use std::path::Path;
use oxc_allocator::Allocator;
use oxc_ast::ast::{ImportDeclarationSpecifier, ModuleExportName, Statement};
use oxc_parser::Parser;
use oxc_span::SourceType;
pub fn rewrite_cjs_interop(
source: &str,
path: &Path,
interop: &dyn Fn(&str) -> Option<String>,
) -> Option<String> {
let source_type = SourceType::from_path(path).unwrap_or_default();
let allocator = Allocator::default();
let parsed = Parser::new(&allocator, source, source_type).parse();
if parsed.panicked {
return None;
}
let mut edits: Vec<(usize, usize, String)> = Vec::new();
let mut idx = 0usize;
for stmt in &parsed.program.body {
match stmt {
Statement::ImportDeclaration(decl) => {
if decl.import_kind.is_type() {
continue;
}
let Some(url) = interop(decl.source.value.as_str()) else { continue };
let ns = format!("__ojcjs{idx}");
idx += 1;
let mut out = format!("import {ns} from {};", json_str(&url));
match &decl.specifiers {
None => {
out = format!("import {};", json_str(&url));
}
Some(specs) => {
let mut names: Vec<String> = Vec::new();
for spec in specs {
match spec {
ImportDeclarationSpecifier::ImportDefaultSpecifier(s) => {
out.push_str(&format!(
"const {} = {ns} && {ns}.__esModule ? {ns}.default : {ns};",
s.local.name
));
}
ImportDeclarationSpecifier::ImportNamespaceSpecifier(s) => {
out.push_str(&format!("const {} = {ns};", s.local.name));
}
ImportDeclarationSpecifier::ImportSpecifier(s) => {
names.push(format!(
"{}: {}",
json_key(&export_name(&s.imported)),
s.local.name
));
}
}
}
if !names.is_empty() {
out.push_str(&format!("const {{ {} }} = {ns};", names.join(", ")));
}
}
}
edits.push((decl.span.start as usize, decl.span.end as usize, out));
}
Statement::ExportFromDeclaration(decl) => {
if decl.export_kind.is_type() {
continue;
}
let Some(url) = interop(decl.source.value.as_str()) else { continue };
let n = idx;
let ns = format!("__ojcjs{n}");
idx += 1;
let mut out = format!("import {ns} from {};", json_str(&url));
let mut tmp = 0usize;
for spec in &decl.specifiers {
if spec.export_kind.is_type() {
continue;
}
let local = export_name(&spec.local);
let exported = export_name(&spec.exported);
let value = if local == "default" {
format!("{ns} && {ns}.__esModule ? {ns}.default : {ns}")
} else {
format!("{ns}[{}]", json_str(&local))
};
let t = format!("__ojex{n}_{tmp}");
tmp += 1;
out.push_str(&format!("const {t} = {value};"));
out.push_str(&format!("export {{ {t} as {} }};", json_key(&exported)));
}
edits.push((decl.span.start as usize, decl.span.end as usize, out));
}
_ => continue,
}
}
if edits.is_empty() {
return None;
}
edits.sort_by_key(|e| std::cmp::Reverse(e.0));
let mut result = source.to_string();
for (start, end, text) in edits {
result.replace_range(start..end, &text);
}
Some(result)
}
fn export_name(n: &ModuleExportName) -> String {
match n {
ModuleExportName::IdentifierName(i) => i.name.to_string(),
ModuleExportName::IdentifierReference(i) => i.name.to_string(),
ModuleExportName::StringLiteral(l) => l.value.to_string(),
}
}
fn json_str(s: &str) -> String {
let mut out = String::with_capacity(s.len() + 2);
out.push('"');
for c in s.chars() {
match c {
'"' => out.push_str("\\\""),
