module: support pattern trailers

doc/api/esm.md

@@ -1176,25 +1176,36 @@ The resolver can throw the following errors:
 **PACKAGE_IMPORTS_EXPORTS_RESOLVE**(_matchKey_, _matchObj_, _packageURL_,
 _isImports_, _conditions_)
 
-> 1. If _matchKey_ is a key of _matchObj_, and does not end in _"*"_, then
+> 1. If _matchKey_ is a key of _matchObj_ and does not end in _"/"_ or contain
+>    _"*"_, then
 >    1. Let _target_ be the value of _matchObj_\[_matchKey_\].
 >    1. Let _resolved_ be the result of **PACKAGE_TARGET_RESOLVE**(
 >       _packageURL_, _target_, _""_, **false**, _isImports_, _conditions_).
 >    1. Return the object _{ resolved, exact: **true** }_.
-> 1. Let _expansionKeys_ be the list of keys of _matchObj_ ending in _"/"_
->    or _"*"_, sorted by length descending.
+> 1. Let _expansionKeys_ be the list of keys of _matchObj_ either ending in
+>    _"/"_ or containing only a single _"*"_, sorted by the sorting function
+>    **PATTERN_KEY_COMPARE** which orders in descending order of specificity.
 > 1. For each key _expansionKey_ in _expansionKeys_, do
->    1. If _expansionKey_ ends in _"*"_ and _matchKey_ starts with but is
->       not equal to the substring of _expansionKey_ excluding the last _"*"_
->       character, then
->       1. Let _target_ be the value of _matchObj_\[_expansionKey_\].
->       1. Let _subpath_ be the substring of _matchKey_ starting at the
->          index of the length of _expansionKey_ minus one.
->       1. Let _resolved_ be the result of **PACKAGE_TARGET_RESOLVE**(
->          _packageURL_, _target_, _subpath_, **true**, _isImports_,
->          _conditions_).
->       1. Return the object _{ resolved, exact: **true** }_.
->    1. If _matchKey_ starts with _expansionKey_, then
+>    1. Let _patternBase_ be **null**.
+>    1. If _expansionKey_ contains _"*"_, set _patternBase_ to the substring of
+>       _expansionKey_ up to but excluding the first _"*"_ character.
+>    1. If _patternBase_ is not **null** and _matchKey_ starts with but is not
+>       equal to _patternBase_, then
+>       1. Let _patternTrailer_ be the substring of _expansionKey_ from the
+>          index after the first _"*"_ character.
+>       1. If _patternTrailer_ has zero length, or if _matchKey_ ends with
+>          _patternTrailer_ and the length of _matchKey_ is greater than or
+>          equal to the length of _expansionKey_, then
+>          1. Let _target_ be the value of _matchObj_\[_expansionKey_\].
+>          1. Let _subpath_ be the substring of _matchKey_ starting at the
+>             index of the length of _patternBase_ up to the length of
+>             _matchKey_ minus the length of _patternTrailer_.
+>          1. Let _resolved_ be the result of **PACKAGE_TARGET_RESOLVE**(
+>             _packageURL_, _target_, _subpath_, **true**, _isImports_,
+>             _conditions_).
+>          1. Return the object _{ resolved, exact: **true** }_.
+>    1. Otherwise if _patternBase_ is **null** and _matchKey_ starts with
+>       _expansionKey_, then
 >       1. Let _target_ be the value of _matchObj_\[_expansionKey_\].
 >       1. Let _subpath_ be the substring of _matchKey_ starting at the
 >          index of the length of _expansionKey_.
@@ -1204,6 +1215,22 @@ _isImports_, _conditions_)
 >       1. Return the object _{ resolved, exact: **false** }_.
 > 1. Return the object _{ resolved: **null**, exact: **true** }_.
 
