Context Free Grammar Post: 26190

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My Context Free Grammar (CFG)

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LEARN ABOUT BSD

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 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.

EXAMPLE

	      lex lexcommands

       would draw lex instructions from the file lexcommands, and place the output in lex.yy.c

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

       is an example of a lex program that would be put into a lex command file.  This program converts upper case to lower, removes blanks at the
       end of lines, and replaces multiple blanks by single blanks.

SEE ALSO

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

7th Edition							  April 14, 1986							    LEX(1)