%whites =/([ \t]*(?:#.*)?)/
%token NUM =/([0-9]+(?:\.[0-9]+)?)/
%token VAR =/([A-Za-z][A-Za-z0-9_]*)/
%right '='
%left '-' '+'
%left '*' '/'
%left NEG
%right '^'
%%
start:
input
;
input:
line *
;
line:
'\n'
| exp '\n'
| error '\n'
;
exp:
NUM
| VAR
| VAR '=' exp
| exp '+' exp
| exp '-' exp
| exp '*' exp
| exp '/' exp
| '-' exp %prec NEG
| exp '^' exp
| '(' exp ')'
;
%%