maui-linux/System.Maui.Xaml/PruneIgnoredNodesVisitor.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace System.Maui.Xaml
{
	class PruneIgnoredNodesVisitor : IXamlNodeVisitor
	{
		public PruneIgnoredNodesVisitor(bool useDesignProperties = false) => UseDesignProperties = useDesignProperties;

		public TreeVisitingMode VisitingMode => TreeVisitingMode.TopDown;
		public bool StopOnDataTemplate => false;
		public bool StopOnResourceDictionary => false;
		public bool VisitNodeOnDataTemplate => true;
		public bool UseDesignProperties { get; }
		public bool SkipChildren(INode node, INode parentNode) => false;
		public bool IsResourceDictionary(ElementNode node) => false;

		public void Visit(ElementNode node, INode parentNode)
		{
			foreach (var propertyKvp in node.Properties)
			{
				var propertyName = propertyKvp.Key;
				if (!((propertyKvp.Value as ValueNode)?.Value is string propertyValue))
					continue;
				if (!propertyName.Equals(XamlParser.McUri, "Ignorable"))
					continue;
				var prefixes = propertyValue.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
				if (UseDesignProperties) //if we're in design mode for this file
				{
					for (var i = 0; i < prefixes.Count; i++)
						if (node.NamespaceResolver.LookupNamespace(prefixes[i]) == XamlParser.XFDesignUri)
							prefixes.RemoveAt(i--);
				}

				(parentNode.IgnorablePrefixes ?? (parentNode.IgnorablePrefixes = new List<string>())).AddRange(prefixes);
			}

			foreach (var propertyKvp in node.Properties.ToList())
			{
				// skip d:foo="bar"
				var prefix = node.NamespaceResolver.LookupPrefix(propertyKvp.Key.NamespaceURI);
				if (node.SkipPrefix(prefix))
					node.Properties.Remove(propertyKvp.Key);
				var propNs = (propertyKvp.Value as IElementNode)?.NamespaceURI ?? "";
				var propPrefix = node.NamespaceResolver.LookupPrefix(propNs);
				if (node.SkipPrefix(propPrefix))
					node.Properties.Remove(propertyKvp.Key);
			}

			foreach (var prop in node.CollectionItems.ToList())
			{
				var propNs = (prop as IElementNode)?.NamespaceURI ?? "";
				var propPrefix = node.NamespaceResolver.LookupPrefix(propNs);
				if (node.SkipPrefix(propPrefix))
					node.CollectionItems.Remove(prop);
			}

			if (node.SkipPrefix(node.NamespaceResolver.LookupPrefix(node.NamespaceURI)))
			{
				node.Properties.Clear();
				node.CollectionItems.Clear();
			}
		}

		public void Visit(RootNode node, INode parentNode)
		{
			Visit((ElementNode)node, node);
		}

		public void Visit(MarkupNode node, INode parentNode)
		{
		}

		public void Visit(ListNode node, INode parentNode)
		{
			foreach (var prop in node.CollectionItems.ToList())
			{
				var propNs = (prop as IElementNode)?.NamespaceURI ?? "";
				var propPrefix = node.NamespaceResolver.LookupPrefix(propNs);
				if (node.SkipPrefix(propPrefix))
					node.CollectionItems.Remove(prop);
			}
		}

		public void Visit(ValueNode node, INode parentNode)
		{
		}
	}
}