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    Copyright 2005-2018 Intel Corporation.  All Rights Reserved.

    The source code contained or described herein and all documents related
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    by worldwide copyright laws and treaty provisions.  No part of the
    Material may be used, copied, reproduced, modified, published, uploaded,
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    No license under any patent, copyright, trade secret or other
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    disclosure or delivery of the Materials, either expressly, by
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    intellectual property rights must be express and approved by Intel in
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*/

#ifndef __TBB_parallel_invoke_H
#define __TBB_parallel_invoke_H

#include "task.h"
#include "tbb_profiling.h"

#if __TBB_VARIADIC_PARALLEL_INVOKE
    #include <utility> // std::forward
#endif

namespace tbb {

#if !__TBB_TASK_GROUP_CONTEXT
    /** Dummy to avoid cluttering the bulk of the header with enormous amount of ifdefs. **/
    struct task_group_context {
        task_group_context(tbb::internal::string_index){}
    };
#endif /* __TBB_TASK_GROUP_CONTEXT */

//! @cond INTERNAL
namespace internal {
    // Simple task object, executing user method
    template<typename function>
    class function_invoker : public task{
    public:
        function_invoker(const function& _function) : my_function(_function) {}
    private:
        const function &my_function;
        task* execute() __TBB_override
        {
            my_function();
            return NULL;
        }
    };

    // The class spawns two or three child tasks
    template <size_t N, typename function1, typename function2, typename function3>
    class spawner : public task {
    private:
        const function1& my_func1;
        const function2& my_func2;
        const function3& my_func3;
        bool is_recycled;

        task* execute () __TBB_override {
            if(is_recycled){
                return NULL;
            }else{
                __TBB_ASSERT(N==2 || N==3, "Number of arguments passed to spawner is wrong");
                set_ref_count(N);
                recycle_as_safe_continuation();
                internal::function_invoker<function2>* invoker2 = new (allocate_child()) internal::function_invoker<function2>(my_func2);
                __TBB_ASSERT(invoker2, "Child task allocation failed");
                spawn(*invoker2);
                size_t n = N; // To prevent compiler warnings
                if (n>2) {
                    internal::function_invoker<function3>* invoker3 = new (allocate_child()) internal::function_invoker<function3>(my_func3);
                    __TBB_ASSERT(invoker3, "Child task allocation failed");
                    spawn(*invoker3);
                }
                my_func1();
                is_recycled = true;
                return NULL;
            }
        } // execute

    public:
        spawner(const function1& _func1, const function2& _func2, const function3& _func3) : my_func1(_func1), my_func2(_func2), my_func3(_func3), is_recycled(false) {}
    };

    // Creates and spawns child tasks
    class parallel_invoke_helper : public empty_task {
    public:
        // Dummy functor class
        class parallel_invoke_noop {
        public:
            void operator() () const {}
        };
        // Creates a helper object with user-defined number of children expected
        parallel_invoke_helper(int number_of_children)
        {
            set_ref_count(number_of_children + 1);
        }

#if __TBB_VARIADIC_PARALLEL_INVOKE
        void add_children() {}
        void add_children(tbb::task_group_context&) {}

        template <typename function>
        void add_children(function&& _func)
        {
            internal::function_invoker<function>* invoker = new (allocate_child()) internal::function_invoker<function>(std::forward<function>(_func));
            __TBB_ASSERT(invoker, "Child task allocation failed");
            spawn(*invoker);
        }

        template<typename function>
        void add_children(function&& _func, tbb::task_group_context&)
        {
            add_children(std::forward<function>(_func));
        }

        // Adds child(ren) task(s) and spawns them
        template <typename function1, typename function2, typename... function>
        void add_children(function1&& _func1, function2&& _func2, function&&... _func)
        {
            // The third argument is dummy, it is ignored actually.
            parallel_invoke_noop noop;
            typedef internal::spawner<2, function1, function2, parallel_invoke_noop> spawner_type;
            spawner_type & sub_root = *new(allocate_child()) spawner_type(std::forward<function1>(_func1), std::forward<function2>(_func2), noop);
            spawn(sub_root);
            add_children(std::forward<function>(_func)...);
        }
#else
        // Adds child task and spawns it
        template <typename function>
        void add_children (const function &_func)
        {
            internal::function_invoker<function>* invoker = new (allocate_child()) internal::function_invoker<function>(_func);
            __TBB_ASSERT(invoker, "Child task allocation failed");
            spawn(*invoker);
        }

