+ }
+}
+
+unsigned Layout::allocate_turnout_id(bool dbl)
+{
+ set<unsigned> used_ids;
+ for(set<Track *>::const_iterator i=tracks.begin(); i!=tracks.end(); ++i)
+ if((*i)->get_turnout_id())
+ used_ids.insert((*i)->get_turnout_id());
+
+ unsigned result = next_turnout_id;
+ while(used_ids.count(result) || (dbl && used_ids.count(result+1)))
+ ++result;
+ next_turnout_id = result+1+dbl;
+
+ return result;
+}
+
+void Layout::add_block(Block &b)
+{
+ blocks.insert(&b);
+}
+
+Block &Layout::get_block(unsigned id) const
+{
+ for(set<Block *>::const_iterator i=blocks.begin(); i!=blocks.end(); ++i)
+ if((*i)->get_id()==id)
+ return **i;
+
+ throw KeyError("Unknown block", lexical_cast(id));
+}
+
+void Layout::create_blocks()
+{
+ set<Track *> used_tracks;
+ for(set<Block *>::const_iterator i=blocks.begin(); i!=blocks.end(); ++i)
+ {
+ const set<Track *> &btracks = (*i)->get_tracks();
+ used_tracks.insert(btracks.begin(), btracks.end());
+ }
+
+ for(set<Track *>::const_iterator i=tracks.begin(); i!=tracks.end(); ++i)
+ if(used_tracks.count(*i)==0)
+ {
+ Block *block = new Block(*this, **i);
+ used_tracks.insert(block->get_tracks().begin(), block->get_tracks().end());
+ }
+
+ for(set<Block *>::iterator i=blocks.begin(); i!=blocks.end(); ++i)
+ for(set<Block *>::iterator j=i; j!=blocks.end(); ++j)
+ if(j!=i)
+ (*i)->check_link(**j);
+}
+
+void Layout::create_blocks(Track &track)
+{
+ /* Must collect the blocks in a set first while all tracks are still
+ guaranteed to have blocks and to avoid duplicate deletes */
+ set<Block *> del_blocks;
+
+ del_blocks.insert(&track.get_block());
+
+ const vector<Track *> &links = track.get_links();
+ for(vector<Track *>::const_iterator i=links.begin(); i!=links.end(); ++i)
+ if(*i)
+ del_blocks.insert(&(*i)->get_block());
+
+ for(set<Block *>::iterator i=del_blocks.begin(); i!=del_blocks.end(); ++i)
+ delete *i;
+
+ create_blocks();
+}
+
+void Layout::remove_block(Block &b)
+{
+ blocks.erase(&b);