grammar,compiler: Add Support For Fixed-Width Integers

Distinguishing between signed and unsigned fixed-width integer
types must still be done.

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

Sources/P4Compiler/Expression.swift

@@ -101,9 +101,41 @@ extension P4IntValue: CompilableExpression {
     node: SwiftTreeSitter.Node, withContext context: CompilerContext
   ) -> Result<EvaluatableExpression?> {
     let node = node.child(at: 0)!
-    #SkipUnlessNodeType<SwiftTreeSitter.Node>(node: node, type: "integer")
-    if let parsed_int = Int(node.text!) {
-      return .Ok(P4Value(P4IntValue(withValue: parsed_int)))
+
+    #SkipUnlessNodesTypes<SwiftTreeSitter.Node>(
+      node: node, types: ["integer", "integer_elaborated"])
+
+    var bit_width: BitWidth = BitWidth.Infinite
+    let value_source: String
+    if node.nodeType == "integer_elaborated" {
+      let re = /([0-9]+)([ws])([\-0-9]+)/
+      let integer_components = node.text!.matches(of: re)
+
+      if integer_components.isEmpty || integer_components.count > 1 {
+        return .Error(
+          ErrorWithLocation(
+            sourceLocation: node.toSourceLocation(),
+            withError: "Failed to parse elaborated integer: \(node.text!)"))
+      }
+
+      let width_source = "\(integer_components[0].1)"
+      guard let width = Int(width_source) else {
+        return .Error(
+          ErrorWithLocation(
+            sourceLocation: node.toSourceLocation(),
+            withError: "Failed to parse width from elaborated integer: \(width_source)"))
+      }
+
+      /// TODO: Handle signed vs. unsigned.
+
+      bit_width = BitWidth.Width(width)
+      value_source = "\(integer_components[0].3)"
+    } else {
+      value_source = node.text!
+    }
+
+    if let parsed_int = Int(value_source) {
+      return .Ok(P4Value(P4IntValue(withValue: parsed_int, andWidth: bit_width)))
     } else {
       return .Error(
         ErrorWithLocation(