652 lines
18 KiB
C++
652 lines
18 KiB
C++
// commenting everything out when I commit so all commits my code technically
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// compiles
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#include <algorithm>
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#include <cassert>
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#include <cstddef>
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#include <initializer_list>
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#include <iterator>
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#include <optional>
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#include <stdexcept>
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#include <utility>
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#include <vector>
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// everything is super interconnected so some forward declarations are needed at
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// various points
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namespace cs440 {
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template <typename Key_T, typename Mapped_T> class Map;
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namespace {
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enum class Color { Red, Black };
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enum class Direction { Left, Right };
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Direction operator!(Direction dir) {
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switch (dir) {
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case Direction::Left:
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return Direction::Right;
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case Direction::Right:
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return Direction::Left;
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default:
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// unreachable the only directions are left and right
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assert(false);
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}
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}
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template <typename Key_T, typename Mapped_T> struct BookKeeping {
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using Self = BookKeeping<Key_T, Mapped_T>;
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using ValueType = std::pair<const Key_T, Mapped_T>;
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friend class Map<Key_T, Mapped_T>;
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Map<Key_T, Mapped_T> &container;
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ValueType value;
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typename std::vector<Self>::iterator self;
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Color color;
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// nullptr indicates empty
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Self *parent;
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Self *left;
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Self *right;
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Self *prev;
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Self *next;
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// reference to a pointer because the alternatives were worse
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inline Self *&child(Direction dir) {
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switch (dir) {
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case Direction::Left:
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return left;
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break;
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case Direction::Right:
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return right;
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break;
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}
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}
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// this is root/P for this method
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// copying from wikipedia RotateDirRoot with translation into my own idioms
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// https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Operations
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inline void rotate(Direction dir) {
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// wikipedia version uses alphabet soup, might fix later
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Self *P = this;
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auto &T = container;
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Self *G = P->parent;
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Self *S = P->child(!dir);
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Self *C;
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// this method shouldn't be called in cases where this assert will trip
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assert(S != nullptr);
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//
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C = S->child(dir);
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P->child(!dir) = C;
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if (C != nullptr) {
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C->parent = P;
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}
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S->child(dir) = P;
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P->parent = S;
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S->parent = G;
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if (G != nullptr) {
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if (P == G->right) {
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G->right = S;
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} else {
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G->left = S;
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}
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} else {
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T->root = S;
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}
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}
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};
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} // namespace
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// https://en.wikipedia.org/wiki/Red%E2%80%93black_tree
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template <typename Key_T, typename Mapped_T> class Map {
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private:
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using ValueType = std::pair<const Key_T, Mapped_T>;
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using Node = BookKeeping<Key_T, Mapped_T>;
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using Map_T = Map<Key_T, Mapped_T>;
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public:
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class Iterator;
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class ConstIterator;
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class ReverseIterator;
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friend class Iterator;
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friend class ConstIterator;
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friend class ReverseIterator;
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friend Node;
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class Iterator {
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friend Map_T;
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friend Node;
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private:
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// pointer needed so we can replace as needed
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Node *ref;
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Node *escape;
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Iterator(Node *ref, Node *escape = nullptr) : ref{ref}, escape{escape} {}
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public:
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Iterator() = delete;
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Iterator &operator++() {
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if (ref == nullptr) {
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ref = escape;
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return *this;
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}
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if (ref->next == nullptr) {
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escape = ref;
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}
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ref = ref->next;
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return *this;
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}
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Iterator operator++(int) {
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Iterator tmp = *this;
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++(*this);
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return tmp;
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}
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Iterator &operator--() {
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if (ref == nullptr) {
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ref = escape;
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return *this;
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}
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if (ref->prev == nullptr) {
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escape = ref;
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}
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ref = ref->prev;
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return *this;
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}
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Iterator operator--(int) {
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Iterator tmp = *this;
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--(*this);
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return tmp;
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}
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ValueType &operator*() const { return this->ref->value; }
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ValueType *operator->() const { return &this->ref->value; }
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friend bool operator==(Iterator const &lhs, Iterator const &rhs) {
