/**
* Formatter class.
*
- * Note that this class is tricky, as it keeps *references* to its arguments
- * (and doesn't copy the passed-in format string). Thankfully, you can't use
- * this directly, you have to use format(...) below.
+ * Note that this class is tricky, as it keeps *references* to its lvalue
+ * arguments (while it takes ownership of the temporaries), and it doesn't
+ * copy the passed-in format string. Thankfully, you can't use this
+ * directly, you have to use format(...) below.
*/
/* BaseFormatter class.
}
/**
- * metadata to identify generated children of BaseFormatter
+ * Metadata to identify generated children of BaseFormatter
*/
typedef detail::FormatterTag IsFormatter;
typedef BaseFormatter BaseType;
private:
- typedef std::tuple<FormatValue<typename std::decay<Args>::type>...>
- ValueTuple;
+ typedef std::tuple<Args...> ValueTuple;
static constexpr size_t valueCount = std::tuple_size<ValueTuple>::value;
Derived const& asDerived() const {
K<valueCount, int>::type getSizeArgFrom(size_t i, const FormatArg& arg)
const {
if (i == K) {
- return getValue(std::get<K>(values_), arg);
+ return getValue(getFormatValue<K>(), arg);
}
return getSizeArgFrom<K + 1>(i, arg);
}
// for the exclusive use of format() (below). This way, you can't create
// a Formatter object, but can handle references to it (for streaming,
// conversion to string, etc) -- which is good, as Formatter objects are
- // dangerous (they hold references, possibly to temporaries)
+ // dangerous (they may hold references).
BaseFormatter(BaseFormatter&&) = default;
BaseFormatter& operator=(BaseFormatter&&) = default;
+ template <size_t K>
+ using ArgType = typename std::tuple_element<K, ValueTuple>::type;
+
+ template <size_t K>
+ FormatValue<typename std::decay<ArgType<K>>::type> getFormatValue() const {
+ return FormatValue<typename std::decay<ArgType<K>>::type>(
+ std::get<K>(values_));
+ }
+
ValueTuple values_;
};
template <size_t K, class Callback>
void doFormatArg(FormatArg& arg, Callback& cb) const {
- std::get<K>(this->values_).format(arg, cb);
+ this->template getFormatValue<K>().format(arg, cb);
}
friend class BaseFormatter<