private void checkRendering()

in wicket-core/src/main/java/org/apache/wicket/Page.java [561:669]
83 lines of code
16 McCabe index (conditional complexity)

	private void checkRendering(final MarkupContainer renderedContainer)
	{
		// If the application wants component uses checked and
		// the response is not a redirect
		final DebugSettings debugSettings = getApplication().getDebugSettings();
		if (debugSettings.getComponentUseCheck())
		{
			final List<Component> unrenderedComponents = new ArrayList<Component>();
			final StringBuilder buffer = new StringBuilder();
			renderedContainer.visitChildren(new IVisitor<Component, Void>()
			{
				@Override
				public void component(final Component component, final IVisit<Void> visit)
				{
					// If component never rendered
					if (renderedComponents == null || !renderedComponents.contains(component))
					{
						// If not an auto component ...
						if (!component.isAuto() && component.isVisibleInHierarchy())
						{
							// Increase number of unrendered components
							unrenderedComponents.add(component);

							// Add to explanatory string to buffer
							buffer.append(Integer.toString(unrenderedComponents.size()))
								.append(". ")
								.append(component.toString(true))
								.append('\n');
							String metadata = component.getMetaData(Component.CONSTRUCTED_AT_KEY);
							if (metadata != null)
							{
								buffer.append(metadata).append('\n');
							}
							metadata = component.getMetaData(Component.ADDED_AT_KEY);
							if (metadata != null)
							{
								buffer.append(metadata).append('\n');
							}
						}
						else
						{
							// if the component is not visible in hierarchy we
							// should not visit its children since they are also
							// not visible
							visit.dontGoDeeper();
						}
					}
				}
			});

			// Throw exception if any errors were found
			if (unrenderedComponents.size() > 0)
			{
				renderedComponents = null;

				List<Component> transparentContainerChildren = Generics.newArrayList();

				Iterator<Component> iterator = unrenderedComponents.iterator();
				outerWhile : while (iterator.hasNext())
				{
					Component component = iterator.next();

					// If any of the transparentContainerChildren is a parent to component, then
					// ignore it.
					for (Component transparentContainerChild : transparentContainerChildren)
					{
						MarkupContainer parent = component.getParent();
						while (parent != null)
						{
							if (parent == transparentContainerChild)
							{
								iterator.remove();
								continue outerWhile;
							}
							parent = parent.getParent();
						}
					}

					if (hasInvisibleTransparentChild(component.getParent(), component))
					{
						// If we found a transparent container that isn't visible then ignore this
						// component and only do a debug statement here.
						if (log.isDebugEnabled())
						{
							log.debug(
								"Component {} wasn't rendered but might have a transparent parent.",
								component);
						}

						transparentContainerChildren.add(component);
						iterator.remove();
						continue outerWhile;
					}
				}

				// if still > 0
				if (unrenderedComponents.size() > 0)
				{
					// Throw exception
					throw new WicketRuntimeException(
						"The component(s) below failed to render. Possible reasons could be that:\n\t1) you have added a component in code but forgot to reference it in the markup (thus the component will never be rendered),\n\t2) if your components were added in a parent container then make sure the markup for the child container includes them in <wicket:extend>.\n\n" +
							buffer.toString());
				}
			}
		}

		// Get rid of set
		renderedComponents = null;
	}