Add path::branch_path to the PBD::sys::path class

This is basically equivalent to Glib::path_get_dirname but returning an
empty string(path) if a path doesn't contain any directory components rather
than "."


git-svn-id: svn://localhost/ardour2/trunk@2403 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd/filesystem.cc

@@ -58,6 +58,24 @@ path::operator/=(const char* rhs)
 	return *this;
 }
 
+path
+path::branch_path () const
+{
+	string dir = Glib::path_get_dirname (m_path);
+
+	/*
+	 * glib returns "." to signify that the path
+	 * has no directory components(branch path)
+	 * whereas boost::filesystem returns an empty
+	 * string
+	 */
+	if(dir == ".")
+	{
+		return "";
+	}
+	return dir;
+}
+
 bool
 exists (const path & p)
 {

libs/pbd/pbd/filesystem.h

@@ -86,6 +86,13 @@ public:
 
 	const string to_string() const { return m_path; }
 
+	/**
+	 * @returns the directory component of a path without any trailing
+	 * path separator or an empty string if the path has no directory
+	 * component(branch path).
+	 */
+	path branch_path () const;
+
 private:
 
 	string m_path;