[ox/std] Add HashMap

deps/ox/src/ox/std/hashmap.hpp

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2015 - 2018 gtalent2@gmail.com
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include "string.hpp"
+#include "vector.hpp"
+
+namespace ox {
+
+template<typename K, typename T>
+class HashMap {
+
+	private:
+		struct Pair {
+			K key;
+			T value;
+		};
+		Vector<K> m_keys;
+		Vector<Pair*> m_pairs;
+
+	public:
+		explicit HashMap(std::size_t size = 100) noexcept;
+
+		HashMap(HashMap &other) noexcept;
+
+		~HashMap() noexcept;
+
+		HashMap &operator=(HashMap &other) noexcept;
+
+		/**
+		 * K is assumed to be a null terminated string.
+		 */
+		T &operator[](K key) noexcept;
+
+		std::size_t size() const noexcept;
+
+	private:
+		/**
+		 * K is assumed to be a null terminated string.
+		 */
+		static std::uint64_t hash(K, int len = 0xFFFF);
+
+};
+
+template<typename K, typename T>
+HashMap<K, T>::HashMap(std::size_t size) noexcept: m_pairs(size) {
+}
+
+template<typename K, typename T>
+HashMap<K, T>::HashMap(HashMap<K, T> &other) noexcept {
+	m_pairs = other.m_pairs;
+}
+
+template<typename K, typename T>
+HashMap<K, T>::~HashMap() noexcept {
+	for (std::size_t i = 0; i < m_pairs.size(); i++) {
+		delete m_pairs[i];
+	}
+}
+
+template<typename K, typename T>
+HashMap<K, T> &HashMap<K, T>::operator=(HashMap<K, T> &other) noexcept {
+	this->~HashMap<K, T>();
+	m_keys = other.m_keys;
+	m_pairs = other.m_pairs;
+	return *this;
+}
+
+template<typename K, typename T>
+T &HashMap<K, T>::operator[](K k) noexcept {
+	auto h = hash(k) % m_pairs.size();
+	auto hashStr = reinterpret_cast<char*>(&h);
+	while (1) {
+		auto &p = m_pairs[h];
+		if (p == nullptr) {
+			p = new Pair;
+			p->key = k;
+			m_keys.push_back(k);
+			return p->value;
+		} else if (ox_strcmp(p->key, k) == 0) {
+			return p->value;
+		} else {
+			h = hash(hashStr, 8) % m_pairs.size();
+		}
+	}
+}
+
+template<typename K, typename T>
+std::size_t HashMap<K, T>::size() const noexcept {
+	return m_keys.size();
+};
+
+template<typename K, typename T>
+std::uint64_t HashMap<K, T>::hash(K k, int len) {
+	std::uint64_t sum = 1;
+	for (int i = 0; i < len && k[i]; i++) {
+		sum += ((sum + k[i]) * 7) * sum;
+	}
+	return sum;
+}
+
+}