String Modifiers is a gedit plugin, which modifies user selected text in the editor into a formated string. In this 1.0 version, there are 6 (six) modifiers available:
Each modifier has accelerators / shortcut keys that can be configured while enabling the plugin or at run time. No shortcut keys are bound by default, so as to not conflict with other plugins that are already in use.
The plugin itself is easily customizable, if so desired, since it is coded in pygtk and pretty heavily commented. You can download it from github.