Add support for importing index.js from aliased directories path

.gitignore

@@ -1,4 +1,2 @@
 node_modules
 npm-debug.log
-
-dist

dist/rollup-plugin-alias.es2015.js

@@ -0,0 +1,104 @@
+import path, { posix } from 'path';
+import { platform } from 'os';
+import fs from 'fs';
+import slash from 'slash';
+
+const VOLUME = /^([A-Z]:)/;
+const IS_WINDOWS = platform() === 'win32';
+
+// Helper functions
+const noop = () => null;
+const matches = (key, importee) => {
+  if (importee.length < key.length) {
+    return false;
+  }
+  if (importee === key) {
+    return true;
+  }
+  const importeeStartsWithKey = (importee.indexOf(key) === 0);
+  const importeeHasSlashAfterKey = (importee.substring(key.length)[0] === '/');
+  return importeeStartsWithKey && importeeHasSlashAfterKey;
+};
+const endsWith = (needle, haystack) => haystack.slice(-needle.length) === needle;
+const isFilePath = id => /^\.?\//.test(id);
+const exists = uri => {
+  try {
+    return fs.statSync(uri).isFile();
+  } catch (e) {
+    return false;
+  }
+};
+
+const normalizeId = id => {
+  if ((IS_WINDOWS && typeof id === 'string') || VOLUME.test(id)) {
+    return slash(id.replace(VOLUME, ''));
+  }
+
+  return id;
+};
+
+function alias(options = {}) {
+  const hasResolve = Array.isArray(options.resolve);
+  const resolve = hasResolve ? options.resolve : ['.js'];
+  const aliasKeys = hasResolve ?
+                      Object.keys(options).filter(k => k !== 'resolve') : Object.keys(options);
+
+  // No aliases?
+  if (!aliasKeys.length) {
+    return {
+      resolveId: noop,
+    };
+  }
+
+  return {
+    resolveId(importee, importer) {
+      const importeeId = normalizeId(importee);
+      const importerId = normalizeId(importer);
+
+      // First match is supposed to be the correct one
+      const toReplace = aliasKeys.find(key => matches(key, importeeId));
+
+      if (!toReplace || !importerId) {
+        return null;
+      }
+
+      const entry = options[toReplace];
+
+      let updatedId = normalizeId(importeeId.replace(toReplace, entry));
+
+      if (isFilePath(updatedId)) {
+        const directory = posix.dirname(importerId);
+
+        // Resolve file names
+        const filePath = posix.resolve(directory, updatedId);
+
+        const match = resolve.map(ext => (endsWith(ext, filePath) ? filePath : `${filePath}${ext}`))
+                            .find(exists);
+
+        if (match) {
+          updatedId = match;
+        // To keep the previous behaviour we simply return the file path
+        // with extension
+        } else if (endsWith('.js', filePath)) {
+          updatedId = filePath;
+        // See if filePath + /index.js exists, then use it
+        } else if (fs.existsSync(posix.join(filePath, 'index.js'))) {
+          updatedId = posix.join(filePath, 'index.js');
+        } else {
+          updatedId = filePath + '.js';
+        }
+      }
+
+      // if alias is windows absoulate path return resolved path or
+      // rollup on windows will throw:
+      //  [TypeError: Cannot read property 'specifier' of undefined]
+      if (VOLUME.test(entry)) {
+        return path.resolve(updatedId);
+      }
+
+      return updatedId;
+    },
+  };
+}
+
+export default alias;

