Regular Expression Question

Question

I'm trying to use regular expression to extract the comments in the heading of a file.

For example, the source code may look like:

//This is an example file.
//Please help me.

#include "test.h"
int main() //main function
{
  ...
}

What I want to extract from the code are the first two lines, i.e.

//This is an example file.
//Please help me.

Any idea?

Answer 1

>>> code="""//This is an example file.
... //Please help me.
...
... #include "test.h"
... int main() //main function
... {
...   ...
... }
... """
>>>
>>> import re
>>> re.findall("^\s*//.*",code,re.MULTILINE)
['//This is an example file.', '//Please help me.']
>>>

If you only need to match continuous comment lines at the top, you could use following.

>>> re.search("^((?:\s*//.*\n)+)",code).group().strip().split("\n")
['//This is an example file.', '//Please help me.']
>>>

Answer 2

Why use regex?

>>> f = file('/tmp/source')
>>> for line in f.readlines():
...    if not line.startswith('//'):
...       break
...    print line
... 

Answer 3

this doesn't just get the first 2 comment lines, but mulitline and // comments at the back as well. Its not what you required though.

data=open("file").read()
for c in data.split("*/"):
    # multiline
    if "/*" in c:
       print ''.join(c.split("/*")[1:])
    if "//" in c:
       for item in c.split("\n"):
          if "//" in c:
             print ''.join(item.split("//")[1:])

Answer 4

to extend the context into below considerations

1. spaces in front of //...
2. empty lines between each //... line

---

import re

code = """//This is an example file.    
 a
   //  Please help me.

//  ha

#include "test.h"
int main() //main function
{
  ...
}"""

for s in re.finditer(r"^(\s*)(//.*)",code,re.MULTILINE):
    print(s.group(2))

>>>
//This is an example file.    
//  Please help me.
//  ha