take_while.hpp 7.1 KB

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  1. /// \file
  2. // Range v3 library
  3. //
  4. // Copyright Eric Niebler 2013-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_VIEW_TAKE_WHILE_HPP
  14. #define RANGES_V3_VIEW_TAKE_WHILE_HPP
  15. #include <type_traits>
  16. #include <utility>
  17. #include <meta/meta.hpp>
  18. #include <range/v3/range_fwd.hpp>
  19. #include <range/v3/functional/bind_back.hpp>
  20. #include <range/v3/functional/compose.hpp>
  21. #include <range/v3/functional/indirect.hpp>
  22. #include <range/v3/functional/invoke.hpp>
  23. #include <range/v3/iterator/concepts.hpp>
  24. #include <range/v3/range/concepts.hpp>
  25. #include <range/v3/utility/semiregular_box.hpp>
  26. #include <range/v3/utility/static_const.hpp>
  27. #include <range/v3/view/adaptor.hpp>
  28. #include <range/v3/view/view.hpp>
  29. #include <range/v3/detail/prologue.hpp>
  30. namespace ranges
  31. {
  32. /// \addtogroup group-views
  33. /// @{
  34. template<typename Rng, typename Pred>
  35. struct iter_take_while_view
  36. : view_adaptor<iter_take_while_view<Rng, Pred>, Rng,
  37. is_finite<Rng>::value ? finite : unknown>
  38. {
  39. private:
  40. friend range_access;
  41. RANGES_NO_UNIQUE_ADDRESS semiregular_box_t<Pred> pred_;
  42. template<bool IsConst>
  43. struct sentinel_adaptor : adaptor_base
  44. {
  45. private:
  46. friend struct sentinel_adaptor<!IsConst>;
  47. using CRng = meta::const_if_c<IsConst, Rng>;
  48. RANGES_NO_UNIQUE_ADDRESS semiregular_box_ref_or_val_t<Pred, IsConst> pred_;
  49. public:
  50. sentinel_adaptor() = default;
  51. sentinel_adaptor(semiregular_box_ref_or_val_t<Pred, IsConst> pred)
  52. : pred_(std::move(pred))
  53. {}
  54. template(bool Other)(
  55. requires IsConst AND CPP_NOT(Other)) //
  56. sentinel_adaptor(sentinel_adaptor<Other> that)
  57. : pred_(std::move(that.pred_))
  58. {}
  59. bool empty(iterator_t<CRng> const & it, sentinel_t<CRng> const & last) const
  60. {
  61. return it == last || !invoke(pred_, it);
  62. }
  63. };
  64. sentinel_adaptor<false> end_adaptor()
  65. {
  66. return {pred_};
  67. }
  68. template(bool Const = true)(
  69. requires Const AND range<meta::const_if_c<Const, Rng>> AND
  70. invocable<Pred const &, iterator_t<meta::const_if_c<Const, Rng>>>)
  71. sentinel_adaptor<Const> end_adaptor() const
  72. {
  73. return {pred_};
  74. }
  75. public:
  76. iter_take_while_view() = default;
  77. constexpr iter_take_while_view(Rng rng, Pred pred)
  78. : iter_take_while_view::view_adaptor{std::move(rng)}
  79. , pred_(std::move(pred))
  80. {}
  81. };
  82. template<typename Rng, typename Pred>
  83. struct take_while_view : iter_take_while_view<Rng, indirected<Pred>>
  84. {
  85. take_while_view() = default;
  86. constexpr take_while_view(Rng rng, Pred pred)
  87. : iter_take_while_view<Rng, indirected<Pred>>{std::move(rng),
  88. indirect(std::move(pred))}
  89. {}
  90. };
  91. #if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
  92. template(typename Rng, typename Fun)(
  93. requires copy_constructible<Fun>)
  94. take_while_view(Rng &&, Fun)
  95. -> take_while_view<views::all_t<Rng>, Fun>;
  96. #endif
  97. namespace views
  98. {
  99. struct iter_take_while_base_fn
