cuestate

通过状态表生成状态机代码。需要依赖支持C++20的编译器。

#include <iostream>
#include <cassert>

#include "cuestate.hpp"

using namespace cue::state;

// states
struct closed {};
struct opened {};
struct walking {};

// events
struct close {};
struct open {};
struct walk {
    bool is_ready_;
    int distance_;
};
struct stop {};

// actions
const auto do_open = [](const open&) { std::cout << "open" << std::endl; };
const auto do_close = [](const close&) { std::cout << "close" << std::endl; };
const auto do_stop = [](const stop&) { std::cout << "stop" << std::endl; };
const auto do_walk = [](const walk& w) { std::cout << "walking " << w.distance_ << "m" << std::endl; };

// guards
const auto is_ready = [](const walk& w) {
    std::cout << "robot is ready" << std::endl;
    return w.is_ready_;
};

struct light_robot {
    using initial_state = closed;
    using transition_table = table<
        //        +---------+----------+----------+---------------+---------------+
        //        | current |   event  |  target  |     action    |guard(optional)|
        //        +---------+----------+----------+---------------+---------------+
        transition< closed  ,   open   ,  opened  ,    do_open                    >,
        transition< opened  ,   close  ,  closed  ,    do_close                   >,
        transition< opened  ,   walk   ,  walking ,    do_walk    ,    is_ready   >,
        transition< walking ,   stop   ,  opened  ,    do_stop                    >,
        transition< walking ,   close  ,  closed  ,    do_close                   >
    >;
};

int main(int argc, char** argv) {
    machine<light_robot> robot;
    assert(robot.is(closed{}));
    robot.on(open{});
    assert(robot.is(opened{}));
    robot.on(close{});
    assert(robot.is(closed{}));
    robot.on(open{});
    assert(robot.is(opened{}));
    robot.on(walk{.is_ready_ = true, .distance_ = 5});
    assert(robot.is(walking{}));
    robot.on(stop{});
    assert(robot.is(opened{}));
    robot.on(close{});
    assert(robot.is(closed{}));
    robot.on(stop{});
    assert(robot.is(closed{}));

    return 0;
}