Re: [Pyparsing] White space

[Paul M. <pt...@au...>]

Here's your definition of g
>>> g = "$" + "as" + Word(alphas)
>>> print g
{"$as" W:(abcd...)}

"$" + "as" gets interpreted by Python as the addition of two strings,
resulting in "$as".

Force the leading "$" to be a pyparsing Literal, and then you'll get a
better parser:
>>> g = Literal("$") + "as" + Word(alphas)
>>> print g
{{"$" "as"} W:(abcd...)}

-- Paul


-----Original Message-----
From: cathal coffey [mailto:cof...@gm...] 
Sent: Tuesday, June 21, 2011 5:35 PM
To: pyp...@li...
Subject: [Pyparsing] White space

Hello,

I have a quick question. Shouldn't the below grammar accept the given
string?

from pyparsing import Word, alphas
g = "$" + "as" + Word(alphas)
g.parseString('$ as abc')
ParseException: Expected "$as" (at char 0), (line:1, col:1)

I want the grammar to accept $ followed by: any number of spaces
followed by: as followed by: any number of spaces followed by: any
string of characters.

The reason I am confused is that the following grammar accepts
regardless of white space... why doesn't the above?

g = "as" + Word(alphas)
g.parseString('  as abc    ')
Out: (['as', 'abc'], {})

Kind regards,
Cathal

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