X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Flibr2c2%2Ftracktype.cpp;h=59b8f9ca275b4fe508b94fe77c32ec220ab83472;hb=4acf89b0ec739c0bef8b11d3a52a4c551efa881e;hp=7a1f27ad5adcc69ee282a028d10755dabf68d37a;hpb=d405b9943c888e3945c7ea4e496f9d300b114fe0;p=r2c2.git

diff --git a/source/libr2c2/tracktype.cpp b/source/libr2c2/tracktype.cpp
index 7a1f27a..59b8f9c 100644
--- 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;