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transform.hpp
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1 // Range v3 library
3 //
4 // Copyright Eric Niebler 2014-present
5 //
6 // Use, modification and distribution is subject to the
7 // Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
10 //
11 // Project home: https://github.com/ericniebler/range-v3
12 //
13 #ifndef RANGES_V3_ALGORITHM_TRANSFORM_HPP
14 #define RANGES_V3_ALGORITHM_TRANSFORM_HPP
15 
16 #include <utility>
17 
18 #include <meta/meta.hpp>
19 
20 #include <range/v3/range_fwd.hpp>
21 
22 #include <range/v3/algorithm/result_types.hpp>
32 #include <range/v3/utility/static_const.hpp>
33 
34 #include <range/v3/detail/prologue.hpp>
35 
36 namespace ranges
37 {
40  template<typename I, typename O>
41  using unary_transform_result = detail::in_out_result<I, O>;
42 
43  template<typename I1, typename I2, typename O>
44  using binary_transform_result = detail::in1_in2_out_result<I1, I2, O>;
45 
46  RANGES_FUNC_BEGIN(transform)
47 
48  // Single-range variant
50  template(typename I, typename S, typename O, typename F, typename P = identity)(
51  requires input_iterator<I> AND sentinel_for<S, I> AND
52  weakly_incrementable<O> AND copy_constructible<F> AND
53  indirectly_writable<O, indirect_result_t<F &, projected<I, P>>>)
54  constexpr unary_transform_result<I, O> //
55  RANGES_FUNC(transform)(I first, S last, O out, F fun, P proj = P{}) //
56  {
57  for(; first != last; ++first, ++out)
58  *out = invoke(fun, invoke(proj, *first));
59  return {first, out};
60  }
61 
63  template(typename Rng, typename O, typename F, typename P = identity)(
64  requires input_range<Rng> AND weakly_incrementable<O> AND
65  copy_constructible<F> AND
66  indirectly_writable<O, indirect_result_t<F &, projected<iterator_t<Rng>, P>>>)
67  constexpr unary_transform_result<borrowed_iterator_t<Rng>, O> //
68  RANGES_FUNC(transform)(Rng && rng, O out, F fun, P proj = P{}) //
69  {
70  return (*this)(
71  begin(rng), end(rng), std::move(out), std::move(fun), std::move(proj));
72  }
73 
74  // Double-range variant, 4-iterator version
76  template(typename I0,
77  typename S0,
78  typename I1,
79  typename S1,
80  typename O,
81  typename F,
82  typename P0 = identity,
83  typename P1 = identity)(
84  requires input_iterator<I0> AND sentinel_for<S0, I0> AND
85  input_iterator<I1> AND sentinel_for<S1, I1> AND
86  weakly_incrementable<O> AND copy_constructible<F> AND
88  O,
89  indirect_result_t<F &, projected<I0, P0>, projected<I1, P1>>>)
90  constexpr binary_transform_result<I0, I1, O> //
91  RANGES_FUNC(transform)(I0 begin0,
92  S0 end0,
93  I1 begin1,
94  S1 end1,
95  O out,
96  F fun,
97  P0 proj0 = P0{},
98  P1 proj1 = P1{}) //
99  {
100  for(; begin0 != end0 && begin1 != end1; ++begin0, ++begin1, ++out)
101  *out = invoke(fun, invoke(proj0, *begin0), invoke(proj1, *begin1));
102  return {begin0, begin1, out};
103  }
104 
106  template(typename Rng0,
107  typename Rng1,
108  typename O,
109  typename F,
110  typename P0 = identity,
111  typename P1 = identity)(
112  requires input_range<Rng0> AND input_range<Rng1> AND
113  weakly_incrementable<O> AND copy_constructible<F> AND
115  O,
