Imported Upstream version 1.65.0upstream/1.65.0

Change-Id: Icf8400b375482cb11bcf77440a6934ba360d6ba4
Signed-off-by: DongHun Kwak <dh0128.kwak@samsung.com>

1 files changed, 382 insertions, 0 deletions

diff --git a/boost/context/continuation_fcontext.hpp b/boost/context/continuation_fcontext.hpp
new file mode 100644
index 0000000000..5c309c3fed
--- /dev/null
+++ b/boost/context/continuation_fcontext.hpp
@@ -0,0 +1,382 @@
+
+//          Copyright Oliver Kowalke 2017.
+// Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//          http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_CONTEXT_CONTINUATION_H
+#define BOOST_CONTEXT_CONTINUATION_H
+
+#include <boost/context/detail/config.hpp>
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <exception>
+#include <functional>
+#include <memory>
+#include <ostream>
+#include <tuple>
+#include <utility>
+
+#include <boost/assert.hpp>
+#include <boost/config.hpp>
+#include <boost/intrusive_ptr.hpp>
+
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+#include <boost/context/detail/exchange.hpp>
+#endif
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+#include <boost/context/detail/invoke.hpp>
+#endif
+#include <boost/context/detail/disable_overload.hpp>
+#include <boost/context/detail/exception.hpp>
+#include <boost/context/detail/fcontext.hpp>
+#include <boost/context/detail/tuple.hpp>
+#include <boost/context/fixedsize_stack.hpp>
+#include <boost/context/flags.hpp>
+#include <boost/context/preallocated.hpp>
+#include <boost/context/segmented_stack.hpp>
+#include <boost/context/stack_context.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+#if defined(BOOST_MSVC)
+# pragma warning(push)
+# pragma warning(disable: 4702)
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+inline
+transfer_t context_unwind( transfer_t t) {
+    throw forced_unwind( t.fctx);
+    return { nullptr, nullptr };
+}
+
+template< typename Rec >
+transfer_t context_exit( transfer_t t) noexcept {
+    Rec * rec = static_cast< Rec * >( t.data);
+    // destroy context stack
+    rec->deallocate();
+    return { nullptr, nullptr };
+}
+
+template< typename Rec >
+void context_entry( transfer_t t) noexcept {
+    // transfer control structure to the context-stack
+    Rec * rec = static_cast< Rec * >( t.data);
+    BOOST_ASSERT( nullptr != t.fctx);
+    BOOST_ASSERT( nullptr != rec);
+    try {
+        // jump back to `create_context()`
+        t = jump_fcontext( t.fctx, nullptr);
+        // start executing
+        t.fctx = rec->run( t.fctx);
+    } catch ( forced_unwind const& e) {
+        t = { e.fctx, nullptr };
+    }
+    BOOST_ASSERT( nullptr != t.fctx);
+    // destroy context-stack of `this`context on next context
+    ontop_fcontext( t.fctx, rec, context_exit< Rec >);
+    BOOST_ASSERT_MSG( false, "context already terminated");
+}
+
+template< typename Ctx, typename Fn >
+transfer_t context_ontop( transfer_t t) {
+    auto p = static_cast< std::tuple< Fn > * >( t.data);
+    BOOST_ASSERT( nullptr != p);
+    typename std::decay< Fn >::type fn = std::get< 0 >( * p);
+    t.data = nullptr;
+    Ctx c{ t.fctx };
+    // execute function, pass continuation via reference
+    fn( std::move( c) );
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+    return { exchange( c.fctx_, nullptr), nullptr };
+#else
+    return { std::exchange( c.fctx_, nullptr), nullptr };
+#endif
+}
+
+template< typename Ctx, typename StackAlloc, typename Fn >
+class record {
+private:
+    stack_context                                       sctx_;
+    StackAlloc                                          salloc_;
+    typename std::decay< Fn >::type                     fn_;
+
+    static void destroy( record * p) noexcept {
+        StackAlloc salloc = p->salloc_;
+        stack_context sctx = p->sctx_;
+        // deallocate record
+        p->~record();
+        // destroy stack with stack allocator
+        salloc.deallocate( sctx);
+    }
+
+public:
+    record( stack_context sctx, StackAlloc const& salloc,
+            Fn && fn) noexcept :
+        sctx_( sctx),
+        salloc_( salloc),
+        fn_( std::forward< Fn >( fn) ) {
+    }
+
