我正在解析一个源代码文件,我想删除所有行注释(即以“//”开头)和多行注释(即/..../) .但是,如果多行注释中至少有一个换行符 (\n),我希望输出只有一个换行符。
例如代码:
qwe /* 123
456
789 */ asd
应该完全变成:
qwe
asd
而不是“qweasd”或:
qwe
asd
这样做的最佳方式是什么? 谢谢
编辑: 测试示例代码:
comments_test = "hello // comment\n"+\
"line 2 /* a comment */\n"+\
"line 3 /* a comment*/ /*comment*/\n"+\
"line 4 /* a comment\n"+\
"continuation of a comment*/ line 5\n"+\
"/* comment */line 6\n"+\
"line 7 /*********\n"+\
"********************\n"+\
"**************/\n"+\
"line ?? /*********\n"+\
"********************\n"+\
"********************\n"+\
"********************\n"+\
"********************\n"+\
"**************/\n"+\
"line ??"
预期结果:
hello
line 2
line 3
line 4
line 5
line 6
line 7
line ??
line ??
最佳答案
comment_re = re.compile(
r'(^)?[^\S\n]*/(?:\*(.*?)\*/[^\S\n]*|/[^\n]*)($)?',
re.DOTALL | re.MULTILINE
)
def comment_replacer(match):
start,mid,end = match.group(1,2,3)
if mid is None:
# single line comment
return ''
elif start is not None or end is not None:
# multi line comment at start or end of a line
return ''
elif '\n' in mid:
# multi line comment with line break
return '\n'
else:
# multi line comment without line break
return ' '
def remove_comments(text):
return comment_re.sub(comment_replacer, text)
(^)?
将匹配注释从行首开始的情况,只要使用MULTILINE
标志即可。[^\S\n]
将匹配除换行符之外的任何空白字符。如果评论从它自己的行开始,我们不想匹配换行符。/\*(.*?)\*/
将匹配多行注释并捕获内容。惰性匹配,因此我们不会匹配两个或多个评论。DOTALL
-flag 使.
匹配换行符。//[^\n]
将匹配单行注释。不能使用.
因为DOTALL
-flag.($)?
将在注释停在行尾时匹配,只要使用MULTILINE
标志即可。
例子:
>>> s = ("qwe /* 123\n"
"456\n"
"789 */ asd /* 123 */ zxc\n"
"rty // fgh\n")
>>> print '"' + '"\n"'.join(
... remove_comments(s).splitlines()
... ) + '"'
"qwe"
"asd zxc"
"rty"
>>> comments_test = ("hello // comment\n"
... "line 2 /* a comment */\n"
... "line 3 /* a comment*/ /*comment*/\n"
... "line 4 /* a comment\n"
... "continuation of a comment*/ line 5\n"
... "/* comment */line 6\n"
... "line 7 /*********\n"
... "********************\n"
... "**************/\n"
... "line ?? /*********\n"
... "********************\n"
... "********************\n"
... "********************\n"
... "********************\n"
... "**************/\n")
>>> print '"' + '"\n"'.join(
... remove_comments(comments_test).splitlines()
... ) + '"'
"hello"
"line 2"
"line 3 "
"line 4"
"line 5"
"line 6"
"line 7"
"line ??"
"line ??"
编辑:
- 更新到新规范。
- 添加了另一个示例。
关于Python 正则表达式问题 : stripping multi-line comments but maintaining a line break,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/844681/