Danny Robson
a016e98b12
introduces an object that provides iterators suitable for row-major scanning of points covering a region object. mostly a wrapper for the equivalent extent_range.
222 lines
7.1 KiB
C++
222 lines
7.1 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2010-2017 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_REGION_HPP
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#define CRUFT_UTIL_REGION_HPP
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#include "./extent.hpp"
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#include "./point.hpp"
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#include "./vector.hpp"
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#include "./types/traits.hpp"
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#include <ostream>
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namespace util {
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/**
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* A two-dimensional rectangle, with size and position.
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*/
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template <size_t S, typename T>
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struct region {
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using extent_t = util::extent<S,T>;
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using point_t = util::point<S,T>;
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using value_type = T;
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//---------------------------------------------------------------------
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static constexpr size_t dimension = S;
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static constexpr size_t elements = extent_t::elements + point_t::elements;
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point_t p;
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extent_t e;
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//---------------------------------------------------------------------
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region () = default;
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explicit region (extent_t);
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region (point_t, extent_t);
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region (point_t, point_t);
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//---------------------------------------------------------------------
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template <typename U>
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constexpr region<S,U> cast (void) const;
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//---------------------------------------------------------------------
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T area (void) const;
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T diameter (void) const;
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extent_t magnitude (void) const;
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extent_t magnitude (extent_t);
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bool empty (void) const;
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//---------------------------------------------------------------------
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point_t base (void) const;
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point_t away (void) const;
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point_t centre (void) const;
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point_t closest (point_t) const;
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//---------------------------------------------------------------------
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// exclusive of borders
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bool intersects (region<S,T>) const;
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// Compute binary region combinations
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region intersection (region<S,T>) const;
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// Test if a region lies completely within our space
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bool covers (region<S,T>) const noexcept;
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// Test if a point lies within out space. Inclusive of borders
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bool covers (point<S,T>) const noexcept;
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// Move a point to be within the region bounds
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point_t constrain (point_t) const noexcept;
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//---------------------------------------------------------------------
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// Compute a region `mag` units into the region
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region inset (T mag) const;
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region inset (vector<S,T> mag) const;
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region expand (T mag) const;
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region expand (vector<S,T>) const;
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// arithmetic operators
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region operator+ (vector<S,T>) const;
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region operator- (vector<S,T>) const;
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// Logical comparison operators
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bool operator ==(region<S,T> rhs) const;
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bool operator !=(region<S,T> rhs) const
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{ return !(*this == rhs); }
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// Utility constants
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static constexpr region<S,T> max (void);
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static constexpr region<S,T> unit (void);
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static constexpr region<S,T> zero (void)
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{ return { point_t {0}, extent_t {0} }; }
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void sanity (void) const;
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};
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///////////////////////////////////////////////////////////////////////////
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/// constructs the minimal region that encompasses a region and a point.
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template <typename T, size_t S>
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region<S,T>
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make_union (region<S,T> r, point<S,T> p)
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{
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const auto p0 = select (r.p < p, r.p, p);
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const auto p1 = select (r.away () > p, r.away (), p);
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return { p0, p1 };
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}
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///////////////////////////////////////////////////////////////////////////
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/// construct a point iterator across a given region, generating each
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/// valid point in row-major sequence.
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///
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/// this is only defined for integral types as it's not clear how to
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/// handle floats; it's _super_ unlikely anyone actually wants to visit
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/// every single floating point value for a region (and if so they can
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/// damn well code that monstrosity themselves).
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template <
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typename T,
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std::size_t S,
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typename = std::enable_if_t<
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std::is_integral_v<T>, void
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>
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>
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auto
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make_range (region<S,T> r)
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{
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using region_t = region<S,T>;
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using point_t = typename region_t::point_t;
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using vector_t = util::vector<S,T>;
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// this range object is mostly a wrapper around the existing
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// extent_range object with a constant offset. it's not going to be as
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// performant, but when we discover this is an issue we can do write a
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// better version of this object & iterator.
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class region_range {
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public:
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class iterator : public std::iterator<std::forward_iterator_tag, point_t, size_t> {
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public:
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iterator (typename extent_range<S,T>::iterator _inner, vector_t _offset):
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m_inner (_inner),
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m_offset (_offset)
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{ ; }
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point_t operator* (void) const { return *m_inner + m_offset; }
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iterator&
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operator++ (void)
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{
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++m_inner;
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return *this;
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}
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bool operator== (const iterator &rhs) const
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{
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assert (m_offset == rhs.m_offset);
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return m_inner == rhs.m_inner;
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}
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bool operator!= (const iterator &rhs) const
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{ return !(*this == rhs); }
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private:
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typename extent_range<S,T>::iterator m_inner;
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vector_t m_offset;
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};
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region_range (region_t _r):
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m_range { _r.e + T{1} },
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m_offset { _r.p.template as<util::vector> () }
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{ ; }
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iterator begin (void) const { return { m_range.begin (), m_offset }; }
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iterator end (void) const { return { m_range.end (), m_offset }; }
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iterator cbegin (void) const { return begin (); }
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iterator cend (void) const { return end (); }
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private:
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const extent_range<S,T> m_range;
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const vector_t m_offset;
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};
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return region_range { r };
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};
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template <typename T> using region2 = region<2,T>;
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template <typename T> using region3 = region<3,T>;
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using region2u = region2<unsigned>;
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using region2i = region2<int>;
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using region2f = region2<float>;
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using region2d = region2<double>;
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template <size_t S, typename T>
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std::ostream& operator<< (std::ostream&, const util::region<S,T>&);
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}
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#include "region.ipp"
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#endif
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