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# $Id: interactive_calculator.tac,v 1.2 2004/09/08 21:38:44 tang Exp $
# This example expands the simple calculator to be interactive from
# the command line. Note the use of an empty rule (i.e., epsilon
# transition). Also featured are the error token and error recovery.
%{
#!/usr/bin/tclsh
%}
%token ID NEWLINE
%%
start: line NEWLINE start
| line
;
line: E { puts " = $1" }
| error { puts " -- error" }
| # empty
;
E: E '+' T { set _ [expr {$1 + $3}] }
| E '-' T { set _ [expr {$1 - $3}] }
| T
;
T: T '*' F { set _ [expr {$1 * $3}] }
| T '/' F { set _ [expr {$1 / $3}] }
| F
;
F: '(' E ')' { set _ $2 }
| ID { set _ $::yylval }
;
%%
source simple_scanner.tcl
yyparse
|
