Perf improvements in tokenizer

compiler/NubLang/Code/SourceFile.cs

@@ -1,41 +0,0 @@
-namespace NubLang.Code;
-
-public class SourceFile
-{
-    private string? _content;
-
-    public SourceFile(string path)
-    {
-        Path = path ?? throw new ArgumentNullException(nameof(path));
-    }
-
-    public string Path { get; }
-
-    public string GetText() => _content ??= File.ReadAllText(Path);
-    public override string ToString() => Path;
-
-    public override bool Equals(object? obj)
-    {
-        return obj is SourceFile other && other.Path == Path;
-    }
-
-    public override int GetHashCode()
-    {
-        return HashCode.Combine(typeof(SourceFile), Path);
-    }
-
-    public static bool operator ==(SourceFile? left, SourceFile? right) => Equals(left, right);
-    public static bool operator !=(SourceFile? left, SourceFile? right) => !Equals(left, right);
-}
-
-public class SourceFileSpan
-{
-    public SourceFileSpan(SourceFile sourceFile, SourceSpan span)
-    {
-        SourceFile = sourceFile;
-        Span = span;
-    }
-
-    public SourceFile SourceFile { get; }
-    public SourceSpan Span { get; }
-}

compiler/NubLang/Code/SourceLocation.cs

@@ -2,8 +2,6 @@ namespace NubLang.Code;
 
 public readonly struct SourceLocation : IEquatable<SourceLocation>, IComparable<SourceLocation>
 {
-    public static SourceLocation Zero => new(0, 0);
-
     public SourceLocation(int line, int column)
     {
         Line = line;

compiler/NubLang/Code/SourceSpan.cs

@@ -2,34 +2,33 @@ namespace NubLang.Code;
 
 public readonly struct SourceSpan : IEquatable<SourceSpan>, IComparable<SourceSpan>
 {
-    public static SourceSpan Zero => new(SourceLocation.Zero, SourceLocation.Zero);
-
     public static SourceSpan Merge(params IEnumerable<SourceSpan> spans)
     {
         var spanArray = spans as SourceSpan[] ?? spans.ToArray();
-
         if (spanArray.Length == 0)
         {
-            return Zero;
+            return new SourceSpan(string.Empty, new SourceLocation(0, 0), new SourceLocation(0, 0));
         }
 
         var minStart = spanArray.Min(s => s.Start);
         var maxEnd = spanArray.Max(s => s.End);
 
-        return new SourceSpan(minStart, maxEnd);
+        return new SourceSpan(spanArray[0].FilePath, minStart, maxEnd);
     }
 
-    public SourceSpan(SourceLocation start, SourceLocation end)
+    public SourceSpan(string filePath, SourceLocation start, SourceLocation end)
     {
         if (start > end)
         {
             throw new ArgumentException("Start location cannot be after end location");
         }
 
+        FilePath = filePath;
         Start = start;
         End = end;
     }
 
+    public string FilePath { get; }
     public SourceLocation Start { get; }
     public SourceLocation End { get; }
 
@@ -37,15 +36,15 @@ public readonly struct SourceSpan : IEquatable<SourceSpan>, IComparable<SourceSp
     {
         if (Start == End)
         {
-            return $"{Start}";
+            return $"{FilePath}:{Start}";
         }
 
         if (Start.Line == End.Line)
         {
-            return Start.Column == End.Column ? $"{Start}" : $"{Start.Line}:{Start.Column}-{End.Column}";
+            return Start.Column == End.Column ? $"{FilePath}:{Start}" : $"{FilePath}:{Start.Line}:{Start.Column}-{End.Column}";
         }
 
-        return $"{Start}-{End}";
+        return $"{FilePath}:{Start}-{End}";
     }
 
     public bool Equals(SourceSpan other) => Start == other.Start && End == other.End;
@@ -54,7 +53,7 @@ public readonly struct SourceSpan : IEquatable<SourceSpan>, IComparable<SourceSp
 
     public static bool operator ==(SourceSpan left, SourceSpan right) => Equals(left, right);
     public static bool operator !=(SourceSpan left, SourceSpan right) => !Equals(left, right);
-    
+
     public static bool operator <(SourceSpan left, SourceSpan right) => left.CompareTo(right) < 0;
     public static bool operator <=(SourceSpan left, SourceSpan right) => left.CompareTo(right) <= 0;
     public static bool operator >(SourceSpan left, SourceSpan right) => left.CompareTo(right) > 0;