grammar binary;

number
   : bits EOF
        {print("As a decimal value: " + str($bits.value))}
   ;

bits returns [int value]
   : bit
        {$value = $bit.bit_value}
   | high=bits bit
        /* We'd like to use $bits.value to get the value of the high
         * order bits. However, due to an apparent bug in ANTLR, $bits.value
         * results in errors. Giving the bits non-terminal an alias (high)
         * fixes this, so the following code is equivalent to
         *      $value = $bits.value * 2 + $bit.bit_value
         */
        {$value = $high.value * 2 + $bit.bit_value}
   ;

bit returns [int bit_value]
   : '0'
        {$bit_value = 0}
   | '1'
        {$bit_value = 1}
   ;

WS
   : [ \r\n\t]+ -> channel (HIDDEN)
   ;