RE: Structural regular expressions

[Drew Adams]

> There is a related need for searching that could be built on such
> capability: AND.
> 
> Quite often I find myself searching for a node/a tree in a big .org
> file containing both word a and word b.

And in an unspecified order, no doubt.  In vanilla Emacs the closest we have for
this is `apropos' with keyword input.  The behavior is special-built for this
particular command; it is not a general feature.

In Icicles you can hit `S-SPC' to get such `AND' filtering during completion (of
any input).  You can add patterns on the fly, preceding each by `S-SPC', thus
narrowing down the choices progressively, as you see fit.  I call this
"progressive" completion.
http://www.emacswiki.org/emacs/Icicles_-_Nutshell_View#toc10

And you can hit `C-~' to get the complement (`AND NOT') after seeing what
`S-SPC' (`AND') shows.

Example: `M-x for' shows command names that have substring `for' (similarly `C-h
f for', `C-h v for',...).  `M-x for S-SPC ediff' shows the subset of those `for'
commands that also have substring `ediff'.  `M-x for S-SPC ediff C-~' shows the
names that have substring `for' but do not have substring `ediff'.
http://www.emacswiki.org/emacs/Icicles_-_Nutshell_View#toc11