Implement dynamic imports (#2932)

* WIP: 76d7eceed6 Implement dynamic imports

* Expand `ActiveRunnable` to missing places

* Fix memory leak

* Fix docs

* Parse `import` as call expression

* Fix regressions

* Fix copypasted doc

* clippy fix

* Adjust ignored features

* Migrate away from `top_level_*` operations

* Fix more module tests

* Fix doc link

boa_ast/src/declaration/export.rs

@@ -22,7 +22,9 @@ use crate::{
 use boa_interner::Sym;
 
 /// The kind of re-export in an [`ExportDeclaration`].
-#[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum ReExportKind {
     /// Namespaced Re-export (`export * as name from "module-name"`).
     Namespaced {
@@ -76,7 +78,8 @@ impl VisitWith for ReExportKind {
 ///  - [ECMAScript specification][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#prod-ExportDeclaration
-#[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Clone, Debug, PartialEq)]
 pub enum ExportDeclaration {
     /// Re-export.
     ReExport {
@@ -165,7 +168,9 @@ impl VisitWith for ExportDeclaration {
 ///  - [ECMAScript specification][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#prod-ExportSpecifier
-#[derive(Debug, Clone, Copy)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[derive(Clone, Debug, Copy, PartialEq, Eq)]
 pub struct ExportSpecifier {
     alias: Sym,
     private_name: Sym,

boa_ast/src/declaration/import.rs

@@ -21,7 +21,9 @@ use boa_interner::Sym;
 use super::ModuleSpecifier;
 
 /// The kind of import in an [`ImportDeclaration`].
-#[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum ImportKind {
     /// Default (`import defaultName from "module-name"`) or unnamed (`import "module-name").
     DefaultOrUnnamed,
@@ -77,7 +79,8 @@ impl VisitWith for ImportKind {
 ///  - [ECMAScript specification][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#prod-ImportDeclaration
-#[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct ImportDeclaration {
     /// Binding for the default export of `specifier`.
     default: Option<Identifier>,
@@ -155,7 +158,9 @@ impl VisitWith for ImportDeclaration {
 ///  - [ECMAScript specification][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#prod-ImportSpecifier
-#[derive(Debug, Clone, Copy)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct ImportSpecifier {
     binding: Identifier,
     export_name: Sym,

boa_ast/src/declaration/mod.rs

@@ -105,7 +105,9 @@ impl VisitWith for Declaration {
 /// This is equivalent to the [`ModuleSpecifier`] production.
 ///
 /// [`FromClause`]: https://tc39.es/ecma262/#prod-ModuleSpecifier
-#[derive(Debug, Clone, Copy)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[derive(Clone, Debug, Copy, PartialEq, Eq)]
 pub struct ModuleSpecifier {
     module: Sym,
 }

boa_ast/src/expression/call.rs

@@ -162,3 +162,68 @@ impl VisitWith for SuperCall {
         ControlFlow::Continue(())
     }
 }
+
+/// The import() syntax, commonly called dynamic import, is a function-like expression that allows
+/// loading an ECMAScript module asynchronously and dynamically into a potentially non-module
+/// environment.
+///
+/// More information:
+///  - [ECMAScript reference][spec]
+///  - [MDN documentation][mdn]
+///
+/// [spec]: https://tc39.es/ecma262/#prod-ImportCall
+/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[derive(Clone, Debug, PartialEq)]
+pub struct ImportCall {
+    arg: Box<Expression>,
+}
+
+impl ImportCall {
+    /// Creates a new `ImportCall` AST node.
+    pub fn new<A>(arg: A) -> Self
+    where
+        A: Into<Expression>,
+    {
+        Self {
+            arg: Box::new(arg.into()),
+        }
+    }
+
+    /// Retrieves the single argument of the import call.
+    #[must_use]
+    pub const fn argument(&self) -> &Expression {
+        &self.arg
+    }
+}
+
+impl ToInternedString for ImportCall {
+    #[inline]
+    fn to_interned_string(&self, interner: &Interner) -> String {
+        format!("import({})", self.arg.to_interned_string(interner))
+    }
+}
+
+impl From<ImportCall> for Expression {
+    #[inline]
+    fn from(call: ImportCall) -> Self {
+        Self::ImportCall(call)
+    }
+}
+
+impl VisitWith for ImportCall {
+    fn visit_with<'a, V>(&'a self, visitor: &mut V) -> ControlFlow<V::BreakTy>
+    where
+        V: Visitor<'a>,
+    {
+        visitor.visit_expression(&self.arg)
+    }
+
+    fn visit_with_mut<'a, V>(&'a mut self, visitor: &mut V) -> ControlFlow<V::BreakTy>
+    where
+        V: VisitorMut<'a>,
+    {
+        visitor.visit_expression_mut(&mut self.arg)
+    }
+}

