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k-morozovk-morozov
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state machine (#57)
* add state machine in example
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4 files changed

+236
-40
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4 files changed

+236
-40
lines changed

‎example/coro/example_natural_nums.cpp

+1-40
Original file line numberDiff line numberDiff line change
@@ -5,46 +5,7 @@
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#include <coroutine>
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#include <iostream>
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template <typename T>
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struct Generator {
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struct promise_type {
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using coro_handle = std::coroutine_handle<promise_type>;
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T current_value;
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auto yield_value(T value) {
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current_value = value;
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return std::suspend_always();
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}
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std::suspend_always initial_suspend() { return {}; }
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std::suspend_always final_suspend() noexcept { return {}; }
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auto get_return_object() { return coro_handle ::from_promise(*this); }
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auto unhandled_exception() { std::terminate(); }
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};
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Generator(promise_type::coro_handle handle) : handle_(handle) {}
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~Generator() noexcept {
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if (handle_) handle_.destroy();
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}
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bool resume() {
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if (!handle_.done()) handle_();
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return !handle_.done();
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}
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T current_value() const { return handle_.promise().current_value; }
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bool move_next() const {
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return (handle_ ? (handle_.resume(), !handle_.done()) : false);
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}
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private:
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promise_type::coro_handle handle_;
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};
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#include "generator.h"
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Generator<int> natural_nums() {
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int num = 0;

‎example/coro/example_stm.cpp

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@@ -0,0 +1,183 @@
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//
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// Created by konstantin on 27.07.24.
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//
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#include <any>
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#include <cassert>
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#include <concepts>
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#include <coroutine>
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#include <iostream>
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#include <unordered_map>
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#include "generator.h"
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struct Resumable final {
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struct promise_type {
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using coro_handle = std::coroutine_handle<promise_type>;
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size_t current_value{};
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std::suspend_always yield_value(const size_t pos) {
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current_value = pos;
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return {};
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}
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auto get_return_object() { return coro_handle ::from_promise(*this); }
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std::suspend_always initial_suspend() { return {}; }
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std::suspend_always final_suspend() noexcept { return {}; }
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auto unhandled_exception() { std::terminate(); }
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};
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Resumable(promise_type::coro_handle handle) : handle_(handle) {}
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~Resumable() {
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if (handle_) handle_.destroy();
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}
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promise_type::coro_handle handle() {
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promise_type::coro_handle h = handle_;
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handle_ = nullptr;
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return h;
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}
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bool resume() {
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if (handle_) handle_.resume();
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return !handle_.done();
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}
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private:
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promise_type::coro_handle handle_;
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};
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using coro_t = std::coroutine_handle<>;
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enum class Sym : char { A, B, Term };
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enum class State { A, B };
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template <class State, class Sym>
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class StateMachine;
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using stm_t = StateMachine<State, Sym>;
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template <class F>
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concept CanInvokeWithStm = requires(F f, stm_t& stm) {
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{ f(stm) } -> std::same_as<Resumable>;
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};
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Generator<Sym> input_seq(std::string seq) {
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for (char c : seq) {
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switch (c) {
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case 'a':
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co_yield Sym::A;
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break;
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case 'b':
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co_yield Sym::B;
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break;
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default:
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co_yield Sym::Term;
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break;
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}
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}
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for (;;) {
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co_yield Sym::Term;
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}
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}
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template <typename TableTransition, typename SM>
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struct stm_awaiter : public TableTransition {
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SM& stm;
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stm_awaiter(TableTransition transition, SM& stm)
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: TableTransition(transition), stm(stm) {}
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bool await_ready() const noexcept { return false; }
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coro_t await_suspend(std::coroutine_handle<>) noexcept {
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stm.gennext();
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auto sym = stm.genval();
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auto new_state = TableTransition::operator()(sym);
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return stm[new_state];
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}
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[[nodiscard]] bool await_resume() const noexcept {
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return stm.genval() == Sym::Term;
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}
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};
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template <class State, class Sym>
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class StateMachine final {
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public:
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StateMachine(Generator<Sym> gen) : gen(std::move(gen)) {}
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coro_t operator[](State s) { return states[s]; }
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template <typename F>
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auto get_awaiter(F transition) {
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return stm_awaiter(transition, *this);
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}
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template <CanInvokeWithStm F>
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void add_state(State state, F stf) {
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states[state] = stf(*this).handle();
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}
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void run(State initial) {
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current_state = initial;
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states[current_state].resume();
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}
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Sym genval() const { return gen.current_value(); }
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void gennext() { gen.move_next(); }
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State current() const { return current_state; }
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private:
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State current_state{};
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std::unordered_map<State, coro_t> states{};
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Generator<Sym> gen;
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};
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Resumable StateA(stm_t& stm) {
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auto transmission = [](auto sym) {
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if (sym == Sym::B) {
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return State::B;
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}
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return State::A;
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};
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for (;;) {
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std::cout << "State A" << std::endl;
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bool finish = co_await stm.get_awaiter(transmission);
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if (finish) {
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break;
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}
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}
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}
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Resumable StateB(stm_t& stm) {
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auto transmission = [](auto sym) {
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if (sym == Sym::A) {
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return State::A;
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}
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return State::B;
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};
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for (;;) {
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std::cout << "State B" << std::endl;
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bool finish = co_await stm.get_awaiter(transmission);
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if (finish) {
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break;
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}
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}
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}
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int main() {
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auto gen = input_seq("aaabbaba");
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stm_t stm(gen);
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stm.add_state(State::A, StateA);
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stm.add_state(State::B, StateB);
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stm.run(State::A);
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auto curr = stm.current();
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assert(curr == State::A);
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}

‎example/coro/generator.h

+48
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@@ -0,0 +1,48 @@
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//
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// Created by konstantin on 27.07.24.
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//
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#include <coroutine>
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#include <iostream>
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template <typename T>
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struct Generator {
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struct promise_type {
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using coro_handle = std::coroutine_handle<promise_type>;
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T current_value;
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auto yield_value(T value) {
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current_value = value;
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return std::suspend_always();
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}
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std::suspend_always initial_suspend() { return {}; }
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std::suspend_always final_suspend() noexcept { return {}; }
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auto get_return_object() { return coro_handle ::from_promise(*this); }
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auto unhandled_exception() { std::terminate(); }
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};
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Generator(promise_type::coro_handle handle) : handle_(handle) {}
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~Generator() noexcept {
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if (handle_) handle_.destroy();
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}
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bool resume() {
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if (!handle_.done()) handle_();
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return !handle_.done();
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}
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T current_value() const { return handle_.promise().current_value; }
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bool move_next() const {
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return (handle_ ? (handle_.resume(), !handle_.done()) : false);
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}
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private:
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promise_type::coro_handle handle_;
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};
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‎example/coro/meson.build

+4
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@@ -23,3 +23,7 @@ example_subscription = executable('example_subscription',
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example_mutex = executable('example_mutex',
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'example_mutex.cpp'
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)
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example_stm = executable('example_stm',
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'example_stm.cpp'
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)

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