Icicles lets you do the following:
* cycle through completion candidates that match your current
input.
* use a pattern to match completion candidates, including:
- regexp matching (including substring).
- fuzzy matching.
- prefix matching (as in vanilla Emacs).
- command abbreviation matching.
* use multiple regexps to match candidates, chaining these filters
together like piped 'grep' commands.
* see all possible complete inputs (pertinent commands, variables,
and so on) that match your partial or regexp input: the list is
updated dynamically (incrementally) if you change your input.
* see all previous inputs that match your partial or regexp input,
and selectively reuse them.
* match input against completion candidates that do not match a
given regexp; that is, complement the set of matches and use the
result for subsequent matching.
* use multiple regexps to search (and replace) text across
multiple buffers, files, or regions.
* search areas of text that have a certain text property, such as
a face.
* browse Imenu or tags entries that match your partial or regexp
input.
* create and use multiple-choice menus; that is, menus where you
can choose multiple entries any number of times.
* create and use multi-commands so you can perform an action on
any number of candidate inputs any number of times.
* perform set operations (intersection, union, etc) on the fly,
using sets of completion candidates or other strings.
* persistently save and later reuse sets of completion candidates
(e.g. project file names).
* complete input piecewise, against multiple completion
candidates, in parallel.
* complete key sequences, and navigate the key-binding hierarchy
(this includes the menu bar menu hierarchy) (see also LaCarte)
* sort completion candidates on the fly, in multiple,
context-dependent ways.
