iparserdocstream(idocstream & is) : is_(is) {}
-#if (__cplusplus > 19971L)
+#if (__cplusplus > 199711L)
/// Like std::istream::operator bool()
/// Do not convert is_ implicitly to bool, since that is forbidden in C++11.
explicit operator bool() const { return s_.empty() ? !is_.fail() : true; }