Switch

Metafunction

Switch

Metaprogramming switch expression.

Switch<TAG, Case>::Type

Include Headers

seqan/basic.h

Parameters

TAG	The case label. Types: int
Case	Cascade of Case tags. Types: Case, NilCase

Return Values

The selected type from the Case cascade or NilCase.

Examples

int switchTest(Nothing const &) { return -1; }
int switchTest(False const &) { return 0; }
int switchTest(True const &) { return 1; }
int switchTest(NilCase const &) { return 2; }

template <int X>
struct SwitchTest
{
    typedef typename Switch<
        X,
        Case<-1, Nothing,
        Case<0, False,
        Case<1, True
        > > > >::Type Type;
};

SEQAN_DEFINE_TEST(test_metaprogramming_switch)
{
    typedef typename SwitchTest<-1>::Type T1;
    typedef typename SwitchTest< 0>::Type T2;
    typedef typename SwitchTest< 1>::Type T3;
    typedef typename SwitchTest< 2>::Type T4;

    std::cout << switchTest(T1()) << std::endl;  // => -1
    std::cout << switchTest(T2()) << std::endl;  // =>  0
    std::cout << switchTest(T3()) << std::endl;  // =>  1
    std::cout << switchTest(T4()) << std::endl;  // =>  2
}