当前位置：文江博客话题详情

如何在大C++中找到所有相互的友谊源树？

发布于 2024-10-06 14:22:11 字数 122 浏览 3 评论 0原文

在一个大型 C++ 源代码树中，定义了大约 600 个左右的类，我想找到所有类对，其中每个类都将另一个类声明为友元。

有很多情况下，一个类是另一个类的朋友，太多了，以至于不值得费力地浏览一个简单的 grep 结果。

原文

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

你好，陌生人 2024-10-13 14:22:11

你可以在这里实现一种三重循环；算法可以如下：

第一个循环：找到所有有朋友的班级，并记住朋友的名字和实际班级的名字；
然后对所有类运行内部循环，并找到一个具有步骤 1 中朋友名称的类。
然后对步骤 2 中找到的类的所有朋友运行另一个内部循环。如果您找到了具有步骤 1 中名称的类 -瞧——他们是共同的朋友。

我相信 Perl 和正则表达式是处理此类事情的最佳工具。

PS 当然这种方法有其局限性，因为并不是 C++ 中的所有内容都可以用正则表达式进行解析（using namespace 是我首先想到的东西）。但是，在某种程度上，这是可行的方法，如果你没有其他选择，你可以尝试一下。

编辑：
今天早上，当我还躺在床上时，我突然想到了一个想法。 :) 这个想法非常简单明了（就像所有早上的想法一样）：使用 SQL！当然，假设您有一个包含 2 列的类表，其中第一列是类名，第二列是它的朋友的名字。比如说：

ClassName FriendName
C1        C2
C1        C3
C1        C4
C2        C1
C2        C8
C3        C1
C3        C2
...       ...

然后您可以对其运行一个简单的查询。比如说，类似这样的事情（抱歉，我手边没有任何 SQL 数据库，所以没有检查查询，但我希望你能明白并根据需要实现它：

SELECT ClassName as c, FriendName as f FROM T
WHERE c in 
  (SELECT FriendName FROM T
     WHERE FriendName = c AND ClassName = f)

这个变体背后的想法是我们应该使用当您需要处理某些数据集时，有什么可以与 SQL 相比呢？

You could implement a kind of triple loop here; the algorithm could be as follows:

First loop: find all classes who have friends, and remember the name of the friend and the name of the actual class;
Then run inner loop for all the classes and find a class with the name of the friend from step 1.
Then run another inner loop through all the friends of the class found at step 2. If you have found class with name from step 1 - voila - they're mutual friends.

I believe Perl and regexes are the best tools for such things.

P.S. sure this approach has its limits, because not everything in C++ could be parsed with regex (using namespace stuff is the first thing came into my mind). But, to some extent, this is working approach, and if you don't have alternatives, you could give it a try.

EDIT:
An idea came to my mind today in the morning, while I still was lying in my bed. :) The idea is quite simple and clear (like all morning ideas): use SQL! Naturally, imagine you have a table of classes with 2 columns, where first column is class name, and second column is it's friend`s name. Say, something like this:

ClassName FriendName
C1        C2
C1        C3
C1        C4
C2        C1
C2        C8
C3        C1
C3        C2
...       ...

Then you can run a simple query against it. Say, something like this (sorry, I don't have any SQL DB handy, so have not checked the query, but I hope you'll got the idea and implement it as needed:

SELECT ClassName as c, FriendName as f FROM T
WHERE c in 
  (SELECT FriendName FROM T
     WHERE FriendName = c AND ClassName = f)

The idea behind this variant is that we should employ those tolls which exactly fit the task. What can compare to SQL when you need to crunch some sets of data?

回复收藏 0 原文

情徒 2024-10-13 14:22:11

I) 一些优雅的方法：

1) Doxygen ( http://www.doxygen.nl/ ) 可能是能够给你你所需要的。（如果它还没有提供此信息，您可以稍微修改 Doxygen 的 C++ 解析器以获得您需要的信息）。

2) C++ 也有现有的 ANTLR 语法文件。

II）更快的方法（也许是正确的方法）：

正如其他人建议的那样，正则表达式应该适合您的目的。考虑以下伪代码：

rm -f result_file;
foreach source_file
do
  sed 's/[ \t\n]\+/ /g' $source_file >  temp_file;  ## remove newlines, etc
  grep -o -P -i "friend [^;]*;"  >> result_file; ## you can improve this regex for eliminating some possible unwanted matches or post-process result_file later
done

现在您在 result_file 中拥有所有好友关系。您可以使用另一个简单的正则表达式删除“友元函数”和/或根据需要进一步处理 result_file 。

I) Some elegant ways:

1) Doxygen ( http://www.doxygen.nl/ ) might be able to give you what you need. (If it doesn't already give this information, you could hack Doxygen's C++ parser a bit to get what you need).

2) There are also existing ANTLR grammar files for C++ as well.

II) Quicker way (perhaps the right approach here):

Regex should just be fine for your purpose as others suggest. Consider the following pseudo code:

rm -f result_file;
foreach source_file
do
  sed 's/[ \t\n]\+/ /g' $source_file >  temp_file;  ## remove newlines, etc
  grep -o -P -i "friend [^;]*;"  >> result_file; ## you can improve this regex for eliminating some possible unwanted matches or post-process result_file later
done

Now you have all friend relations in result_file. You can remove "friend functions" using another simple regex and/or process the result_file further as per needs.

回复收藏 0 原文