WICKET-7134 Form code refactoring

- centralizing form processing code inside the visit
- replacing form#isSubmitted with form#isVisible/EnabledInHierarchy

Author: pedrosans

wicket-core/src/main/java/org/apache/wicket/markup/html/form/Form.java

@@ -1325,7 +1325,7 @@ protected void delegateSubmit(IFormSubmitter submittingComponent)
 		// collect all forms innermost to outermost before any hierarchy is changed
 		final List<Form<?>> forms = Generics.newArrayList(3);
 		visitFormsPostOrder(processingForm, (form, visit) -> {
-			if (form.isSubmitted())
+			if (form.isVisibleInHierarchy() && form.isEnabledInHierarchy())
 			{
 				forms.add(form);
 			}
@@ -1557,22 +1557,9 @@ public void component(final FormComponent<?> formComponent, IVisit<Void> visit)
 	 * Mark each form component on this form and on nested forms valid.
 	 */
 	protected final void markFormComponentsValid()
-	{
-		markNestedFormComponentsValid();
-		internalMarkFormComponentsValid();
-	}
-
-	/**
-	 * Mark each form component on nested form valid.
-	 */
-	private void markNestedFormComponentsValid()
 	{
 		visitFormsPostOrder(this, (form, visit) -> {
-			if (form == Form.this)
-			{
-				return;
-			}
-			if (form.isSubmitted())
+			if (form.isVisibleInHierarchy() && form.isEnabledInHierarchy())
 			{
 				form.internalMarkFormComponentsValid();
 			}
@@ -1879,24 +1866,9 @@ protected void onSubmit()
 	 * @see org.apache.wicket.markup.html.form.FormComponent#updateModel()
 	 */
 	protected final void updateFormComponentModels()
-	{
-		updateNestedFormComponentModels();
-		internalUpdateFormComponentModels();
-	}
-
-	/**
-	 * Update the model of all components on nested forms.
-	 *
-	 * @see #updateFormComponentModels()
-	 */
-	private void updateNestedFormComponentModels()
 	{
 		visitFormsPostOrder(this, (form, visit) -> {
-			if (form == Form.this)
-			{
-				return;
-			}
-			if (form.isSubmitted())
+			if (form.isVisibleInHierarchy() && form.isEnabledInHierarchy())
 			{
 				form.internalUpdateFormComponentModels();
 			}
@@ -1924,14 +1896,15 @@ private void internalUpdateFormComponentModels()
 	 */
 	protected final void validate()
 	{
-		// since this method can be called directly by users, this additional check is needed
-		if (isEnabledInHierarchy() && isVisibleInHierarchy())
-		{
-			validateNestedForms();
-			validateComponents();
-			validateFormValidators();
-			onValidate();
-		}
+		visitFormsPostOrder(this, (form, visit) -> {
+			// since this method can be called directly by users, this additional check is needed
+			if (form.isVisibleInHierarchy() && form.isEnabledInHierarchy())
+			{
+				form.validateComponents();
+				form.validateFormValidators();
+				form.onValidate();
+			}
+		});
 	}
 
 	/**
@@ -1949,16 +1922,11 @@ protected void onValidate()
 	private void internalOnValidateModelObjects()
 	{
 		visitFormsPostOrder(this, (form, visit) -> {
-			if (form == Form.this)
-			{
-				return;
-			}
-			if (form.isSubmitted())
+			if (form.isVisibleInHierarchy() && form.isEnabledInHierarchy())
 			{
 				form.onValidateModelObjects();
 			}
 		});
-		onValidateModelObjects();
 	}
 
 	/**
@@ -2055,28 +2023,6 @@ protected final void validateFormValidators()
 		}
 	}
 
-	/**
-	 * Validates {@link FormComponent}s as well as {@link IFormValidator}s in nested {@link Form}s.
-	 *
-	 * @see #validate()
-	 */
-	private void validateNestedForms()
-	{
-		visitFormsPostOrder(this, (form, visit) -> {
-			if (form == Form.this)
-			{
-				return;
-			}
-
-			if (form.isSubmitted())
-			{
-				form.validateComponents();
-				form.validateFormValidators();
-				form.onValidate();
-			}
-		});
-	}
-
 	/**
 	 * Allows to customize input names of form components inside this form.
 	 *