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Top Forums Programming parsing fixed length field with yacc/bison Post 302279115 by sungita on Thursday 22nd of January 2009 02:28:02 AM
Old 01-22-2009
Network parsing fixed length field with yacc/bison

How to specify the token length in a yacc file?
sample input format
<field1,data type ans,fixed length 6> followed by <field2,data type ans,fixed length 3>

Example i/p and o/p
Sample Input: "ab* d2 9o"
O/p : "Field1 [ab* d2] Field2 [ 9o] "

yacc/bison grammar:
record : AlphaNumericSpecialOfLength6 AlphaNAumericSpecialOfLength3
/** not like
record : FIELD1 FIELD2 { ....};
FIELD1 : ANS ANS ANS ANS ANS ANS;
FIELD2 : ANS ANS ANS { ...} ; ***/
{ printf("Field1 [%s] Field2 [%s] \n", $1 , $2); }

How to define grammar for this in yacc/bison?
 

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LEMON(1)						    BSD General Commands Manual 						  LEMON(1)

NAME
lemon -- The Lemon Parser Generator SYNOPSIS
lemon [-bcgmqsx] input DESCRIPTION
lemon is an LALR(1) parser generator for C or C++. It does the same job as bison and yacc. But lemon is not another bison or yacc clone. It uses a different grammar syntax which is designed to reduce the number of coding errors. lemon also uses a more sophisticated parsing engine that is faster than yacc and bison and which is both reentrant and thread-safe. Furthermore, lemon implements features that can be used to eliminate resource leaks, making is suitable for use in long-running programs such as graphical user interfaces or embedded con- trollers. lemon will read the grammer from input and write out a parser for that grammar in the C language. OPTIONS
-b Print only the basis in report. -c Don't compress the action table. -g Print grammar without actions. -m Output a makeheaders compatible file. -q (Quiet) Don't print the report file. -s Print parser stats to standard output. -x Print the version number. FILES
/usr/share/lemon/lempar.c Driver template for the lemon parser generator. AUTHOR
lemon has been written by D. Richard Hipp <drh@hwaci.com>. This manual page was written by Guus Sliepen <guus@debian.org> for the Debian GNU/Linux system. Debian GNU/Linux June 1, 2019 Debian GNU/Linux
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