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make kv store return its type interface directly

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This commit is contained in:
Sky Johnson 2025-06-13 14:24:14 -05:00
parent f1c989ad36
commit 8b4302a7db
2 changed files with 43 additions and 10 deletions
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47
kv_store.hpp
View File

@ -5,20 +5,29 @@
#include <fstream> #include <fstream>
#include <optional> #include <optional>
#include <string> #include <string>
#include <variant>
#include <sstream>
using std::string; using std::string;
class KeyValueStore { class KeyValueStore {
public: public:
void set(const string& key, const string& value) { using Value = std::variant<int, double, string, bool>;
void set(const string& key, const Value& value) {
std::lock_guard<std::mutex> lock(mutex_); std::lock_guard<std::mutex> lock(mutex_);
data_[key] = value; data_[key] = value;
} }
std::optional<string> get(const string& key) { template<typename T>
std::optional<T> get(const string& key) {
std::lock_guard<std::mutex> lock(mutex_); std::lock_guard<std::mutex> lock(mutex_);
auto it = data_.find(key); auto it = data_.find(key);
return it != data_.end() ? std::optional<string>{it->second} : std::nullopt; if (it == data_.end()) return std::nullopt;
if (auto* ptr = std::get_if<T>(&it->second)) {
return *ptr;
}
return std::nullopt;
} }
bool del(const string& key) { bool del(const string& key) {
@ -43,8 +52,17 @@ public:
string line; string line;
while (std::getline(file, line)) { while (std::getline(file, line)) {
size_t eq = line.find('='); size_t eq = line.find('=');
if (eq != string::npos) { if (eq == string::npos || eq < 2) continue;
data_[line.substr(0, eq)] = line.substr(eq + 1);
string key = line.substr(2, eq - 2);
string val_str = line.substr(eq + 1);
char type = line[0];
switch (type) {
case 'i': data_[key] = std::stoi(val_str); break;
case 'd': data_[key] = std::stod(val_str); break;
case 's': data_[key] = val_str; break;
case 'b': data_[key] = (val_str == "1"); break;
} }
} }
} }
@ -55,12 +73,27 @@ public:
if (!file.is_open()) return; if (!file.is_open()) return;
for (const auto& [key, value] : data_) { for (const auto& [key, value] : data_) {
file << key << "=" << value << "\n"; file << serialize_entry(key, value) << "\n";
} }
} }
private: private:
std::unordered_map<string, string> data_; string serialize_entry(const string& key, const Value& value) {
return std::visit([&key](const auto& val) -> string {
using T = std::decay_t<decltype(val)>;
if constexpr (std::is_same_v<T, int>) {
return "i:" + key + "=" + std::to_string(val);
} else if constexpr (std::is_same_v<T, double>) {
return "d:" + key + "=" + std::to_string(val);
} else if constexpr (std::is_same_v<T, string>) {
return "s:" + key + "=" + val;
} else if constexpr (std::is_same_v<T, bool>) {
return "b:" + key + "=" + (val ? "1" : "0");
}
}, value);
}
std::unordered_map<string, Value> data_;
mutable std::mutex mutex_; mutable std::mutex mutex_;
string filename_ = "store.txt"; string filename_ = "store.txt";
}; };

6
main.cpp
View File

@ -61,9 +61,9 @@ int main() {
}); });
router.get("/admin/counter", [](const HttpRequest& req, HttpResponse& res) { router.get("/admin/counter", [](const HttpRequest& req, HttpResponse& res) {
auto current = server->store.get("visit_count"); auto current = server->store.get<int>("visit_count");
int count = current ? std::stoi(current.value()) : 0; int count = current ? current.value() : 0;
server->store.set("visit_count", std::to_string(count + 1)); server->store.set("visit_count", count + 1);
res.set_text("Counter: " + std::to_string(count + 1)); res.set_text("Counter: " + std::to_string(count + 1));
}); });