Class TypeVariableInvocationHandler

output/java_guava/1.4.17/Types.java:363–404

Invocation handler to work around a compatibility problem between Java 7 and Java 8. Java 8 introduced a new method getAnnotatedBounds() in the TypeVariable interface, whose return type AnnotatedType[] is also new in Java 8. That means that we cannot implement that interf

   */

  private static final class TypeVariableInvocationHandler implements InvocationHandler {

    private static final ImmutableMap<String, Method> typeVariableMethods;

    static {
      ImmutableMap.Builder<String, Method> builder = ImmutableMap.builder();
      for (Method method : TypeVariableImpl.class.getMethods()) {
        if (method.getDeclaringClass().equals(TypeVariableImpl.class)) {
          try {
            method.setAccessible(true);
          } catch (AccessControlException e) {
            // OK: the method is accessible to us anyway. The setAccessible call is only for
            // unusual execution environments where that might not be true.
          }
          builder.put(method.getName(), method);
        }
      }
      typeVariableMethods = builder.build();
    }


    private final TypeVariableImpl<?> typeVariableImpl;

    TypeVariableInvocationHandler(TypeVariableImpl<?> typeVariableImpl) {
      this.typeVariableImpl = typeVariableImpl;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
      String methodName = method.getName();
      Method typeVariableMethod = typeVariableMethods.get(methodName);
      if (typeVariableMethod == null) {
        throw new UnsupportedOperationException(methodName);
      } else {
        try {
          return typeVariableMethod.invoke(typeVariableImpl, args);
        } catch (InvocationTargetException e) {
          throw e.getCause();
        }
      }
    }
  }

  private static final class TypeVariableImpl<D extends GenericDeclaration> {