Although regular expression searches were possible with plugins, it is now available by default in gedit. The search and replace works too, and you can use backreferences (
\1, …) in the replacement text.
All this work has been merged upstream, just in time before the freeze.
Reworked search and replace API in GtkSourceView
Behind the scene, the regex search is implemented in GtkSourceView. For most cases, it scales well for big text buffers, since multi-segment matching is done: when a partial match is returned, we take a bigger segment. Read the lengthy implementation overview at the top of
gtksourcesearchcontext.c for more details.
Besides the regex search, the API is now more flexible. Roughly speaking, it was initially a one-to-one relationship: only one search was possible at a time in a text buffer. It is now a many-to-many relationship: several searches can execute at the same time in the same text buffer (it can be useful for non-highlighted, background searches). And the search settings can be shared between several buffers.
Next step for my GSoC: rework the GtkSourceView style schemes to use CSS.