Updated lexer abstractions.

src/Pasper/Parsing/ILexer.cs

@@ -1,31 +1,15 @@
+using System.Collections;
+
 namespace Pasper.Parsing;
 
 /// <summary>
 /// Represents a lexer for a serialization format.
 /// </summary>
 public interface ILexer
+    : IEnumerator<IToken?>
 {
     /// <summary>
     /// Gets the token at the previous position of the lexer.
     /// </summary>
     public IToken? Previous { get; }
-
-    /// <summary>
-    /// Gets the token at the current position of the lexer.
-    /// </summary>
-    public IToken? Current { get; }
-
-    /// <summary>
-    /// Advances the lexer to the next token.
-    /// </summary>
-    /// <returns>
-    ///     <see langword="true"/> if the lexer was successfully advanced to the next token;
-    ///     otherwise, <see langword="false"/>.
-    /// </returns>
-    public bool MoveNext();
-
-    /// <summary>
-    /// Resets the lexer to its initial position.
-    /// </summary>
-    public void Reset();
 }

src/Pasper/Parsing/Lexer.cs

@@ -0,0 +1,50 @@
+using System.Collections;
+
+namespace Pasper.Parsing;
+
+/// <summary>
+/// Represents a lexer for a serialization format.
+/// </summary>
+public abstract class Lexer
+    : ILexer
+{
+    private bool _disposed;
+
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        Dispose(true);
+        GC.SuppressFinalize(this);
+    }
+
+    /// <inheritdoc/>
+    public abstract bool MoveNext();
+
+    /// <inheritdoc/>
+    public abstract void Reset();
+
+    /// <inheritdoc/>
+    public IToken? Current { get; protected set; }
+
+    /// <inheritdoc/>
+    object IEnumerator.Current =>
+        Current!;
+
+    /// <inheritdoc/>
+    public IToken? Previous { get; protected set; }
+
+    /// <summary>
+    /// Releases the unmanaged resources used by the <see cref="Lexer"/> and optionally releases the managed resources.
+    /// </summary>
+    /// <param name="disposing">Indicates whether the method was called from the <see cref="Dispose"/> method.</param>
+    protected virtual void Dispose(bool disposing)
+    {
+        if (_disposed)
+            return;
+
+        if (!disposing)
+            return;
+
+        _disposed = true;
+    }
+}