TestSequencePointsIndex.cs

using System.Reflection.Metadata;
using System.Text;

namespace Foo;

class TestSequencePointsIndex
{
    private readonly Dictionary<string, List<SequencePoint>> _index = new ();
    
    public FooClass(params string[] pdbPaths)
    {
        var documentPaths = new Dictionary<Document, string>();
        foreach (var pdbPath in pdbPaths)
        {
            IndexPdbFile(pdbPath, documentPaths);
        }
    }

    public List<int> FindOffsets(string sourceFilePath, int startLine, int startColumn)
    {
        if (!_index.ContainsKey(sourceFilePath))
        {
            return new List<int>();
        }

        var sf = _index[sourceFilePath];
        return sf.Where(sp => sp.StartLine == startLine).Select(sp => sp.Offset).ToList();       
    }

    private void IndexPdbFile(string pdbPath, Dictionary<Document, string> documentPaths)
    {
        using var fs = new FileStream(pdbPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
        using var provider = MetadataReaderProvider.FromPortablePdbStream(fs);
        var reader = provider.GetMetadataReader();
        foreach (var di in reader.MethodDebugInformation)
        {
            var mdi = reader.GetMethodDebugInformation(di);
            if (mdi.Document.IsNil) continue;
            
            var doc = reader.GetDocument(mdi.Document);
            if (!documentPaths.ContainsKey(doc))
            {
                var path = ReadDocumentPath(reader, doc);
                documentPaths[doc] = path;
                _index[path] = new List<SequencePoint>();
            }
            
            var notHiddenPoints = mdi.GetSequencePoints().Where(sp => !sp.IsHidden);
            var sourceFilePath = documentPaths[doc];
            _index[sourceFilePath].AddRange(notHiddenPoints);
        }
    }
    
    private static string ReadDocumentPath(MetadataReader reader, Document doc)
    {
        var blob = reader.GetBlobReader(doc.Name);

        // Read path separator character
        var separator = (char)blob.ReadByte();
        var sb = new StringBuilder(blob.Length * 2);

        // Read path segments
        while (true)
        {
            var bh = blob.ReadBlobHandle();

            if (!bh.IsNil)
            {
                var nameBytes = reader.GetBlobBytes(bh);
                sb.Append(Encoding.UTF8.GetString(nameBytes));
            }

            if (blob.Offset >= blob.Length) break;

            sb.Append(separator);
        }

        return sb.ToString();
    }
}