ceph/src/boost/libs/range/doc/style.qbk

   1 [/
   2     Copyright 2010 Neil Groves
   3     Distributed under the Boost Software License, Version 1.0.
   4     (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5 /]
   6 [section:style_guide Terminology and style guidelines]
   7
   8 The use of a consistent terminology is as important for __ranges__ and range-based algorithms as it is for iterators and iterator-based algorithms. If a conventional set of names are adopted, we can avoid misunderstandings and write generic function prototypes that are [*/self-documenting/].
   9
  10 Since ranges are characterized by a specific underlying iterator type, we get a type of range for each type of iterator. Hence we can speak of the following types of ranges:
  11
  12 * [*/Value access/] category:
  13   * Readable Range
  14   * Writeable Range
  15   * Swappable Range
  16   * Lvalue Range
  17 * [*/Traversal/] category:
  18   * __single_pass_range__
  19   * __forward_range__
  20   * __bidirectional_range__
  21   * __random_access_range__
  22
  23 Notice how we have used the categories from the __new_style_iterators__.
  24
  25 Notice that an iterator (and therefore an range) has one [*/traversal/] property and one or more properties from the [*/value access/] category. So in reality we will mostly talk about mixtures such as
  26
  27 * Random Access Readable Writeable Range
  28 * Forward Lvalue Range
  29
  30 By convention, we should always specify the [*/traversal/] property first as done above. This seems reasonable since there will only be one [*/traversal/] property, but perhaps many [*/value access/] properties.
  31
  32 It might, however, be reasonable to specify only one category if the other category does not matter. For example, the __iterator_range__ can be constructed from a Forward Range. This means that we do not care about what [*/value access/] properties the Range has. Similarly, a Readable Range will be one that has the lowest possible [*/traversal/] property (Single Pass).
  33
  34 As another example, consider how we specify the interface of `std::sort()`. Algorithms are usually more cumbersome to specify the interface of since both [*/traversal/] and [*/value access/] properties must be exactly defined. The iterator-based version looks like this:
  35
  36 ``
  37    template< class RandomAccessTraversalReadableWritableIterator >
  38    void sort( RandomAccessTraversalReadableWritableIterator first,
  39               RandomAccessTraversalReadableWritableIterator last );
  40 ``
  41
  42 For ranges the interface becomes
  43
  44 ``
  45    template< class RandomAccessReadableWritableRange >
  46    void sort( RandomAccessReadableWritableRange& r );
  47 ``
  48
  49 [endsect]
  50