pyparsing-users

[Pyparsing] SkipToMatching?

[stefaan.himpe <ste...@gm...>]

Hello,

I am trying to parse the following:

SECTION {
...
}

where the ... stands for C++ code. I would like to extract the raw C++ 
code from this section { }. Problem of course is that the C++
code can also contain { and }.

I have tried using nestedExpr, but I cannot seem to get raw C++ code
with its original white space (or even with a whitespace that keeps the
code compilable).

The code below illustrates my latest attempt (I left out the "SECTION" 
as it is not relevant for the question)

import pyparsing as p
s = """
{
   // {
   if (1) { dosomething; } else { if (0) then { a; } else { b } }
   printf ( "{" ); /* {
   {
   {
   */
   { nog; iets; }
}
"""

nE = 
p.nestedExpr("{","}",ignoreExpr=p.quotedString|p.cppStyleComment|p.cStyleComment)
nC = p.Combine(nE)
r = nC.parseString(s)

The "Combine" more or less returns the contents between the outer { and 
}, but everything is glued together without whitespace, and some { and } 
  have disappeared:

['// {if(1)dosomething;elseif(0)thena;elsebprintf("{");/* { \n  {\n  {\n 
  */nog;iets;']

Am I going this the right way?
Would it be possible to add something like a SkipToMatching function 
instead?

I imagine I could use it as follows:

import pyparsing as p
grammar = p.Literal("{").suppress() + \ 
p.SkipToMatching("{","}",ignoreExpr=p.quotedString|p.cppStyleComment|p.cStyleComment).setResultsName("RawCode")


Best regards,
Stefaan.

Re: [Pyparsing] SkipToMatching?

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

To preserve the original text that matches an expression in your parser, try
attaching the parse action keepOriginalText.

nC = p.Combine(nE).setParseAction(p.keepOriginalText)

-- Paul


-----Original Message-----
From: pyp...@li...
[mailto:pyp...@li...] On Behalf Of
stefaan.himpe
Sent: Thursday, May 01, 2008 6:23 AM
To: pyp...@li...
Subject: [Pyparsing] SkipToMatching?

Hello,

I am trying to parse the following:

SECTION {
...
}

where the ... stands for C++ code. I would like to extract the raw C++ code
from this section { }. Problem of course is that the C++ code can also
contain { and }.

I have tried using nestedExpr, but I cannot seem to get raw C++ code with
its original white space (or even with a whitespace that keeps the code
compilable).

The code below illustrates my latest attempt (I left out the "SECTION" 
as it is not relevant for the question)

import pyparsing as p
s = """
{
   // {
   if (1) { dosomething; } else { if (0) then { a; } else { b } }
   printf ( "{" ); /* {
   {
   {
   */
   { nog; iets; }
}
"""

nE =
p.nestedExpr("{","}",ignoreExpr=p.quotedString|p.cppStyleComment|p.cStyleCom
ment)
nC = p.Combine(nE)
r = nC.parseString(s)

The "Combine" more or less returns the contents between the outer { and },
but everything is glued together without whitespace, and some { and }
  have disappeared:

['// {if(1)dosomething;elseif(0)thena;elsebprintf("{");/* { \n  {\n  {\n
  */nog;iets;']

Am I going this the right way?
Would it be possible to add something like a SkipToMatching function
instead?

I imagine I could use it as follows:

import pyparsing as p
grammar = p.Literal("{").suppress() + \
p.SkipToMatching("{","}",ignoreExpr=p.quotedString|p.cppStyleComment|p.cStyl
eComment).setResultsName("RawCode")


Best regards,
Stefaan.


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Re: [Pyparsing] SkipToMatching?

[Stefaan H. <ste...@gm...>]

Hello Paul,

Thank you for the prompt and helpful response!

And thank you for conceiving and implementing such
a wonderful parsing package! 

Writing parsers never was so addictive...

Best regards,
Stefaan.