正则表达式查找C注释 [英] Regexp to find C comments

问题描述

我需要在Ruby中使用正则表达式才能在C指令之前找到注释.

I need a regexp in Ruby to find the comment before a C instruction.

例如，我有此文件example.c

/*
 * COMMENT NUMBER 1
 */
x = rb_define_class_under (foo, "MyClassName1", bar);

/*
 * COMMENT NUMBER 2
 */
y = rb_define_class_under (foo, "MyClassName2", bar);

/*
 * COMMENT NUMBER 3
 */
z = rb_define_class_under (foo, "MyClassName3", bar);

然后我将解析器放在ruby parser.rb中，如下所示:

Then I have my parser in ruby parser.rb like this:

content = File.open('example.c').read

if content =~ /((?>\/\*.*?\*\/))([\w\.\s]+\s=\s)?rb_define_class_under.*?"(MyClassName1)"/m
  puts "Comment number 1 is:"
  puts $1
end

if content =~ /((?>\/\*.*?\*\/))([\w\.\s]+\s=\s)?rb_define_class_under.*?"(MyClassName2)"/m
  puts "Comment number 2 is:"
  puts $1
end

if content =~ /((?>\/\*.*?\*\/))([\w\.\s]+\s=\s)?rb_define_class_under.*?"(MyClassName3)"/m
  puts "Comment number 3 is:"
  puts $1
end

现在我期望的输出是这样:

Now the output I expect is this:

Comment number 1 is:
/*
 * COMMENT NUMBER 1
 */
Comment number 2 is:
/*
 * COMMENT NUMBER 2
 */
Comment number 3 is:
/*
 * COMMENT NUMBER 3
 */

但是我得到了

Comment number 1 is:
/*
 * COMMENT NUMBER 1
 */
Comment number 2 is:
/*
 * COMMENT NUMBER 1
 */
Comment number 3 is:
/*
 * COMMENT NUMBER 1
 */

有什么主意吗?什么是正确的正则表达式以获取预期的输出?

Any idea? What is the right regexp to get the expected output?

推荐答案

尝试将.*添加到正则表达式的开头.

Try adding .* to the beginning of the regex.

当前，正则表达式中rb_define_class_under之后的.*?会导致您始终匹配并捕获字符串的第一部分，并且.*?会一直匹配，直到您真正要查找的类名为止.

Currently the .*? after rb_define_class_under in your regex is causing you to always match and capture the first part of the string, and the .*? matches up until the class name you are actually looking for.

通过在正则表达式的开头添加贪婪的匹配项，可以确保仅在想要的类名之前的最后一个/*处开始捕获组.

By adding a greedy match at the beginning of the regex you make sure that you only start your capture group at the last /* before the class name you want.

示例: http://www.rubular.com/r/Orja089zAI

请注意，您仍然从字符串的开头开始进行匹配，但是第一个捕获组是正确的注释.

Note that you still match from the beginning of the string, but the first capture group is the correct comment.

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