Allow Declaring Instances of Structs

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

tree-sitter-p4/grammar.js

@@ -34,7 +34,7 @@ export default grammar({
         direction: $ => choice($.in, $.out, $.inout),
 
         // Common - Types
-        typeRef: $ => $.baseType,
+        typeRef: $ => choice($.baseType, $.type_identifier),
         baseType: $ => choice($.bool, $.error, $.string, $.int, $.bit /* omitting "templated" types" */),
         constructorParameters: $ => seq('(', optional($.parameterList), ')'),
 
@@ -148,11 +148,11 @@ export default grammar({
         varbit: $ => "varbit",
         valueset: $ => "valueset",
         void: $ => "void",
-        identifier: $ => /[a-z_]+/,
-        type_identifier: $ => /[a-z]+/,
+        identifier: $ => /[A-Za-z_]+/,
+        type_identifier: $ => /[A-Za-z_]+/,
         string_literal: $ => /".*"/,
         integer: $ => /[0-9]+/,
-        annotation_literal: $ => /@[a-z_]+/,
+        annotation_literal: $ => /@[A-Za-z_]+/,
         double_equal: $=> '==',
         open_bracket: $=> '[',
         close_bracket: $=> ']',

tree-sitter-p4/test/corpus/declarations.txt

@@ -186,3 +186,47 @@ parser simple() {
  )
 )
 
+=========================
+Non Basic Type Declaration (No Initial Value)
+=========================
+parser simple() {
+  state start {
+    header_t header;
+    transition accept;
+  }
+};
+
+---
+(p4program
+ (declaration
+  (parserDeclaration
+   (parserType
+    (parser)
+    (identifier)
+   )
+   (parserStates
+    (parserState
+     (state)
+     (identifier)
+     (parserStatements
+      (parserStatement
+       (variableDeclaration
+        (typeRef
+         (type_identifier)
+        )
+        (identifier)
+       )
+      )
+     )
+     (parserTransitionStatement
+      (transition)
+      (transitionSelectionExpression
+       (identifier)
+      )
+     )
+    )
+   )
+  )
+ )
+)
+