refactor(node_resolver): remove some allocations and lookups (#27799)

resolvers/node/resolution.rs

@@ -971,7 +971,7 @@ impl<
       }
       return Err(last_error.unwrap());
     } else if let Some(target_obj) = target.as_object() {
-      for key in target_obj.keys() {
+      for (key, condition_target) in target_obj {
         // TODO(bartlomieju): verify that keys are not numeric
         // return Err(errors::err_invalid_package_config(
         //   to_file_path_string(package_json_url),
@@ -983,8 +983,6 @@ impl<
           || conditions.contains(&key.as_str())
           || resolution_kind.is_types() && key.as_str() == "types"
         {
-          let condition_target = target_obj.get(key).unwrap();
-
           let resolved = self.resolve_package_target(
             package_json_path,
             condition_target,
@@ -1032,11 +1030,9 @@ impl<
     conditions: &[&str],
     resolution_kind: NodeResolutionKind,
   ) -> Result<Url, PackageExportsResolveError> {
-    if package_exports.contains_key(package_subpath)
-      && package_subpath.find('*').is_none()
-      && !package_subpath.ends_with('/')
+    if let Some(target) = package_exports.get(package_subpath) {
+      if package_subpath.find('*').is_none() && !package_subpath.ends_with('/')
       {
-      let target = package_exports.get(package_subpath).unwrap();
         let resolved = self.resolve_package_target(
           package_json_path,
           target,
@@ -1062,14 +1058,19 @@ impl<
           ),
         };
       }
+    }
 
     let mut best_match = "";
-    let mut best_match_subpath = None;
-    for key in package_exports.keys() {
-      let pattern_index = key.find('*');
-      if let Some(pattern_index) = pattern_index {
+    let mut best_match_data = None;
+    for (key, target) in package_exports {
+      let Some(pattern_index) = key.find('*') else {
+        continue;
+      };
       let key_sub = &key[0..pattern_index];
-        if package_subpath.starts_with(key_sub) {
+      if !package_subpath.starts_with(key_sub) {
+        continue;
+      }
+
       // When this reaches EOL, this can throw at the top of the whole function:
       //
       // if (StringPrototypeEndsWith(packageSubpath, '/'))
@@ -1087,22 +1088,19 @@ impl<
         && key.rfind('*') == Some(pattern_index)
       {
         best_match = key;
-            best_match_subpath = Some(
-              package_subpath[pattern_index
-                ..(package_subpath.len() - pattern_trailer.len())]
-                .to_string(),
-            );
-          }
-        }
+        best_match_data = Some((
+          target,
+          &package_subpath
+            [pattern_index..(package_subpath.len() - pattern_trailer.len())],
+        ));
       }
     }
 
-    if !best_match.is_empty() {
-      let target = package_exports.get(best_match).unwrap();
+    if let Some((target, subpath)) = best_match_data {
       let maybe_resolved = self.resolve_package_target(
         package_json_path,
         target,
-        &best_match_subpath.unwrap(),
+        subpath,
         best_match,
         maybe_referrer,
         resolution_mode,
@@ -1152,7 +1150,7 @@ impl<
       self.pkg_json_resolver.get_closest_package_json(referrer)?
     {
       // ResolveSelf
-      if package_config.name.as_ref() == Some(&package_name) {
+      if package_config.name.as_deref() == Some(package_name) {
         if let Some(exports) = &package_config.exports {
           return self
             .package_exports_resolve(
@@ -1170,7 +1168,7 @@ impl<
     }
 
     self.resolve_package_subpath_for_package(
-      &package_name,
+      package_name,
       &package_subpath,
       referrer,
       resolution_mode,
@@ -1760,10 +1758,10 @@ fn throw_invalid_subpath(
   }
 }
 
-pub fn parse_npm_pkg_name(
-  specifier: &str,
+pub fn parse_npm_pkg_name<'a>(
+  specifier: &'a str,
   referrer: &Url,
-) -> Result<(String, String, bool), InvalidModuleSpecifierError> {
+) -> Result<(&'a str, Cow<'static, str>, bool), InvalidModuleSpecifierError> {
   let mut separator_index = specifier.find('/');
   let mut valid_package_name = true;
   let mut is_scoped = false;
@@ -1780,10 +1778,11 @@ pub fn parse_npm_pkg_name(
     }
   }
 
-  let package_name = if let Some(index) = separator_index {
-    specifier[0..index].to_string()
+  let (package_name, subpath) = if let Some(index) = separator_index {
+    let (package_name, subpath) = specifier.split_at(index);
+    (package_name, Cow::Owned(format!(".{}", subpath)))
   } else {
-    specifier.to_string()
+    (specifier, Cow::Borrowed("."))
   };
 
   // Package name cannot have leading . and cannot have percent-encoding or separators.
@@ -1802,13 +1801,7 @@ pub fn parse_npm_pkg_name(
     });
   }
 
-  let package_subpath = if let Some(index) = separator_index {
-    format!(".{}", specifier.chars().skip(index).collect::<String>())
-  } else {
-    ".".to_string()
-  };
-
-  Ok((package_name, package_subpath, is_scoped))
+  Ok((package_name, subpath, is_scoped))
 }
 
 /// Resolves a specifier that is pointing into a node_modules folder.
@@ -2055,18 +2048,18 @@ mod tests {
 
     assert_eq!(
       parse_npm_pkg_name("fetch-blob", &dummy_referrer).unwrap(),
-      ("fetch-blob".to_string(), ".".to_string(), false)
+      ("fetch-blob", Cow::Borrowed("."), false)
     );
     assert_eq!(
       parse_npm_pkg_name("@vue/plugin-vue", &dummy_referrer).unwrap(),
-      ("@vue/plugin-vue".to_string(), ".".to_string(), true)
+      ("@vue/plugin-vue", Cow::Borrowed("."), true)
     );
     assert_eq!(
       parse_npm_pkg_name("@astrojs/prism/dist/highlighter", &dummy_referrer)
         .unwrap(),
       (
-        "@astrojs/prism".to_string(),
-        "./dist/highlighter".to_string(),
+        "@astrojs/prism",
+        Cow::Owned("./dist/highlighter".to_string()),
         true
       )
     );