From: Shannon Fang <xrfang@...>
Date: 2002-12-13T05:59:08+09:00
Subject: Re: String.scan (Regexp again...)

Hi,

Thanks a lot! That makes my program easier, because in the input file
specification, it is described as offset/length, so I used
unpack("@4a3a6a3 @17a16...").

Shannon

On Thu, 12 Dec 2002 22:05:35 +0900
Mike Stok <mike@stok.co.uk> wrote:

> In article <F165JLtosJ3Ih7jtrSB000144b2@hotmail.com>, Shannon Fang wrote:
> > Hi gurus,
> > 
> > I used the following regexp to parse a text file:
> > 
> > p=/.{4}((.{3})(.{6})(.{3})).{17}(.{16}).{13}(.).{33}(.{7}).{17}((.{3})(.{6})(.{3}))/
> > 
> > line="PFPT0YH100010                    NUT-SPRG-EXPN          980101G     A
> > 00001000010001WA100001050000000                            OYH100010
> >      "
> > result=line.match(p)
> > p result >>
> > 
> > [["0YH100010   ", "0YH", "100010", "   ", "NUT-SPRG-EXPN   ", "G", 
> > "0000105", "
> >            ", "   ", "      ", "   "]]
> > 
> > It seems that result is flattened. I expect result like this:
> > [[a,b,c], d,e,f,[g,h,i]]
> > 
> > Could anyone tell me how can I achieve that? Thanks a lot!
> 
> one thing you might consider as you seem to be using fixed width chunks
> maiching with . is to use String#unpack to dismember the string and its
> subcomponents.  After that you could do some manyal packing.
> 
> If this happens more than once then you might consider using a more
> sophisticated approach with some higher level tools as another poster has
> suggested.
> 
> Unpack is usually easier to read (x means skip, a means non-null ASCII chars,
> if you wantes the spaces trimmed from the NUT_SPRG-EXPN field then you 
> could use A rather than a.)  E.g.
> 
>   result = line.unpack('x4 a12 x17 a16 x13 a x33 a7 x17 a12')
>   [0, -1].each { |i| result[i] = result[i].unpack('a3a6a3') }
> 
> It isn't hard to imagine writing a routine to let you use a modifed pack
> specifier to show some structure e.g.
> 
>   result = line.my_unpack('x4 [a3 a6 a3] x17 a16 x13 a x33 a7 x17 [a3 a6 a3]')
> 
> Just a thought.
> 
> Hope this helps,
> 
> Mike
> 
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