INT regex
    [0-9]+

OP list
    || && -- ++ = == !
    / * - + << >> % ^
    /= *= -= += <<= >>= &= |= %= ^=
    -> .
    < > <= >= !=
    ? :
    ( ) { } [ ]
    , ;

EXPR nonterm .start
    EXPR OP EXPR
    INT
    ( EXPR )
    EXPR ? EXPR : EXPR