Add obfuscation detector.

The rule is quite simple (simpler than what was originally planned).
It marks any classes and interfaces whose name only consist of lowercase
alphabets and $ as obfuscated="true" in the <class> element.

obfuscated types are later filtered out by generator.

Users can overwrite this "obfuscated" attribute by Metadata.xml.

JavaClass.java

@@ -1,5 +1,5 @@
 /* 
- *  Copyright (c) 2011 Xamarin Inc.
+ *  Copyright (c) 2011-2012 Xamarin Inc.
  * 
  *  Permission is hereby granted, free of charge, to any person 
  *  obtaining a copy of this software and associated documentation 
@@ -55,6 +55,7 @@ public class JavaClass implements Comparable<JavaClass> {
 	private Map<String,FieldNode> asmFields;
 	private List<String> deprecatedFields;
 	private List<String> deprecatedMethods;
+	private boolean is_obfuscated;
 
 	public JavaClass (Class jclass, ClassNode asm)
 	{
@@ -77,6 +78,16 @@ public String getName ()
 	{
 		return asm.name.replace ('/', '.');
 	}
+
+	public boolean isObfuscated ()
+	{
+		return is_obfuscated;
+	}
+
+	public void setObfuscated (boolean value)
+	{
+		is_obfuscated = value;
+	}
 
 	String[] getParameterNames (String name, Type[] types, boolean isVarArgs)
 	{
@@ -478,6 +489,8 @@ void doAppendToDocument (Document doc, Element parent)
 		e.setAttribute ("static", Modifier.isStatic (mods) ? "true" : "false");
 		e.setAttribute ("abstract", Modifier.isAbstract (mods) ? "true" : "false");
 		e.setAttribute ("visibility", Modifier.isPublic (mods) ? "public" : Modifier.isProtected (mods) ? "protected" : "");
+		if (is_obfuscated)
+			e.setAttribute ("obfuscated", Boolean.toString (is_obfuscated));
 
 		Element typeParameters = getTypeParametersNode (doc, jclass.getTypeParameters ());
 		if (typeParameters != null)

JavaPackage.java

@@ -1,5 +1,5 @@
 /* 
- *  Copyright (c) 2011 Xamarin Inc.
+ *  Copyright (c) 2011-2012 Xamarin Inc.
  * 
  *  Permission is hereby granted, free of charge, to any person 
  *  obtaining a copy of this software and associated documentation 
@@ -62,8 +62,23 @@ public void appendToDocument (Document doc, Element parent)
 		e.setAttribute ("name", name);
 		parent.appendChild (e);
 		Collections.sort (classes);
+		for (int i = 0; i < classes.size (); i++) {
+			String name = classes.get (i).getName ();
+			int idx = name.lastIndexOf ('.');
+			String body = idx < 0 ? name : name.substring (idx + 1);
+			if (isObfuscatedName (body))
+				classes.get (i).setObfuscated (true);
+		}
 		for (JavaClass c : classes)
 			c.appendToDocument (doc, e);
 	}
+
+	static boolean isObfuscatedName (String name)
+	{
+		for (char c : name.toCharArray ())
+			if (c != '$' && (c < 'a' || 'z' < c))
+				return false;
+		return true;
+	}
 }