Chris@16: //
Chris@16: // detail/call_stack.hpp
Chris@16: // ~~~~~~~~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_DETAIL_CALL_STACK_HPP
Chris@16: #define BOOST_ASIO_DETAIL_CALL_STACK_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/config.hpp>
Chris@16: #include <boost/asio/detail/noncopyable.hpp>
Chris@16: #include <boost/asio/detail/tss_ptr.hpp>
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: namespace detail {
Chris@16: 
Chris@16: // Helper class to determine whether or not the current thread is inside an
Chris@16: // invocation of io_service::run() for a specified io_service object.
Chris@16: template <typename Key, typename Value = unsigned char>
Chris@16: class call_stack
Chris@16: {
Chris@16: public:
Chris@16:   // Context class automatically pushes the key/value pair on to the stack.
Chris@16:   class context
Chris@16:     : private noncopyable
Chris@16:   {
Chris@16:   public:
Chris@16:     // Push the key on to the stack.
Chris@16:     explicit context(Key* k)
Chris@16:       : key_(k),
Chris@16:         next_(call_stack<Key, Value>::top_)
Chris@16:     {
Chris@16:       value_ = reinterpret_cast<unsigned char*>(this);
Chris@16:       call_stack<Key, Value>::top_ = this;
Chris@16:     }
Chris@16: 
Chris@16:     // Push the key/value pair on to the stack.
Chris@16:     context(Key* k, Value& v)
Chris@16:       : key_(k),
Chris@16:         value_(&v),
Chris@16:         next_(call_stack<Key, Value>::top_)
Chris@16:     {
Chris@16:       call_stack<Key, Value>::top_ = this;
Chris@16:     }
Chris@16: 
Chris@16:     // Pop the key/value pair from the stack.
Chris@16:     ~context()
Chris@16:     {
Chris@16:       call_stack<Key, Value>::top_ = next_;
Chris@16:     }
Chris@16: 
Chris@16:     // Find the next context with the same key.
Chris@16:     Value* next_by_key() const
Chris@16:     {
Chris@16:       context* elem = next_;
Chris@16:       while (elem)
Chris@16:       {
Chris@16:         if (elem->key_ == key_)
Chris@16:           return elem->value_;
Chris@16:         elem = elem->next_;
Chris@16:       }
Chris@16:       return 0;
Chris@16:     }
Chris@16: 
Chris@16:   private:
Chris@16:     friend class call_stack<Key, Value>;
Chris@16: 
Chris@16:     // The key associated with the context.
Chris@16:     Key* key_;
Chris@16: 
Chris@16:     // The value associated with the context.
Chris@16:     Value* value_;
Chris@16: 
Chris@16:     // The next element in the stack.
Chris@16:     context* next_;
Chris@16:   };
Chris@16: 
Chris@16:   friend class context;
Chris@16: 
Chris@16:   // Determine whether the specified owner is on the stack. Returns address of
Chris@16:   // key if present, 0 otherwise.
Chris@16:   static Value* contains(Key* k)
Chris@16:   {
Chris@16:     context* elem = top_;
Chris@16:     while (elem)
Chris@16:     {
Chris@16:       if (elem->key_ == k)
Chris@16:         return elem->value_;
Chris@16:       elem = elem->next_;
Chris@16:     }
Chris@16:     return 0;
Chris@16:   }
Chris@16: 
Chris@16:   // Obtain the value at the top of the stack.
Chris@16:   static Value* top()
Chris@16:   {
Chris@16:     context* elem = top_;
Chris@16:     return elem ? elem->value_ : 0;
Chris@16:   }
Chris@16: 
Chris@16: private:
Chris@16:   // The top of the stack of calls for the current thread.
Chris@16:   static tss_ptr<context> top_;
Chris@16: };
Chris@16: 
Chris@16: template <typename Key, typename Value>
Chris@16: tss_ptr<typename call_stack<Key, Value>::context>
Chris@16: call_stack<Key, Value>::top_;
Chris@16: 
Chris@16: } // namespace detail
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #endif // BOOST_ASIO_DETAIL_CALL_STACK_HPP