Adds support for "paths" being a function

Author: Maël Nison

lib/async.js

@@ -225,6 +225,7 @@ module.exports = function resolve(x, options, callback) {
         }
     }
     function loadNodeModules(x, start, cb) {
+        opts.request = x;
         processDirs(cb, nodeModulesPaths(start, opts));
     }
 };

lib/node-modules-paths.js

@@ -40,5 +40,13 @@ module.exports = function nodeModulesPaths(start, opts) {
         }));
     }, []);
 
-    return opts && opts.paths ? dirs.concat(opts.paths) : dirs;
+    if (opts && opts.paths) {
+        if (typeof opts.paths === 'function') {
+            dirs = dirs.concat(opts.paths(absoluteStart, opts));
+        } else {
+            dirs = dirs.concat(opts.paths);
+        }
+    }
+
+    return dirs;
 };

lib/sync.js

@@ -137,6 +137,7 @@ module.exports = function (x, options) {
     }
 
     function loadNodeModulesSync(x, start) {
+        opts.request = x;
         var dirs = nodeModulesPaths(start, opts);
         for (var i = 0; i < dirs.length; i++) {
             var dir = dirs[i];

readme.markdown

@@ -74,6 +74,11 @@ options are:
 
 * opts.paths - require.paths array to use if nothing is found on the normal `node_modules` recursive walk (probably don't use this)
 
+  For advanced users, `paths` can also be a `opts.paths(start, opts)` function
+    * start - lookup path
+    * opts - the resolution options
+    * opts.request - the import specifier being resolved
+
 * opts.moduleDirectory - directory (or directories) in which to recursively look for modules. default: `"node_modules"`
 
 * opts.preserveSymlinks - if true, doesn't resolve `basedir` to real path before resolving.

test/node-modules-paths.js

@@ -7,6 +7,11 @@ var nodeModulesPaths = require('../lib/node-modules-paths');
 
 var verifyDirs = function verifyDirs(t, start, dirs, moduleDirectories, paths) {
     var moduleDirs = [].concat(moduleDirectories || 'node_modules');
+    if (paths) {
+        for (var k = 0; k < paths.length; ++k) {
+            moduleDirs.push(path.basename(paths[k]));
+        }
+    }
 
     var foundModuleDirs = {};
     var uniqueDirs = {};
@@ -20,7 +25,7 @@ var verifyDirs = function verifyDirs(t, start, dirs, moduleDirectories, paths) {
     }
     t.equal(keys(parsedDirs).length >= start.split(path.sep).length, true, 'there are >= dirs than "start" has');
     var foundModuleDirNames = keys(foundModuleDirs);
-    t.deepEqual(foundModuleDirNames, moduleDirs.concat(paths || []), 'all desired module dirs were found');
+    t.deepEqual(foundModuleDirNames, moduleDirs, 'all desired module dirs were found');
     t.equal(keys(uniqueDirs).length, dirs.length, 'all dirs provided were unique');
 
     var counts = {};
@@ -49,7 +54,7 @@ test('node-modules-paths', function (t) {
         t.end();
     });
 
-    t.test('with paths option', function (t) {
+    t.test('with paths=array option', function (t) {
         var start = path.join(__dirname, 'resolver');
         var paths = ['a', 'b'];
         var dirs = nodeModulesPaths(start, { paths: paths });
@@ -59,6 +64,16 @@ test('node-modules-paths', function (t) {
         t.end();
     });
 
+    t.test('with paths=function option', function (t) {
+        var paths = function paths(absoluteStart, opts) {
+            return [path.join(absoluteStart, 'not node modules', opts.request)];
+        };
+         var start = path.join(__dirname, 'resolver');
+        var dirs = nodeModulesPaths(start, { paths: paths, request: 'pkg' });
+         verifyDirs(t, start, dirs, null, [path.join(start, 'not node modules', 'pkg')]);
+         t.end();
+    });
+
     t.test('with moduleDirectory option', function (t) {
         var start = path.join(__dirname, 'resolver');
         var moduleDirectory = 'not node modules';