Implement new serial algorithms from Parallelism TS (P0024R2)

These new (non-parallel) algorithms were added to C++17 along with the
parallel algorithms, but were missing from libstdc++.

	* include/bits/algorithmfwd.h: Change title of doc group.
	* include/bits/stl_algo.h (for_each_n): Add new C++17 algorithm from
	P0024R2.
	* include/bits/stl_numeric.h: Define doc group and add algos to it.
	* include/std/numeric (__is_random_access_iter): New internal trait.
	(reduce, transform_reduce, exclusive_scan, inclusive_scan)
	(transform_exclusive_scan, transform_inclusive_scan): Likewise.
	* testsuite/25_algorithms/for_each/for_each_n.cc: New test.
	* testsuite/26_numerics/exclusive_scan/1.cc: New test.
	* testsuite/26_numerics/inclusive_scan/1.cc: New test.
	* testsuite/26_numerics/reduce/1.cc: New test.
	* testsuite/26_numerics/transform_exclusive_scan/1.cc: New test.
	* testsuite/26_numerics/transform_inclusive_scan/1.cc: New test.
	* testsuite/26_numerics/transform_reduce/1.cc: New test.
	* testsuite/util/testsuite_iterators.h (test_container::size()): New
	member function.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@272459 138bc75d-0d04-0410-961f-82ee72b054a4

libstdc++-v3/ChangeLog

@@ -1,5 +1,22 @@
 2019-06-18  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/algorithmfwd.h: Change title of doc group.
+	* include/bits/stl_algo.h (for_each_n): Add new C++17 algorithm from
+	P0024R2.
+	* include/bits/stl_numeric.h: Define doc group and add algos to it.
+	* include/std/numeric (__is_random_access_iter): New internal trait.
+	(reduce, transform_reduce, exclusive_scan, inclusive_scan)
+	(transform_exclusive_scan, transform_inclusive_scan): Likewise.
+	* testsuite/25_algorithms/for_each/for_each_n.cc: New test.
+	* testsuite/26_numerics/exclusive_scan/1.cc: New test.
+	* testsuite/26_numerics/inclusive_scan/1.cc: New test.
+	* testsuite/26_numerics/reduce/1.cc: New test.
+	* testsuite/26_numerics/transform_exclusive_scan/1.cc: New test.
+	* testsuite/26_numerics/transform_inclusive_scan/1.cc: New test.
+	* testsuite/26_numerics/transform_reduce/1.cc: New test.
+	* testsuite/util/testsuite_iterators.h (test_container::size()): New
+	member function.
+
 	* include/c_global/cstddef (std::byte): Perform arithmetic operations
 	in unsigned int to avoid promotion (LWG 2950).
 

libstdc++-v3/include/bits/algorithmfwd.h

@@ -154,7 +154,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    */
 
   /**
-   * @defgroup set_algorithms Set Operation
+   * @defgroup set_algorithms Set Operations
    * @ingroup sorting_algorithms
    *
    * These algorithms are common set operations performed on sequences

libstdc++-v3/include/bits/stl_algo.h

@@ -3867,6 +3867,39 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       return __f; // N.B. [alg.foreach] says std::move(f) but it's redundant.
     }
 
+#if __cplusplus >= 201703L
+  /**
+   *  @brief Apply a function to every element of a sequence.
+   *  @ingroup non_mutating_algorithms
+   *  @param  __first  An input iterator.
+   *  @param  __n      A value convertible to an integer.
+   *  @param  __f      A unary function object.
+   *  @return   `__first+__n`
+   *
+   *  Applies the function object `__f` to each element in the range
+   *  `[first, first+n)`.  `__f` must not modify the order of the sequence.
+   *  If `__f` has a return value it is ignored.
+  */
+  template<typename _InputIterator, typename _Size, typename _Function>
+    _InputIterator
+    for_each_n(_InputIterator __first, _Size __n, _Function __f)
+    {
+      auto __n2 = std::__size_to_integer(__n);
+      using _Cat = typename iterator_traits<_InputIterator>::iterator_category;
+      if constexpr (is_base_of_v<random_access_iterator_tag, _Cat>)
+	return std::for_each(__first, __first + __n2, __f);
+      else
+	{
+	  while (__n2-->0)
+	    {
+	      __f(*__first);
+	      ++__first;
+	    }
+	  return __first;
+	}
+    }
+#endif // C++17
+
   /**
    *  @brief Find the first occurrence of a value in a sequence.
    *  @ingroup non_mutating_algorithms

libstdc++-v3/include/bits/stl_numeric.h

@@ -60,12 +60,16 @@
 #include <debug/debug.h>
 #include <bits/move.h> // For _GLIBCXX_MOVE
 
-#if __cplusplus >= 201103L
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+  /** @defgroup numeric_ops Generalized Numeric operations
+   *  @ingroup algorithms
+   */
+
+#if __cplusplus >= 201103L
   /**
    *  @brief  Create a range of sequentially increasing values.
    *
@@ -76,6 +80,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  @param  __last  End of range.
    *  @param  __value  Starting value.
    *  @return  Nothing.
+   *  @ingroup numeric_ops
    */
   template<typename _ForwardIterator, typename _Tp>
     void
@@ -94,14 +99,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  ++__value;
 	}
     }
+#endif
 
 _GLIBCXX_END_NAMESPACE_VERSION
-} // namespace std
 
-#endif
-
-namespace std _GLIBCXX_VISIBILITY(default)
-{
 _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
 #if __cplusplus > 201703L
@@ -112,6 +113,9 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 # define _GLIBCXX_MOVE_IF_20(_E) _E
 #endif
 
+  /// @addtogroup numeric_ops
+  /// @{
+
   /**
    *  @brief  Accumulate values in a range.
    *
@@ -139,8 +143,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
   /**
    *  @brief  Accumulate values in a range with operation.
    *
-   *  Accumulates the values in the range [first,last) using the function
-   *  object @p __binary_op.  The initial value is @p __init.  The values are
+   *  Accumulates the values in the range `[first,last)` using the function
+   *  object `__binary_op`.  The initial value is `__init`.  The values are
    *  processed in order.
    *
    *  @param  __first  Start of range.
@@ -390,6 +394,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       return ++__result;
     }
 
+  // @} group numeric_ops
+
 #undef _GLIBCXX_MOVE_IF_20
 
 _GLIBCXX_END_NAMESPACE_ALGO