deLayering is implemented as a grammar analysis

shared/rascal/src/analyse/Layers.rsc

@@ -0,0 +1,61 @@
+@contributor{Vadim Zaytsev - vadim@grammarware.net - SWAT, CWI}
+module analyse::Layers
+
+import syntax::BGF;
+import syntax::XBGF;
+import io::ReadBGF;
+import lib::Rascalware;
+import analyse::Metrics;
+import normal::BGF;
+import transform::XBGF;
+import export::BNF;
+import Relation;
+
+rel[str,str] detectLayers(BGFGrammar g)
+{
+	rel[str,str] res = {};
+	rel[str,str] dres = {};
+	for (n1 <- definedNs(g), n2 <- definedNs(g))
+	{
+		BGFProdList ps1 = prodsOfN(n1,g.prods);
+		BGFProdList ps2 = prodsOfN(n2,g.prods);
+		// n2 chains to n1, but not exclusively
+		if (
+				/p:production(_,n2,nonterminal(n1)) := ps2
+				&& !isEmpty(ps2 - p)
+			)
+			res += <n1,n2>;
+		if (
+				/production(_,n2,choice([*L1,nonterminal(n1),*L2])) := ps2
+				&& !isEmpty(L1+L2)
+			)
+			res += <n1,n2>;
+
+		for (<n1,n2> <- res)
+			if (/production(_,n1,e) := ps1 && /nonterminal(n2) := e && n1!=n2)
+				dres += <n1,n2>;
+	}
+	return dres;
+}
+
+public void main()
+{
+	for (src <- ["antlr","dcg","ecore","emf","jaxb","om","python","rascal-a","rascal-c","sdf","txl","xsd"])
+	//for (src <- ["python"])
+	{
+		println("Reading <src>...");
+		BGFGrammar g = readBGF(|home:///projects/slps/topics/convergence/guided/bgf/<src>.bgf|);
+		println("Normalising <src>...");
+		g = visit(g)
+		{
+			case selectable(s,e) => e
+			case terminal(_) => epsilon()
+		}
+		for (n <- [n | n <- usedNs(g), len(prodsOfN(n,g.prods))==1, len([n | /nonterminal(n) := g])==1])
+			g = transform([inline(n)],g);
+		println("Analysing <src>...");
+		rel[str,str] layers = detectLayers(g);
+		if(!isEmpty(layers))
+			println("Found <layers>");
+	}
+}