73ef4ff3
 Hu Chunming
提交三方库
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
[/
Copyright 2010 Neil Groves
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:style_guide Terminology and style guidelines]
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/].
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:
* [*/Value access/] category:
* Readable Range
* Writeable Range
* Swappable Range
* Lvalue Range
* [*/Traversal/] category:
* __single_pass_range__
* __forward_range__
* __bidirectional_range__
* __random_access_range__
Notice how we have used the categories from the __new_style_iterators__.
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
* Random Access Readable Writeable Range
* Forward Lvalue Range
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.
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).
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:
``
template< class RandomAccessTraversalReadableWritableIterator >
void sort( RandomAccessTraversalReadableWritableIterator first,
RandomAccessTraversalReadableWritableIterator last );
``
For ranges the interface becomes
``
template< class RandomAccessReadableWritableRange >
void sort( RandomAccessReadableWritableRange& r );
``
[endsect]
|
