Initial work

Ryujinx.Graphics.Shader/StructuredIr/AstBlockVisitor.cs

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+using System;
+using System.Collections.Generic;
+
+using static Ryujinx.Graphics.Shader.StructuredIr.AstHelper;
+
+namespace Ryujinx.Graphics.Shader.StructuredIr
+{
+    class AstBlockVisitor
+    {
+        public AstBlock Block { get; private set; }
+
+        public class BlockVisitationEventArgs : EventArgs
+        {
+            public AstBlock Block { get; }
+
+            public BlockVisitationEventArgs(AstBlock block)
+            {
+                Block = block;
+            }
+        }
+
+        public event EventHandler<BlockVisitationEventArgs> BlockEntered;
+        public event EventHandler<BlockVisitationEventArgs> BlockLeft;
+
+        public AstBlockVisitor(AstBlock mainBlock)
+        {
+            Block = mainBlock;
+        }
+
+        public IEnumerable<IAstNode> Visit()
+        {
+            IAstNode node = Block.First;
+
+            while (node != null)
+            {
+                // We reached a child block, visit the nodes inside.
+                while (node is AstBlock childBlock)
+                {
+                    Block = childBlock;
+
+                    node = childBlock.First;
+
+                    BlockEntered?.Invoke(this, new BlockVisitationEventArgs(Block));
+                }
+
+                // Node may be null, if the block is empty.
+                if (node != null)
+                {
+                    IAstNode next = Next(node);
+
+                    yield return node;
+
+                    node = next;
+                }
+
+                // We reached the end of the list, go up on tree to the parent blocks.
+                while (node == null && Block.Type != AstBlockType.Main)
+                {
+                    BlockLeft?.Invoke(this, new BlockVisitationEventArgs(Block));
+
+                    node = Next(Block);
+
+                    Block = Block.Parent;
+                }
+            }
+        }
+    }
+}