+    record( record const&) = delete;
+    record & operator=( record const&) = delete;
+
+    void deallocate() noexcept {
+        destroy( this);
+    }
+
+    fcontext_t run( fcontext_t fctx) {
+        Ctx c{ fctx };
+        // invoke context-function
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+        c = invoke( fn_, std::move( c) );
+#else
+        c = std::invoke( fn_, std::move( c) );
+#endif
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+        return exchange( c.fctx_, nullptr);
+#else
+        return std::exchange( c.fctx_, nullptr);
+#endif
+    }
+};
+
+template< typename Record, typename StackAlloc, typename Fn >
+fcontext_t create_context1( StackAlloc salloc, Fn && fn) {
+    auto sctx = salloc.allocate();
+    // reserve space for control structure
+	void * storage = reinterpret_cast< void * >(
+			( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( Record) ) )
+            & ~static_cast< uintptr_t >( 0xff) );
+    // placment new for control structure on context stack
+    Record * record = new ( storage) Record{
+            sctx, salloc, std::forward< Fn >( fn) };
+    // 64byte gab between control structure and stack top
+    // should be 16byte aligned
+    void * stack_top = reinterpret_cast< void * >(
+            reinterpret_cast< uintptr_t >( storage) - static_cast< uintptr_t >( 64) );
+    void * stack_bottom = reinterpret_cast< void * >(
+            reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sctx.size) );
+    // create fast-context
+    const std::size_t size = reinterpret_cast< uintptr_t >( stack_top) - reinterpret_cast< uintptr_t >( stack_bottom);
+    const fcontext_t fctx = make_fcontext( stack_top, size, & context_entry< Record >);
+    BOOST_ASSERT( nullptr != fctx);
+    // transfer control structure to context-stack
+    return jump_fcontext( fctx, record).fctx;
+}
+
+template< typename Record, typename StackAlloc, typename Fn >
+fcontext_t create_context2( preallocated palloc, StackAlloc salloc, Fn && fn) {
+    // reserve space for control structure
+    void * storage = reinterpret_cast< void * >(
+            ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( Record) ) )
+            & ~ static_cast< uintptr_t >( 0xff) );
+    // placment new for control structure on context-stack
+    Record * record = new ( storage) Record{
+            palloc.sctx, salloc, std::forward< Fn >( fn) };
+    // 64byte gab between control structure and stack top
+    void * stack_top = reinterpret_cast< void * >(
+            reinterpret_cast< uintptr_t >( storage) - static_cast< uintptr_t >( 64) );
+    void * stack_bottom = reinterpret_cast< void * >(
+            reinterpret_cast< uintptr_t >( palloc.sctx.sp) - static_cast< uintptr_t >( palloc.sctx.size) );
+    // create fast-context
+    const std::size_t size = reinterpret_cast< uintptr_t >( stack_top) - reinterpret_cast< uintptr_t >( stack_bottom);
+    const fcontext_t fctx = make_fcontext( stack_top, size, & context_entry< Record >);
+    BOOST_ASSERT( nullptr != fctx);
+    // transfer control structure to context-stack
+    return jump_fcontext( fctx, record).fctx;
+}
+
+}
+
+class continuation {
+private:
+    template< typename Ctx, typename StackAlloc, typename Fn >
+    friend class detail::record;
+
+    template< typename Ctx, typename Fn >
+    friend detail::transfer_t
+    detail::context_ontop( detail::transfer_t);
+
+    template< typename StackAlloc, typename Fn >
+    friend continuation
+    callcc( std::allocator_arg_t, StackAlloc, Fn &&);
+
+    template< typename StackAlloc, typename Fn >
+    friend continuation
+    callcc( std::allocator_arg_t, preallocated, StackAlloc, Fn &&);
+
+    detail::fcontext_t  fctx_{ nullptr };
+
+    continuation( detail::fcontext_t fctx) noexcept :
+        fctx_{ fctx } {
+    }
+
+public:
+    continuation() noexcept = default;
+
+    ~continuation() {
+        if ( BOOST_UNLIKELY( nullptr != fctx_) ) {
+            detail::ontop_fcontext(
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+                    detail::exchange( fctx_, nullptr),
+#else
+                    std::exchange( fctx_, nullptr),
+#endif
