re.compile versus r''
Hello, I'm using a tool (PLY) which apparently expects the tokens to
be created using r''
But because one token is a rather complex regular expression, I want
to create the regular expression programmatically.
How can I generate a string and then create something of the same type
that the r'' function does?
Concretely, in the program below, consonant is not the same type as
t_NAME, but I assume that it needs to be for PLY to use it for
tokenizing:
import re
t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'
guttural = 'kh?|gh?|\n'
palatal= '(?:chh?|jh?|\~n)'
cerebral = '\.(?:th?|dh?|n)'
dental = '(?:th?|dh?|n)'
semivowel = '[yrlv]'
sibilant = '[\\.]?s'
aspirant = 'h'
consonant = re.compile('|'.join([guttural , palatal , cerebral ,
dental , semivowel , sibilant , aspirant]))
print consonant
print t_NAME
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Re: re.compile versus r''
Oh my god, how embarrassing. the r'' notation is to create raw string http://www.swc.scipy.org/lec/glossary.html#gdef-raw_string I thought it was some form of blessing a string into a regular expression class. -- http://mail.python.org/mailman/listinfo/python-list
Re: re.compile versus r''
Terrence Brannon wrote: Hello, I'm using a tool (PLY) which apparently expects the tokens to be created using r'' But because one token is a rather complex regular expression, I want to create the regular expression programmatically. How can I generate a string and then create something of the same type that the r'' function does? r'' is an alternative syntax for string literals that affects how escape sequences are interpreted; there's no separate string type for strings created by this syntax. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: re.compile versus r''
On Thu, Aug 28, 2008 at 12:23 PM, Terrence Brannon [EMAIL PROTECTED] wrote:
Hello, I'm using a tool (PLY) which apparently expects the tokens to
be created using r''
But because one token is a rather complex regular expression, I want
to create the regular expression programmatically.
How can I generate a string and then create something of the same type
that the r'' function does?
The r prefix isn't a function or a type, it's merely a special
literal syntax for strings that's handy when you're writing regexes
and therefore have to deal with another level of backslash escaping.
See the second to last paragraph of
http://docs.python.org/ref/strings.html for more info.
Regards,
Chris
Concretely, in the program below, consonant is not the same type as
t_NAME, but I assume that it needs to be for PLY to use it for
tokenizing:
import re
t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'
guttural = 'kh?|gh?|\n'
palatal= '(?:chh?|jh?|\~n)'
cerebral = '\.(?:th?|dh?|n)'
dental = '(?:th?|dh?|n)'
semivowel = '[yrlv]'
sibilant = '[\\.]?s'
aspirant = 'h'
consonant = re.compile('|'.join([guttural , palatal , cerebral ,
dental , semivowel , sibilant , aspirant]))
print consonant
print t_NAME
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