116  indirect_result_t<F &,
117  projected<iterator_t<Rng0>, P0>,
118  projected<iterator_t<Rng1>, P1>>>)
119  constexpr binary_transform_result<borrowed_iterator_t<Rng0>,
120  borrowed_iterator_t<Rng1>,
121  O> //
122  RANGES_FUNC(transform)(
123  Rng0 && rng0, Rng1 && rng1, O out, F fun, P0 proj0 = P0{}, P1 proj1 = P1{}) //
124  {
125  return (*this)(begin(rng0),
126  end(rng0),
127  begin(rng1),
128  end(rng1),
129  std::move(out),
130  std::move(fun),
131  std::move(proj0),
132  std::move(proj1));
133  }
134 
135  // Double-range variant, 3-iterator version
137  template(typename I0,
138  typename S0,
139  typename I1,
140  typename O,
141  typename F,
142  typename P0 = identity,
143  typename P1 = identity)(
144  requires input_iterator<I0> AND sentinel_for<S0, I0> AND
145  input_iterator<I1> AND weakly_incrementable<O> AND
146  copy_constructible<F> AND
148  O,
149  indirect_result_t<F &, projected<I0, P0>, projected<I1, P1>>>)
150  RANGES_DEPRECATED(
151  "Use the variant of ranges::transform that takes an upper bound "
152  "for both input ranges")
153  binary_transform_result<I0, I1, O> //
154  RANGES_FUNC(transform)(I0 begin0,
155  S0 end0,
156  I1 begin1,
157  O out,
158  F fun,
159  P0 proj0 = P0{},
160  P1 proj1 = P1{})
161  {
162  return (*this)(std::move(begin0),
163  std::move(end0),
164  std::move(begin1),
165  unreachable,
166  std::move(out),
167  std::move(fun),
168  std::move(proj0),
169  std::move(proj1));
170  }
171 
173  template(typename Rng0,
174  typename I1Ref,
175  typename O,
176  typename F,
177  typename P0 = identity,
178  typename P1 = identity)(
179  requires input_range<Rng0> AND input_iterator<uncvref_t<I1Ref>> AND
180  weakly_incrementable<O> AND copy_constructible<F> AND
182  O,
183  indirect_result_t<F &,
184  projected<iterator_t<Rng0>, P0>,
185  projected<uncvref_t<I1Ref>, P1>>>)
186  RANGES_DEPRECATED(
187  "Use the variant of ranges::transform that takes an upper bound "
188  "for both input ranges")
189  binary_transform_result<borrowed_iterator_t<Rng0>, uncvref_t<I1Ref>, O> //
190  RANGES_FUNC(transform)(Rng0 && rng0,
191  I1Ref && begin1,
192  O out,
193  F fun,
194  P0 proj0 = P0{},
195  P1 proj1 = P1{}) //
196  {
197  return (*this)(begin(rng0),
198  end(rng0),
199  static_cast<I1Ref &&>(begin1),
200  unreachable,
201  std::move(out),
202  std::move(fun),
203  std::move(proj0),
204  std::move(proj1));
205  }
206 
207  RANGES_FUNC_END(transform)
208 
209  namespace cpp20
210  {
211  using ranges::binary_transform_result;
212  using ranges::transform;
213  using ranges::unary_transform_result;
214  } // namespace cpp20
216 } // namespace ranges
217 
218 #include <range/v3/detail/epilogue.hpp>
219 
220 #endif
CPP_concept input_iterator
\concept input_iterator
Definition: concepts.hpp:362
CPP_concept indirectly_writable
\concept indirectly_writable
Definition: concepts.hpp:169
decltype(begin(declval(Rng &))) iterator_t
Definition: access.hpp:698
typename Fn::template invoke< Args... > invoke
Evaluate the invocable Fn with the arguments Args.
Definition: meta.hpp:541
front< Pair > first
Retrieve the first element of the pair Pair.
Definition: meta.hpp:2251
Tiny meta-programming library.
Definition: identity.hpp:25