Restructure solution layout by module

src/Signals/StellaOps.Signals/Parsing/ICallgraphParserResolver.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+
+namespace StellaOps.Signals.Parsing;
+
+/// <summary>
+/// Resolves callgraph parsers for specific languages.
+/// </summary>
+public interface ICallgraphParserResolver
+{
+    /// <summary>
+    /// Resolves a parser for the supplied language.
+    /// </summary>
+    ICallgraphParser Resolve(string language);
+}
+
+internal sealed class CallgraphParserResolver : ICallgraphParserResolver
+{
+    private readonly IReadOnlyDictionary<string, ICallgraphParser> parsersByLanguage;
+
+    public CallgraphParserResolver(IEnumerable<ICallgraphParser> parsers)
+    {
+        ArgumentNullException.ThrowIfNull(parsers);
+
+        var map = new Dictionary<string, ICallgraphParser>(StringComparer.OrdinalIgnoreCase);
+        foreach (var parser in parsers)
+        {
+            map[parser.Language] = parser;
+        }
+
+        parsersByLanguage = map;
+    }
+
+    public ICallgraphParser Resolve(string language)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(language);
+
+        if (parsersByLanguage.TryGetValue(language, out var parser))
+        {
+            return parser;
+        }
+
+        throw new CallgraphParserNotFoundException(language);
+    }
+}