Move path coercion to TrackType

[r2c2.git] / source / libr2c2 / tracktype.cpp

diff --git a/source/libr2c2/tracktype.cpp b/source/libr2c2/tracktype.cpp
index 7a1f27ad5adcc69ee282a028d10755dabf68d37a..59b8f9ca275b4fe508b94fe77c32ec220ab83472 100644 (file)
--- a/source/libr2c2/tracktype.cpp
+++ b/source/libr2c2/tracktype.cpp
@@ -44,6 +44,36 @@ unsigned TrackType::get_n_paths() const
        return n;
 }
 
+unsigned TrackType::coerce_path(unsigned entry, unsigned path) const
+{
+       const Endpoint &ep = get_endpoint(entry);
+       if(ep.has_path(path))
+               return path;
+
+       unsigned paths = get_paths();
+       if(paths>>(1<<state_bits))
+       {
+               /* There are more paths than can be expressed with state_bits, so
+               multiple paths are set at once.  See if one of the alternatives fits. */
+               unsigned step = 1<<state_bits;
+               for(unsigned p=path+step; paths>>p; p+=step)
+                       if(ep.has_path(p))
+                               return p;
+       }
+
+       // Find an endpoint that's connected to the entry and has the requested path
+       for(vector<Endpoint>::const_iterator i=endpoints.begin(); i!=endpoints.end(); ++i)
+               if(i->has_path(path) && i->has_common_paths(ep))
+               {
+                       unsigned p = 1;
+                       for(unsigned m=i->paths&ep.paths; m>>p; ++p) ;
+                       return p-1;
+               }
+
+       // TODO crossings fall here
+       throw logic_error("TrackType::coerce_path");
+}
+
 bool TrackType::is_turnout() const
 {
        return endpoints.size()>2;