enums

compiler/NubLang/Syntax/Parser.cs

@@ -78,9 +78,10 @@ public sealed class Parser
                 {
                     Symbol.Func => ParseFunc(startIndex, exported, null),
                     Symbol.Struct => ParseStruct(startIndex, exported),
+                    Symbol.Enum => ParseEnum(startIndex, exported),
                     _ => throw new ParseException(Diagnostic
-                        .Error($"Expected 'func', 'struct', 'import' or 'module' but found '{keyword.Symbol}'")
-                        .WithHelp("Valid top level statements are 'func', 'struct', 'import' and 'module'")
+                        .Error($"Expected 'func', 'struct', 'enum', 'import' or 'module' but found '{keyword.Symbol}'")
+                        .WithHelp("Valid top level statements are 'func', 'struct', 'enum', 'import' and 'module'")
                         .At(keyword)
                         .Build())
                 };
@@ -176,6 +177,54 @@ public sealed class Parser
         return new StructSyntax(GetTokens(startIndex), name.Value, exported, fields);
     }
 
+    private EnumSyntax ParseEnum(int startIndex, bool exported)
+    {
+        var name = ExpectIdentifier();
+
+        TypeSyntax? type = null;
+
+        if (TryExpectSymbol(Symbol.Colon))
+        {
+            type = ParseType();
+        }
+
+        List<EnumFieldSyntax> fields = [];
+
+        ExpectSymbol(Symbol.OpenBrace);
+
+        long value = -1;
+
+        while (!TryExpectSymbol(Symbol.CloseBrace))
+        {
+            var memberStartIndex = _tokenIndex;
+            var fieldName = ExpectIdentifier().Value;
+            long fieldValue;
+
+            if (TryExpectSymbol(Symbol.Assign))
+            {
+                if (!TryExpectIntLiteral(out var intLiteralToken))
+                {
+                    throw new ParseException(Diagnostic
+                        .Error("Value of enum field must be an integer literal")
+                        .At(CurrentToken)
+                        .Build());
+                }
+
+                fieldValue = Convert.ToInt64(intLiteralToken.Value, intLiteralToken.Base);
+                value = fieldValue;
+            }
+            else
+            {
+                fieldValue = value + 1;
+                value = fieldValue;
+            }
+
+            fields.Add(new EnumFieldSyntax(GetTokens(memberStartIndex), fieldName, fieldValue));
+        }
+
+        return new EnumSyntax(GetTokens(startIndex), name.Value, exported, type, fields);
+    }
+
     private StatementSyntax ParseStatement()
     {
         var startIndex = _tokenIndex;