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src/lang/Nub.Lang/Frontend/Diagnostics/SourceText.cs

@@ -0,0 +1,102 @@
+using Nub.Lang.Frontend.Lexing;
+using Nub.Lang.Frontend.Parsing;
+
+namespace Nub.Lang.Frontend.Diagnostics;
+
+public readonly struct SourceText(string path, string content)
+{
+    public string Path { get; } = path;
+    public string Content { get; } = content;
+}
+
+public readonly struct SourceLocation(int line, int column)
+{
+    public int Line { get; } = line;
+    public int Column { get; } = column;
+}
+
+public readonly struct SourceSpan(SourceLocation start, SourceLocation end)
+{
+    public SourceLocation Start { get; } = start;
+    public SourceLocation End { get; } = end;
+
+    public override string ToString()
+    {
+        if (Start.Line == End.Line)
+        {
+            if (Start.Column == End.Column)
+            {
+                return $"{Start.Line}:{Start.Column}";
+            }
+
+            return $"{Start.Line}:{Start.Column}-{End.Column}";
+        }
+        
+        return $"{Start.Line}:{Start.Column}-{End.Line}:{End.Column}";
+    }
+}
+
+public static class SourceLocationCalculator
+{
+    private static int[] GetLineStarts(string content)
+    {
+        var lineStarts = new List<int> { 0 }; 
+
+        for (var i = 0; i < content.Length; i++)
+        {
+            if (content[i] == '\n')
+            {
+                lineStarts.Add(i + 1);
+            }
+        }
+
+        return lineStarts.ToArray();
+    }
+
+    private static SourceLocation IndexToLocation(string content, int index)
+    {
+        if (index < 0 || index > content.Length)
+        {
+            throw new ArgumentOutOfRangeException(nameof(index), $"Index {index} is out of range for content of length {content.Length}");
+        }
+
+        var lineStarts = GetLineStarts(content);
+
+        var line = Array.BinarySearch(lineStarts, index);
+        if (line < 0)
+        {
+            line = ~line - 1;
+        }
+
+        if (line < lineStarts.Length - 1 && lineStarts[line + 1] == index && index < content.Length && content[index] == '\n')
+        {
+            line++;
+        }
+
+        var column = index - lineStarts[line] + 1;
+        return new SourceLocation(line + 1, column);
+    }
+
+    public static SourceSpan GetSpan(Token token)
+    {
+        var start = IndexToLocation(token.SourceText.Content, token.StartIndex);
+        var end = IndexToLocation(token.SourceText.Content, token.EndIndex);
+        return new SourceSpan(start, end);
+    }
+
+    public static SourceSpan GetSpan(Node node)
+    {
+        if (!node.Tokens.Any())
+        {
+            throw new ArgumentException("Node has no tokens", nameof(node));
+        }
+
+        var firstToken = node.Tokens[0];
+        var lastToken = node.Tokens[^1];
+
+        var start = IndexToLocation(firstToken.SourceText.Content, firstToken.StartIndex);
+        var end = IndexToLocation(lastToken.SourceText.Content, lastToken.EndIndex);
+
+        return new SourceSpan(start, end);
+    }
+}