actions before parsing rules in lex n yacc

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11-26-2008

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actions before parsing rules in lex n yacc

Hi ,

We have developed a grammer for our domain language using lex n yacc.
I want to know is there any pre defined lex-yacc function which gets call before executing any rule (or rules).
Oue requirement is, before processing any rule ,we want to perform some specific actions ?
is there any pre defined lex-yacc function which get call before processing rules?

In case of ANTLR (Another Tool for Language Recognition), we can specify actions before processing rule using a block "@init" . Is there anything like "@init" in lex n yacc ?

Regards,
Suprit

supritjain

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lex

LEX(1)							      General Commands Manual							    LEX(1)

NAME

       lex - generator of lexical analysis programs

SYNOPSIS

       lex [ -tvfn ] [ file ] ...

DESCRIPTION

       Lex  generates programs to be used in simple lexical analyis of text.  The input files (standard input default) contain regular expressions
       to be searched for, and actions written in C to be executed when expressions are found.

       A C source program, `lex.yy.c' is generated, to be compiled thus:

	      cc lex.yy.c -ll

       This program, when run, copies unrecognized portions of the input to the output, and executes the associated  C	action	for  each  regular
       expression that is recognized.

       The following lex program converts upper case to lower, removes blanks at the end of lines, and replaces multiple blanks by single blanks.

	      %%
	      [A-Z] putchar(yytext[0]+'a'-'A');
	      [ ]+$
	      [ ]+  putchar(' ');

       The options have the following meanings.

       -t     Place the result on the standard output instead of in file `lex.yy.c'.

       -v     Print a one-line summary of statistics of the generated analyzer.

       -n     Opposite of -v; -n is default.

       -f     `Faster' compilation: don't bother to pack the resulting tables; limited to small programs.

SEE ALSO

       yacc(1)
       M. E. Lesk and E. Schmidt, LEX - Lexical Analyzer Generator

																	    LEX(1)

Programming