+**PATTERN_KEY_COMPARE**(_keyA_, _keyB_)
+
+> 1. Assert: _keyA_ ends with _"/"_ or contains only a single _"*"_.
+> 1. Assert: _keyB_ ends with _"/"_ or contains only a single _"*"_.
+> 1. Let _baseLengthA_ be the index of _"*"_ in _keyA_ plus one, if _keyA_
+>    contains _"*"_, or the length of _keyA_ otherwise.
+> 1. Let _baseLengthB_ be the index of _"*"_ in _keyB_ plus one, if _keyB_
+>    contains _"*"_, or the length of _keyB_ otherwise.
+> 1. If _baseLengthA_ is greater than _baseLengthB_, return -1.
+> 1. If _baseLengthB_ is greater than _baseLengthA_, return 1.
+> 1. If _keyA_ does not contain _"*"_, return 1.
+> 1. If _keyB_ does not contain _"*"_, return -1.
+> 1. If the length of _keyA_ is greater than the length of _keyB_, return -1.
+> 1. If the length of _keyB_ is greater than the length of _keyA_, return 1.
+> 1. Return 0.
+
 **PACKAGE_TARGET_RESOLVE**(_packageURL_, _target_, _subpath_, _pattern_,
 _internal_, _conditions_)
 

doc/api/packages.md

@@ -361,9 +361,8 @@ For these use cases, subpath export patterns can be used instead:
 **`*` maps expose nested subpaths as it is a string replacement syntax
 only.**
 
