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From: Kaz Kylheku <k...@kylheku.com>
Newsgroups: comp.lang.lisp
Subject: Re: read text from file, a chunk of more lines at a time
Date: Mon, 31 Oct 2011 17:57:17 +0000 (UTC)
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On 2011-10-31, Kaz Kylheku <k...@kylheku.com> wrote:
> On 2011-10-31, Tim Bradshaw <t...@tfeb.org> wrote:
>> hans <schatzer.joh...@gmail.com> wrote:
>>> How to read a file, one "record" (of more lines, with a consistent
>>> record delimiter) at a time?
>>> 
>>
>> I will no doubt be crucified for saying so but: Perl. Read it in Perl, spit
>> out sexps from Perl, and read those with Lisp.
>
> No way. There is a new text mangler with Lisp roots.
>
> http://www.nongnu.org/txr
>
> @(collect)
> RECORD@num
> @  (collect)
> @text
> @  (until)
> RECORD@(skip)
> @  (end)
> @(end)
> @(output)
> @  (repeat)
> (@num @(rep)@text @(last)@text@(end))
> @  (end)
> @(end)

Improved. 

- :vars on in inner collect ensure that empty collects still
  produces a binding for the text variable (a binding to the empty list nil),
  even if there is no match.

- Output simplified.

@(collect)
RECORD@num
@  (collect :vars (text))
@text
@  (until)
RECORD@(skip)
@  (end)
@(end)
@(output)
@  (repeat)
(@num@(rep) @text@(end))
@  (end)
@(end)

$ ./txr rec2sexp.txr  -
RECORD1
RECORD2
a      
RECORD3
a   
b
foo RECORD4
RECORD4
[Ctrl-D]
(1)
(2 a)
(3 a b foo RECORD4)
(4)