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transforms.rs
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transforms.rs
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use deno_ast::swc::ast as swc_ast;
use deno_ast::swc::common::DUMMY_SP;
use deno_ast::swc::visit::noop_fold_type;
use deno_ast::swc::visit::Fold;
/// Transforms import declarations to variable declarations
/// with a dynamic import. This is used to provide import
/// declaration support in the REPL.
pub struct DownlevelImportsFolder;
impl Fold for DownlevelImportsFolder {
noop_fold_type!(); // skip typescript specific nodes
fn fold_module_item(
&mut self,
module_item: swc_ast::ModuleItem,
) -> swc_ast::ModuleItem {
use deno_ast::swc::ast::*;
match module_item {
ModuleItem::ModuleDecl(ModuleDecl::Import(import_decl)) => {
// Handle type only imports
if import_decl.type_only {
// should have no side effects
return create_empty_stmt();
}
// The initializer (ex. `await import('./mod.ts')`)
let initializer =
create_await_import_expr(&import_decl.src.value, import_decl.asserts);
// Handle imports for the side effects
// ex. `import "module.ts"` -> `await import("module.ts");`
if import_decl.specifiers.is_empty() {
return ModuleItem::Stmt(Stmt::Expr(ExprStmt {
span: DUMMY_SP,
expr: initializer,
}));
}
// Collect the specifiers and create the variable statement
let named_import_props = import_decl
.specifiers
.iter()
.filter_map(|specifier| match specifier {
ImportSpecifier::Default(specifier) => Some(create_key_value(
"default".to_string(),
specifier.local.sym.to_string(),
)),
ImportSpecifier::Named(specifier) => {
Some(match specifier.imported.as_ref() {
Some(name) => create_key_value(
name.sym.to_string(),
specifier.local.sym.to_string(),
),
None => create_assignment(specifier.local.sym.to_string()),
})
}
ImportSpecifier::Namespace(_) => None,
})
.collect::<Vec<_>>();
let namespace_import_name =
import_decl
.specifiers
.iter()
.find_map(|specifier| match specifier {
ImportSpecifier::Namespace(specifier) => {
Some(create_binding_ident(specifier.local.sym.to_string()))
}
_ => None,
});
ModuleItem::Stmt(Stmt::Decl(Decl::Var(VarDecl {
span: DUMMY_SP,
kind: VarDeclKind::Const,
declare: false,
decls: {
let mut decls = Vec::new();
if !named_import_props.is_empty() {
decls.push(VarDeclarator {
span: DUMMY_SP,
name: Pat::Object(ObjectPat {
span: DUMMY_SP,
optional: false,
props: named_import_props,
type_ann: None,
}),
definite: false,
init: Some(initializer.clone()),
});
}
if let Some(namespace_import) = namespace_import_name {
decls.push(VarDeclarator {
span: DUMMY_SP,
name: Pat::Ident(namespace_import),
definite: false,
init: Some(initializer),
});
}
decls
},
})))
}
_ => module_item,
}
}
}
/// Strips export declarations and exports on named exports for the REPL.
pub struct StripExportsFolder;
impl Fold for StripExportsFolder {
noop_fold_type!(); // skip typescript specific nodes
fn fold_module_item(
&mut self,
module_item: swc_ast::ModuleItem,
) -> swc_ast::ModuleItem {
use deno_ast::swc::ast::*;
match module_item {
ModuleItem::ModuleDecl(ModuleDecl::ExportAll(export_all)) => {
ModuleItem::Stmt(Stmt::Expr(ExprStmt {
span: DUMMY_SP,
expr: create_await_import_expr(
&export_all.src.value,
export_all.asserts,
),
}))
}
ModuleItem::ModuleDecl(ModuleDecl::ExportNamed(export_named)) => {
if let Some(src) = export_named.src {
ModuleItem::Stmt(Stmt::Expr(ExprStmt {
span: DUMMY_SP,
expr: create_await_import_expr(&src.value, export_named.asserts),
}))
} else {
create_empty_stmt()
}
}
ModuleItem::ModuleDecl(ModuleDecl::ExportDefaultExpr(default_expr)) => {
// transform a default export expression to its expression
ModuleItem::Stmt(Stmt::Expr(ExprStmt {
span: DUMMY_SP,
expr: default_expr.expr,
}))
}
ModuleItem::ModuleDecl(ModuleDecl::ExportDecl(export_decl)) => {
// strip the export keyword on an exported declaration
ModuleItem::Stmt(Stmt::Decl(export_decl.decl))
}
ModuleItem::ModuleDecl(ModuleDecl::ExportDefaultDecl(default_decl)) => {
