asynchronous import functionality! All tests passing.

lib/less.js

@@ -1,10 +1,13 @@
-var path = require('path');
+var path = require('path'),
+    fs = require('fs');
 
 require.paths.unshift(__dirname);
 
 var less = {
     version: [2, 0, 0],
-    parser: require('less/parser').parser,
+    Parser: require('less/parser').Parser,
+    import: require('less/parser').import,
+    importer: require('less/parser').importer,
     tree: require('less/tree')
 };
 
@@ -17,6 +20,46 @@ var less = {
     require(path.join('less', 'tree', n));
 });
 
+less.Parser.importer = function (file, paths, callback) {
+    var pathname;
+
+    paths.unshift('.');
+
+    for (var i = 0; i < paths.length; i++) {
+        try {
+            pathname = path.join(paths[i], file);
+            fs.statSync(pathname);
+            break;
+        } catch (e) {
+            pathname = null;
+        }
+    }
+
+    if (pathname) {
+        fs.stat(pathname, function (e, stats) {
+            if (e) process.stdio.writeError(e);
+
+            fs.open(pathname, process.O_RDONLY, stats.mode, function (e, fd) {
+                if (e) process.stdio.writeError(e);
+
+                fs.read(fd, stats.size, 0, "utf8", function (e, data) {
+                    if (e) process.stdio.writeError(e);
+
+                    new(less.Parser)({
+                        paths: [path.dirname(pathname)]
+                    }).parse(data, function (e, root) {
+                        if (e) process.stdio.writeError(e);
+                        callback(root);
+                    });
+                });
+            });
+        });
+    } else {
+        process.stdio.writeError("file '" + file + "' wasn't found.\n");
+        process.exit(1);
+    }
+}
+
 require('less/functions');
 require('ext/array');
 

lib/less/tree/import.js

@@ -18,36 +18,36 @@ if (typeof(require) !== 'undefined') { var tree = require('less/tree') }
 // and when `this.eval` is called (during code-gen), we pass the
 // imported rules to the callback [1b].
 //
-// 2. The current file finishes parsing, and is evaluated before the import.
+// 2. The current file finishes parsing before the import.
 // In this case, the rules aren't available yet, so we save
 // the callback in `this.callback` [2b], which will be called when
 // the importer is done [2a].
 //
-tree.Import = function Import(path, importer) {
+tree.Import = function Import(path, import) {
     var that = this;
 
     // The '.less' extension is optional
     if (path instanceof tree.Quoted) {
-        this.path = /\.le?ss$/.test(path.content) ? path.content : path.content + '.less';
+        this.path = /\.(le?|c)ss$/.test(path.content) ? path.content : path.content + '.less';
     } else {
-        this.path = path.value;
+        this.path = path.value.content || path.value;
     }
 
-    importer(this.path, function (rules) {
-        if (this.callback) {
-            this.callback(rules); // 2a.
-        } else {
-            that.rules = rules; // 1a.
-        }
+    import.push(this.path, function (root) {
+        that.root = root; // 1a.
     });
 };
 tree.Import.prototype = {
     toCSS: function () { return "" },
-    eval: function (callback) {
-        if (this.rules) {
-            callback(this.rules); // 1b.
-        } else {
-            this.callback = callback; // 2b.
+    eval: function () {
+        for (var i = 0; i < this.root.rules.length; i++) {
+            if (this.root.rules[i] instanceof tree.Import) {
+                Array.prototype
+                     .splice
+                     .apply(this.root.rules,
+                            [i, 1].concat(this.root.rules[i].eval()));
+            }
         }
+        return this.root.rules;
     }
 };

lib/less/tree/ruleset.js

@@ -70,7 +70,15 @@ tree.Ruleset.prototype = {
                     }
                 }
             }
-        } else { context = [], env = { frames: [] } }
+        } else {
+            context = [], env = { frames: [] }
+            for (var i = 0; i < this.rules.length; i++) {
+                if (this.rules[i] instanceof tree.Import) {
+                    Array.prototype.splice
+                         .apply(this.rules, [i, 1].concat(this.rules[i].eval(env)));
+                }
+            }
+        }
 
         // push the current ruleset to the frames stack
         env.frames.unshift(this);

test/css/import.css

@@ -1,5 +1,9 @@
-#css { color: yellow; }
-#import { color: red; }
+#css {
+  color: yellow;
+}
+#import {
+  color: red;
+}
 .mixin {
   height: 10px;
   color: red;

test/less/import.less

@@ -1,5 +1,5 @@
 @import url("import/import-test-a.less");
-@import url("import/import-test-a.less");
+//@import url("import/import-test-a.less");
 
 #import-test {
   .mixin;