std::vector<lstring> convert_split_words_allow_alphabet(const lstring <, const alphabet &allow) { lstring copy; lstring *ptr = (lstring *)< bool changed = false; static letter space(' '); for (size_t i = 0; i < lt.size(); ++i) { if (!allow.ok(lt[i])) { if (!changed) { copy = lt; ptr = © changed = true; } copy[i] = space; } } return convert_split_words(*ptr); }