Re: [Pyparsing] escape sequence in identifieres - with inline sourcecode

[Diez B. R. <de...@we...>]

Hi,

I somehow lost the mail by Denis, so I quote it by hand here, hope that works:

> (Not really sure about your intent.)

My intent is to simply parse a string like this:

  div . class\.name

as 

 tag[div], class[class.name]

instead of 

 tag[div], class[class], class[name]

For this to happen, I need to special-case escape-codes beginning with \ so 
that they are *not* treated as  identifier followed by a dot, but instead 
always group the two characters "\." together.

> You seem to be using pyparsing features rather strangely.
> The 'Word' pattern type allows defining distinct patterns for start and ( >
> optional) following characters. Both are character _classes_. You could use  
> it like:

> nameStartChar = ...
> nameFollowingChar = ...
> name = Word(nameStartChar,nameFollowingChar)

> If you want to generalize name to include a dotted format, then rename the
> above to namePart and write a pattern including dots.


I'm not sure what you mean by this, nor if it helps me. I try to come up with 
a more concise example, here it is:

from pyparsing import *

nmstart = Word(srange(r"[\\_a-zA-Z]")) # |{nonascii}|{escape}
name = OneOrMore(Word(srange(r"[\\A-Z_a-z0-9]"))) # TODO: nonascii &  

ident = nmstart + ZeroOrMore(name)

#ident = Word(srange(r"[_a-zA-Z]"), srange(r"[A-Z_a-z0-9]"))

MINUS = Literal("-")
IDENT = Combine(Optional(MINUS) + ident, adjacent=True) # TODO

DOT = Literal(".")
ASTERISK = Literal("*")

class_ = Combine(DOT + IDENT)
element_name = IDENT | ASTERISK

selector = (element_name + (ZeroOrMore( class_ )) |
            OneOrMore( class_ ))


print selector.parseString(r"foo.bar")
print selector.parseString(r"foo.bar\baz")
print selector.parseString(r"foo.bar\.baz")



The result is 

['foo', '.bar']
['foo', '.bar\\baz']
['foo', '.bar\\', '.baz']


So clearly the escaping isn't considering the second dot as part of IDENT 
instead of a DOT. And for this to happen, I need a specific lexer rule like 
quotedString - I guess. 

Diez