esm: port loader code to JS

There is no reason for this to be in C++. Using JavaScript means that
the code is more accessible to more developers, which is important
for any Node.js feature. This also simplifies the code significantly
in some areas. On the technical side, this potentially also enables
making some of the file system operations that are involved
asynchronous.

PR-URL: https://github.com/nodejs/node/pull/32201
Reviewed-By: Bradley Farias <bradley.meck@gmail.com>
Reviewed-By: Guy Bedford <guybedford@gmail.com>

1 files changed, 43 insertions, 16 deletions

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 5221c8f8c4f..8f39e0c1d78 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -1078,10 +1078,17 @@ E('ERR_INVALID_FILE_URL_PATH', 'File URL path %s', TypeError);
 E('ERR_INVALID_HANDLE_TYPE', 'This handle type cannot be sent', TypeError);
 E('ERR_INVALID_HTTP_TOKEN', '%s must be a valid HTTP token ["%s"]', TypeError);
 E('ERR_INVALID_IP_ADDRESS', 'Invalid IP address: %s', TypeError);
-E('ERR_INVALID_MODULE_SPECIFIER', (pkgPath, subpath) => {
-  assert(subpath !== '.');
-  return `Package subpath '${subpath}' is not a valid module request for the ` +
-      `"exports" resolution of ${pkgPath}${sep}package.json`;
+E('ERR_INVALID_MODULE_SPECIFIER', (pkgPath, subpath, base = undefined) => {
+  if (subpath === undefined) {
+    return `Invalid package name '${pkgPath}' imported from ${base}`;
+  } else if (base === undefined) {
+    assert(subpath !== '.');
+    return `Package subpath '${subpath}' is not a valid module request for ` +
+      `the "exports" resolution of ${pkgPath}${sep}package.json`;
+  } else {
+    return `Package subpath '${subpath}' is not a valid module request for ` +
+      `the "exports" resolution of ${pkgPath} imported from ${base}`;
+  }
 }, TypeError);
 E('ERR_INVALID_OPT_VALUE', (name, value) =>
   `The value "${String(value)}" is invalid for option "${name}"`,
@@ -1089,18 +1096,32 @@ E('ERR_INVALID_OPT_VALUE', (name, value) =>
   RangeError);
 E('ERR_INVALID_OPT_VALUE_ENCODING',
   'The value "%s" is invalid for option "encoding"', TypeError);
-E('ERR_INVALID_PACKAGE_CONFIG',
-  `Invalid package config %s${sep}package.json, %s`, Error);
-E('ERR_INVALID_PACKAGE_TARGET', (pkgPath, key, subpath, target) => {
-  if (key === '.') {
-    return `Invalid "exports" main target ${JSONStringify(target)} defined ` +
+E('ERR_INVALID_PACKAGE_CONFIG', (path, message, hasMessage = true) => {
+  if (hasMessage)
+    return `Invalid package config ${path}${sep}package.json, ${message}`;
+  else
+    return `Invalid JSON in ${path} imported from ${message}`;
+}, Error);
+E('ERR_INVALID_PACKAGE_TARGET',
+  (pkgPath, key, subpath, target, base = undefined) => {
+    if (key === null) {
+      if (subpath !== '') {
+        return `Invalid "exports" target ${JSONStringify(target)} defined ` +
+        `for '${subpath}' in the package config ${pkgPath} imported from ` +
+        base;
+      } else {
+        return `Invalid "exports" main target ${target} defined in the ` +
+          `package config ${pkgPath} imported from ${base}.`;
+      }
+    } else if (key === '.') {
+      return `Invalid "exports" main target ${JSONStringify(target)} defined ` +
       `in the package config ${pkgPath}${sep}package.json`;
-  } else {
-    return `Invalid "exports" target ${JSONStringify(target)} defined for '${
-      StringPrototypeSlice(key, 0, -subpath.length || key.length)}' in the ` +
+    } else {
+      return `Invalid "exports" target ${JSONStringify(target)} defined for '${
+        StringPrototypeSlice(key, 0, -subpath.length || key.length)}' in the ` +
       `package config ${pkgPath}${sep}package.json`;
-  }
-}, Error);
+    }
+  }, Error);
 E('ERR_INVALID_PERFORMANCE_MARK',
   'The "%s" performance mark has not been set', Error);
 E('ERR_INVALID_PROTOCOL',
@@ -1211,6 +1232,9 @@ E('ERR_MISSING_DYNAMIC_INSTANTIATE_HOOK',
   'The ES Module loader may not return a format of \'dynamic\' when no ' +
   'dynamicInstantiate function was provided', Error);
 E('ERR_MISSING_OPTION', '%s is required', TypeError);
+E('ERR_MODULE_NOT_FOUND', (path, base, type = 'package') => {
+  return `Cannot find ${type} '${path}' imported from ${base}`;
+}, Error);
 E('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times', Error);
 E('ERR_NAPI_CONS_FUNCTION', 'Constructor must be a function', TypeError);
 E('ERR_NAPI_INVALID_DATAVIEW_ARGS',
@@ -1245,12 +1269,15 @@ E('ERR_OUT_OF_RANGE',
     msg += ` It must be ${range}. Received ${received}`;
     return msg;
   }, RangeError);
-E('ERR_PACKAGE_PATH_NOT_EXPORTED', (pkgPath, subpath) => {
+E('ERR_PACKAGE_PATH_NOT_EXPORTED', (pkgPath, subpath, base = undefined) => {
   if (subpath === '.') {
     return `No "exports" main resolved in ${pkgPath}${sep}package.json`;
-  } else {
+  } else if (base === undefined) {
     return `Package subpath '${subpath}' is not defined by "exports" in ${
       pkgPath}${sep}package.json`;
+  } else {
+    return `Package subpath '${subpath}' is not defined by "exports" in ${
+      pkgPath} imported from ${base}`;
   }
 }, Error);
 E('ERR_REQUIRE_ESM',