/**
 * test/demos/parser/parser.yy
 * Copyright (C) 2008 Markus Broeker
 */

%{
   #include <stdio.h>
   #include <ctype.h>

   int regs[26];
   int base;

   int yyerror();
   int yylex();
%}

%start list
%token DIGIT LETTER
%left MINUS PLUS MUL DIV
%left UMINUS
%%

list:
    /* empty */
    | list stat '\n'
    | list error '\n' { yyerrok; };

stat:
    expr { (void) printf( "RESULT: %d\n", $1 ); }
    | LETTER '=' expr { regs[$1] = $3; }
    ;

expr:
    '(' expr ')'
    {
        $$ = $2;
    }
    | expr PLUS expr
    {
        $$ = $1 + $3;
    }
    | expr MINUS expr
    {
        $$ = $1 - $3;
    }
    | expr MUL expr
    {
        $$ = $1 * $3;
    }
    | expr DIV expr
    {
            $$ = $1 / $3;
    }
    | MINUS expr  %prec UMINUS
    {
        $$ = -$2;
    }
    | LETTER
    {
        $$ = regs[$1];
    }
    |  number
    ;

number:
    DIGIT
    {
        $$ = $1; base = ($1==0) ? 8 : 10;
    }
    | number DIGIT
    {
        $$ = base * $1 + $2;
    }
    ;
%%

int yyerror()
{
    printf("ERROR\n");
    return 0;
}

int yywrap()
{
    return 1;
}