bug#41006: 26.3; regular expressions documentation

[Mattias Engdegård]

4 maj 2020 kl. 05.10 skrev Richard Stallman <rms@gnu.org>:

> Would you like to propose an ordering and classification by function?

Start with the lexical details: special chars, escaping, literals.
Then something like this:

* concatenation and alternative
* repetition: * + ? etc
* bracketing: \(?: ... \)
* single-character expressions: [...] '.' \cX etc
* zero-width assertions: ^ $ \< etc
* capture groups and backrefs

Aim for all in a single node, using subheadings as appropriate, as this is what 
the user probably wants to see. Use subnodes for some in-depth information such 
as named character classes.

As Stefan pointed out, a section comparing the syntax with that of other regexp 
implementations likely seen by the user would be very welcome. It would permit 
the reader to make use of existing knowledge while reducing mistakes coming 
from incorrect assumptions.