'\\' => out.push_str("\\\\"),
_ => out.push(c),
}
}
out.push('"');
out
}
fn json_key(s: &str) -> String {
if !s.is_empty()
&& s.chars().next().map(|c| c.is_ascii_alphabetic() || c == '_' || c == '$').unwrap_or(false)
&& s.chars().all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '$')
{
s.to_string()
} else {
json_str(s)
}
}
#[cfg(test)]
mod tests {
use super::*;
fn interop_all(url: &str) -> impl Fn(&str) -> Option<String> + '_ {
move |spec: &str| (spec == "cjs-dep").then(|| url.to_string())
}
fn run(src: &str) -> String {
rewrite_cjs_interop(src, Path::new("m.js"), &interop_all("/@oj-deps/cjs-dep.mjs")).unwrap()
}
#[test]
fn default_import_unwraps_esmodule() {
let out = run(r#"import Foo from "cjs-dep";"#);
assert!(out.contains(r#"import __ojcjs0 from "/@oj-deps/cjs-dep.mjs";"#), "{out}");
assert!(out.contains("const Foo = __ojcjs0 && __ojcjs0.__esModule ? __ojcjs0.default : __ojcjs0;"), "{out}");
}
#[test]
fn named_imports_destructure_from_module_exports() {
let out = run(r#"import { a, b as c } from "cjs-dep";"#);
assert!(out.contains("const { a: a, b: c } = __ojcjs0;"), "{out}");
}
#[test]
fn mixed_default_and_named() {
let out = run(r#"import D, { x } from "cjs-dep";"#);
assert!(out.contains("const D = __ojcjs0 && __ojcjs0.__esModule ? __ojcjs0.default : __ojcjs0;"), "{out}");
assert!(out.contains("const { x: x } = __ojcjs0;"), "{out}");
}
#[test]
fn namespace_import_binds_module_exports() {
let out = run(r#"import * as ns from "cjs-dep";"#);
assert!(out.contains("const ns = __ojcjs0;"), "{out}");
}
#[test]
fn side_effect_import_just_rewrites_specifier() {
let out = run(r#"import "cjs-dep";"#);
assert_eq!(out.trim(), r#"import "/@oj-deps/cjs-dep.mjs";"#);
}
#[test]
fn non_interop_and_type_imports_untouched() {
assert!(rewrite_cjs_interop(r#"import x from "other";"#, Path::new("m.ts"), &interop_all("/u")).is_none());
assert!(rewrite_cjs_interop(r#"import type T from "cjs-dep";"#, Path::new("m.ts"), &interop_all("/u")).is_none());
}
#[test]
fn string_named_import() {
let out = run(r#"import { "weird-name" as w } from "cjs-dep";"#);
assert!(out.contains(r#"const { "weird-name": w } = __ojcjs0;"#), "{out}");
}
#[test]
fn reexport_named_from_cjs() {
let out = run(r#"export { a, b as c } from "cjs-dep";"#);
assert!(out.contains(r#"import __ojcjs0 from "/@oj-deps/cjs-dep.mjs";"#), "{out}");
assert!(out.contains(r#"const __ojex0_0 = __ojcjs0["a"];export { __ojex0_0 as a };"#), "{out}");
assert!(out.contains(r#"const __ojex0_1 = __ojcjs0["b"];export { __ojex0_1 as c };"#), "{out}");
}
#[test]
fn reexport_default_from_cjs_unwraps() {
let out = run(r#"export { default as X } from "cjs-dep";"#);
assert!(
out.contains("const __ojex0_0 = __ojcjs0 && __ojcjs0.__esModule ? __ojcjs0.default : __ojcjs0;"),
"{out}",
);
assert!(out.contains("export { __ojex0_0 as X };"), "{out}");
}
#[test]
fn reexport_from_non_interop_untouched() {
assert!(rewrite_cjs_interop(r#"export { a } from "other";"#, Path::new("m.js"), &interop_all("/u")).is_none());
}
#[test]
fn local_export_without_source_untouched() {
assert!(rewrite_cjs_interop(r#"const foo = 1; export { foo };"#, Path::new("m.js"), &interop_all("/u")).is_none());
}
}