void tokenize(const std::string str, vstring &v) {
std::string buffer;
for (int i = 0; i < str.length(); ++i) {
if (!isPunc(str[i]) && !isspace(str[i]) && str[i] != '.') {
buffer += str[i];
}
else if (!buffer.empty()) {
v.push_back(buffer);
buffer.erase();
}
}
if ((v.empty() && !buffer.empty()) || !buffer.empty()) {
v.push_back(buffer);
}
}