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return lhs.ref == rhs.ref;
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}
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friend bool operator!=(Iterator const &lhs, Iterator const &rhs) {
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return lhs.ref != rhs.ref;
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}
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friend bool operator==(ConstIterator const &lhs, Iterator const &rhs) {
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return lhs.store_iter.ref == rhs.ref;
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}
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friend bool operator!=(ConstIterator const &lhs, Iterator const &rhs) {
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return lhs.store_iter.ref != rhs.ref;
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}
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friend bool operator==(Iterator const &lhs, ConstIterator const &rhs) {
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return lhs.ref == rhs.store_iter.ref;
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}
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friend bool operator!=(Iterator const &lhs, ConstIterator const &rhs) {
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return lhs.ref != rhs.store_iter.ref;
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}
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};
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class ConstIterator {
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public:
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friend class Map<Key_T, Mapped_T>;
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friend class Iterator;
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using underlying = Iterator;
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private:
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underlying store_iter;
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ConstIterator(underlying iter) : store_iter{iter} {}
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public:
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ConstIterator() = delete;
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friend bool operator==(ConstIterator const &lhs, ConstIterator const &rhs) {
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return lhs.store_iter == rhs.store_iter;
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}
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ConstIterator &operator++() {
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++this->store_iter;
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return *this;
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}
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ConstIterator operator++(int) {
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ConstIterator tmp = *this;
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this->store_iter++;
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return tmp;
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}
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ConstIterator &operator--() {
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--this->store_iter;
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return *this;
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}
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ConstIterator operator--(int) {
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ConstIterator tmp = *this;
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this->store_iter--;
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return tmp;
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}
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const ValueType &operator*() const { return *this->store_iter; }
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const ValueType *operator->() const {
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return this->store_iter.operator->();
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}
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friend bool operator!=(ConstIterator const &lhs, ConstIterator const &rhs) {
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return lhs.store_iter != rhs.store_iter;
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}
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};
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class ReverseIterator {
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public:
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friend class Map<Key_T, Mapped_T>;
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friend class Iterator;
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using underlying = Iterator;
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private:
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underlying store_iter;
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public:
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ReverseIterator() = delete;
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ReverseIterator(underlying store_iter) : store_iter{store_iter} {}
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ReverseIterator &operator++() {
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--store_iter;
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return *this;
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}
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ReverseIterator operator++(int) {
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ReverseIterator ret = *this;
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++(*this);
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return ret;
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}
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ReverseIterator &operator--() {
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++store_iter;
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return *this;
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}
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ReverseIterator operator--(int) {
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ReverseIterator ret = *this;
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--(*this);
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return ret;
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}
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ValueType &operator*() const { return this->store_iter.ref->value; }
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ValueType *operator->() const { return &this->store_iter.ref->value; }
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friend bool operator==(ReverseIterator const &lhs,
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ReverseIterator const &rhs) {
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return lhs.store_iter == rhs.store_iter;
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}
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friend bool operator!=(ConstIterator const &lhs, ConstIterator const &rhs) {
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return lhs.store_iter != rhs.store_iter;
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}
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};
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private:
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Node *root;
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Node *min;
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Node *max;
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std::vector<Node> nodes;
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public:
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Map() : root{nullptr}, min{nullptr}, max{nullptr}, nodes{} {}
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Map(const Map &rhs)
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: root{rhs.root}, min{nullptr}, max{nullptr}, nodes{rhs.nodes} {}
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Map &operator=(const Map &rhs) {
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this->root = rhs.root;
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this->min = rhs.min;
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this->max = rhs.max;
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this->nodes = rhs.nodes;
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}
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Map(std::initializer_list<ValueType> elems) : root{nullptr}, nodes{} {
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this->insert(elems.begin(), elems.end());
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}
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~Map() {}
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size_t size() const {
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root = nullptr;
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return this->nodes.size();
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}
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bool empty() const { return this->size() == 0; }
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Iterator begin() { return Iterator{min}; }
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Iterator end() { return Iterator{nullptr, max}; }
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ConstIterator begin() const { return ConstIterator{this->begin()}; }
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ConstIterator end() const { return ConstIterator{this->end()}; }
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ConstIterator cbegin() const { return this->begin(); }
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ConstIterator cend() const { return this->end(); }
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ReverseIterator rbegin() { return ReverseIterator{Iterator{this->max}}; }
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ReverseIterator rend() { return ReverseIterator{Iterator{nullptr, min}}; }
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Iterator find(const Key_T &key) {
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// we need a locate slot function for insert regardless so might as well use
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// it here
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auto [parent, dir] = this->locate_slot(key);
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if (parent == nullptr) {
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return this->end();
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}
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if (parent->child(dir) == nullptr) {
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return this->end();