// only keep named default exports
match default_decl.decl {
DefaultDecl::Fn(FnExpr {
ident: Some(ident),
function,
}) => ModuleItem::Stmt(Stmt::Decl(Decl::Fn(FnDecl {
declare: false,
ident,
function,
}))),
DefaultDecl::Class(ClassExpr {
ident: Some(ident),
class,
}) => ModuleItem::Stmt(Stmt::Decl(Decl::Class(ClassDecl {
declare: false,
ident,
class,
}))),
_ => create_empty_stmt(),
}
}
_ => module_item,
}
}
}
fn create_empty_stmt() -> swc_ast::ModuleItem {
use swc_ast::*;
ModuleItem::Stmt(Stmt::Empty(EmptyStmt { span: DUMMY_SP }))
}
fn create_binding_ident(name: String) -> swc_ast::BindingIdent {
swc_ast::BindingIdent {
id: create_ident(name),
type_ann: None,
}
}
fn create_ident(name: String) -> swc_ast::Ident {
swc_ast::Ident {
span: DUMMY_SP,
sym: name.into(),
optional: false,
}
}
fn create_key_value(key: String, value: String) -> swc_ast::ObjectPatProp {
swc_ast::ObjectPatProp::KeyValue(swc_ast::KeyValuePatProp {
key: swc_ast::PropName::Ident(swc_ast::Ident {
span: DUMMY_SP,
sym: key.into(),
optional: false,
}),
value: Box::new(swc_ast::Pat::Ident(swc_ast::BindingIdent {
id: swc_ast::Ident {
span: DUMMY_SP,
sym: value.into(),
optional: false,
},
type_ann: None,
})),
})
}
fn create_await_import_expr(
module_specifier: &str,
maybe_asserts: Option<swc_ast::ObjectLit>,
) -> Box<swc_ast::Expr> {
use swc_ast::*;
let mut args = vec![ExprOrSpread {
spread: None,
expr: Box::new(Expr::Lit(Lit::Str(Str {
span: DUMMY_SP,
has_escape: false,
kind: StrKind::Normal {
contains_quote: false,
},
value: module_specifier.into(),
}))),
}];
// add assert object if it exists
if let Some(asserts) = maybe_asserts {
args.push(ExprOrSpread {
spread: None,
expr: Box::new(Expr::Object(ObjectLit {
span: DUMMY_SP,
props: vec![PropOrSpread::Prop(Box::new(Prop::KeyValue(
KeyValueProp {
key: PropName::Ident(create_ident("assert".to_string())),
value: Box::new(Expr::Object(asserts)),
},
)))],
})),
})
}
Box::new(Expr::Await(AwaitExpr {
span: DUMMY_SP,
arg: Box::new(Expr::Call(CallExpr {
span: DUMMY_SP,
callee: ExprOrSuper::Expr(Box::new(Expr::Ident(Ident {
span: DUMMY_SP,
sym: "import".into(),
optional: false,
}))),
args,
type_args: None,
})),
}))
}
fn create_assignment(key: String) -> swc_ast::ObjectPatProp {
swc_ast::ObjectPatProp::Assign(swc_ast::AssignPatProp {
span: DUMMY_SP,
key: create_ident(key),
value: None,
})
}
#[cfg(test)]
mod test {
use deno_ast::swc::ast::Module;
use deno_ast::swc::codegen::text_writer::JsWriter;
use deno_ast::swc::codegen::Node;
use deno_ast::swc::common::FileName;
use deno_ast::swc::common::SourceMap;
use deno_ast::swc::parser::Parser;
use deno_ast::swc::parser::StringInput;
use deno_ast::swc::parser::Syntax;
use deno_ast::swc::parser::TsConfig;
use deno_ast::swc::visit::Fold;
use deno_ast::swc::visit::FoldWith;
use deno_ast::ModuleSpecifier;
use pretty_assertions::assert_eq;
use std::rc::Rc;
use super::*;
#[test]
fn test_downlevel_imports_type_only() {
test_transform(
DownlevelImportsFolder,
r#"import type { test } from "./mod.ts";"#,
";",
);
}
#[test]
fn test_downlevel_imports_specifier_only() {
test_transform(
DownlevelImportsFolder,
r#"import "./mod.ts";"#,
r#"await import("./mod.ts");"#,
);
test_transform(
DownlevelImportsFolder,
r#"import {} from "./mod.ts";"#,
r#"await import("./mod.ts");"#,
);
}
#[test]
fn test_downlevel_imports_default() {
test_transform(
DownlevelImportsFolder,
r#"import mod from "./mod.ts";"#,
r#"const { default: mod } = await import("./mod.ts");"#,
);
}
#[test]
fn test_downlevel_imports_named() {
test_transform(
DownlevelImportsFolder,
r#"import { A } from "./mod.ts";"#,
r#"const { A } = await import("./mod.ts");"#,
);
test_transform(
DownlevelImportsFolder,
r#"import { A, B, C } from "./mod.ts";"#,
r#"const { A , B , C } = await import("./mod.ts");"#,
);
test_transform(
DownlevelImportsFolder,
r#"import { A as LocalA, B, C as LocalC } from "./mod.ts";"#,
r#"const { A: LocalA , B , C: LocalC } = await import("./mod.ts");"#,
);
}
#[test]
fn test_downlevel_imports_namespace() {
