#ifndef XBT_FUNCTIONAL_HPP
#define XBT_FUNCTIONAL_HPP
+#include <cstddef>
#include <cstdlib>
+#include <cstring>
#include <exception>
#include <functional>
-#include <future>
+#include <memory>
+#include <string>
+#include <tuple>
#include <utility>
+#include <vector>
#include <xbt/sysdep.h>
+#include <xbt/utility.hpp>
namespace simgrid {
namespace xbt {
-class args {
+template<class F>
+class MainFunction {
private:
- int argc_ = 0;
- char** argv_ = nullptr;
+ F code_;
+ std::shared_ptr<const std::vector<std::string>> args_;
public:
+ MainFunction(F code, std::vector<std::string> args) :
+ code_(std::move(code)),
+ args_(std::make_shared<const std::vector<std::string>>(std::move(args)))
+ {}
+ int operator()() const
+ {
+ const int argc = args_->size();
+ std::vector<std::string> args = *args_;
+ std::unique_ptr<char*[]> argv(new char*[argc + 1]);
+ for (int i = 0; i != argc; ++i)
+ argv[i] = args[i].empty() ? const_cast<char*>(""): &args[i].front();
+ argv[argc] = nullptr;
+ return code_(argc, argv.get());
+ }
+};
+
+template<class F> inline
+std::function<void()> wrapMain(F code, std::vector<std::string> args)
+{
+ return MainFunction<F>(std::move(code), std::move(args));
+}
- // Main constructors
- args() {}
+template<class F> inline
+std::function<void()> wrapMain(F code, int argc, const char*const argv[])
+{
+ std::vector<std::string> args(argv, argv + argc);
+ return MainFunction<F>(std::move(code), std::move(args));
+}
+
+namespace bits {
+template <class F, class Tuple, std::size_t... I>
+constexpr auto apply(F&& f, Tuple&& t, simgrid::xbt::index_sequence<I...>)
+ -> decltype(std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...))
+{
+ return std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...);
+}
+}
- void assign(int argc, const char*const* argv)
+/** Call a functional object with the values in the given tuple (from C++17)
+ *
+ * @code{.cpp}
+ * int foo(int a, bool b);
+ *
+ * auto args = std::make_tuple(1, false);
+ * int res = apply(foo, args);
+ * @encode
+ **/
+template <class F, class Tuple>
+constexpr auto apply(F&& f, Tuple&& t)
+ -> decltype(simgrid::xbt::bits::apply(
+ std::forward<F>(f),
+ std::forward<Tuple>(t),
+ simgrid::xbt::make_index_sequence<
+ std::tuple_size<typename std::decay<Tuple>::type>::value
+ >()))
+{
+ return simgrid::xbt::bits::apply(
+ std::forward<F>(f),
+ std::forward<Tuple>(t),
+ simgrid::xbt::make_index_sequence<
+ std::tuple_size<typename std::decay<Tuple>::type>::value
+ >());
+}
+
+template<class T> class Task;
+
+namespace bits {
+
+ // Something similar exist in C++14:
+ template<class T>
+ constexpr T max(T a, T b)
{
- clear();
- char** new_argv = xbt_new(char*,argc + 1);
- for (int i = 0; i < argc; i++)
- new_argv[i] = xbt_strdup(argv[i]);
- new_argv[argc] = nullptr;
- this->argc_ = argc;
- this->argv_ = new_argv;
+ return (a > b) ? a : b;
}
- args(int argc, const char*const* argv)
+ template<class T, class... Args>
+ constexpr T max(T a, Args... b)
{
- this->assign(argc, argv);
+ return max(std::forward<T>(a), max(std::forward<Args>(b)...));
}
- char** to_argv() const
+ struct whatever {};
+
+ // What we can store in a Task:
+ typedef void* ptr_callback;
+ struct funcptr_callback {
+ // Placeholder for any function pointer:
+ void(*callback)();
+ void* data;
+ };
+ struct member_funcptr_callback {
+ // Placeholder for any pointer to member function:
+ void (whatever::* callback)();
+ whatever* data;
+ };
+ typedef char any_callback[max(
+ sizeof(ptr_callback),
+ sizeof(funcptr_callback),
+ sizeof(member_funcptr_callback)
+ )];
+
+ // Union of what we can store in a Task:
+ union TaskErasure {
+ ptr_callback ptr;
+ funcptr_callback funcptr;
+ member_funcptr_callback member_funcptr;
+ any_callback any;
+ };
+
+ // Can we copy F in Task (or do we have to use the heap)?
+ template<class F>
+ constexpr bool isUsableDirectlyInTask()
{
- const int argc = argc_;
- char** argv = xbt_new(char*, argc + 1);
- for (int i=0; i< argc; i++)
- argv[i] = xbt_strdup(argv_[i]);
- argv[argc] = nullptr;
- return argv;
+ // The only types we can portably store directly in the Task are the
+ // trivially copyable ones (we can memcpy) which are small enough to fit:
+ return std::is_trivially_copyable<F>::value &&
+ sizeof(F) <= sizeof(bits::any_callback);
}
- // Free
- void clear()
+}
+
+/** Type-erased run-once task
+ *
+ * * Like std::function but callable only once.
+ * However, it works with move-only types.
+ *
+ * * Like std::packaged_task<> but without the shared state.