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}
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return Iterator{parent->child(dir)};
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}
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// implicit cast to ConstIterator from Iterator
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ConstIterator find(const Key_T &key) const { return this->find(key); }
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Mapped_T &at(const Key_T &key) { return (this->find(key))->second; }
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const Mapped_T &at(const Key_T &key) const { return this->at(key); }
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Mapped_T &operator[](const Key_T &key) { return this->at(key); }
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private:
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void handle_root_rotation(Node *grandparent, Node *parent, Node *inserting,
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Direction dir) {
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// making inner grandchild into outer grandchild
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if (inserting == parent->child(!dir)) {
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parent->rotate(dir);
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inserting = parent;
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parent = grandparent->child(dir);
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}
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// RotateDirRoot(T,G,1-dir);
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Node *gr_grandparent = grandparent->parent;
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Node *sibling = grandparent->child(!dir);
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assert(sibling != nullptr);
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Node *child = sibling->child(dir);
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grandparent->child(!dir) = child;
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sibling->child(dir) = grandparent;
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grandparent->parent = sibling;
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sibling->parent = gr_grandparent;
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if (gr_grandparent != nullptr) {
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Direction grandparent_direction;
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if (gr_grandparent->left == grandparent) {
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grandparent_direction = Direction::Left;
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} else {
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grandparent_direction = Direction::Right;
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}
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gr_grandparent->child(grandparent_direction) = sibling;
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} else {
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this->root = sibling;
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}
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parent->color = Color::Black;
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grandparent->color = Color::Red;
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}
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// heavily referencing the wikipedia implementation for this
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// https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Insertion
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void insert_helper(Node *to_insert, Node *parent, Direction dir) {
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// initialize the element we're inserting
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to_insert->color = Color::Red;
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to_insert->left = nullptr;
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to_insert->right = nullptr;
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to_insert->parent = parent;
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switch (dir) {
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case Direction::Left:
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to_insert->next = parent;
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to_insert->prev = parent->prev;
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parent->prev = to_insert;
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break;
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case Direction::Right:
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to_insert->prev = parent;
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to_insert->next = parent->next;
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parent->next = to_insert;
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break;
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}
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// if this is the first element to be inserted it's root
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if (to_insert->parent == nullptr) {
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this->root = to_insert;
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return;
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}
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switch (dir) {
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case Direction::Left:
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parent->left = to_insert;
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break;
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case Direction::Right:
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parent->right = to_insert;
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break;
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}
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do {
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// don't need to keep track of these in between loops they get
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// recalculated
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Node *grandparent;
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Node *uncle;
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if (parent->color == Color::Black) {
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// black parent means invariants definitely hold
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return;
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}
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grandparent = parent->parent;
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if (grandparent == nullptr) {
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// parent is root, just need to recolor it to black
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parent->color = Color::Black;
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return;
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}
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Direction parent_direction;
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if (grandparent->left == parent) {
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parent_direction = Direction::Left;
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uncle = grandparent->right;
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} else {
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parent_direction = Direction::Right;
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uncle = grandparent->left;
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}
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if (uncle == nullptr || uncle->color == Color::Black) {
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// case 5 and 6
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this->handle_root_rotation(grandparent, parent, to_insert,
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parent_direction);
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return;
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}
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// now we know parent and uncle are both red so red-black coloring can be
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// pushed down from grandparent
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parent->color = Color::Black;
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uncle->color = Color::Black;
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grandparent->color = Color::Red;
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to_insert = grandparent;
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parent = to_insert->parent;
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} while (parent != nullptr);
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// case 3: current node is red root so we're done
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}
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// returns nullptr iff map is empty
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std::pair<Node *, Direction> locate_slot(const Key_T &key) {
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Node *current = this->root;
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Node *parent = nullptr;
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Direction dir;
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while (current != nullptr && current->value.first != key) {
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parent = current;
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if (current->value.fist < key) {
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dir = Direction::Left;
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current = current->left;
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} else {
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dir = Direction::Right;
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current = current->right;
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}
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}
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return std::make_pair(parent, dir);
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}
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public:
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// If the key does not already exist in the map, it returns an iterator
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// pointing to the new element, and true. If the key already exists, no
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// insertion is performed nor is the mapped object changed, and it returns
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// an iterator pointing to the element with the same key, and false.