dist/rollup-plugin-alias.js

@@ -0,0 +1,109 @@
+'use strict';
+
+function _interopDefault (ex) { return (ex && (typeof ex === 'object') && 'default' in ex) ? ex['default'] : ex; }
+
+var path = require('path');
+var path__default = _interopDefault(path);
+var os = require('os');
+var fs = _interopDefault(require('fs'));
+var slash = _interopDefault(require('slash'));
+
+const VOLUME = /^([A-Z]:)/;
+const IS_WINDOWS = os.platform() === 'win32';
+
+// Helper functions
+const noop = () => null;
+const matches = (key, importee) => {
+  if (importee.length < key.length) {
+    return false;
+  }
+  if (importee === key) {
+    return true;
+  }
+  const importeeStartsWithKey = (importee.indexOf(key) === 0);
+  const importeeHasSlashAfterKey = (importee.substring(key.length)[0] === '/');
+  return importeeStartsWithKey && importeeHasSlashAfterKey;
+};
+const endsWith = (needle, haystack) => haystack.slice(-needle.length) === needle;
+const isFilePath = id => /^\.?\//.test(id);
+const exists = uri => {
+  try {
+    return fs.statSync(uri).isFile();
+  } catch (e) {
+    return false;
+  }
+};
+
+const normalizeId = id => {
+  if ((IS_WINDOWS && typeof id === 'string') || VOLUME.test(id)) {
+    return slash(id.replace(VOLUME, ''));
+  }
+
+  return id;
+};
+
+function alias(options = {}) {
+  const hasResolve = Array.isArray(options.resolve);
+  const resolve = hasResolve ? options.resolve : ['.js'];
+  const aliasKeys = hasResolve ?
+                      Object.keys(options).filter(k => k !== 'resolve') : Object.keys(options);
+
+  // No aliases?
+  if (!aliasKeys.length) {
+    return {
+      resolveId: noop,
+    };
+  }
+
+  return {
+    resolveId(importee, importer) {
+      const importeeId = normalizeId(importee);
+      const importerId = normalizeId(importer);
+
+      // First match is supposed to be the correct one
+      const toReplace = aliasKeys.find(key => matches(key, importeeId));
+
+      if (!toReplace || !importerId) {
+        return null;
+      }
+
+      const entry = options[toReplace];
+
+      let updatedId = normalizeId(importeeId.replace(toReplace, entry));
+
+      if (isFilePath(updatedId)) {
+        const directory = path.posix.dirname(importerId);
+
+        // Resolve file names
+        const filePath = path.posix.resolve(directory, updatedId);
+
+        const match = resolve.map(ext => (endsWith(ext, filePath) ? filePath : `${filePath}${ext}`))
+                            .find(exists);
+
+        if (match) {
+          updatedId = match;
+        // To keep the previous behaviour we simply return the file path
+        // with extension
+        } else if (endsWith('.js', filePath)) {
+          updatedId = filePath;
+        // See if filePath + /index.js exists, then use it
+        } else if (fs.existsSync(path.posix.join(filePath, 'index.js'))) {
+          updatedId = path.posix.join(filePath, 'index.js');
+        } else {
+          updatedId = filePath + '.js';
+        }
+      }
+
+      // if alias is windows absoulate path return resolved path or
+      // rollup on windows will throw:
+      //  [TypeError: Cannot read property 'specifier' of undefined]
+      if (VOLUME.test(entry)) {
+        return path__default.resolve(updatedId);
+      }
+
+      return updatedId;
+    },
+  };
+}
+
+module.exports = alias;

src/index.js

@@ -72,6 +72,7 @@ export default function alias(options = {}) {
 
         // Resolve file names
         const filePath = posix.resolve(directory, updatedId);
+
         const match = resolve.map(ext => (endsWith(ext, filePath) ? filePath : `${filePath}${ext}`))
                             .find(exists);
 
@@ -81,6 +82,9 @@ export default function alias(options = {}) {
         // with extension
         } else if (endsWith('.js', filePath)) {
           updatedId = filePath;
+        // See if filePath + /index.js exists, then use it
+        } else if (fs.existsSync(posix.join(filePath, 'index.js'))) {
+          updatedId = posix.join(filePath, 'index.js');
         } else {
           updatedId = filePath + '.js';
         }

test/files/folder/index.js

@@ -0,0 +1 @@
+export default 123;

test/files/index.js

@@ -3,5 +3,6 @@ import fancyNumber from 'fancyNumber';
 import anotherFancyNumber from './anotherFancyNumber';
 import anotherNumber from './numberFolder/anotherNumber';
 import moreNumbers from 'numberFolder/anotherNumber';
+import index from './numberFolder';
 
-export default fancyNumber + anotherFancyNumber + nonAliased + anotherNumber + moreNumbers;
+export default fancyNumber + anotherFancyNumber + nonAliased + anotherNumber + moreNumbers + index;

test/index.js

@@ -164,6 +164,16 @@ test('Platform path.resolve(\'file-with.ext\') aliasing', t => {
   t.is(resolved, path.resolve('./files/folder/hipster.jsx'));
 });
 
+test('index.js resolve', t => {
+  const result = alias({
+    test: path.resolve('./files/folder'),
+  });
+
+  const resolved = result.resolveId('test', posix.resolve(DIRNAME, './files/index.js'));
+
+  t.is(resolved, path.resolve('./files/folder/index.js'));
+});
+
 // Tests in Rollup
 test(t =>
   rollup({
@@ -179,7 +189,8 @@ test(t =>
     t.is(stats.modules[1].id.endsWith(path.normalize('/files/aliasMe.js')), true);
     t.is(stats.modules[2].id.endsWith(path.normalize('/files/localAliasMe.js')), true);
     t.is(stats.modules[3].id.endsWith(path.normalize('/files/folder/anotherNumber.js')), true);
-    t.is(stats.modules[4].id.endsWith(path.normalize('/files/index.js')), true);
-    t.is(stats.modules.length, 5);
+    t.is(stats.modules[4].id.endsWith(path.normalize('/files/folder/index.js')), true);
+    t.is(stats.modules[5].id.endsWith(path.normalize('/files/index.js')), true);
+    t.is(stats.modules.length, 6);
   })
 );