nullptr &&
-             ref->r() == nullptr) {
-      if (ref->parent.has_value()) {
-        if (this->nodes[ref->parent.value()].right == pos.ref.value()) {
-          this->nodes[ref->parent.value()].right = std::nullopt;
-        } else {
-          this->nodes[ref->parent.value()].left = std::nullopt;
-        }
-      }
-    }
-    // complicated case of black node with no kids
-    else {
-      this->complex_erase(pos);
-    }
-    if (ref->next.has_value()) {
-      this->nodes[ref->next.value()].prev = this->pred(ref->next.value());
-    }
-    if (ref->prev.has_value()) {
-      this->nodes[ref->next.value()].next = this->succ(ref->next.value());
-    }
-  }
-  void erase(const Key_T &key) { this->erase(this->find(key)); }
-  void clear() {
-    this->root = std::nullopt;
-    this->nodes.clear();
-  }
-  friend bool operator==(const Map &lhs, const Map &rhs) {
-    if (lhs.nodes.size() != rhs.nodes.size()) {
-      return false;
-    }
-    auto liter = lhs.cbegin();
-    auto riter = rhs.cbegin();
-    // both must be the same length so this is fine
-    while (liter != lhs.cend()) {
-      if (*liter != *riter) {
-        return false;
-      }
-      liter++;
-      riter++;
-    }
-    return true;
-  }
-  friend bool operator!=(const Map &lhs, const Map &rhs) {
-    return !(lhs == rhs);
-  }
-  friend bool operator<(const Map &lhs, const Map &rhs) {
-    auto l_iter = lhs.cbegin();
-    auto r_iter = rhs.cbegin();
-    for (; l_iter != lhs.cend() && r_iter != rhs.cend(); l_iter++, r_iter++) {
-      if (*l_iter < *r_iter) {
-        return true;
-      }
-    }
-    return lhs.size() < rhs.size();
-  }
-};
-} // namespace cs440