// Boost.Signals library
//
// Copyright (C) 2001 Doug Gregor (gregod@cs.rpi.edu)
//
// Permission to copy, use, sell and distribute this software is granted
// provided this copyright notice appears in all copies.
// Permission to modify the code and to distribute modified code is granted
// provided this copyright notice appears in all copies, and a notice
// that the code was modified is included with the copyright notice.
//
// This software is provided "as is" without express or implied warranty,
// and with no claim as to its suitability for any purpose.

// For more information, see http://www.boost.org

#include <boost/signals/detail/signal_base.hpp>
#include <cassert>

namespace boost {
  namespace BOOST_SIGNALS_NAMESPACE {
    namespace detail {
      signal_base_impl::signal_base_impl(const compare_type& comp) :
	call_depth(0),
	slots_(comp)
      {
	flags.delayed_disconnect = false;
	flags.clearing = false;
      }

      signal_base_impl::~signal_base_impl()
      {
	// Set the "clearing" flag to ignore extraneous disconnect requests,
	// because all slots will be disconnected on destruction anyway.
	flags.clearing = true;
      }

      void signal_base_impl::disconnect_all_slots()
      {
	// Do nothing if we're already clearing the slot list
	if (flags.clearing)
	  return;

	if (call_depth == 0) {
	  // Clearing the slot list will disconnect all slots automatically
	  temporarily_set_clearing set_clearing(this);
	  slots_.clear();
	}
	else {
	  // We can't actually remove elements from the slot list because there
	  // are still iterators into the slot list that must not be
	  // invalidated by this operation. So just disconnect each slot
	  // without removing it from the slot list. When the call depth does
	  // reach zero, the call list will be cleared.
	  flags.delayed_disconnect = true;
	  temporarily_set_clearing set_clearing(this);
	  for (slot_iterator i = slots_.begin(); i != slots_.end(); ++i) {
	    i->second.first.disconnect();
	  }
	}
      }

      connection
      signal_base_impl::
	connect_slot(const any& slot,
		     const any& name,
		     const std::vector<const trackable*>& bound_objects)
      {
	// Allocate storage for a new basic_connection object to represent the
	// connection
	basic_connection* con = new basic_connection();

	// Create a new connection handle object and place the basic_connection
	// object we just created under its control. Note that the "reset"
	// routine will delete con if allocation throws.
	connection slot_connection;
	slot_connection.reset(con);

	// Allocate storage for an iterator that will hold the point of
	// insertion of the slot into the list. This is used to later remove
	// the slot when it is disconnected.
	std::auto_ptr<slot_iterator> saved_iter(new slot_iterator());

	// Add the slot to the list.

	slot_iterator pos =
	  slots_.insert(stored_slot_type(name,
					connection_slot_pair(slot_connection,
							     slot)));

	// Make the copy of the connection in the list disconnect when it is
	// destroyed
	pos->second.first.set_controlling();

	// The assignment operation here absolutely must not throw, which
	// intuitively makes sense (because any container's insert method
	// becomes impossible to use in an exception-safe manner without this
	// assumption), but doesn't appear to be mentioned in the standard.
	*saved_iter = pos;

	// Fill out the connection object appropriately. None of these
	// operations can throw
	con->signal = this;
	con->signal_data = saved_iter.release();
	con->signal_disconnect = &signal_base_impl::slot_disconnected;

	// If an exception is thrown the connection will automatically be
	// disconnected.
	scoped_connection safe_connection = slot_connection;

	// Connect each of the bound objects
	for(std::vector<const trackable*>::const_iterator i =
	      bound_objects.begin();
	    i != bound_objects.end();
	    ++i) {
	  // Notify the object that the signal is connecting to it by passing
	  // it a copy of the connection. If the connection
	  // should throw, the scoped connection safe_connection will
	  // disconnect the connection completely.
	  bound_object binding;
	  (*i)->signal_connected(slot_connection, binding);

	  // This will notify the bound object that the connection just made
	  // should be disconnected if an exception is thrown before the
	  // end of this iteration
	  auto_disconnect_bound_object disconnector(binding);

	  // Add the binding to the list of bindings for the connection.
	  con->bound_objects.push_back(binding);

	  // The connection object now knows about the bound object, so if an
	  // exception is thrown later the connection object will notify the
	  // bound object of the disconnection automatically
	  disconnector.release();
	}

	// No exceptions will be thrown past this point, and we must not
	// disconnect the connection now
	safe_connection.release();

	return slot_connection;
      }

      bool signal_base_impl::empty() const
      {
	// Disconnected slots may still be in the list of slots if
	//   a) this is called while slots are being invoked (call_depth > 0)
	//   b) an exception was thrown in remove_disconnected_slots
	for (slot_iterator i = slots_.begin(); i != slots_.end(); ++i) {
	  if (i->second.first.connected())
	    return false;
	}

	return true;
      }

      void signal_base_impl::disconnect(const any& group)
      {
	std::pair<slot_iterator, slot_iterator> group_slots =
	  slots_.equal_range(group);
	while (group_slots.first != group_slots.second) {
	  slot_iterator next = group_slots.first;
	  ++next;

	  group_slots.first->second.first.disconnect();
	  group_slots.first = next;
	}
      }

      void signal_base_impl::slot_disconnected(void* obj, void* data)
      {
	signal_base_impl* self = reinterpret_cast<signal_base_impl*>(obj);

	// We won't need the slot iterator after this
	std::auto_ptr<slot_iterator> slot(
				      reinterpret_cast<slot_iterator*>(data));

	// If we're flags.clearing, we don't bother updating the list of slots
	if (!self->flags.clearing) {
	  // If we're in a call, note the fact that a slot has been deleted so
	  // we can come back later to remove the iterator
	  if (self->call_depth > 0) {
	    self->flags.delayed_disconnect = true;
	  }
	  else {
	    // Just remove the slot now, it's safe
	    self->slots_.erase(*slot);
	  }
	}
      }

      void signal_base_impl::remove_disconnected_slots() const
      {
	// Remove any disconnected slots
	for (slot_iterator i = slots_.begin(); i != slots_.end(); /* none */) {
	  if (!i->second.first.connected())
	    slots_.erase(i++);
	  else
	    ++i;
	}
      }

      call_notification::
	call_notification(const shared_ptr<signal_base_impl>& b) :
	  impl(b)
      {
	// A call will be made, so increment the call depth as a notification
	impl->call_depth++;
      }

      call_notification::~call_notification()
      {
	impl->call_depth--;

	// If the call depth is zero and we have some slots that have been
	// disconnected during the calls, remove those slots from the list
	if (impl->call_depth == 0 &&
	    impl->flags.delayed_disconnect) {
	  impl->remove_disconnected_slots();
	  impl->flags.delayed_disconnect = false;
	}
      }

      signal_base::~signal_base()
      {
      }
    } // namespace detail
  } // namespace BOOST_SIGNALS_NAMESPACE
} // namespace boost

#ifndef BOOST_MSVC
// Explicit instantiations to keep in the library
template class boost::function2<bool, boost::any, boost::any>;
template class std::multimap<boost::any,
			     boost::BOOST_SIGNALS_NAMESPACE::detail::connection_slot_pair,
			     boost::function2<bool, boost::any, boost::any> >;
#endif