refactor(parser): refactor visitor in regexp example (#8524)

Refactor visitor in example to use `visit_*` methods instead of `enter_node`. This is our recommended style as it's more performant.

crates/oxc_parser/examples/regular_expression.rs

@@ -2,7 +2,7 @@
 use std::{env, fs, path::Path, sync::Arc};
 
 use oxc_allocator::Allocator;
-use oxc_ast::{ast, AstKind, Visit};
+use oxc_ast::{ast::*, Visit};
 use oxc_parser::{ParseOptions, Parser};
 use oxc_regular_expression::{ConstructorParser as RegExpParser, Options as RegExpParserOptions};
 use oxc_span::SourceType;
@@ -43,35 +43,33 @@ struct RegularExpressionVisitor {
 }
 
 impl<'a> Visit<'a> for RegularExpressionVisitor {
-    fn enter_node(&mut self, kind: AstKind<'a>) {
-        let allocator = Allocator::default();
-
-        match kind {
-            AstKind::RegExpLiteral(re) => {
+    fn visit_reg_exp_literal(&mut self, re: &RegExpLiteral<'a>) {
         println!("🍀 {}", re.span.source_text(self.source_text.as_ref()));
 
         println!("{re:#?}");
         println!();
     }
-            AstKind::NewExpression(new_expr)
+
+    fn visit_new_expression(&mut self, new_expr: &NewExpression<'a>) {
         if new_expr
             .callee
             .get_identifier_reference()
             .filter(|ident| ident.name == "RegExp")
-                    .is_some() =>
+            .is_some()
         {
             println!("🍀 {}", new_expr.span.source_text(&self.source_text));
 
             let pattern_span = match new_expr.arguments.first() {
-                    Some(ast::Argument::StringLiteral(sl)) => sl.span,
+                Some(Argument::StringLiteral(sl)) => sl.span,
                 _ => return,
             };
 
             let flags_span = match new_expr.arguments.get(1) {
-                    Some(ast::Argument::StringLiteral(sl)) => Some(sl.span),
+                Some(Argument::StringLiteral(sl)) => Some(sl.span),
                 _ => None,
             };
 
+            let allocator = Allocator::default();
             let parsed = RegExpParser::new(
                 &allocator,
                 pattern_span.source_text(&self.source_text),
@@ -91,7 +89,5 @@ impl<'a> Visit<'a> for RegularExpressionVisitor {
             println!("{parsed:#?}");
             println!();
         }
-            _ => {}
-        }
     }
 }