test_transform(
DownlevelImportsFolder,
r#"import * as mod from "./mod.ts";"#,
r#"const mod = await import("./mod.ts");"#,
);
}
#[test]
fn test_downlevel_imports_mixed() {
test_transform(
DownlevelImportsFolder,
r#"import myDefault, { A, B as LocalB } from "./mod.ts";"#,
r#"const { default: myDefault , A , B: LocalB } = await import("./mod.ts");"#,
);
test_transform(
DownlevelImportsFolder,
r#"import myDefault, * as mod from "./mod.ts";"#,
r#"const { default: myDefault } = await import("./mod.ts"), mod = await import("./mod.ts");"#,
);
}
#[test]
fn test_downlevel_imports_assertions() {
test_transform(
DownlevelImportsFolder,
r#"import data from "./mod.json" assert { type: "json" };"#,
"const { default: data } = await import(\"./mod.json\", {\n assert: {\n type: \"json\"\n }\n});",
);
}
#[test]
fn test_strip_exports_export_all() {
test_transform(
StripExportsFolder,
r#"export * from "./test.ts";"#,
r#"await import("./test.ts");"#,
);
}
#[test]
fn test_strip_exports_export_named() {
test_transform(
StripExportsFolder,
r#"export { test } from "./test.ts";"#,
r#"await import("./test.ts");"#,
);
test_transform(StripExportsFolder, r#"export { test };"#, ";");
}
#[test]
fn test_strip_exports_assertions() {
test_transform(
StripExportsFolder,
r#"export { default as data } from "./mod.json" assert { type: "json" };"#,
"await import(\"./mod.json\", {\n assert: {\n type: \"json\"\n }\n});",
);
}
#[test]
fn test_strip_exports_export_all_assertions() {
// even though this doesn't really make sense for someone to do
test_transform(
StripExportsFolder,
r#"export * from "./mod.json" assert { type: "json" };"#,
"await import(\"./mod.json\", {\n assert: {\n type: \"json\"\n }\n});",
);
}
#[test]
fn test_strip_exports_export_default_expr() {
test_transform(StripExportsFolder, "export default 5;", "5;");
}
#[test]
fn test_strip_exports_export_default_decl_name() {
test_transform(
StripExportsFolder,
"export default class Test {}",
"class Test {\n}",
);
test_transform(
StripExportsFolder,
"export default function test() {}",
"function test() {\n}",
);
}
#[test]
fn test_strip_exports_export_default_decl_no_name() {
test_transform(StripExportsFolder, "export default class {}", ";");
test_transform(StripExportsFolder, "export default function() {}", ";");
}
#[test]
fn test_strip_exports_export_named_decls() {
test_transform(
StripExportsFolder,
"export class Test {}",
"class Test {\n}",
);
test_transform(
StripExportsFolder,
"export function test() {}",
"function test() {\n}",
);
test_transform(StripExportsFolder, "export enum Test {}", "enum Test {\n}");
test_transform(
StripExportsFolder,
"export namespace Test {}",
"module Test {\n}",
);
}
#[test]
fn test_strip_exports_not_in_namespace() {
test_transform(
StripExportsFolder,
"namespace Test { export class Test {} }",
"module Test {\n export class Test {\n }\n}",
);
}
fn test_transform(
mut transform: impl Fold,
src: &str,
expected_output: &str,
) {
let (source_map, module) = parse(src);
let output = print(source_map, module.fold_with(&mut transform));
assert_eq!(output, format!("{}\n", expected_output));
}
fn parse(src: &str) -> (Rc<SourceMap>, Module) {
let source_map = Rc::new(SourceMap::default());
let source_file = source_map.new_source_file(
FileName::Url(ModuleSpecifier::parse("file:https:///test.ts").unwrap()),
src.to_string(),
);
let input = StringInput::from(&*source_file);
let syntax = Syntax::Typescript(TsConfig {
..Default::default()
});
let mut parser = Parser::new(syntax, input, None);
(source_map, parser.parse_module().unwrap())
}
fn print(source_map: Rc<SourceMap>, module: Module) -> String {
let mut buf = vec![];
{
let writer =
Box::new(JsWriter::new(source_map.clone(), "\n", &mut buf, None));
let config = deno_ast::swc::codegen::Config { minify: false };
let mut emitter = deno_ast::swc::codegen::Emitter {
cfg: config,
comments: None,
cm: source_map,
wr: writer,
};
module.emit_with(&mut emitter).unwrap();
}
String::from_utf8(buf).unwrap()
}
}