boa_ast/src/expression/literal/object.rs

@@ -256,16 +256,32 @@ impl ToIndentedString for ObjectLiteral {
                             MethodDefinition::Get(expression)
                             | MethodDefinition::Set(expression)
                             | MethodDefinition::Ordinary(expression) => {
-                                block_to_string(expression.body(), interner, indent_n + 1)
+                                block_to_string(
+                                    expression.body().statements(),
+                                    interner,
+                                    indent_n + 1,
+                                )
                             }
                             MethodDefinition::Generator(expression) => {
-                                block_to_string(expression.body(), interner, indent_n + 1)
+                                block_to_string(
+                                    expression.body().statements(),
+                                    interner,
+                                    indent_n + 1,
+                                )
                             }
                             MethodDefinition::AsyncGenerator(expression) => {
-                                block_to_string(expression.body(), interner, indent_n + 1)
+                                block_to_string(
+                                    expression.body().statements(),
+                                    interner,
+                                    indent_n + 1,
+                                )
                             }
                             MethodDefinition::Async(expression) => {
-                                block_to_string(expression.body(), interner, indent_n + 1)
+                                block_to_string(
+                                    expression.body().statements(),
+                                    interner,
+                                    indent_n + 1,
+                                )
                             }
                         },
                     )

boa_ast/src/expression/mod.rs

@@ -33,7 +33,7 @@ mod tagged_template;
 mod r#yield;
 
 use crate::visitor::{VisitWith, Visitor, VisitorMut};
-pub use call::{Call, SuperCall};
+pub use call::{Call, ImportCall, SuperCall};
 pub use identifier::{Identifier, RESERVED_IDENTIFIERS_STRICT};
 pub use new::New;
 pub use optional::{Optional, OptionalOperation, OptionalOperationKind};
@@ -121,10 +121,12 @@ pub enum Expression {
     /// See [`SuperCall`].
     SuperCall(SuperCall),
 
+    /// See [`ImportCall`].
+    ImportCall(ImportCall),
+
     /// See [`Optional`].
     Optional(Optional),
 
-    // TODO: Import calls
     /// See [`TaggedTemplate`].
     TaggedTemplate(TaggedTemplate),
 
@@ -192,6 +194,7 @@ impl Expression {
             Self::New(new) => new.to_interned_string(interner),
             Self::Call(call) => call.to_interned_string(interner),
             Self::SuperCall(supc) => supc.to_interned_string(interner),
+            Self::ImportCall(impc) => impc.to_interned_string(interner),
             Self::Optional(opt) => opt.to_interned_string(interner),
             Self::NewTarget => "new.target".to_owned(),
             Self::TaggedTemplate(tag) => tag.to_interned_string(interner),
@@ -300,6 +303,7 @@ impl VisitWith for Expression {
             Self::New(n) => visitor.visit_new(n),
             Self::Call(c) => visitor.visit_call(c),
             Self::SuperCall(sc) => visitor.visit_super_call(sc),
+            Self::ImportCall(ic) => visitor.visit_import_call(ic),
             Self::Optional(opt) => visitor.visit_optional(opt),
             Self::TaggedTemplate(tt) => visitor.visit_tagged_template(tt),
             Self::Assign(a) => visitor.visit_assign(a),
@@ -341,6 +345,7 @@ impl VisitWith for Expression {
             Self::New(n) => visitor.visit_new_mut(n),
             Self::Call(c) => visitor.visit_call_mut(c),
             Self::SuperCall(sc) => visitor.visit_super_call_mut(sc),
+            Self::ImportCall(ic) => visitor.visit_import_call_mut(ic),
             Self::Optional(opt) => visitor.visit_optional_mut(opt),
             Self::TaggedTemplate(tt) => visitor.visit_tagged_template_mut(tt),
             Self::Assign(a) => visitor.visit_assign_mut(a),

boa_ast/src/function/arrow_function.rs

@@ -2,12 +2,12 @@ use crate::try_break;
 use crate::visitor::{VisitWith, Visitor, VisitorMut};
 use crate::{
     expression::{Expression, Identifier},
-    join_nodes, StatementList,
+    join_nodes,
 };
 use boa_interner::{Interner, ToIndentedString};
 use core::ops::ControlFlow;
 