+ */
+template<class R, class... Args>
+class Task<R(Args...)> {
+private:
+
+ typedef bits::TaskErasure TaskErasure;
+ struct TaskErasureVtable {
+ // Call (and possibly destroy) the function:
+ R (*call)(TaskErasure&, Args...);
+ // Destroy the function:
+ void (*destroy)(TaskErasure&);
+ };
+
+ TaskErasure code_;
+ const TaskErasureVtable* vtable_ = nullptr;
+
+public:
+ Task() {}
+ Task(std::nullptr_t) {}
+ ~Task()
{
- for (int i = 0; i < this->argc_; i++)
- std::free(this->argv_[i]);
- std::free(this->argv_);
- this->argc_ = 0;
- this->argv_ = nullptr;
+ if (vtable_ && vtable_->destroy)
+ vtable_->destroy(code_);
}
- ~args() { clear(); }
- // Copy
- args(args const& that)
+ Task(Task const&) = delete;
+ Task& operator=(Task const&) = delete;
+
+ Task(Task&& that)
{
- this->assign(that.argc(), that.argv());
+ std::memcpy(&code_, &that.code_, sizeof(code_));
+ vtable_ = that.vtable_;
+ that.vtable_ = nullptr;
}
- args& operator=(args const& that)
+ Task& operator=(Task&& that)
{
- this->assign(that.argc(), that.argv());
+ if (vtable_ && vtable_->destroy)
+ vtable_->destroy(code_);
+ std::memcpy(&code_, &that.code_, sizeof(code_));
+ vtable_ = that.vtable_;
+ that.vtable_ = nullptr;
return *this;
}
- // Move:
- args(args&& that) : argc_(that.argc_), argv_(that.argv_)
+ template<class F,
+ typename = typename std::enable_if<bits::isUsableDirectlyInTask<F>()>::type>
+ Task(F const& code)
{
- that.argc_ = 0;
- that.argv_ = nullptr;
+ const static TaskErasureVtable vtable {
+ // Call:
+ [](TaskErasure& erasure, Args... args) -> R {
+ // We need to wrap F un a union because F might not have a default
+ // constructor: this is especially the case for lambdas.
+ union no_ctor {
+ no_ctor() {}
+ ~no_ctor() {}
+ F code ;
+ } code;
+ if (!std::is_empty<F>::value)
+ // AFAIU, this is safe as per [basic.types]:
+ std::memcpy(&code.code, &erasure.any, sizeof(code.code));
+ code.code(std::forward<Args>(args)...);
+ },
+ // Destroy:
+ nullptr
+ };
+ if (!std::is_empty<F>::value)
+ std::memcpy(&code_.any, &code, sizeof(code));
+ vtable_ = &vtable;
}
- args& operator=(args&& that)
+
+ template<class F,
+ typename = typename std::enable_if<!bits::isUsableDirectlyInTask<F>()>::type>
+ Task(F code)
{
- this->argc_ = that.argc_;
- this->argv_ = that.argv_;
- that.argc_ = 0;
- that.argv_ = nullptr;
- return *this;
+ const static TaskErasureVtable vtable {
+ // Call:
+ [](TaskErasure& erasure, Args... args) -> R {
+ // Delete F when we go out of scope:
+ std::unique_ptr<F> code(static_cast<F*>(erasure.ptr));
+ (*code)(std::forward<Args>(args)...);
+ },
+ // Destroy:
+ [](TaskErasure& erasure) {
+ F* code = static_cast<F*>(erasure.ptr);
+ delete code;
+ }
+ };
+ code_.ptr = new F(std::move(code));
+ vtable_ = &vtable;
}
- int argc() const { return argc_; }
- char** argv() { return argv_; }
- const char*const* argv() const { return argv_; }
- char* operator[](std::size_t i) { return argv_[i]; }
-};
+ template<class F>
+ Task(std::reference_wrapper<F> code)
+ {
+ const static TaskErasureVtable vtable {
+ // Call:
+ [](TaskErasure& erasure, Args... args) -> R {
+ F* code = static_cast<F*>(erasure.ptr);
+ (*code)(std::forward<Args>(args)...);
+ },
+ // Destroy:
+ nullptr
+ };
+ code.code_.ptr = code.get();
+ vtable_ = &vtable;
+ }
-template<class F> inline
-std::function<void()> wrapMain(F code, std::shared_ptr<simgrid::xbt::args> args)
-{
- return [=]() {
- code(args->argc(), args->argv());
- };
-}
+ operator bool() const { return vtable_ != nullptr; }
+ bool operator!() const { return vtable_ == nullptr; }
-template<class F> inline
-std::function<void()> wrapMain(F code, simgrid::xbt::args args)
-{
- return wrapMain(std::move(code),
- std::unique_ptr<simgrid::xbt::args>(new simgrid::xbt::args(std::move(args))));
-}
+ R operator()(Args... args)
+ {
+ if (!vtable_)
+ throw std::bad_function_call();
+ const TaskErasureVtable* vtable = vtable_;
+ vtable_ = nullptr;
+ return vtable->call(code_, std::forward<Args>(args)...);
+ }
+};
-template<class F> inline
-std::function<void()> wrapMain(F code, int argc, const char*const* argv)
+template<class F, class... Args>
+class TaskImpl {
+private:
+ F code_;
+ std::tuple<Args...> args_;
+ typedef decltype(simgrid::xbt::apply(std::move(code_), std::move(args_))) result_type;
+public:
+ TaskImpl(F code, std::tuple<Args...> args) :
+ code_(std::move(code)),
+ args_(std::move(args))
+ {}
+ result_type operator()()
+ {
+ return simgrid::xbt::apply(std::move(code_), std::move(args_));
+ }
+};
+
+template<class F, class... Args>
+auto makeTask(F code, Args... args)
+-> Task< decltype(code(std::move(args)...))() >
{
- return wrapMain(std::move(code), args(argc, argv));
+ TaskImpl<F, Args...> task(std::move(code), std::make_tuple(std::move(args)...));
+ return std::move(task);
}
}
