is<TState> method only checks first orthogonal state if a single state is provided

[guiserle]

According to user guide, is<TState> should return true when any current state matches TState, false otherwise.

However current implementation only checks the first of the orthogonal states

Expected Behavior

Following code (Based on orthogonal region example) should complete with no errors

#include <cassert>
#include <https://raw.githubusercontent.com/boost-ext/sml/master/include/boost/sml.hpp>

namespace sml = boost::sml;

namespace {
struct e1 {};
struct e2 {};
struct e3 {};

struct orthogonal_regions {
    auto operator()() const noexcept {
        using namespace sml;
        return make_transition_table(
            *"idle"_s + event<e1> = "s1"_s, "s1"_s + event<e2> = X

            ,
            *"idle2"_s + event<e2> = "s2"_s, "s2"_s + event<e3> = X);
    }
};

}  // namespace

int main() {
    sml::sm<orthogonal_regions> sm;
    using namespace sml;
    assert(sm.is("idle"_s, "idle2"_s));
    sm.process_event(e1{});
    assert(sm.is("s1"_s, "idle2"_s));
    assert(sm.is("s1"_s));      // <-- Single state check
    assert(sm.is("idle2"_s));   // <-- Single state check
    sm.process_event(e2{});
    assert(sm.is(X, "s2"_s));
    sm.process_event(e3{});
    assert(sm.is(X, X));
}

Actual Behavior

assert(sm.is("idle2"_s)); fails (assert(sm.is("s1"_s)); passes only because it is the first orthogonal state)

Steps to Reproduce the Problem

Execute above code, available on compiler explorer: https://godbolt.org/z/MzWaqoh33

Specifications

• Version: 1.1.4
• Platform: Any
• Subsystem: Any