Implement resolutions of LWG 2399, 2400 and 2401.

[gcc.git] / libstdc++-v3 / include / bits / stl_algo.h

diff --git a/libstdc++-v3/include/bits/stl_algo.h b/libstdc++-v3/include/bits/stl_algo.h
index f2dfc208ce5a9b531366d8b73a6315a41692c422..0ce73c1bbb3fd7d80dd29eb3742ab164fceb5b93 100644 (file)
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -1511,34 +1511,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // partition
 
-  /// This is a helper function...
-  /// Requires __len != 0 and !__pred(*__first),
-  /// same as __stable_partition_adaptive.
-  template<typename _ForwardIterator, typename _Predicate, typename _Distance>
-    _ForwardIterator
-    __inplace_stable_partition(_ForwardIterator __first,
-                              _Predicate __pred, _Distance __len)
-    {
-      if (__len == 1)
-       return __first;
-      _ForwardIterator __middle = __first;
-      std::advance(__middle, __len / 2);
-      _ForwardIterator __left_split =
-       std::__inplace_stable_partition(__first, __pred, __len / 2);
-      // Advance past true-predicate values to satisfy this
-      // function's preconditions.
-      _Distance __right_len = __len - __len / 2;
-      _ForwardIterator __right_split =
-       std::__find_if_not_n(__middle, __right_len, __pred);
-      if (__right_len)
-       __right_split = std::__inplace_stable_partition(__middle,
-                                                       __pred,
-                                                       __right_len);
-      std::rotate(__left_split, __middle, __right_split);
-      std::advance(__left_split, std::distance(__middle, __right_split));
-      return __left_split;
-    }
-
   /// This is a helper function...
   /// Requires __first != __last and !__pred(__first)
   /// and __len == distance(__first, __last).
@@ -1554,10 +1526,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                _Pointer __buffer,
                                _Distance __buffer_size)
     {
+      if (__len == 1)
+       return __first;
+
       if (__len <= __buffer_size)
        {
          _ForwardIterator __result1 = __first;
          _Pointer __result2 = __buffer;
+
          // The precondition guarantees that !__pred(__first), so
          // move that element to the buffer before starting the loop.
          // This ensures that we only call __pred once per element.
@@ -1575,31 +1551,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                *__result2 = _GLIBCXX_MOVE(*__first);
                ++__result2;
              }
+
          _GLIBCXX_MOVE3(__buffer, __result2, __result1);
          return __result1;
        }
-      else
-       {
-         _ForwardIterator __middle = __first;
-         std::advance(__middle, __len / 2);
-         _ForwardIterator __left_split =
-           std::__stable_partition_adaptive(__first, __middle, __pred,
-                                            __len / 2, __buffer,
-                                            __buffer_size);
-         // Advance past true-predicate values to satisfy this
-         // function's preconditions.
-         _Distance __right_len = __len - __len / 2;
-         _ForwardIterator __right_split =
-           std::__find_if_not_n(__middle, __right_len, __pred);
-         if (__right_len)
-           __right_split =
-             std::__stable_partition_adaptive(__right_split, __last, __pred,
-                                              __right_len,
-                                              __buffer, __buffer_size);
-         std::rotate(__left_split, __middle, __right_split);
-         std::advance(__left_split, std::distance(__middle, __right_split));
-         return __left_split;
-       }
+
+      _ForwardIterator __middle = __first;
+      std::advance(__middle, __len / 2);
+      _ForwardIterator __left_split =
+       std::__stable_partition_adaptive(__first, __middle, __pred,
+                                        __len / 2, __buffer,
+                                        __buffer_size);
+
+      // Advance past true-predicate values to satisfy this
+      // function's preconditions.
+      _Distance __right_len = __len - __len / 2;
+      _ForwardIterator __right_split =
+       std::__find_if_not_n(__middle, __right_len, __pred);
+
+      if (__right_len)
+       __right_split =
+         std::__stable_partition_adaptive(__right_split, __last, __pred,
+                                          __right_len,
+                                          __buffer, __buffer_size);
+
+      std::rotate(__left_split, __middle, __right_split);
+      std::advance(__left_split, std::distance(__middle, __right_split));
+      return __left_split;
     }
 
   template<typename _ForwardIterator, typename _Predicate>
@@ -1618,16 +1596,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        _DistanceType;
 
       _Temporary_buffer<_ForwardIterator, _ValueType> __buf(__first, __last);
-      if (__buf.size() > 0)
-       return
-         std::__stable_partition_adaptive(__first, __last, __pred,
-                                          _DistanceType(__buf.requested_size()),
-                                          __buf.begin(),
-                                          _DistanceType(__buf.size()));
-      else
-       return
-         std::__inplace_stable_partition(__first, __pred,
-                                         _DistanceType(__buf.requested_size()));
+      return
+       std::__stable_partition_adaptive(__first, __last, __pred,
+                                        _DistanceType(__buf.requested_size()),
+                                        __buf.begin(),
+                                        _DistanceType(__buf.size()));
     }
 
   /**
@@ -2471,6 +2444,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                     __gnu_cxx::__ops::__val_comp_iter(__comp));
              __len11 = std::distance(__first, __first_cut);
            }
+
          _BidirectionalIterator __new_middle
            = std::__rotate_adaptive(__first_cut, __middle, __second_cut,
                                     __len1 - __len11, __len22, __buffer,
@@ -2496,12 +2470,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       if (__len1 == 0 || __len2 == 0)
        return;
+
       if (__len1 + __len2 == 2)
        {
          if (__comp(__middle, __first))
            std::iter_swap(__first, __middle);
          return;
        }
+
       _BidirectionalIterator __first_cut = __first;
       _BidirectionalIterator __second_cut = __middle;
       _Distance __len11 = 0;
@@ -2524,6 +2500,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                                 __gnu_cxx::__ops::__val_comp_iter(__comp));
          __len11 = std::distance(__first, __first_cut);
        }
+
       std::rotate(__first_cut, __middle, __second_cut);
       _BidirectionalIterator __new_middle = __first_cut;
       std::advance(__new_middle, std::distance(__middle, __second_cut));