lang: basic ast work

crates/lang/src/lib.rs

@@ -1,2 +1,24 @@
 #![feature(type_alias_impl_trait, lint_reasons)]
+
+use crate::lst_parser::syntax_kind::SyntaxKind;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Lang {}
+impl rowan::Language for Lang {
+    type Kind = SyntaxKind;
+    #[allow(unsafe_code)]
+    fn kind_from_raw(raw: rowan::SyntaxKind) -> Self::Kind {
+        assert!(raw.0 <= SyntaxKind::ROOT as u16);
+        unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
+    }
+    fn kind_to_raw(kind: Self::Kind) -> rowan::SyntaxKind {
+        kind.into()
+    }
+}
+
+pub type SyntaxNode = rowan::SyntaxNode<Lang>;
+pub type SyntaxToken = rowan::SyntaxNode<Lang>;
+pub type SyntaxElement = rowan::NodeOrToken<SyntaxNode, SyntaxToken>;
+
+pub mod ast;
 pub mod lst_parser;