Initial support for conditional imports

holepunchto · Nov 16, 2023 · 96060af · 96060af
1 parent 9c3d49b
commit 96060af
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Showing 2 changed files with 176 additions and 22 deletions.
diff --git a/index.js b/index.js
@@ -257,22 +257,8 @@ const Module = module.exports = exports = class Module {
     const module = this._cache[specifier] = new this(specifier)
 
     module._defaultType = defaultType
-
-    let dirname = path.dirname(module._filename)
-    do {
-      const pkg = path.join(dirname, 'package.json')
-
-      if (protocol.exists(pkg)) {
-        try {
-          module._info = this.load(pkg, { protocol })._exports
-        } catch {}
-        break
-      }
-
-      dirname = path.dirname(dirname)
-    } while (dirname !== path.sep && dirname !== '.')
-
     module._main = main || module
+    module._info = this._loadPackageManifest(path.dirname(module._filename), protocol)
 
     let extension = this._extensionFor(type) || path.extname(specifier)
 
@@ -290,6 +276,22 @@ const Module = module.exports = exports = class Module {
     return this._transform(module, referrer, dynamic)
   }
 
+  static _loadPackageManifest (dirname, protocol) {
+    do {
+      const pkg = path.join(dirname, 'package.json')
+
+      if (protocol.exists(pkg)) {
+        try {
+          return this.load(pkg, { protocol })._exports
+        } catch {}
+      }
+
+      dirname = path.dirname(dirname)
+    } while (dirname !== path.sep && dirname !== '.')
+
+    return {}
+  }
+
   static resolve (specifier, dirname = os.cwd(), opts = {}) {
     if (typeof dirname !== 'string') {
       opts = dirname
@@ -334,7 +336,9 @@ const Module = module.exports = exports = class Module {
   }
 
   static * _resolve (specifier, dirname, protocol, imports) {
-    specifier = this._mapConditionalSpecifier(specifier, specifier, imports, protocol.imports)
+    const info = this._loadPackageManifest(dirname, protocol)
+
+    specifier = this._mapConditionalSpecifier(specifier, specifier, imports, protocol.imports, info.imports)
 
     protocol = this._protocolFor(specifier, protocol)
 
@@ -443,13 +447,13 @@ const Module = module.exports = exports = class Module {
     }
   }
 
-  static _mapConditionalSpecifier (specifier, fallback, ...exportMaps) {
-    const exports = this._flattenSpecifierMaps(exportMaps)
+  static _mapConditionalSpecifier (specifier, fallback, ...specifierMaps) {
+    const specifiers = this._flattenSpecifierMaps(specifierMaps)
 
-    if (specifier in exports) {
-      specifier = search(exports[specifier])
+    if (specifier in specifiers) {
+      specifier = search(specifiers[specifier])
     } else {
-      specifier = search(exports)
+      specifier = search(specifiers)
     }
 
     return specifier || fallback

diff --git a/test.js b/test.js
@@ -1114,7 +1114,7 @@ test('exports in package.json', (t) => {
 
     read (filename) {
       if (filename === '/package.json') {
-        return '{ "exports": "./foo.js" }'
+        return '{ "exports": "./foo" }'
       }
 
       t.fail()
@@ -1187,6 +1187,156 @@ test('exports in node_modules', (t) => {
   t.is(Module.resolve('foo', '/', { protocol }), '/node_modules/foo/foo.js')
 })
 
+test('imports in package.json', (t) => {
+  t.teardown(onteardown)
+
+  const protocol = new Module.Protocol({
+    preresolve (specifier, dirname) {
+      t.is(specifier, './baz')
+      t.is(dirname, '/')
+
+      return path.resolve(dirname, specifier)
+    },
+
+    exists (filename) {
+      return (
+        filename === '/package.json' ||
+        filename === '/baz.js'
+      )
+    },
+
+    read (filename) {
+      if (filename === '/package.json') {
+        return '{ "imports": { "bar": "./baz" } }'
+      }
+
+      if (filename === '/foo.js') {
+        return 'const bar = require(\'bar\')'
+      }
+
+      if (filename === '/baz.js') {
+        return 'module.exports = 42'
+      }
+
+      t.fail()
+    }
+  })
+
+  Module.load('/foo.js', { protocol })
+})
+
+test('conditional imports in package.json, .cjs before .mjs', (t) => {
+  t.teardown(onteardown)
+
+  const protocol = new Module.Protocol({
+    preresolve (specifier, dirname) {
+      t.is(specifier, './baz.cjs')
+      t.is(dirname, '/')
+
+      return path.resolve(dirname, specifier)
+    },
+
+    exists (filename) {
+      return (
+        filename === '/package.json' ||
+        filename === '/baz.cjs' ||
+        filename === '/baz.mjs'
+      )
+    },
+
+    read (filename) {
+      if (filename === '/package.json') {
+        return '{ "imports": { "bar": { "require": "./baz.cjs", "import": "./baz.mjs" } } }'
+      }
+
+      if (filename === '/foo.cjs') {
+        return 'const bar = require(\'bar\')'
+      }
+
+      if (filename === '/baz.cjs') {
+        return 'module.exports = 42'
+      }
+
+      t.fail()
+    }
+  })
+
+  Module.load('/foo.cjs', { protocol })
+})
+
+test('conditional imports in package.json, .mjs before .cjs', (t) => {
+  t.teardown(onteardown)
+
+  const protocol = new Module.Protocol({
+    preresolve (specifier, dirname) {
+      t.is(specifier, './baz.mjs')
+      t.is(dirname, '/')
+
+      return path.resolve(dirname, specifier)
+    },
+
+    exists (filename) {
+      return filename === '/package.json' || filename === '/baz.cjs' || filename === '/baz.mjs'
+    },
+
+    read (filename) {
+      if (filename === '/package.json') {
+        return '{ "imports": { "bar": { "import": "./baz.mjs", "require": "./baz.cjs" } } }'
+      }
+
+      if (filename === '/foo.cjs') {
+        return 'const bar = require(\'bar\')'
+      }
+
+      if (filename === '/baz.mjs') {
+        return 'export default 42'
+      }
+
+      t.fail()
+    }
+  })
+
+  Module.load('/foo.cjs', { protocol })
+})
+
+test('imports in node_modules', (t) => {
+  t.teardown(onteardown)
+
+  const protocol = new Module.Protocol({
+    preresolve (specifier, dirname) {
+      t.is(specifier, './baz')
+      t.is(dirname, '/node_modules/foo')
+
+      return path.resolve(dirname, specifier)
+    },
+
+    exists (filename) {
+      return (
+        filename === '/node_modules/foo/package.json' ||
+        filename === '/node_modules/foo/baz.js'
+      )
+    },
+
+    read (filename) {
+      if (filename === '/node_modules/foo/package.json') {
+        return '{ "imports": { "bar": "./baz" } }'
+      }
+
+      if (filename === '/node_modules/foo/foo.js') {
+        return 'const bar = require(\'bar\')'
+      }
+
+      if (filename === '/node_modules/foo/baz.js') {
+        return 'module.exports = 42'
+      }
+
+      t.fail()
+    }
+  })
+
+  Module.load('/node_modules/foo/foo.js', { protocol })
+})
+
 test('load file that cannot be read', async (t) => {
   t.teardown(onteardown)