X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/d1f1e22acb2e2342b535c3847e804b4a5fee3167..b6693befe6eb03c83ec1e5fd44c588518223f3d9:/include/xbt/functional.hpp

diff --git a/include/xbt/functional.hpp b/include/xbt/functional.hpp
index 31f9430ea4..49d33f4e1c 100644
--- a/include/xbt/functional.hpp
+++ b/include/xbt/functional.hpp
@@ -7,114 +7,301 @@
 #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 <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:
+  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);
 }
 
 }