Merge 2022-07 LWG Motion 8

P1223R5 find_last

Author: tkoeppe

source/algorithms.tex

@@ -780,6 +780,29 @@
         find_if_not(R&& r, Pred pred, Proj proj = {});
   }
 
+  // \ref{alg.find.last}, find last
+  namespace ranges {
+    template<@\libconcept{forward_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class T, class Proj = identity>
+      requires @\libconcept{indirect_binary_predicate}@<ranges::equal_to, projected<I, Proj>, const T*>
+      constexpr subrange<I> find_last(I first, S last, const T& value, Proj proj = {});
+    template<@\libconcept{forward_range}@ R, class T, class Proj = identity>
+      requires
+        @\libconcept{indirect_binary_predicate}@<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
+      constexpr borrowed_subrange_t<R> find_last(R&& r, const T& value, Proj proj = {});
+    template<@\libconcept{forward_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class Proj = identity,
+             @\libconcept{indirect_unary_predicate}@<projected<I, Proj>> Pred>
+      constexpr subrange<I> find_last_if(I first, S last, Pred pred, Proj proj = {});
+    template<@\libconcept{forward_range}@ R, class Proj = identity,
+             @\libconcept{indirect_unary_predicate}@<projected<iterator_t<R>, Proj>> Pred>
+      constexpr borrowed_subrange_t<R> find_last_if(R&& r, Pred pred, Proj proj = {});
+    template<@\libconcept{forward_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class Proj = identity,
+             @\libconcept{indirect_unary_predicate}@<projected<I, Proj>> Pred>
+      constexpr subrange<I> find_last_if_not(I first, S last, Pred pred, Proj proj = {});
+    template<@\libconcept{forward_range}@ R, class Proj = identity,
+             @\libconcept{indirect_unary_predicate}@<projected<iterator_t<R>, Proj>> Pred>
+      constexpr borrowed_subrange_t<R> find_last_if_not(R&& r, Pred pred, Proj proj = {});
+  }
+
   // \ref{alg.find.end}, find end
   template<class ForwardIterator1, class ForwardIterator2>
     constexpr ForwardIterator1
@@ -3514,6 +3537,55 @@
 of the corresponding predicate and any projection.
 \end{itemdescr}
 
+\rSec2[alg.find.last]{Find last}
+
+\indexlibraryglobal{find_last}%
+\begin{itemdecl}
+template<@\libconcept{forward_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class T, class Proj = identity>
+  requires @\libconcept{indirect_binary_predicate}@<ranges::equal_to, projected<I, Proj>, const T*>
+  constexpr subrange<I> ranges::find_last(I first, S last, const T& value, Proj proj = {});
+template<@\libconcept{forward_range}@ R, class T, class Proj = identity>
+  requires @\libconcept{indirect_binary_predicate}@<ranges::equal_to, projected<iterator_t<R>, Proj>, const T*>
+  constexpr borrowed_subrange_t<R> ranges::find_last(R&& r, const T& value, Proj proj = {});
+template<@\libconcept{forward_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class Proj = identity,
+         @\libconcept{indirect_unary_predicate}@<projected<I, Proj>> Pred>
+  constexpr subrange<I> ranges::find_last_if(I first, S last, Pred pred, Proj proj = {});
+template<@\libconcept{forward_range}@ R, class Proj = identity,
+         @\libconcept{indirect_unary_predicate}@<projected<iterator_t<R>, Proj>> Pred>
+  constexpr borrowed_subrange_t<R> ranges::find_last_if(R&& r, Pred pred, Proj proj = {});
+template<@\libconcept{forward_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class Proj = identity,
+         @\libconcept{indirect_unary_predicate}@<projected<I, Proj>> Pred>
+  constexpr subrange<I> ranges::find_last_if_not(I first, S last, Pred pred, Proj proj = {});
+template<@\libconcept{forward_range}@ R, class Proj = identity,
+         @\libconcept{indirect_unary_predicate}@<projected<iterator_t<R>, Proj>> Pred>
+  constexpr borrowed_subrange_t<R> ranges::find_last_if_not(R&& r, Pred pred, Proj proj = {});
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let $E$ be:
+\begin{itemize}
+\item
+\tcode{bool(invoke(proj, *i) == value)} for \tcode{ranges::find_last};
+\item
+\tcode{bool(invoke(pred, invoke(proj, *i)))} for \tcode{ranges::find_last_if};
+\item
+\tcode{bool(!invoke(pred, invoke(proj, *i)))} for \tcode{ranges::find_last_if_not}.
+\end{itemize}
+
+\pnum
+\returns
+Let \tcode{i} be the last iterator in the range \range{first}{last}
+for which $E$ is \tcode{true}.
+Returns \tcode{\{i, last\}}, or
+\tcode{\{last, last\}} if no such iterator is found.
+
+\pnum
+\complexity
+At most \tcode{last - first} applications of
+the corresponding predicate and projection.
+\end{itemdescr}
+
 \rSec2[alg.find.end]{Find end}
 
 \indexlibraryglobal{find_end}%

source/support.tex

@@ -616,6 +616,7 @@
 #define @\defnlibxname{cpp_lib_execution}@                         201902L // also in \libheader{execution}
 #define @\defnlibxname{cpp_lib_expected}@                          202202L // also in \libheader{expected}
 #define @\defnlibxname{cpp_lib_filesystem}@                        201703L // also in \libheader{filesystem}
+#define @\defnlibxname{cpp_lib_find_last}@                         202207L // also in \libheader{algorithm}
 #define @\defnlibxname{cpp_lib_flat_map}@                          202207L // also in \libheader{flat_map}
 #define @\defnlibxname{cpp_lib_format}@                            202110L // also in \libheader{format}
 #define @\defnlibxname{cpp_lib_gcd_lcm}@                           201606L // also in \libheader{numeric}