...

compiler/NubLang/Parsing/Parser.cs

@@ -11,6 +11,7 @@ public sealed class Parser
     private List<Token> _tokens = [];
     private int _tokenIndex;
     private string _moduleName = string.Empty;
+    private HashSet<string> _templateArguments = [];
 
     private Token? CurrentToken => _tokenIndex < _tokens.Count ? _tokens[_tokenIndex] : null;
     private bool HasToken => CurrentToken != null;
@@ -26,6 +27,7 @@ public sealed class Parser
         _tokens = tokens;
         _tokenIndex = 0;
         _moduleName = string.Empty;
+        _templateArguments.Clear();
 
         var metadata = ParseMetadata();
         var definitions = ParseDefinitions();
@@ -39,13 +41,13 @@ public sealed class Parser
 
         try
         {
-            ExpectSymbol(Symbol.Module);
-            _moduleName = ExpectLiteral(LiteralKind.String).Value;
-
             while (TryExpectSymbol(Symbol.Import))
             {
                 imports.Add(ExpectLiteral(LiteralKind.String).Value);
             }
+
+            ExpectSymbol(Symbol.Module);
+            _moduleName = ExpectLiteral(LiteralKind.String).Value;
         }
         catch (ParseException e)
         {
@@ -167,12 +169,11 @@ public sealed class Parser
     {
         var name = ExpectIdentifier();
 
-        var templateArguments = new List<string>();
         if (TryExpectSymbol(Symbol.LessThan))
         {
             while (!TryExpectSymbol(Symbol.GreaterThan))
             {
-                templateArguments.Add(ExpectIdentifier().Value);
+                _templateArguments.Add(ExpectIdentifier().Value);
                 TryExpectSymbol(Symbol.Comma);
             }
         }
@@ -217,8 +218,10 @@ public sealed class Parser
             }
         }
 
-        if (templateArguments.Count > 0)
+        if (_templateArguments.Count > 0)
         {
+            var templateArguments = _templateArguments.ToList();
+            _templateArguments.Clear();
             return new StructTemplateSyntax(GetTokens(startIndex), templateArguments, name.Value, exported, fields, funcs);
         }
 
@@ -670,6 +673,11 @@ public sealed class Parser
         var startIndex = _tokenIndex;
         if (TryExpectIdentifier(out var name))
         {
+            if (_templateArguments.Contains(name.Value))
+            {
+                return new SubstitutionTypeSyntax(GetTokens(startIndex), name.Value);
+            }
+
             if (name.Value[0] == 'u' && int.TryParse(name.Value[1..], out var size))
             {
                 if (size is not 8 and not 16 and not 32 and not 64)
@@ -745,7 +753,7 @@ public sealed class Parser
 
                     if (templateParameters.Count > 0)
                     {
-                        return new TemplateTypeSyntax(GetTokens(startIndex), templateParameters, module, name.Value);
+                        return new StructTemplateTypeSyntax(GetTokens(startIndex), templateParameters, module, name.Value);
                     }
 
                     return new CustomTypeSyntax(GetTokens(startIndex), module, name.Value);