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std::pair<Iterator, bool> insert(const ValueType &val) {
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auto [parent, dir] = locate_slot(val.first);
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bool ret = parent->child(dir) == nullptr;
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if (!ret) {
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return std::make_pair(Iterator{parent->child(dir)}, ret);
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}
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Node to_insert;
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to_insert.value = val;
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this->nodes.push_back(std::move(to_insert));
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insert_helper(&nodes.back(), parent, dir);
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if (min == nullptr || val.first < min->value.first) {
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min = &nodes.back();
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}
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if (max == nullptr || val.first > max->value.first) {
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max = &nodes.back();
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}
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return std::make_pair(Iterator{&nodes.back()}, ret);
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}
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template <typename IT_T> void insert(IT_T range_beg, IT_T range_end) {
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std::for_each(range_beg, range_end,
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[&](ValueType &val) { this->insert(val); });
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}
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private:
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void case5(Node *parent, Node *sibling, Node *close_nephew,
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Node *distant_nephew, Direction dir) {
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sibling->rotate(!dir);
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sibling->color = Color::Red;
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close_nephew->color = Color::Black;
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distant_nephew = sibling;
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sibling = close_nephew;
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case6(parent, sibling, distant_nephew, dir);
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}
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void case6(Node *parent, Node *sibling, Node *distant_nephew, Direction dir) {
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parent->rotate(dir);
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sibling->color = parent->color;
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parent->color = Color::Black;
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distant_nephew->color = Color::Black;
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}
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// heavily referring to
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// https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Removal_of_a_black_non-root_leaf
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void complex_erase(Iterator pos) {
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Node *to_delete = pos.ref;
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Node *parent = to_delete->parent;
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assert(parent != nullptr);
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Direction dir =
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parent->right == to_delete ? Direction::Right : Direction::Left;
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Node *sibling;
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;
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Node *close_nephew;
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Node *distant_nephew;
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parent->child(dir) = nullptr;
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do {
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dir = parent->right == to_delete ? Direction::Right : Direction::Left;
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sibling = parent->child(!dir);
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distant_nephew = sibling->child(!dir);
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close_nephew = sibling->child(dir);
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if (sibling->color == Color::Red) {
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// case 3
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parent->rotate(dir);
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parent->color = Color::Red;
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sibling->color = Color::Black;
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sibling = close_nephew;
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// redundant?
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distant_nephew = sibling->child(!dir);
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if (distant_nephew != nullptr && distant_nephew->color == Color::Red) {
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case6(parent, sibling, distant_nephew, dir);
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return;
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}
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close_nephew = sibling->child(dir);
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if (close_nephew != nullptr && close_nephew->color == Color::Red) {
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case5(parent, sibling, close_nephew, distant_nephew, dir);
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return;
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}
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sibling->color = Color::Red;
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parent->color = Color::Black;
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return;
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}
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if (distant_nephew != nullptr && distant_nephew->color == Color::Red) {
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case6(parent, sibling, distant_nephew, dir);
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return;
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}
|
|
|
|
if (close_nephew != nullptr && close_nephew->color == Color::Red) {
|
|
case5(parent, sibling, close_nephew, distant_nephew, dir);
|
|
return;
|
|
}
|
|
|
|
if (parent->color == Color::Red) {
|
|
// case 4
|
|
sibling->color = Color::Red;
|
|
parent->color = Color::Black;
|
|
return;
|
|
}
|
|
|
|
// case 2
|
|
sibling->color = Color::Red;
|
|
to_delete = parent;
|
|
parent = to_delete->parent;
|
|
} while (parent != nullptr);
|
|
}
|
|
|
|
public:
|
|
// TODO: check that the way of reconnecting next and prev works
|
|
// TODO: need to revalidate
|
|
void erase(Iterator pos) {
|
|
auto revalidate_begin = pos.ref->container.begin() - pos.ref->self;
|
|
auto &container = pos.ref->container;
|
|
// simple cases
|
|
Node *ref = pos.ref;
|
|
// 2 children
|
|
if (ref->left != nullptr && ref->right != nullptr) {
|
|
Node *next = ref->next;
|
|
Node *prev = ref->prev;
|
|
*ref = *next;
|
|
prev->next = next;
|
|
next->prev = prev;
|
|
this->erase(Iterator{next});
|
|
}
|
|
// single child which is left
|
|
else if (ref->left != nullptr && ref->right == nullptr) {
|
|
Node *next = ref->next;
|
|
Node *prev = ref->prev;
|
|
*ref = *ref->left;
|
|
prev->next = next;
|
|
next->prev = prev;
|
|
}
|
|
// single child which is right
|
|
else if (ref->left == nullptr && ref->right != nullptr) {
|
|
Node *next = ref->next;
|
|
Node *prev = ref->prev;
|
|
*ref = *ref->right;
|
|
prev->next = next;
|
|
next->prev = prev;
|
|
}
|
|
// no children and root
|
|
else if (ref->left == nullptr && ref->right == nullptr) {
|
|
this->root = nullptr;
|
|
this->nodes.erase(ref->value);
|
|
}
|
|
// no children and red
|
|
else if (ref->left == nodes.end() && ref->right == nodes.end()) {
|
|
Node *next = ref->next;
|
|
Node *prev = ref->prev;
|
|
prev->next = next;
|
|
next->prev = prev;
|
|
this->nodes.erase(ref->value);
|
|
}
|
|
// complicated case of black node with no kids
|
|
else {
|
|
this->complex_erase(pos);
|
|
}
|
|
// need to revalidate iterators now so future erasures aren't fucked
|
|
for (auto iter = container.begin() + revalidate_begin;
|
|
iter != container.end(); ++iter) {
|
|
iter->self = iter;
|
|
}
|
|
}
|
|
void erase(const Key_T &key) { this->erase(this->find(key)); }
|
|
void clear() {
|
|
this->root = nullptr;
|
|
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
|