2.2 Ãæ´Öµ­Ë¡ÅÅÂcalc

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/* Ãæ´Öµ­Ë¡ÅÅÂî -- calc */

%{
#define YYSTYPE double
#include <math.h>
%}

/* BISONÀë¸À */
%token NUM
%left '-' '+'
%left '*' '/'
%left NEG     /* negation--ñ¹à¥Þ¥¤¥Ê¥¹ */
%right '^'    /* ¤Ù¤­¾è´Ø¿ô        */

/* ʸˡµ¬Â§¤¬Â³¤¯ */
%%
input:    /* ¶õʸ»úÎó */
        | input line
;

line:     '\n'
        | exp '\n'  { printf ("\t%.10g\n", $1); }
;

exp:      NUM                { $$ = $1;         }
        | exp '+' exp        { $$ = $1 + $3;    }
        | exp '-' exp        { $$ = $1 - $3;    }
        | exp '*' exp        { $$ = $1 * $3;    }
        | exp '/' exp        { $$ = $1 / $3;    }
        | '-' exp  %prec NEG { $$ = -$2;        }
        | exp '^' exp        { $$ = pow ($1, $3); }
        | '(' exp ')'        { $$ = $2;         }
;
%%

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°Ê²¼¤Ïcalc.y¤Î¼Â¹ÔÎã¤Ç¤¹¡£

% calc
4 + 4.5 - (34/(8*3+-3))
6.880952381
-56 + 2
-54
3 ^ 2
9