introduce java_class_typet::methodt

This has three benefits:

* Ordinary fields no longer have get_is_native/set_is_native, which isn't
  applicable.

* Java methods now offer final/native getters/setters.

* Java methods now have the type java_method_typet.

Author: Daniel Kroening

jbmc/src/java_bytecode/java_types.h

@@ -208,13 +208,65 @@ class java_class_typet:public class_typet
     {
     }
 
-    /// is a method or field 'final'?
+    /// is a field 'final'?
     bool get_is_final() const
     {
       return get_bool(ID_final);
     }
 
-    /// is a method or field 'final'?
+    /// is a field 'final'?
+    void set_is_final(const bool is_final)
+    {
+      set(ID_final, is_final);
+    }
+  };
+
+  using componentst = std::vector<componentt>;
+
+  const componentst &components() const
+  {
+    return (const componentst &)(find(ID_components).get_sub());
+  }
+
+  componentst &components()
+  {
+    return (componentst &)(add(ID_components).get_sub());
+  }
+
+  const componentt &get_component(const irep_idt &component_name) const
+  {
+    return static_cast<const componentt &>(
+      class_typet::get_component(component_name));
+  }
+
+  class methodt : public class_typet::methodt
+  {
+  public:
+    methodt() = delete;
+
+    methodt(const irep_idt &_name, java_method_typet _type)
+      : class_typet::methodt(_name, std::move(_type))
+    {
+    }
+
+    const java_method_typet &type() const
+    {
+      return static_cast<const java_method_typet &>(
+        class_typet::methodt::type());
+    }
+
+    java_method_typet &type()
+    {
+      return static_cast<java_method_typet &>(class_typet::methodt::type());
+    }
+
+    /// is a method 'final'?
+    bool get_is_final() const
+    {
+      return get_bool(ID_final);
+    }
+
+    /// is a method 'final'?
     void set_is_final(const bool is_final)
     {
       set(ID_final, is_final);
@@ -233,22 +285,16 @@ class java_class_typet:public class_typet
     }
   };
 
-  using componentst = std::vector<componentt>;
+  using methodst = std::vector<methodt>;
 
-  const componentst &components() const
+  const methodst &methods() const
   {
-    return (const componentst &)(find(ID_components).get_sub());
+    return (const methodst &)(find(ID_methods).get_sub());
   }
 
-  componentst &components()
+  methodst &methods()
   {
-    return (componentst &)(add(ID_components).get_sub());
-  }
-
-  const componentt &get_component(const irep_idt &component_name) const
-  {
-    return static_cast<const componentt &>(
-      class_typet::get_component(component_name));
+    return (methodst &)(add(ID_methods).get_sub());
   }
 
   using static_membert = componentt;