Rework ranges library
Better matches the standard library, and iterators moved to their own filefeature/simd
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/* Quicktex Texture Compression Library
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Copyright (C) 2021 Andrew Cassidy <drewcassidy@me.com>
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Partially derived from rgbcx.h written by Richard Geldreich <richgel99@gmail.com>
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and licenced under the public domain
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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namespace quicktex {
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namespace detail {
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template <class R> using subs_value_t = std::remove_reference_t<decltype(std::declval<R &>()[0])>;
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}
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template <typename D, typename T> class index_iterator_base {
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public:
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using value_type = T;
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using size_type = int;
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using difference_type = int;
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D &operator++() {
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_index++;
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return static_cast<D &>(*this);
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}
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D operator++(int) {
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D old = static_cast<D &>(*this);
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_index++;
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return old;
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}
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D &operator--() {
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_index--;
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return static_cast<D &>(*this);
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}
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D operator--(int) {
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D old = static_cast<D &>(*this);
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_index--;
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return old;
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}
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D operator+(difference_type rhs) const {
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D d = static_cast<const D &>(*this);
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d._index += rhs;
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return d;
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}
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D operator-(difference_type rhs) const {
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D d = static_cast<const D &>(*this);
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d._index -= rhs;
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return d;
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}
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D &operator+=(difference_type rhs) {
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*this = *this + rhs;
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return *this;
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}
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D &operator-=(difference_type rhs) {
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*this = *this - rhs;
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return *this;
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}
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difference_type operator-(const D &rhs) const { return (difference_type)_index - rhs._index; }
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friend D operator+(difference_type lhs, const D &rhs) { return rhs + lhs; }
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friend auto operator<=>(const D &lhs, const D &rhs) { return lhs._index <=> rhs._index; }
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T &operator[](difference_type i) { return *(static_cast<D &>(*this) + i); }
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T &operator[](difference_type i) const { return *(static_cast<const D &>(*this) + i); }
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protected:
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int _index;
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private:
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friend D;
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index_iterator_base(size_t index = 0) : _index(index) {}
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};
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template <typename R>
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requires requires(const R &r) { r[0]; }
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class index_iterator : public index_iterator_base<index_iterator<R>, detail::subs_value_t<R>> {
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public:
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using base = index_iterator_base<index_iterator<R>, detail::subs_value_t<R>>;
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using typename base::difference_type;
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using typename base::size_type;
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using typename base::value_type;
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index_iterator() : base(0), _range(nullptr) {}
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index_iterator(R &range, int index) : base(index), _range(&range) {}
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value_type &operator*() const {
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assert(_range != nullptr);
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assert(this->_index >= 0);
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assert(this->_index < (size_type)_range->size());
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return (*_range)[this->_index];
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}
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value_type *operator->() const { return &(this->operator*()); }
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friend bool operator==(const index_iterator &lhs, const index_iterator &rhs) {
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return (lhs._range == rhs._range) && (lhs._index == rhs._index);
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}
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private:
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R *_range;
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};
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template <typename T> class const_iterator : public index_iterator_base<const_iterator<T>, const T> {
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public:
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using base = index_iterator_base<const_iterator<T>, const T>;
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using typename base::difference_type;
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using typename base::size_type;
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using typename base::value_type;
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const_iterator() : base(0), _value(T{}) {}
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const_iterator(T value, int index = 0) : base(index), _value(value) {}
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value_type &operator*() const { return _value; }
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value_type *operator->() const { return &_value; }
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friend bool operator==(const const_iterator &lhs, const const_iterator &rhs) {
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return (lhs._value == rhs._value) && (lhs._index == rhs._index);
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}
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private:
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T _value;
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};
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// const_iterator is guaranteed to be a random access iterator. it is not writable for obvious reasons
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static_assert(std::random_access_iterator<const_iterator<int>>);
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// index_iterator satisfied forward_iterator
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static_assert(std::random_access_iterator<index_iterator<std::array<int, 4>>>);
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} // namespace quicktex
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