Update MkvInfoReader, Add MkvNode extensions

MkvToolnixWrapper/MkvInfo/Reader/MkvInfoReader.cs

@@ -0,0 +1,121 @@
+using System.Runtime.CompilerServices;
+
+namespace MkvPropEditWrapper.MkvInfo.Reader;
+
+public class MkvInfoReader
+{
+    public const char LineDelimiter = '\n';
+
+    private readonly ReadOnlyMemory<char> _memory;
+    private ReadOnlyMemory<char> _remainingMemory;
+
+    private readonly MkvNodeRoot _root;
+    private MkvNode _currentNode;
+
+    private int _currentPosition;
+
+    public MkvInfoReader(string mkvInfoOutput)
+    {
+        _memory = mkvInfoOutput.AsMemory();
+        _remainingMemory = _memory;
+
+        _root = new MkvNodeRoot();
+        _currentNode = _root;
+
+        _currentPosition = 0;
+    }
+
+    public MkvNodeRoot Read()
+    {
+        if (_root.Children.Count > 0)
+        {
+            return _root;
+        }
+
+        while (_currentPosition < _memory.Length)
+        {
+            var line = ReadLine();
+
+            // Skip empty lines
+            if (line.Length < 1)
+            {
+                continue;
+            }
+
+            ProcessLine(line);
+        }
+
+        return _root;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private void ProcessLine(ReadOnlyMemory<char> line)
+    {
+        var lineSpan = line.Span;
+
+        // Find depth
+        int depth = lineSpan.IndexOf('+');
+
+        // Climb up the node tree
+        while (depth <= _currentNode.Depth)
+        {
+            _currentNode = _currentNode.Parent!;
+        }
+
+        // Node content
+        var content = line[(depth + 2)..];
+        var contentSpan = content.Span;
+
+        // Check for property
+        int propertyIndex = contentSpan.IndexOf(':');
+
+        MkvNode node;
+        // Property node
+        if (propertyIndex != -1)
+        {
+            var name = content[..propertyIndex];
+            var value = content[(propertyIndex + 2)..];
+
+            node = new MkvProperty(_currentNode, name, value);
+        }
+        // Generic node
+        else
+        {
+            node = new MkvNode(_currentNode, content);
+        }
+
+        _currentNode.Children.Add(node);
+
+        _currentNode = node;
+    }
+
+    /// <summary>
+    /// Read in the span till next \n or EOF while incrementing _currentPosition
+    /// </summary>
+    /// <returns></returns>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private ReadOnlyMemory<char> ReadLine()
+    {
+        var remainingSpan = _remainingMemory.Span;
+        ReadOnlyMemory<char> line;
+
+        int index = remainingSpan.IndexOf(LineDelimiter);
+
+        // Reach the end
+        if (index == -1)
+        {
+            line = _remainingMemory;
+            _currentPosition = _memory.Length;
+        }
+        else
+        {
+            line = _remainingMemory[..(index - 1)]; // -1 to skip \r
+            _currentPosition += index + 1; // Skip \n
+        }
+
+        // Move forward in the span
+        _remainingMemory = _memory[_currentPosition..];
+
+        return line;
+    }
+}