Re: [Pyparsing] Combine problem

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

This question comes up every so often.  Please see this writeup on the
Discussion page of the pyparsing wiki:
http://pyparsing.wikispaces.com/message/view/home/1089023

In addition to the solution posted there, you could try one of these options
instead of using Combine:

Use a parse action to join the parsed tokens with an intervening ' '
character:

entry = vType+Word(alphanums)+":"+regs+";"
entry.setParseString( lambda tokens: ' '.join(tokens) )

Or use the recent originalTextFor helper method:

entry = originalTextFor( vType+Word(alphanums)+":"+regs+";"  )

Write back if that doesn't answer your question.

(Also, check out the C struct parser on the wiki on the
http://pyparsing.wikispaces.com/UnderDevelopment page.)

-- Paul


> -----Original Message-----
> From: Sebastian Schoellhammer [mailto:ssc...@gm...]
> Sent: Wednesday, June 10, 2009 10:01 PM
> To: pyp...@li...
> Subject: [Pyparsing] Combine problem
> 
> Hello there!
> 
> This is my first post to this list - first of all thanks for this awesome
> module, I could not live without it these days!
> 
> 
> My goal is to parse the following structure:
> s = """
> struct VS_OUTPUT {
>     float4 pos        : SV_Position;
>     float2 UV    : TEXCOORD0;
>     float3 vVec    : TEXCOORD1;
>     float3 lVec    : TEXCOORD2;
>     float3 nor     : TEXCOORD3;
>     float4 col     : TEXCOORD4;
>     float3 tan     : TEXCOORD5;
>     float4 lpos     : TEXCOORD6;
>     float depth     : TEXCOORD7;
>     float2 dof     : TEXCOORD8;
>     float2 VelocityUV      : TEXCOORD9;
> };"""
> 
> entryString = "float3 tan     : TEXCOORD5;"
> 
> def readStruct(s):
>     header = Literal("struct VS_OUTPUT")+"{"
> 
>     regs = Combine("TEXCOORD"+Word(nums)) | "SV_Position"
>     vType = Combine("float"+Optional(Word(nums)))
>     entry = vType+Word(alphanums)+":"+regs+";"
>     struct = header + OneOrMore(entry) + "};"
> 
>     print entry.parseString(entryString)
> 
> This is working as is - but when i change
> 
> entry = vType+Word(alphanums)+":"+regs+";"  to entry =
> Combine(vType+Word(alphanums)+":"+regs+";")
> 
> to make this into a single string, I get a parse Exception - it's not a
> big
> problem but I just don't understand why it doesn't work in this case :)
> Somehow I can't see the difference to where I use Combine in the lines
> above, where it seems just fine.
> 
> Maybe I'm missing something really simple.. thanks for looking!
> 
> seb
> 
> --
> Sebastian Schoellhammer
> 
> Sr. Technical Artist
> Square Enix LTD
> www.square-enix.com
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