Re: [PATCH] git-grep: --and to combine patterns with and instead of or

[Matthias Lederhofer <matled@gmx.net>]

(Junio: please reply to this one, forgot the Cc in the first one :/)

Junio C Hamano wrote:
> Matthias Lederhofer <matled@gmx.net> writes:
> 
> > OR and AND have precedence, so there are two possibilities, I'd take
> > the first one.
> > 1. OR, AND:
> >     This will make it easier to read because OR can be skipped:
> >       pat1 pat2 AND pat3 pat4
> >     = pat1 OR pat2 AND pat3 OR pat4
> >     = (pat1 OR pat2) AND (pat3 OR pat4)
> > 2. AND, OR:
> >     This is a bit more logic if you think of AND as * and OR as +.
> 
> > ... FOO should not be named --and imo but I don't have any idea
> > for a good name atm.
> 
> I personally feel FOO should not even exist.  An option that
> covers the entire expression to make operator precedence in it
> sounds quite evil.  
> 
> I would say make --and bind tighter than --or and use parentheses as
> needed.
Ok, perhaps changing operator precedence is a bit much. What do you
think of that then:
Operator precedence AND, OR. The FOO options changes the default
operator to AND. This also seems quite natural if you think of
AND as * and OR as +:
A B + C D = A * B + C * D = (A * B) + (C * D)

A few examples to get an impression how the command line could look
like:
A OR B OR (C AND D)    => A B C AND D
(A OR B OR C) AND D    => (A B C) AND D
A AND B AND (C OR D)   => -FOO A B (C OR D)
(A AND B AND C) OR D   => -FOO A B C OR D

Perhaps we even could use options which are similar to * and +, for
example:
 - -* and -+ (-* should not be expanded often but is annoying anyway)
 - -. and -+
 - -t and -p (A -t B is A times B, A -p B is A plus B)

> Making --or optional sounds fine as that
> would make the default "multiple -e" case similar to what GNU
> grep does without any --and nor --or.
That's exactly what I was thinking about: make extended expressions
compatible to current grep options. This will confuse less people and
there is no need for an extra option to activate this.