cache.h

// Copyright (c) 2020-now by the Zeek Project. See LICENSE for details.
 
#pragma once
 
#include <map>
#include <optional>
#include <utility>
 
namespace hilti::util {
 
template<typename Key, typename Value>
class Cache {
public:
    Cache() = default;
 
    bool has(const Key& key) const { return _cache.find(key) != _cache.end(); }
 
    std::optional<Value> get(const Key& key, std::optional<Value> default_ = {}) const {
        if ( auto i = _cache.find(key); i != _cache.end() )
            return i->second;
 
        return std::move(default_);
    }
 
    template<typename Callback>
    const Value& getOrCreate(const Key& key, Callback&& cb) {
        if ( auto i = _cache.find(key); i != _cache.end() )
            return i->second;
 
        return put(key, cb());
    }
 
    template<typename Callback1, typename Callback2>
    const Value& getOrCreate(const Key& key, Callback1&& cb1, Callback2&& cb2) {
        if ( auto i = _cache.find(key); i != _cache.end() )
            return i->second;
 
        _cache[key] = cb1();
        return _cache[key] = cb2(_cache[key]);
    }
 
    const Value& put(const Key& key, Value value) { return _cache[key] = std::move(value); }
 
    void remove(const Key& key) { _cache.erase(key); }
 
private:
    std::map<Key, Value> _cache;
};
 
} // namespace hilti::util