Support abstract components (detected by special dirname prefix)

.stylcorc

@@ -14,6 +14,7 @@
     "ensure_trailing_newline": true,
     "file_write_options": "utf8",
     "virtual_component_prefix": null,
+    "abstract_dir_prefix": null,
     "files": {
         ".": {
             "filename": "{{NAME}}",

README.md

@@ -200,6 +200,20 @@ For virtual components, [you can disable](#no_virtual) creating some of componen
 If option value is `null`, no virtual component recognition is made, and every component's files are generated by the same rules.
 
 
+#### abstract_dir_prefix ####
+`string` or `null`, default `null`
+
+Consider component abstract if it is created inside directory with specified prefix in the name begin.
+
+Abstract component is _not imported in any buildfile_, and is only used for as extend base for other components.
+
+For example, if you set this option to `"_"`, component `foo` created with directory `_common` (i.e. `_oommon/foo`,
+as well as `bar/_common/foo`) is recognized as virtual.
+
+If option value is `null`, no abstract component recognition is made, and every component is appended to buildfile
+(if [correspondent option](#append_to_buildfile) is enabled).
+
+
 #### files ####
 `object` containing `object`s
 
@@ -294,6 +308,7 @@ Here are default configuration values for Stylco. You can override any of them w
     "ensure_trailing_newline": true,
     "file_write_options": "utf8",
     "virtual_component_prefix": null,
+    "abstract_dir_prefix": null,
     "files": {
         ".": {
             "filename": "{{NAME}}",

lib/stylco.js

@@ -142,7 +142,7 @@ module.exports = function (debug) {
 
         // Append component entry to build file
         // @todo recursively create buildfiles for each level?
-        if (_config.append_to_buildfile) {
+        if (_config.append_to_buildfile && !this._isAbstractComponent(destination)) {
             buildfile_path = path.join(destination_dir, '..') + this._config.file_ext;
             if (_config.allow_buildfile_outside_basedir || !_isPathOutsideDir(_config.basedir, buildfile_path)) {
                 // Check whether buildfile exists, and if it has any content
@@ -278,6 +278,27 @@ module.exports = function (debug) {
         }
     };
 
+    /**
+     * Determine whether component should be treated as abstract
+     * Looks for correspondent dirname prefix (if specified in config) on each path level, excluding last one
+     * @param {string} destination Component destination as specified by user (e.g. 'somedir/mycomponent')
+     * @returns {boolean}
+     * @private
+     */
+    Stylco.prototype._isAbstractComponent = function (destination) {
+        var _this = this,
+            parts;
+        if (this._config.abstract_dir_prefix) {
+            parts = _splitPath(destination);
+            parts.pop(); // remove component name
+            return parts.some(function (item) {
+                return _beginsWith(_this._config.abstract_dir_prefix, item);
+            });
+        } else {
+            return false;
+        }
+    };
+
     /**
      * Filter files list depending on file existence and availability for current component
      * @param {string|string[]} imports Input list of file IDs (or single item as string)
@@ -453,6 +474,7 @@ module.exports = function (debug) {
      * @property {boolean} ensure_trailing_newline
      * @property {FileWriteOptions} file_write_options
      * @property {string|null} virtual_component_prefix
+     * @property {string|null} abstract_dir_prefix
      * @property {object<string, StylcoConfigFileItem>} files
      */