        // Adds a task with multiple child tasks and spawns it
        // two arguments
        template <typename function1, typename function2>
        void add_children (const function1& _func1, const function2& _func2)
        {
            // The third argument is dummy, it is ignored actually.
            parallel_invoke_noop noop;
            internal::spawner<2, function1, function2, parallel_invoke_noop>& sub_root = *new(allocate_child())internal::spawner<2, function1, function2, parallel_invoke_noop>(_func1, _func2, noop);
            spawn(sub_root);
        }
        // three arguments
        template <typename function1, typename function2, typename function3>
        void add_children (const function1& _func1, const function2& _func2, const function3& _func3)
        {
            internal::spawner<3, function1, function2, function3>& sub_root = *new(allocate_child())internal::spawner<3, function1, function2, function3>(_func1, _func2, _func3);
            spawn(sub_root);
        }
#endif // __TBB_VARIADIC_PARALLEL_INVOKE

        // Waits for all child tasks
        template <typename F0>
        void run_and_finish(const F0& f0)
        {
            internal::function_invoker<F0>* invoker = new (allocate_child()) internal::function_invoker<F0>(f0);
            __TBB_ASSERT(invoker, "Child task allocation failed");
            spawn_and_wait_for_all(*invoker);
        }
    };
    // The class destroys root if exception occurred as well as in normal case
    class parallel_invoke_cleaner: internal::no_copy {
    public:
#if __TBB_TASK_GROUP_CONTEXT
        parallel_invoke_cleaner(int number_of_children, tbb::task_group_context& context)
            : root(*new(task::allocate_root(context)) internal::parallel_invoke_helper(number_of_children))
#else
        parallel_invoke_cleaner(int number_of_children, tbb::task_group_context&)
            : root(*new(task::allocate_root()) internal::parallel_invoke_helper(number_of_children))
#endif /* !__TBB_TASK_GROUP_CONTEXT */
        {}

        ~parallel_invoke_cleaner(){
            root.destroy(root);
        }
        internal::parallel_invoke_helper& root;
    };

#if __TBB_VARIADIC_PARALLEL_INVOKE
//  Determine whether the last parameter in a pack is task_group_context
    template<typename... T> struct impl_selector; // to workaround a GCC bug

    template<typename T1, typename... T> struct impl_selector<T1, T...> {
        typedef typename impl_selector<T...>::type type;
    };

    template<typename T> struct impl_selector<T> {
        typedef false_type type;
    };
    template<> struct impl_selector<task_group_context&> {
        typedef true_type  type;
    };

    // Select task_group_context parameter from the back of a pack
    inline task_group_context& get_context( task_group_context& tgc ) { return tgc; }

    template<typename T1, typename... T>
    task_group_context& get_context( T1&& /*ignored*/, T&&... t )
    { return get_context( std::forward<T>(t)... ); }

    // task_group_context is known to be at the back of the parameter pack
    template<typename F0, typename F1, typename... F>
    void parallel_invoke_impl(true_type, F0&& f0, F1&& f1, F&&... f) {
        __TBB_STATIC_ASSERT(sizeof...(F)>0, "Variadic parallel_invoke implementation broken?");
        // # of child tasks: f0, f1, and a task for each two elements of the pack except the last
        const size_t number_of_children = 2 + sizeof...(F)/2;
        parallel_invoke_cleaner cleaner(number_of_children, get_context(std::forward<F>(f)...));
        parallel_invoke_helper& root = cleaner.root;

        root.add_children(std::forward<F>(f)...);
        root.add_children(std::forward<F1>(f1));
        root.run_and_finish(std::forward<F0>(f0));
    }

    // task_group_context is not in the pack, needs to be added
    template<typename F0, typename F1, typename... F>
    void parallel_invoke_impl(false_type, F0&& f0, F1&& f1, F&&... f) {
        tbb::task_group_context context(PARALLEL_INVOKE);
        // Add context to the arguments, and redirect to the other overload
        parallel_invoke_impl(true_type(), std::forward<F0>(f0), std::forward<F1>(f1), std::forward<F>(f)..., context);
    }
#endif
} // namespace internal
//! @endcond

/** \name parallel_invoke
    **/
//@{
//! Executes a list of tasks in parallel and waits for all tasks to complete.
/** @ingroup algorithms */

