Prototype of Async library

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diff --git a/async/src/async.h b/async/src/async.h
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+/*
+ * Copyright 2014  Daniel Vrátil <dvratil@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef ASYNC_H
+#define ASYNC_H
+
+#include <functional>
+#include <list>
+#include <type_traits>
+#include <iostream>
+#include <cassert>
+
+#include "future.h"
+#include "async_impl.h"
+
+
+namespace Async {
+
+template<typename Out, typename ... In>
+class Job;
+
+template<typename Out, typename ... In>
+Job<Out, In ...> start(const std::function<Async::Future<Out>(In ...)> &func);
+
+
+class JobBase
+{
+public:
+    JobBase(JobBase *prev = nullptr)
+    : mPrev(prev)
+    , mResult(0)
+    {}
+
+    virtual void exec() = 0;
+
+public:
+    JobBase *mPrev;
+    void *mResult;
+};
+
+namespace Private {
+
+    template<typename Out, typename In>
+    typename std::enable_if<!std::is_void<In>::value, void>::type
+    doExec(JobBase *prev, JobBase *jobBase);
+
+    template<typename Out, typename ... In>
+    typename std::enable_if<sizeof...(In) == 0, void>::type
+    doExec(JobBase *prev, JobBase *jobBase, int * /* disambiguate */ = 0);
+}
+
+template<typename Out, typename ... In>
+class Job : public JobBase
+{
+    template<typename Out_, typename ... In_>
+    friend class Job;
+
+    template<typename Out_, typename ... In_, typename F_>
+    friend Job<Out_, In_ ...> start(F_ func);
+
+public:
+    ~Job()
+    {
+        // Can't delete in JobBase, since we don't know the type
+        // and deleting void* is undefined
+        delete reinterpret_cast<Async::Future<Out>*>(mResult);
+    }
+
+    template<typename Out_, typename ... In_, typename F>
+    Job<Out_, In_ ...> then(F func)
+    {
+        Job<Out_, In_ ...> job(this);
+        job.mFunc = func;
+        return job;
+    }
+
+    Async::Future<Out> result() const
+    {
+        return *reinterpret_cast<Async::Future<Out>*>(mResult);
+    }
+
+
+    void exec()
+    {
+        Async::Private::doExec<Out, In ...>(mPrev, this);
+    }
+
+private:
+    Job(JobBase *parent = nullptr)
+        : JobBase(parent)
+    {}
+
+public:
+    std::function<Async::Future<Out>(In ...)> mFunc;
+};
+
+template<typename Out, typename ... In, typename F>
+Job<Out, In ...> start(F func)
+{
+    Job<Out, In ...> job;
+    job.mFunc = std::function<Async::Future<Out>(In ...)>(func);
+    return job;
+}
+
+} // namespace Async
+
+template<typename Out, typename In>
+typename std::enable_if<!std::is_void<In>::value, void>::type
+Async::Private::doExec(JobBase *prev, JobBase *jobBase)
+{
+    prev->exec();
+    Async::Future<In> *in = reinterpret_cast<Async::Future<In>*>(prev->mResult);
+    assert(in->isFinished());
+
+    Job<Out, In> *job = dynamic_cast<Job<Out, In>*>(jobBase);
+    Async::Future<Out> *out = new Async::Future<Out>(job->mFunc(in->value()));
+    out->waitForFinished();
+    job->mResult = reinterpret_cast<void*>(out);
+};
+
+template<typename Out, typename ... In>
+typename std::enable_if<sizeof...(In) == 0, void>::type
+Async::Private::doExec(JobBase *prev, JobBase *jobBase, int * /* disambiguation */ = 0)
+{
+    if (prev) {
+        prev->exec();
+        Async::Future<void> *in = reinterpret_cast<Async::Future<void>*>(prev->mResult);
+        assert(in->isFinished());
+    }
+
+    Job<Out> *job = dynamic_cast<Job<Out>*>(jobBase);
+    Async::Future<Out> *out = new Async::Future<Out>(job->mFunc());
+    out->waitForFinished();
+    job->mResult = reinterpret_cast<void*>(out);
+};
+
+
+#endif // ASYNC_H
+
+