1 files changed, 113 insertions, 0 deletions
diff --git a/cli/tools/vendor/analyze.rs b/cli/tools/vendor/analyze.rs
new file mode 100644
index 000000000..0639c0487
--- /dev/null
+++ b/cli/tools/vendor/analyze.rs
@@ -0,0 +1,113 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+
+use deno_ast::swc::ast::ExportDefaultDecl;
+use deno_ast::swc::ast::ExportSpecifier;
+use deno_ast::swc::ast::ModuleExportName;
+use deno_ast::swc::ast::NamedExport;
+use deno_ast::swc::ast::Program;
+use deno_ast::swc::visit::noop_visit_type;
+use deno_ast::swc::visit::Visit;
+use deno_ast::swc::visit::VisitWith;
+use deno_ast::ParsedSource;
+
+/// Gets if the parsed source has a default export.
+pub fn has_default_export(source: &ParsedSource) -> bool {
+  let mut visitor = DefaultExportFinder {
+    has_default_export: false,
+  };
+  let program = source.program();
+  let program: &Program = &program;
+  program.visit_with(&mut visitor);
+  visitor.has_default_export
+}
+
+struct DefaultExportFinder {
+  has_default_export: bool,
+}
+
+impl<'a> Visit for DefaultExportFinder {
+  noop_visit_type!();
+
+  fn visit_export_default_decl(&mut self, _: &ExportDefaultDecl) {
+    self.has_default_export = true;
+  }
+
+  fn visit_named_export(&mut self, named_export: &NamedExport) {
+    if named_export
+      .specifiers
+      .iter()
+      .any(export_specifier_has_default)
+    {
+      self.has_default_export = true;
+    }
+  }
+}
+
+fn export_specifier_has_default(s: &ExportSpecifier) -> bool {
+  match s {
+    ExportSpecifier::Default(_) => true,
+    ExportSpecifier::Namespace(_) => false,
+    ExportSpecifier::Named(named) => {
+      let export_name = named.exported.as_ref().unwrap_or(&named.orig);
+
+      match export_name {
+        ModuleExportName::Str(_) => false,
+        ModuleExportName::Ident(ident) => &*ident.sym == "default",
+      }
+    }
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use deno_ast::MediaType;
+  use deno_ast::ParseParams;
+  use deno_ast::ParsedSource;
+  use deno_ast::SourceTextInfo;
+
+  use super::has_default_export;
+
+  #[test]
+  fn has_default_when_export_default_decl() {
+    let parsed_source = parse_module("export default class Class {}");
+    assert!(has_default_export(&parsed_source));
+  }
+
+  #[test]
+  fn has_default_when_named_export() {
+    let parsed_source = parse_module("export {default} from './test.ts';");
+    assert!(has_default_export(&parsed_source));
+  }
+
+  #[test]
+  fn has_default_when_named_export_alias() {
+    let parsed_source =
+      parse_module("export {test as default} from './test.ts';");
+    assert!(has_default_export(&parsed_source));
+  }
+
+  #[test]
+  fn not_has_default_when_named_export_not_exported() {
+    let parsed_source =
+      parse_module("export {default as test} from './test.ts';");
+    assert!(!has_default_export(&parsed_source));
+  }
+
+  #[test]
+  fn not_has_default_when_not() {
+    let parsed_source = parse_module("export {test} from './test.ts'; export class Test{} export * from './test';");
+    assert!(!has_default_export(&parsed_source));
+  }
+
+  fn parse_module(text: &str) -> ParsedSource {
+    deno_ast::parse_module(ParseParams {
+      specifier: "file:///mod.ts".to_string(),
+      capture_tokens: false,
+      maybe_syntax: None,
+      media_type: MediaType::TypeScript,
+      scope_analysis: false,
+      source: SourceTextInfo::from_string(text.to_string()),
+    })
+    .unwrap()
+  }
+}