+ * Other points of customization: + *
+ *non-null, the modifier could not be fetched, e.g. adapted
+ * from the specified INodeContext.
+ */
+ protected Throwable modifierFailed;
+
+
+ /**
+ * @param context
+ * @param session
+ */
+ public AbstractStringModifier(NodeContext context, RequestProcessor processor) {
+ this.context = context;
+ this.session = processor.getSession();
+
+ final Resource r = getResourceToModify();
+ if (r == null)
+ throw new IllegalArgumentException("This modifier does not work for INodeContexts that are not adaptable to a Resource. The context input is: " + context.getConstant(BuiltinKeys.INPUT));
+
+ try {
+ processor.syncRequest(new ReadRequest() {
+ @Override
+ public void run(ReadGraph g) throws DatabaseException {
+ initialValue = getInitialValue(g);
+ AbstractStringModifier.this.modifier = g.adapt(r, StringModifier.class);
+ initializeModifier(g);
+ }
+ });
+ } catch (DatabaseException e) {
+ modifierFailed = e;
+ }
+ }
+
+ protected void initializeModifier(ReadGraph g) {
+ }
+
+ /**
+ * @param g
+ * @return the value that shall be returned by {@link #getValue()}
+ */
+ protected String getInitialValue(ReadGraph g) throws DatabaseException {
+ return g.adapt(getResourceToModify(), String.class);
+ }
+
+ /**
+ * @return the Resource to modify based on the input INodeContext. This
+ * resource must be adaptable to a {@link StringModifier} in order
+ * for this modifier to work.
+ */
+ protected Resource getResourceToModify() {
+ return (Resource) context.getAdapter(Resource.class);
+ }
+
+ /**
+ * @return the modifier
+ */
+ protected StringModifier getModifier() {
+ return modifier;
+ }
+
+ @Override
+ public String getValue() {
+ return initialValue;
+ }
+
+ @Override
+ public String isValid(String label) {
+ if (modifierFailed != null)
+ return "Could not resolve validator for this value, modification denied. Reason: " + modifierFailed.getMessage();
+ String t = createModifierInput(label);
+ return modifier.isValid(t);
+ }
+
+ @Override
+ public final void modify(String label) {
+ if (modifierFailed != null)
+ // TODO: throw exception?
+ return;
+ String t = createModifierInput(label);
+ if (!verifyModification(t))
+ return;
+ doModify(t);
+ }
+
+ /**
+ * Called one last time before actually performing the modifying write
+ * transaction to verify whether this is really desired or not.
+ *
+ * + * This default implementation will always allow the modification to proceed. + *
+ * + * @param label the label to be given to the modifier + * @returntrue to go forward with the transaction,
+ * false to bail out
+ */
+ protected boolean verifyModification(String label) {
+ return true;
+ }
+
+ public abstract void doModify(String label);
+
+ /**
+ * Override if necessary.
+ *
+ * @param label
+ * @return
+ */
+ public String createModifierInput(String label) {
+ return label;
+ }
+
+};