-use super::FormalParameterList;
+use super::{FormalParameterList, FunctionBody};
 
 /// An arrow function expression, as defined by the [spec].
 ///
@@ -24,7 +24,7 @@ use super::FormalParameterList;
 pub struct ArrowFunction {
     name: Option<Identifier>,
     parameters: FormalParameterList,
-    body: StatementList,
+    body: FunctionBody,
 }
 
 impl ArrowFunction {
@@ -34,7 +34,7 @@ impl ArrowFunction {
     pub const fn new(
         name: Option<Identifier>,
         params: FormalParameterList,
-        body: StatementList,
+        body: FunctionBody,
     ) -> Self {
         Self {
             name,
@@ -66,7 +66,7 @@ impl ArrowFunction {
     /// Gets the body of the arrow function.
     #[inline]
     #[must_use]
-    pub const fn body(&self) -> &StatementList {
+    pub const fn body(&self) -> &FunctionBody {
         &self.body
     }
 }
@@ -102,7 +102,7 @@ impl VisitWith for ArrowFunction {
             try_break!(visitor.visit_identifier(ident));
         }
         try_break!(visitor.visit_formal_parameter_list(&self.parameters));
-        visitor.visit_statement_list(&self.body)
+        visitor.visit_script(&self.body)
     }
 
     fn visit_with_mut<'a, V>(&'a mut self, visitor: &mut V) -> ControlFlow<V::BreakTy>
@@ -113,6 +113,6 @@ impl VisitWith for ArrowFunction {
             try_break!(visitor.visit_identifier_mut(ident));
         }
         try_break!(visitor.visit_formal_parameter_list_mut(&mut self.parameters));
-        visitor.visit_statement_list_mut(&mut self.body)
+        visitor.visit_script_mut(&mut self.body)
     }
 }

boa_ast/src/function/async_arrow_function.rs

@@ -1,11 +1,11 @@
 use std::ops::ControlFlow;
 
-use super::FormalParameterList;
+use super::{FormalParameterList, FunctionBody};
 use crate::try_break;
 use crate::visitor::{VisitWith, Visitor, VisitorMut};
 use crate::{
     expression::{Expression, Identifier},
-    join_nodes, StatementList,
+    join_nodes,
 };
 use boa_interner::{Interner, ToIndentedString};
 
@@ -24,7 +24,7 @@ use boa_interner::{Interner, ToIndentedString};
 pub struct AsyncArrowFunction {
     name: Option<Identifier>,
     parameters: FormalParameterList,
-    body: StatementList,
+    body: FunctionBody,
 }
 
 impl AsyncArrowFunction {
@@ -34,7 +34,7 @@ impl AsyncArrowFunction {
     pub const fn new(
         name: Option<Identifier>,
         parameters: FormalParameterList,
-        body: StatementList,
+        body: FunctionBody,
     ) -> Self {
         Self {
             name,
@@ -66,7 +66,7 @@ impl AsyncArrowFunction {
     /// Gets the body of the arrow function.
     #[inline]
     #[must_use]
-    pub const fn body(&self) -> &StatementList {
+    pub const fn body(&self) -> &FunctionBody {
         &self.body
     }
 }
@@ -102,7 +102,7 @@ impl VisitWith for AsyncArrowFunction {
             try_break!(visitor.visit_identifier(ident));
         }
         try_break!(visitor.visit_formal_parameter_list(&self.parameters));
-        visitor.visit_statement_list(&self.body)
+        visitor.visit_script(&self.body)
     }
 
     fn visit_with_mut<'a, V>(&'a mut self, visitor: &mut V) -> ControlFlow<V::BreakTy>
@@ -113,6 +113,6 @@ impl VisitWith for AsyncArrowFunction {
             try_break!(visitor.visit_identifier_mut(ident));
         }
         try_break!(visitor.visit_formal_parameter_list_mut(&mut self.parameters));
-        visitor.visit_statement_list_mut(&mut self.body)
+        visitor.visit_script_mut(&mut self.body)
     }
 }