C++ APIs for Iteration

gistfile1.cpp

// *** design #1

if (!forOf(cx, obj, [cx] (const Value &v) {
    ...
})) {
    return false;
}


// *** design #2

for (IterationRange it(cx, obj); !it.empty(); it.popFront()) {
    ... it.front() ...
}
if (!it.good())
    return false;


// *** design #3

Iteration it;
if (!it.start(cx, obj))
    return false;
for (;;) {
    Value val;
    if (!it.next(&val))
        return false; // error - already close()d and discarded the iterator
    if (val.isMagic(BREAK))
        break;  // StopIteration - already close()d and discarded the iterator
    ...
}