82 行
2.4 KiB
C++
82 行
2.4 KiB
C++
#pragma once
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#include <nall/maybe.hpp>
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namespace nall {
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template<typename T = s64>
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struct range_t {
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struct iterator {
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iterator(T position, T step = 0) : position(position), step(step) {}
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auto operator*() const -> T { return position; }
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auto operator!=(const iterator& source) const -> bool { return step > 0 ? position < source.position : position > source.position; }
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auto operator++() -> iterator& { position += step; return *this; }
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private:
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T position;
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const T step;
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};
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struct reverse_iterator {
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reverse_iterator(T position, T step = 0) : position(position), step(step) {}
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auto operator*() const -> T { return position; }
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auto operator!=(const reverse_iterator& source) const -> bool { return step > 0 ? position > source.position : position < source.position; }
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auto operator++() -> reverse_iterator& { position -= step; return *this; }
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private:
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T position;
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const T step;
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};
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auto begin() const -> iterator { return {origin, stride}; }
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auto end() const -> iterator { return {target}; }
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auto rbegin() const -> reverse_iterator { return {target - stride, stride}; }
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auto rend() const -> reverse_iterator { return {origin - stride}; }
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T origin;
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T target;
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T stride;
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};
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template<typename T = s64>
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inline auto range(s64 size) {
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return range_t<T>{0, size, 1};
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}
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template<typename T = s64>
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inline auto range(s64 offset, s64 size) {
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return range_t<T>{offset, size, 1};
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}
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template<typename T = s64>
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inline auto range(s64 offset, s64 size, s64 step) {
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return range_t<T>{offset, size, step};
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}
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//returns true if {offset ... offset+length-1} is within {min ... max} in range {lo ... hi}
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template<s64 lo, s64 hi>
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inline auto within(s64 offset, s64 length, s64 min, s64 max) -> bool {
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static_assert(lo <= hi);
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static constexpr s64 range = hi - lo + 1;
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s64 lhs = (offset - lo) % range;
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s64 rhs = (lhs + length - 1) % range;
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min = (min - lo) % range;
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max = (max - lo) % range;
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return lhs >= min && lhs <= max || rhs >= min && rhs <= max;
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}
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//returns index of target within {offset ... offset+length-1} in range {lo ... hi}
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template<s64 lo, s64 hi>
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inline auto within(s64 offset, s64 length, s64 target) -> maybe<u64> {
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static_assert(lo <= hi);
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static constexpr s64 range = hi - lo + 1;
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s64 start = (offset - lo) % range;
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s64 index = (target - lo) % range - start;
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if(index < 0) index += range;
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if(index < length) return index;
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return {};
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}
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}
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