X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/a15797ea55151ddfdbae48147e74159efe01b411..c1103c3a2b794d6f7e4599cf0182d72937b9a021:/include/xbt/functional.hpp

diff --git a/include/xbt/functional.hpp b/include/xbt/functional.hpp
index 31f9430ea4..7596ef6f1e 100644
--- a/include/xbt/functional.hpp
+++ b/include/xbt/functional.hpp
@@ -7,114 +7,297 @@
 #ifndef XBT_FUNCTIONAL_HPP
 #define XBT_FUNCTIONAL_HPP
 
+#include <cstddef>
 #include <cstdlib>
+#include <cstring>
 
+#include <array>
 #include <exception>
 #include <functional>
-#include <future>
+#include <memory>
+#include <string>
+#include <tuple>
+#include <type_traits>
 #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:
-
-  // Main constructors
-  args() {}
-
-  void assign(int argc, const char*const* argv)
+  MainFunction(F code, std::vector<std::string> args) :
+    code_(std::move(code)),
+    args_(std::make_shared<const std::vector<std::string>>(std::move(args)))
+  {}
+  void operator()() const
   {
-    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;
+    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;
+    code_(argc, argv.get());
   }
-  args(int argc, const char*const* argv)
+};
+
+template<class F> inline
+std::function<void()> wrapMain(F code, std::vector<std::string> args)
+{
+  return MainFunction<F>(std::move(code), std::move(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))...);
+}
+}
+
+/** 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);
+ *  @endcode
+ **/
+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;
+
+/** 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:
+
+  // Placeholder for some class type:
+  struct whatever {};
+
+  // Union used for storage:
+#if 0
+  typedef typename std::aligned_union<0,
+    void*,
+    std::pair<void(*)(),void*>,
+    std::pair<void(whatever::*)(), whatever*>
+  >::type TaskUnion;
+#else
+  union TaskUnion {
+    void* ptr;
+    std::pair<void(*)(),void*> funcptr;
+    std::pair<void(whatever::*)(), whatever*> memberptr;
+    char any1[sizeof(std::pair<void(*)(),void*>)];
+    char any2[sizeof(std::pair<void(whatever::*)(), whatever*>)];
+    TaskUnion() {}
+    ~TaskUnion() {}
+  };
+#endif
+
+  // Is F suitable for small buffer optimization?
+  template<class F>
+  static constexpr bool canSBO()
   {
-    this->assign(argc, argv);
+    return sizeof(F) <= sizeof(TaskUnion) &&
+      alignof(F) <= alignof(TaskUnion);
   }
 
-  char** to_argv() const
+  static_assert(canSBO<std::reference_wrapper<whatever>>(),
+    "SBO not working for reference_wrapper");
+
+  // Call (and possibly destroy) the function:
+  typedef R (*call_function)(TaskUnion&, Args...);
+  // Destroy the function (of needed):
+  typedef void (*destroy_function)(TaskUnion&);
+  // Move the function (otherwise memcpy):
+  typedef void (*move_function)(TaskUnion& dest, TaskUnion& src);
+
+  // Vtable of functions for manipulating whatever is in the TaskUnion:
+  struct TaskVtable {
+    call_function call;
+    destroy_function destroy;
+    move_function move;
+  };
+
+  TaskUnion buffer_;
+  const TaskVtable* vtable_ = nullptr;
+
+  void clear()
   {
-    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;
+    if (vtable_ && vtable_->destroy)
+      vtable_->destroy(buffer_);
   }
 
-  // Free
-  void clear()
+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;
+    this->clear();
   }
-  ~args() { clear(); }
 
-  // Copy
-  args(args const& that)
+  Task(Task const&) = delete;
+
+  Task(Task&& that)
   {
-    this->assign(that.argc(), that.argv());
+    if (that.vtable_ && that.vtable_->move)
+      that.vtable_->move(buffer_, that.buffer_);
+    else
+      std::memcpy(&buffer_, &that.buffer_, sizeof(buffer_));
+    vtable_ = that.vtable_;
+    that.vtable_ = nullptr;
   }
-  args& operator=(args const& that)
+  Task& operator=(Task that)
   {
-    this->assign(that.argc(), that.argv());
+    this->clear();
+    if (that.vtable_ && that.vtable_->move)
+      that.vtable_->move(buffer_, that.buffer_);
+    else
+      std::memcpy(&buffer_, &that.buffer_, sizeof(buffer_));
+    vtable_ = that.vtable_;
+    that.vtable_ = nullptr;
     return *this;
   }
 
-  // Move:
-  args(args&& that) : argc_(that.argc_), argv_(that.argv_)
+private:
+
+  template<class F>
+  typename std::enable_if<canSBO<F>()>::type
+  init(F code)
   {
-    that.argc_ = 0;
-    that.argv_ = nullptr;
+    const static TaskVtable vtable {
+      // Call:
+      [](TaskUnion& buffer, Args... args) -> R {
+        F* src = reinterpret_cast<F*>(&buffer);
+        F code = std::move(*src);
+        src->~F();
+        code(std::forward<Args>(args)...);
+      },
+      // Destroy:
+      std::is_trivially_destructible<F>::value ?
+      static_cast<destroy_function>(nullptr) :
+      [](TaskUnion& buffer) {
+        F* code = reinterpret_cast<F*>(&buffer);
+        code->~F();
+      },
+      // Move:
+      [](TaskUnion& dst, TaskUnion& src) {
+        F* src_code = reinterpret_cast<F*>(&src);
+        F* dst_code = reinterpret_cast<F*>(&dst);
+        new(dst_code) F(std::move(*src_code));
+        src_code->~F();
+      }
+    };
+    new(&buffer_) F(std::move(code));
+    vtable_ = &vtable;
   }
-  args& operator=(args&& that)
+
+  template<class F>
+  typename std::enable_if<!canSBO<F>()>::type
+  init(F code)
   {
-    this->argc_ = that.argc_;
-    this->argv_ = that.argv_;
-    that.argc_ = 0;
-    that.argv_ = nullptr;
-    return *this;
+    const static TaskVtable vtable {
+      // Call:
+      [](TaskUnion& buffer, Args... args) -> R {
+        // Delete F when we go out of scope:
+        std::unique_ptr<F> code(*reinterpret_cast<F**>(&buffer));
+        return (*code)(std::forward<Args>(args)...);
+      },
+      // Destroy:
+      [](TaskUnion& buffer) {
+        F* code = *reinterpret_cast<F**>(&buffer);
+        delete code;
+      },
+      // Move:
+      nullptr
+    };
+    *reinterpret_cast<F**>(&buffer_) = 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]; }
-};
+public:
 
-template<class F> inline
-std::function<void()> wrapMain(F code, std::shared_ptr<simgrid::xbt::args> args)
-{
-  return [=]() {
-    code(args->argc(), args->argv());
-  };
-}
+  template<class F>
+  Task(F code)
+  {
+    this->init(std::move(code));
+  }
 
-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))));
-}
+  operator bool() const { return vtable_ != nullptr; }
+  bool operator!() const { return vtable_ == nullptr; }
 
-template<class F> inline
-std::function<void()> wrapMain(F code, int argc, const char*const* argv)
+  R operator()(Args... args)
+  {
+    if (vtable_ == nullptr)
+      throw std::bad_function_call();
+    const TaskVtable* vtable = vtable_;
+    vtable_ = nullptr;
+    return vtable->call(buffer_, std::forward<Args>(args)...);
+  }
+};
+
+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);
 }
 
 }