ceph/src/boost/libs/iterator/doc/facade_iterator_category.rst

   1 .. |iterator-category| replace:: *iterator-category*
   2 .. _iterator-category:
   3
   4 .. parsed-literal::
   5
   6   *iterator-category*\ (C,R,V) :=
   7      if (C is convertible to std::input_iterator_tag
   8          || C is convertible to std::output_iterator_tag
   9      )
  10          return C
  11
  12      else if (C is not convertible to incrementable_traversal_tag)
  13          *the program is ill-formed*
  14
  15      else return a type X satisfying the following two constraints:
  16
  17         1. X is convertible to X1, and not to any more-derived
  18            type, where X1 is defined by:
  19
  20              if (R is a reference type
  21                  && C is convertible to forward_traversal_tag)
  22              {
  23                  if (C is convertible to random_access_traversal_tag)
  24                      X1 = random_access_iterator_tag
  25                  else if (C is convertible to bidirectional_traversal_tag)
  26                      X1 = bidirectional_iterator_tag
  27                  else
  28                      X1 = forward_iterator_tag
  29              }
  30              else
  31              {
  32                  if (C is convertible to single_pass_traversal_tag
  33                      && R is convertible to V)
  34                      X1 = input_iterator_tag
  35                  else
  36                      X1 = C
  37              }
  38
  39         2. |category-to-traversal|_\ (X) is convertible to the most
  40            derived traversal tag type to which X is also
  41            convertible, and not to any more-derived traversal tag
  42            type.
  43
  44 .. |category-to-traversal| replace:: *category-to-traversal*
  45 .. _`category-to-traversal`: new-iter-concepts.html#category-to-traversal
  46
  47 [Note: the intention is to allow ``iterator_category`` to be one of
  48 the five original category tags when convertibility to one of the
  49 traversal tags would add no information]
  50
  51 .. Copyright David Abrahams 2004. Use, modification and distribution is
  52 .. subject to the Boost Software License, Version 1.0. (See accompanying
  53 .. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)