trie_keys.hpp

template<typename T>
vector<string> string_map<T>::keys() const {
    vector<string> keys;
    keys.reserve(_size);
    _root->collectKeys("", &keys);
    return keys;
}

template<typename T>
void string_map<T>::Node::collectKeys(const string& prefix, vector<string>* keys) {
    if (value != nullptr) {
        keys->push_back(prefix);
    }
    for (int c = 0; c < MAX_CHILDREN; c++) {
        if (children[c] != nullptr) {
            children[c]->collectKeys(prefix + char(c), keys);
        }
    }
}