feat(compat): integrate import map and classic resolutions in ESM res…

…olution (denoland#12549)

This commit integrates import map and "classic" resolutions in
the "--compat" mode when using ES modules; in effect
"http:", "https:" and "blob:" imports now work in compat mode.

The algorithm works as follows:

1. If there's an import map, try to resolve using it and if succeeded
return the specifier
2. Try to resolve using "Node ESM resolution", and if succeeded return
the specifier
3. Fall back to regular ESM resolution

cli/compat/esm_resolver.rs

@@ -1,6 +1,7 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
 use super::errors;
+use crate::resolver::ImportMapResolver;
 use deno_core::error::generic_error;
 use deno_core::error::AnyError;
 use deno_core::serde_json;
@@ -13,21 +14,60 @@ use regex::Regex;
 use std::path::PathBuf;
 
 #[derive(Debug, Default)]
-pub struct NodeEsmResolver;
+pub(crate) struct NodeEsmResolver<'a> {
+ maybe_import_map_resolver: Option<ImportMapResolver<'a>>,
+}
+
+impl<'a> NodeEsmResolver<'a> {
+ pub fn new(maybe_import_map_resolver: Option<ImportMapResolver<'a>>) -> Self {
+ Self {
+ maybe_import_map_resolver,
+ }
+ }
 
-impl NodeEsmResolver {
  pub fn as_resolver(&self) -> &dyn Resolver {
  self
  }
 }
 
-impl Resolver for NodeEsmResolver {
+impl Resolver for NodeEsmResolver<'_> {
  fn resolve(
  &self,
  specifier: &str,
  referrer: &ModuleSpecifier,
  ) -> Result<ModuleSpecifier, AnyError> {
- node_resolve(specifier, referrer.as_str(), &std::env::current_dir()?)
+ // First try to resolve using import map, ignoring any errors
+ if !specifier.starts_with("node:") {
+ if let Some(import_map_resolver) = &self.maybe_import_map_resolver {
+ if let Ok(specifier) = import_map_resolver.resolve(specifier, referrer)
+ {
+ return Ok(specifier);
+ }
+ }
+ }
+
+ let node_resolution =
+ node_resolve(specifier, referrer.as_str(), &std::env::current_dir()?);
+
+ match node_resolution {
+ Ok(specifier) => {
+ // If node resolution succeeded, return the specifier
+ Ok(specifier)
+ }
+ Err(err) => {
+ // If node resolution failed, check if it's because of unsupported
+ // URL scheme, and if so try to resolve using regular resolution algorithm
+ if err
+ .to_string()
+ .starts_with("[ERR_UNSUPPORTED_ESM_URL_SCHEME]")
+ {
+ return deno_core::resolve_import(specifier, referrer.as_str())
+ .map_err(|err| err.into());
+ }
+
+ Err(err)
+ }
+ }
  }
 }
 

cli/compat/mod.rs

@@ -8,7 +8,7 @@ use deno_core::located_script_name;
 use deno_core::url::Url;
 use deno_core::JsRuntime;
 
-pub use esm_resolver::NodeEsmResolver;
+pub(crate) use esm_resolver::NodeEsmResolver;
 
 // TODO(bartlomieju): this needs to be bumped manually for
 // each release, a better mechanism is preferable, but it's a quick and dirty
@@ -86,7 +86,7 @@ fn try_resolve_builtin_module(specifier: &str) -> Option<Url> {
  }
 }
 
-pub async fn check_if_should_use_esm_loader(
+pub(crate) async fn check_if_should_use_esm_loader(
  js_runtime: &mut JsRuntime,
  main_module: &str,
 ) -> Result<bool, AnyError> {
@@ -113,7 +113,7 @@ pub async fn check_if_should_use_esm_loader(
  Ok(use_esm_loader)
 }
 
-pub fn load_cjs_module(
+pub(crate) fn load_cjs_module(
  js_runtime: &mut JsRuntime,
  main_module: &str,
 ) -> Result<(), AnyError> {

cli/proc_state.rs

@@ -298,7 +298,9 @@ impl ProcState {
  );
  let maybe_locker = as_maybe_locker(self.lockfile.clone());
  let maybe_imports = self.get_maybe_imports();
- let node_resolver = NodeEsmResolver;
+ let node_resolver = NodeEsmResolver::new(
+ self.maybe_import_map.as_ref().map(ImportMapResolver::new),
+ );
  let import_map_resolver =
  self.maybe_import_map.as_ref().map(ImportMapResolver::new);
  let maybe_resolver = if self.flags.compat {

cli/tests/integration/compat_tests.rs

@@ -18,6 +18,11 @@ itest!(node_prefix_fs_promises {
  output: "compat/fs_promises.out",
 });
 
+itest!(compat_with_import_map_and_https_imports {
+ args: "run --quiet --compat --unstable -A --import-map=compat/import_map.json compat/import_map_https_imports.mjs",
+ output: "compat/import_map_https_imports.out",
+});
+
 #[test]
 fn globals_in_repl() {
  let (out, _err) = util::run_and_collect_output_with_args(

cli/tests/testdata/compat/import_map.json

@@ -0,0 +1,5 @@
+{
+ "imports": {
+ "std/": "https://deno.land/[email protected]/"
+ }
+}

cli/tests/testdata/compat/import_map_https_imports.mjs

@@ -0,0 +1,7 @@
+import { sortBy } from "std/collections/sort_by.ts";
+import { findSingle } from "https://deno.land/[email protected]/collections/find_single.ts";
+import os from "node:os";
+
+console.log(sortBy([2, 3, 1], (it) => it));
+console.log(findSingle([2, 3, 1], (it) => it == 2));
+console.log("arch", os.arch());

cli/tests/testdata/compat/import_map_https_imports.out

@@ -0,0 +1,3 @@
+[ 1, 2, 3 ]
+2
+arch [WILDCARD]