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# $Id: infix_calc.tac,v 1.1 2004/09/29 16:23:28 tang Exp $
# This example demonstrates how taccle handles operator precedence.
# The code is shamelessly borrowed from the GNU Bison info manual.
# taccle Declarations
%token ID NEWLINE
%left '-' '+'
%left '*' '/'
%left NEG # negation--unary minus
%right '^' # exponentiation
# Grammar follows
%%
input: # empty string
| input line
;
line: NEWLINE
| exp NEWLINE { puts [format "\t%.10g" $1] }
;
exp: ID { set _ $1 }
| exp '+' exp { set _ [expr {$1 + $3}] }
| exp '-' exp { set _ [expr {$1 - $3}] }
| exp '*' exp { set _ [expr {$1 * $3}] }
| exp '/' exp { set _ [expr {$1 / $3}] }
| '-' exp %prec NEG { set _ [expr {-1.0 * $2}] }
| exp '^' exp { set _ [expr {pow($1, $3)}] }
| '(' exp ')' { set _ $2 }
;
%%
source simple_scanner.tcl
yyparse
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