build(rust): vendor rnix parser crate

third_party/crates/rnix-0.14.0/src/ast/expr_ext.rs

@@ -0,0 +1,29 @@
+use crate::ast::{self, support::*};
+
+// this is a separate type because it mixes tokens and nodes
+// for example, a Str is a node because it can contain nested subexpressions but an Integer is a token.
+// This means that we have to write it out manually instead of using the macro to create the type for us.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum LiteralKind {
+    Float(ast::Float),
+    Integer(ast::Integer),
+    Uri(ast::Uri),
+}
+
+impl ast::Literal {
+    pub fn kind(&self) -> LiteralKind {
+        if let Some(it) = token(self) {
+            return LiteralKind::Float(it);
+        }
+
+        if let Some(it) = token(self) {
+            return LiteralKind::Integer(it);
+        }
+
+        if let Some(it) = token(self) {
+            return LiteralKind::Uri(it);
+        }
+
+        unreachable!()
+    }
+}