-The left hand matching pattern must always end in `*`. All instances of `*` on
-the right hand side will then be replaced with this value, including if it
-contains any `/` separators.
+All instances of `*` on the right hand side will then be replaced with this
+value, including if it contains any `/` separators.
 
 ```js
 import featureX from 'es-module-package/features/x';

lib/internal/modules/esm/resolve.js

@@ -15,7 +15,9 @@ const {
   SafeSet,
   String,
   StringPrototypeEndsWith,
+  StringPrototypeIncludes,
   StringPrototypeIndexOf,
+  StringPrototypeLastIndexOf,
   StringPrototypeReplace,
   StringPrototypeSlice,
   StringPrototypeSplit,
@@ -114,7 +116,7 @@ function emitLegacyIndexDeprecation(url, packageJSONUrl, base, main) {
       `Package ${pkgPath} has a "main" field set to ${JSONStringify(main)}, ` +
       `excluding the full filename and extension to the resolved file at "${
         StringPrototypeSlice(path, pkgPath.length)}", imported from ${
-        basePath}.\n Automatic extension resolution of the "main" field is` +
+        basePath}.\n Automatic extension resolution of the "main" field is ` +
       'deprecated for ES modules.',
       'DeprecationWarning',
       'DEP0151'
@@ -607,7 +609,9 @@ function packageExportsResolve(
   if (isConditionalExportsMainSugar(exports, packageJSONUrl, base))
     exports = { '.': exports };
 
-  if (ObjectPrototypeHasOwnProperty(exports, packageSubpath)) {
+  if (ObjectPrototypeHasOwnProperty(exports, packageSubpath) &&
+      !StringPrototypeIncludes(packageSubpath, '*') &&
+      !StringPrototypeEndsWith(packageSubpath, '/')) {
     const target = exports[packageSubpath];
     const resolved = resolvePackageTarget(
       packageJSONUrl, target, '', packageSubpath, base, false, false, conditions
@@ -618,30 +622,38 @@ function packageExportsResolve(
   }
 
   let bestMatch = '';
+  let bestMatchSubpath;
   const keys = ObjectGetOwnPropertyNames(exports);
   for (let i = 0; i < keys.length; i++) {
     const key = keys[i];
-    if (key[key.length - 1] === '*' &&
+    const patternIndex = StringPrototypeIndexOf(key, '*');
+    if (patternIndex !== -1 &&
         StringPrototypeStartsWith(packageSubpath,
-                                  StringPrototypeSlice(key, 0, -1)) &&
-        packageSubpath.length >= key.length &&
-        key.length > bestMatch.length) {
-      bestMatch = key;
+                                  StringPrototypeSlice(key, 0, patternIndex))) {
+      const patternTrailer = StringPrototypeSlice(key, patternIndex + 1);
+      if (packageSubpath.length >= key.length &&
+          StringPrototypeEndsWith(packageSubpath, patternTrailer) &&
+          patternKeyCompare(bestMatch, key) === 1 &&
+          StringPrototypeLastIndexOf(key, '*') === patternIndex) {
+        bestMatch = key;
+        bestMatchSubpath = StringPrototypeSlice(
+          packageSubpath, patternIndex,
+          packageSubpath.length - patternTrailer.length);
+      }
     } else if (key[key.length - 1] === '/' &&
       StringPrototypeStartsWith(packageSubpath, key) &&
-      key.length > bestMatch.length) {
+      patternKeyCompare(bestMatch, key) === 1) {
       bestMatch = key;
+      bestMatchSubpath = StringPrototypeSlice(packageSubpath, key.length);
     }
   }
 
   if (bestMatch) {
     const target = exports[bestMatch];
-    const pattern = bestMatch[bestMatch.length - 1] === '*';
-    const subpath = StringPrototypeSubstr(packageSubpath, bestMatch.length -
-      (pattern ? 1 : 0));
-    const resolved = resolvePackageTarget(packageJSONUrl, target, subpath,
-                                          bestMatch, base, pattern, false,
-                                          conditions);
+    const pattern = StringPrototypeIncludes(bestMatch, '*');
+    const resolved = resolvePackageTarget(packageJSONUrl, target,
+                                          bestMatchSubpath, bestMatch, base,
+                                          pattern, false, conditions);
     if (resolved === null || resolved === undefined)
       throwExportsNotFound(packageSubpath, packageJSONUrl, base);
     if (!pattern)
@@ -652,6 +664,20 @@ function packageExportsResolve(
   throwExportsNotFound(packageSubpath, packageJSONUrl, base);
 }
 
+function patternKeyCompare(a, b) {
+  const aPatternIndex = StringPrototypeIndexOf(a, '*');
+  const bPatternIndex = StringPrototypeIndexOf(b, '*');
+  const baseLenA = aPatternIndex === -1 ? a.length : aPatternIndex + 1;
+  const baseLenB = bPatternIndex === -1 ? b.length : bPatternIndex + 1;
+  if (baseLenA > baseLenB) return -1;
+  if (baseLenB > baseLenA) return 1;
+  if (aPatternIndex === -1) return 1;
+  if (bPatternIndex === -1) return -1;
+  if (a.length > b.length) return -1;
+  if (b.length > a.length) return 1;
+  return 0;
+}
+
 /**
  * @param {string} name
  * @param {string | URL | undefined} base

test/es-module/test-esm-exports.mjs

@@ -35,7 +35,12 @@ import fromInside from '../fixtures/node_modules/pkgexports/lib/hole.js';
     ['pkgexports-sugar', { default: 'main' }],
     // Path patterns
     ['pkgexports/subpath/sub-dir1', { default: 'main' }],
+    ['pkgexports/subpath/sub-dir1.js', { default: 'main' }],
     ['pkgexports/features/dir1', { default: 'main' }],
+    ['pkgexports/dir1/dir1/trailer', { default: 'main' }],
+    ['pkgexports/dir2/dir2/trailer', { default: 'index' }],
+    ['pkgexports/a/dir1/dir1', { default: 'main' }],
+    ['pkgexports/a/b/dir1/dir1', { default: 'main' }],
   ]);
 
   if (isRequire) {
@@ -77,6 +82,8 @@ import fromInside from '../fixtures/node_modules/pkgexports/lib/hole.js';
     ['pkgexports/null/subpath', './null/subpath'],
     // Empty fallback
     ['pkgexports/nofallback1', './nofallback1'],
+    // Non pattern matches
+    ['pkgexports/trailer', './trailer'],
   ]);
 
   const invalidExports = new Map([
@@ -147,6 +154,8 @@ import fromInside from '../fixtures/node_modules/pkgexports/lib/hole.js';
     ['pkgexports/sub/not-a-file.js', `pkgexports${sep}not-a-file.js`],
     // No extension lookups
     ['pkgexports/no-ext', `pkgexports${sep}asdf`],
+    // Pattern specificity
+    ['pkgexports/dir2/trailer', `subpath${sep}dir2.js`],
   ]);
 
   if (!isRequire) {