#if __TBB_VARIADIC_PARALLEL_INVOKE

// parallel_invoke for two or more arguments via variadic templates
// presence of task_group_context is defined automatically
template<typename F0, typename F1, typename... F>
void parallel_invoke(F0&& f0, F1&& f1, F&&... f) {
    typedef typename internal::impl_selector<internal::false_type, F...>::type selector_type;
    internal::parallel_invoke_impl(selector_type(), std::forward<F0>(f0), std::forward<F1>(f1), std::forward<F>(f)...);
}

#else

// parallel_invoke with user-defined context
// two arguments
template<typename F0, typename F1 >
void parallel_invoke(const F0& f0, const F1& f1, tbb::task_group_context& context) {
    internal::parallel_invoke_cleaner cleaner(2, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f1);

    root.run_and_finish(f0);
}

// three arguments
template<typename F0, typename F1, typename F2 >
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, tbb::task_group_context& context) {
    internal::parallel_invoke_cleaner cleaner(3, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f2);
    root.add_children(f1);

    root.run_and_finish(f0);
}

// four arguments
template<typename F0, typename F1, typename F2, typename F3>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(4, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f3);
    root.add_children(f2);
    root.add_children(f1);

    root.run_and_finish(f0);
}

// five arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4 >
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(3, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f4, f3);
    root.add_children(f2, f1);

    root.run_and_finish(f0);
}

// six arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4, typename F5>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4, const F5& f5,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(3, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f5, f4, f3);
    root.add_children(f2, f1);

    root.run_and_finish(f0);
}

// seven arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4, typename F5, typename F6>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(3, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f6, f5, f4);
    root.add_children(f3, f2, f1);

    root.run_and_finish(f0);
}

// eight arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4,
         typename F5, typename F6, typename F7>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6, const F7& f7,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(4, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f7, f6, f5);
    root.add_children(f4, f3);
    root.add_children(f2, f1);

    root.run_and_finish(f0);
}

// nine arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4,
         typename F5, typename F6, typename F7, typename F8>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6, const F7& f7, const F8& f8,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(4, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f8, f7, f6);
    root.add_children(f5, f4, f3);
    root.add_children(f2, f1);

    root.run_and_finish(f0);
}

// ten arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4,
         typename F5, typename F6, typename F7, typename F8, typename F9>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6, const F7& f7, const F8& f8, const F9& f9,
                     tbb::task_group_context& context)
{
    internal::parallel_invoke_cleaner cleaner(4, context);
    internal::parallel_invoke_helper& root = cleaner.root;

    root.add_children(f9, f8, f7);
    root.add_children(f6, f5, f4);
    root.add_children(f3, f2, f1);

    root.run_and_finish(f0);
}

// two arguments
template<typename F0, typename F1>
void parallel_invoke(const F0& f0, const F1& f1) {
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1>(f0, f1, context);
}
// three arguments
template<typename F0, typename F1, typename F2>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2) {
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2>(f0, f1, f2, context);
}
// four arguments
template<typename F0, typename F1, typename F2, typename F3 >
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3) {
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3>(f0, f1, f2, f3, context);
}
// five arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4) {
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3, F4>(f0, f1, f2, f3, f4, context);
}
// six arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4, typename F5>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4, const F5& f5) {
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3, F4, F5>(f0, f1, f2, f3, f4, f5, context);
}
// seven arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4, typename F5, typename F6>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6)
{
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3, F4, F5, F6>(f0, f1, f2, f3, f4, f5, f6, context);
}
// eight arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4,
         typename F5, typename F6, typename F7>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6, const F7& f7)
{
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3, F4, F5, F6, F7>(f0, f1, f2, f3, f4, f5, f6, f7, context);
}
// nine arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4,
         typename F5, typename F6, typename F7, typename F8>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6, const F7& f7, const F8& f8)
{
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3, F4, F5, F6, F7, F8>(f0, f1, f2, f3, f4, f5, f6, f7, f8, context);
}
// ten arguments
template<typename F0, typename F1, typename F2, typename F3, typename F4,
         typename F5, typename F6, typename F7, typename F8, typename F9>
void parallel_invoke(const F0& f0, const F1& f1, const F2& f2, const F3& f3, const F4& f4,
                     const F5& f5, const F6& f6, const F7& f7, const F8& f8, const F9& f9)
{
    task_group_context context(internal::PARALLEL_INVOKE);
    parallel_invoke<F0, F1, F2, F3, F4, F5, F6, F7, F8, F9>(f0, f1, f2, f3, f4, f5, f6, f7, f8, f9, context);
}
#endif // __TBB_VARIADIC_PARALLEL_INVOKE
//@}

} // namespace

#endif /* __TBB_parallel_invoke_H */