  100. {
  101. template(typename Rng, typename Pred)(
  102. requires viewable_range<Rng> AND input_range<Rng> AND
  103. predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
  104. constexpr iter_take_while_view<all_t<Rng>, Pred> //
  105. operator()(Rng && rng, Pred pred) const
  106. {
  107. return {all(static_cast<Rng &&>(rng)), std::move(pred)};
  108. }
  109. };
  110. struct iter_take_while_fn : iter_take_while_base_fn
  111. {
  112. using iter_take_while_base_fn::operator();
  113. template<typename Pred>
  114. constexpr auto operator()(Pred pred) const
  115. {
  116. return make_view_closure(
  117. bind_back(iter_take_while_base_fn{}, std::move(pred)));
  118. }
  119. };
  120. struct take_while_base_fn
  121. {
  122. template(typename Rng, typename Pred)(
  123. requires viewable_range<Rng> AND input_range<Rng> AND
  124. indirect_unary_predicate<Pred &, iterator_t<Rng>>)
  125. constexpr take_while_view<all_t<Rng>, Pred> //
  126. operator()(Rng && rng, Pred pred) const
  127. {
  128. return {all(static_cast<Rng &&>(rng)), std::move(pred)};
  129. }
  130. template(typename Rng, typename Pred, typename Proj)(
  131. requires viewable_range<Rng> AND input_range<Rng> AND
  132. indirect_unary_predicate<composed<Pred, Proj> &, iterator_t<Rng>>)
  133. constexpr take_while_view<all_t<Rng>, composed<Pred, Proj>> //
  134. operator()(Rng && rng, Pred pred, Proj proj) const
  135. {
  136. return {all(static_cast<Rng &&>(rng)),
  137. compose(std::move(pred), std::move(proj))};
  138. }
  139. };
  140. struct take_while_bind_fn
  141. {
  142. template<typename Pred>
  143. constexpr auto operator()(Pred pred) const // TODO: underconstrained
  144. {
  145. return make_view_closure(
  146. bind_back(take_while_base_fn{}, std::move(pred)));
  147. }
  148. template(typename Pred, typename Proj)(
  149. requires (!range<Pred>)) // TODO: underconstrained
  150. constexpr auto operator()(Pred && pred, Proj proj) const
  151. {
  152. return make_view_closure(bind_back(
  153. take_while_base_fn{}, static_cast<Pred &&>(pred), std::move(proj)));
  154. }
  155. };
  156. struct RANGES_EMPTY_BASES take_while_fn
  157. : take_while_base_fn, take_while_bind_fn
  158. {
  159. using take_while_base_fn::operator();
  160. using take_while_bind_fn::operator();
  161. };
  162. /// \relates iter_take_while_fn
  163. /// \ingroup group-views
  164. RANGES_INLINE_VARIABLE(iter_take_while_fn, iter_take_while)
  165. /// \relates take_while_fn
  166. /// \ingroup group-views
  167. RANGES_INLINE_VARIABLE(take_while_fn, take_while)
  168. } // namespace views
  169. namespace cpp20
  170. {
  171. namespace views
  172. {
  173. using ranges::views::take_while;
  174. }
  175. template(typename Rng, typename Pred)(
  176. requires viewable_range<Rng> AND input_range<Rng> AND
  177. predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
  178. using take_while_view = ranges::take_while_view<Rng, Pred>;
  179. } // namespace cpp20
  180. /// @}
  181. } // namespace ranges
  182. #include <range/v3/detail/epilogue.hpp>
  183. #include <range/v3/detail/satisfy_boost_range.hpp>
  184. RANGES_SATISFY_BOOST_RANGE(::ranges::iter_take_while_view)
  185. RANGES_SATISFY_BOOST_RANGE(::ranges::take_while_view)
  186. #endif