isBitFlagEnum

Detect whether an enum is of integral type and has only "flag" values (i.e. values with a bit count of exactly 1). Additionally, a zero value is allowed for compatibility with enums including a "None" value.

template isBitFlagEnum (

) {

enum isBitFlagEnum;

}

Examples

enum A
{
    None,
    A = 1 << 0,
    B = 1 << 1,
    C = 1 << 2,
    D = 1 << 3,
}

static assert(isBitFlagEnum!A);

Test an enum with default (consecutive) values

enum B
{
    A,
    B,
    C,
    D // D == 3
}

static assert(!isBitFlagEnum!B);

Test an enum with non-integral values

enum C: double
{
    A = 1 << 0,
    B = 1 << 1
}

static assert(!isBitFlagEnum!C);

isBitFlagEnum

Examples

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