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polybar/include/utils/action_router.hpp
patrick96 1a59599388 fix(modules): Avoid downcast in module constructor
The previous CAST_MOD(Impl) for the action_router constructor was
illegal because `this` is not yet of type Impl (because the subclass
constructor has not run yet).

The action_router now accepts std::function for its callbacks.

Fixes #2519
2021-10-03 03:18:39 +02:00

60 lines
1.5 KiB
C++

#pragma once
#include <cassert>
#include <stdexcept>
#include <unordered_map>
#include "common.hpp"
POLYBAR_NS
/**
* Maps action names to lambdas and invokes them.
*
* Each module has one instance of this class and uses it to register action.
* For each action the module has to register the name, whether it can take
* additional data, and a callback that is called whenever the action is triggered.
*
* The input() function in the base class uses this for invoking the actions
* of that module.
*
* Any module that does not reimplement that function will automatically use
* this class for action routing.
*/
class action_router {
using callback = std::function<void(void)>;
using callback_data = std::function<void(const std::string&)>;
public:
void register_action(const string& name, callback func);
void register_action_with_data(const string& name, callback_data func);
bool has_action(const string& name);
void invoke(const string& name, const string& data);
protected:
struct entry {
union {
callback without;
callback_data with;
};
bool with_data;
entry(callback func);
entry(callback_data func);
~entry();
};
template <typename F>
void register_entry(const string& name, const F& e) {
if (has_action(name)) {
throw std::invalid_argument("Tried to register action '" + name + "' twice. THIS IS A BUG!");
}
callbacks.emplace(name, std::move(e));
}
private:
std::unordered_map<string, entry> callbacks;
};
POLYBAR_NS_END