feat(ast): compute max value that can be mapped to AstType

Author: Cameron McHenry

crates/oxc_ast/src/generated/ast_kind.rs

@@ -203,6 +203,9 @@ pub enum AstType {
     JSDocUnknownType = 186,
 }
 
+/// The largest `usize` value that can be mapped to an `AstType`.
+pub const AST_TYPE_MAX: usize = 186usize;
+
 /// Untyped AST Node Kind
 #[derive(Debug, Clone, Copy)]
 #[repr(C, u8)]

tasks/ast_tools/src/generators/ast_kind.rs

@@ -87,6 +87,7 @@ impl Generator for AstKindGenerator {
         let mut span_match_arms = quote!();
         let mut address_match_arms = quote!();
         let mut as_methods = quote!();
+        let mut ast_type_max_usize: usize = 0;
 
         let mut next_index = 0u16;
         for type_def in &schema.types {
@@ -104,6 +105,7 @@ impl Generator for AstKindGenerator {
 
             assert!(u8::try_from(next_index).is_ok());
             let index = number_lit(next_index);
+            ast_type_max_usize = next_index as usize;
             type_variants.extend(quote!( #type_ident = #index, ));
             kind_variants.extend(quote!( #type_ident(&'a #type_ty) = AstType::#type_ident as u8, ));
 
@@ -152,6 +154,10 @@ impl Generator for AstKindGenerator {
                 #type_variants
             }
 
+            ///@@line_break
+            /// The largest `usize` value that can be mapped to an `AstType`.
+            pub const AST_TYPE_MAX: usize = #ast_type_max_usize;
+
             ///@@line_break
             /// Untyped AST Node Kind
             #[derive(Debug, Clone, Copy)]