+                   nullptr,
+                   detail::context_unwind);
+        }
+    }
+
+    continuation( continuation && other) noexcept {
+        std::swap( fctx_, other.fctx_);
+    }
+
+    continuation & operator=( continuation && other) noexcept {
+        if ( BOOST_LIKELY( this != & other) ) {
+            continuation tmp = std::move( other);
+            swap( tmp);
+        }
+        return * this;
+    }
+
+    continuation( continuation const& other) noexcept = delete;
+    continuation & operator=( continuation const& other) noexcept = delete;
+
+    continuation resume() {
+        BOOST_ASSERT( nullptr != fctx_);
+        return detail::jump_fcontext(
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+                    detail::exchange( fctx_, nullptr),
+#else
+                    std::exchange( fctx_, nullptr),
+#endif
+                    nullptr).fctx;
+    }
+
+    template< typename Fn >
+    continuation resume_with( Fn && fn) {
+        BOOST_ASSERT( nullptr != fctx_);
+        auto p = std::make_tuple( std::forward< Fn >( fn) );
+        return detail::ontop_fcontext(
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+                    detail::exchange( fctx_, nullptr),
+#else
+                    std::exchange( fctx_, nullptr),
+#endif
+                    & p,
+                    detail::context_ontop< continuation, Fn >).fctx;
+    }
+
+    explicit operator bool() const noexcept {
+        return nullptr != fctx_;
+    }
+
+    bool operator!() const noexcept {
+        return nullptr == fctx_;
+    }
+
+    bool operator==( continuation const& other) const noexcept {
+        return fctx_ == other.fctx_;
+    }
+
+    bool operator!=( continuation const& other) const noexcept {
+        return fctx_ != other.fctx_;
+    }
+
+    bool operator<( continuation const& other) const noexcept {
+        return fctx_ < other.fctx_;
+    }
+
+    bool operator>( continuation const& other) const noexcept {
+        return other.fctx_ < fctx_;
+    }
+
+    bool operator<=( continuation const& other) const noexcept {
+        return ! ( * this > other);
+    }
+
+    bool operator>=( continuation const& other) const noexcept {
+        return ! ( * this < other);
+    }
+
+    template< typename charT, class traitsT >
+    friend std::basic_ostream< charT, traitsT > &
+    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other) {
+        if ( nullptr != other.fctx_) {
+            return os << other.fctx_;
+        } else {
+            return os << "{not-a-context}";
+        }
+    }
+
+    void swap( continuation & other) noexcept {
+        std::swap( fctx_, other.fctx_);
+    }
+};
+
+template<
+    typename Fn,
+    typename = detail::disable_overload< continuation, Fn >
+>
+continuation
+callcc( Fn && fn) {
+    return callcc(
+            std::allocator_arg, fixedsize_stack(),
+            std::forward< Fn >( fn) );
+}
+
+template< typename StackAlloc, typename Fn >
+continuation
+callcc( std::allocator_arg_t, StackAlloc salloc, Fn && fn) {
+    using Record = detail::record< continuation, StackAlloc, Fn >;
+    return continuation{
+                detail::create_context1< Record >(
+                        salloc, std::forward< Fn >( fn) ) }.resume();
+}
+
+template< typename StackAlloc, typename Fn >
+continuation
+callcc( std::allocator_arg_t, preallocated palloc, StackAlloc salloc, Fn && fn) {
+    using Record = detail::record< continuation, StackAlloc, Fn >;
+    return continuation{
+                detail::create_context2< Record >(
+                        palloc, salloc, std::forward< Fn >( fn) ) }.resume();
+}
+
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+template< typename Fn >
+continuation
+callcc( std::allocator_arg_t, segmented_stack, Fn &&);
+
+template< typename StackAlloc, typename Fn >
+continuation
+callcc( std::allocator_arg_t, preallocated, segmented_stack, Fn &&);
+#endif
+
+// swap
+inline
+void swap( continuation & l, continuation & r) noexcept {
+    l.swap( r);
+}
+
+}}
+
+#if defined(BOOST_MSVC)
+# pragma warning(pop)
+#endif
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_CONTINUATION_H