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240 rader
5.7 KiB
240 rader
5.7 KiB
#pragma once
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#include <cstddef>
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#include <cstdint>
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// BUG: none of this is in a namespace
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// TODO: Specify the concept of an iterator
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namespace gp {
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/**
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* @brief An enumeration that may be used to determine iterator categories
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*
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*/
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enum class iterator_type_t{
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contiguous_iterator, /**< Defines an iterator for something that is continuous and random access */
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non_contiguous_iterator, /**< Defines an iterator for a non contiguous datastructure, for example an iterator over a hashmap or a tree*/
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lazy_iterator /**< Defines an iterator for which the actual data layout and availability are still unknown*/
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};
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/**
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* @brief An abstraction of a pointer to iterate against, in both normal and reverse order
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*
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* @tparam T The type of data pointed by the iterator
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* @tparam sign the direction in which data is scrutinized, should be either 1 or -1, behaviour for other value is left undefined
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*/
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template<typename T, int sign = 1>
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struct pointer_iterator final
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{
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T* data; /**< the only data field of the class */
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typedef T value_type; /**< The type of which a reference will be returned on dereferencing */
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typedef std::size_t difference_type; /**< The type of the substraction of two pointers */
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static constexpr iterator_type_t iterator_type = iterator_type_t::contiguous_iterator; /**< @see iterator_type_t */
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/**
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* @brief Generates an empty iterator
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*/
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constexpr pointer_iterator()
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: data{nullptr}
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{}
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constexpr pointer_iterator(const pointer_iterator& oth)
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: data{oth.data}
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{}
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/**
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* @brief Generates an iterator from any pointer
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*/
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constexpr pointer_iterator(T* ptr)
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: data{ptr}
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{}
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/**
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* @brief Dereference unary operator
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*
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* @return constexpr T& returns a reference to the pointed value
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*/
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constexpr T& operator*() const
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{
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return *data;
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}
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constexpr pointer_iterator& operator++()
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{
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data += sign;
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return *this;
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}
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constexpr pointer_iterator operator++(int)
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{
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auto p = *this;
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data += sign;
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return p;
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}
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constexpr pointer_iterator& operator--()
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{
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data -= sign;
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return *this;
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}
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constexpr pointer_iterator operator--(int)
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{
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auto p = *this;
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data -= sign;
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return p;
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}
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constexpr pointer_iterator operator+(const std::size_t offset) const
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{
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return pointer_iterator{data+sign*offset};
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}
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constexpr pointer_iterator operator+(const int offset) const
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{
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return pointer_iterator{data+sign*offset};
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}
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constexpr pointer_iterator operator-(const std::size_t offset) const
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{
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return pointer_iterator{data-sign*offset};
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}
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constexpr pointer_iterator operator-(const int offset) const
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{
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return pointer_iterator{data-sign*offset};
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}
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constexpr difference_type operator-(const pointer_iterator& oth) const
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{
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return ((T*)data-(T*)oth.data)*sign;
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}
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constexpr bool operator==(const pointer_iterator oth) const
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{
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return data==oth.data;
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}
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constexpr bool operator!=(pointer_iterator oth) const
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{
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return data!=oth.data;
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}
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constexpr bool before_or_equal(const pointer_iterator oth) const
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{
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return reinterpret_cast<std::intptr_t>(data) <= reinterpret_cast<std::intptr_t>(oth.data);
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}
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constexpr bool operator<=(const pointer_iterator oth) const
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{
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return before_or_equal(oth);
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}
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};
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/**
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* @brief An identical twin to the pointer_iterator, but which dereference to a const reference
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*
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* @see pointer_iterator
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* @tparam T @see pointer_iterator
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* @tparam sign @see pointer_iterator
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*/
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template<typename T, int sign = 1>
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struct const_pointer_iterator final
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{
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const T* data; /**< @see pointer_iterator */
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typedef T value_type; /**< @see pointer_iterator */
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typedef std::size_t difference_type; /**< @see pointer_iterator */
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static constexpr iterator_type_t iterator_type = iterator_type_t::contiguous_iterator; /**< @see pointer_iterator */
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constexpr const_pointer_iterator(const const_pointer_iterator& oth)
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: data{oth.data}
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{}
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/**
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* @brief @see pointer_iterator
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*/
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constexpr const_pointer_iterator(const T* ptr)
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: data{ptr}
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{}
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/**
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* @brief Dereferencing returns a const version of what a pointer_iterator would return
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*/
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constexpr const T& operator*() const
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{
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return *data;
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}
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constexpr const_pointer_iterator& operator++()
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{
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data += sign;
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return *this;
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}
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constexpr const_pointer_iterator operator++(int)
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{
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auto p = data;
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data += sign;
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return const_pointer_iterator{p};
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}
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constexpr const_pointer_iterator& operator--()
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{
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data -= sign;
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return *this;
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}
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constexpr const_pointer_iterator operator--(int)
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{
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auto p = data;
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data -= sign;
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return const_pointer_iterator{p};
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}
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constexpr const_pointer_iterator operator+(const std::size_t offset) const
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{
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return const_pointer_iterator{data+sign*offset};
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}
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constexpr const_pointer_iterator operator+(const int offset) const
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{
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return const_pointer_iterator{data+sign*offset};
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}
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constexpr const_pointer_iterator operator-(const std::size_t offset) const
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{
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return const_pointer_iterator{data-sign*offset};
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}
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constexpr const_pointer_iterator operator-(const int offset)
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{
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return const_pointer_iterator{data-sign*offset};
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}
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constexpr difference_type operator-(const const_pointer_iterator& oth) const
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{
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return ((T*)data-(T*)oth.data)*sign;
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}
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constexpr bool operator==(const const_pointer_iterator oth) const
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{
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return data==oth.data;
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}
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constexpr bool operator!=(const_pointer_iterator oth) const
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{
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return data!=oth.data;
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}
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constexpr bool before_or_equal(const const_pointer_iterator oth) const
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{
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return reinterpret_cast<std::intptr_t>(data) <= reinterpret_cast<std::intptr_t>(oth.data);
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}
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constexpr bool operator<=(const const_pointer_iterator oth) const
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{
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return before_or_equal(oth);
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}
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};
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}
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