Work On Derived Types

1. Add support for field access
2. Add support for proper type checking of array access
3. Add tests for nested field and array access

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Tests/p4rseTests/TypeTests.swift

@@ -0,0 +1,38 @@
+// p4rse, Copyright 2026, Will Hawkins
+//
+// This file is part of p4rse.
+//
+// This file is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+import Foundation
+import Common
+import Macros
+import SwiftTreeSitter
+import Testing
+import TreeSitter
+import TreeSitterP4
+
+@testable import P4Compiler
+
+@Test func test_simple_struct() async throws {
+  let fields = P4StructFields([
+    P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
+    P4StructFieldIdentifier(name: "count", withType: P4Int()),
+  ])
+
+  let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
+
+  #expect(struct_type.fields.count() == 2)
+  #expect(struct_type.fields == fields)
+}