add another build/watch option --symlink

lib/command/build.js

@@ -562,6 +562,9 @@ build._is_type = function(build_type, type){
 build.copy_csses = function (options, callback) {
   var css = options.pkg.css;
   var build_type = options.build_type;
+  var symlink = options.symlink;
+  var common_root;
+
   if (!css) {
     return callback(null);
   }
@@ -575,6 +578,12 @@ build.copy_csses = function (options, callback) {
 
   if(build_type == 'css'){
     css = [node_path.relative(options.cwd, options.file)];
+  } else if (symlink && (common_root = self.parse_common_root(css))) {
+    var linkFrom = node_path.join(options.to, common_root);
+    var linkTo = node_path.join(options.cwd, common_root);
+
+    self.symlink(linkFrom, linkTo, callback);
+    return;
   }
 
   async.eachSeries(css, function (path, done) {
@@ -625,6 +634,32 @@ build.copy_csses = function (options, callback) {
   }, callback);
 };
 
+// Accept a file list and return their longest common prefix
+// NOTICE:
+//   every file path should be relative to cwd and not beyond cwd
+//   if no common path except cwd, return undefined
+build.parse_common_root = function(files) {
+  var all_paths = files.filter(function(file) {
+    return file.indexOf('.' + node_path.sep) == 0;
+  });
+
+  if (!all_paths.length) {return;}
+
+  all_paths = all_paths.map(function(file) {
+    return file.split(node_path.sep);
+  });
+
+  var i, len, is_common;
+  for (i = 0, len = all_paths[0].length; i < len; i++) {
+    is_common = all_paths.every(function(paths) {
+      return paths.length > i && paths[i] == all_paths[0][i];
+    });
+    if (!is_common) break;
+  }
+
+  return i ? all_paths[0].slice(0, i).join(node_path.sep) : '';
+};
+
 build.parse_css_images = function(csspath, done){
   var self = this;
 
@@ -674,6 +709,7 @@ build.copy_directories = function(options, callback) {
   var to = options.to;
   var file = options.file;
   var build_type = options.build_type;
+  var symlink = options.symlink;
 
   if(!this._is_type(build_type, 'dir')){
     return callback(null);
@@ -701,6 +737,15 @@ build.copy_directories = function(options, callback) {
 
   async.eachSeries(tasks, function (name, done) {
     var dir = directories[name];
+
+    if (symlink) {
+      var linkTo = node_path.join(cwd, dir);
+      var linkFrom = node_path.join(to, dir);
+
+      self.symlink(linkFrom, linkTo, done);
+      return;
+    }
+
     self.copy(cwd, to, dir, function (err) {
       if (err && err.code === 'SRC_NOT_FOUND') {
         err = {
@@ -718,16 +763,25 @@ build.copy_directories = function(options, callback) {
   }, callback);
 };
 
+// Creates a symlink from `from` to `to`.
+build.symlink = function(from, to, callback) {
+  var self = this;
+
+  fs.lstat(to, function(err, stats) {
+    if (err) {
+      return callback(err);
+    }
+
+    self.logger.info(' {{cyan link}} ' + from + ' -> ' + to);
+    ln.link(from, to, callback);
+  });
+}
 
 // Copy item from `from` to `to`
 // @param {String=} item If is undefined, will copy `from` to `to`
 // @param {Boolean} strict
 build.copy = function(from, to, item, callback, strict) {
   var self = this;
-  if (from === to) {
-    callback(null);
-    return;
-  }
 
   if (item) {
     if (item != item.toLowerCase()) {
@@ -739,6 +793,16 @@ build.copy = function(from, to, item, callback, strict) {
     to = node_path.join(to, item);
   }
 
+  // after fs-extra #198 is solved, can delete this check
+  try{
+    var fromStats = fs.statSync(from);
+    var toStats = fs.statSync(to);
+    if (fromStats && toStats && fromStats.ino === toStats.ino) {
+      callback(null);
+      return;
+    }
+  } catch(e) {}
+
   fs.exists(from, function (exists) {
     if (!exists) {
       // if strict and the source is not found, an error will throw.

lib/command/watch.js

@@ -225,6 +225,11 @@ watch._rebuild = function(options, cwd, init) {
       argv.push("--prerelease", prerelease);
     }
 
+    var symlink = options.symlink;
+    if (symlink) {
+      argv.push("--symlink", "true");
+    }
+
     var commander = self.commander;
     var parsed = commander.parse(argv, function(err, result, details) {
       if (err) {

lib/option/build.js

@@ -79,6 +79,13 @@ exports.options = {
     default: false
   },
 
+  symlink: {
+    enumerable: false,
+    type: Boolean,
+    info: 'create symbolic links, instead of copying css files and directories',
+    default: false
+  },
+
   prerelease: {
     enumerable: false,
     info: 'build as a pre-release package.'

lib/option/watch.js

@@ -54,6 +54,13 @@ exports.options = {
     info: 'whether cortex should build the project when begins to watch.',
     default: true
   },
+
+  symlink: {
+    enumerable: false,
+    type: Boolean,
+    info: 'create symbolic links, instead of copying css files and directories',
+    default: false
+  },
 
   prerelease: {
     enumerable: false,