rspack_loader_swc 0.102.2

// This file is derived from Next.js
// Copyright (c) 2024 Vercel, Inc.
// Licensed under the MIT License

use swc_core::ecma::{
  ast::*,
  visit::{Visit, VisitWith},
};

pub fn contains_cjs(m: &Module) -> bool {
  let mut v = CjsFinder::default();
  m.visit_with(&mut v);
  v.found && !v.is_esm
}

#[derive(Copy, Clone, Default)]
struct CjsFinder {
  found: bool,
  is_esm: bool,
  ignore_module: bool,
  ignore_exports: bool,
}

impl CjsFinder {
  /// If the given pattern contains `module` as a parameter, we don't need to
  /// recurse into it because `module` is shadowed.
  fn adjust_state<'a, I>(&mut self, iter: I)
  where
    I: Iterator<Item = &'a Pat>,
  {
    iter.for_each(|p| {
      if let Pat::Ident(i) = p {
        if &*i.id.sym == "module" {
          self.ignore_module = true;
        }
        if &*i.id.sym == "exports" {
          self.ignore_exports = true;
        }
      }
    })
  }
}

/// This visitor implementation supports typescript, because the api of `swc`
/// does not support changing configuration based on content of the file.
impl Visit for CjsFinder {
  fn visit_arrow_expr(&mut self, n: &ArrowExpr) {
    let old_ignore_module = self.ignore_module;
    let old_ignore_exports = self.ignore_exports;

    self.adjust_state(n.params.iter());

    n.visit_children_with(self);

    self.ignore_module = old_ignore_module;
    self.ignore_exports = old_ignore_exports;
  }

  // Detect `Object.defineProperty(exports, "__esModule", ...)`
  // Note that `Object.defineProperty(module.exports, ...)` will be handled by
  // `visit_member_expr`.
  fn visit_call_expr(&mut self, e: &CallExpr) {
    if !self.ignore_exports
      && let Callee::Expr(expr) = &e.callee
      && let Expr::Member(member_expr) = &**expr
      && let (Expr::Ident(obj), MemberProp::Ident(prop)) = (&*member_expr.obj, &member_expr.prop)
      && &*obj.sym == "Object"
      && &*prop.sym == "defineProperty"
      && let Some(ExprOrSpread { expr: expr0, .. }) = e.args.first()
      && let Expr::Ident(arg0) = &**expr0
      && &*arg0.sym == "exports"
      && let Some(ExprOrSpread { expr: expr1, .. }) = e.args.get(1)
      && let Expr::Lit(Lit::Str(arg1)) = &**expr1
      && &*arg1.value == "__esModule"
    {
      self.found = true;
      return;
    }
    e.callee.visit_with(self);
  }

  fn visit_class_method(&mut self, n: &ClassMethod) {
    let old_ignore_module = self.ignore_module;
    let old_ignore_exports = self.ignore_exports;

    self.adjust_state(n.function.params.iter().map(|v| &v.pat));

    n.visit_children_with(self);

    self.ignore_module = old_ignore_module;
    self.ignore_exports = old_ignore_exports;
  }

  fn visit_function(&mut self, n: &Function) {
    let old_ignore_module = self.ignore_module;
    let old_ignore_exports = self.ignore_exports;

    self.adjust_state(n.params.iter().map(|v| &v.pat));

    n.visit_children_with(self);

    self.ignore_module = old_ignore_module;
    self.ignore_exports = old_ignore_exports;
  }

  fn visit_member_expr(&mut self, e: &MemberExpr) {
    if let Expr::Ident(obj) = &*e.obj
      && let MemberProp::Ident(prop) = &e.prop
    {
      // Detect `module.exports` and `exports.__esModule`
      if (!self.ignore_module && &*obj.sym == "module" && &*prop.sym == "exports")
        || (!self.ignore_exports && &*obj.sym == "exports")
      {
        self.found = true;
        return;
      }
    }

    e.obj.visit_with(self);
    e.prop.visit_with(self);
  }

  fn visit_method_prop(&mut self, n: &MethodProp) {
    let old_ignore_module = self.ignore_module;
    let old_ignore_exports = self.ignore_exports;

    self.adjust_state(n.function.params.iter().map(|v| &v.pat));

    n.visit_children_with(self);

    self.ignore_module = old_ignore_module;
    self.ignore_exports = old_ignore_exports;
  }

  fn visit_module_decl(&mut self, n: &ModuleDecl) {
    match n {
      ModuleDecl::Import(_) => {}
      _ => {
        self.is_esm = true;
      }
    }
  }
}