if / case expression about veryl

[dalance]

if/case expression has been supported. It is translated to conditional operator.

    assign a = if x {
        1
    } else {
        if y {
            1
        } else {
            2
        }
    };

    assign b = case a {
        1      : 0,
        2      : 1,
        default: 2,
    };

to

    assign a = ((x) ? (
        1
    ) : (
        ((y) ? (
            1
        ) : (
            2
        ))
    ));

    assign b = ((a == 1) ? (
        0
    ) : (a == 2) ? (
        1
    ) : (
        2
    ));