Re: binary operators on integers - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: binary operators on integers
Date
Msg-id 200101192130.QAA12409@candle.pha.pa.us
Whole thread Raw
In response to Re: binary operators on integers  (Peter Eisentraut <peter_e@gmx.net>)
Responses Re: binary operators on integers  (Marko Kreen <marko@l-t.ee>)
List pgsql-patches
Looks like this is fixed:

    test=> select 5 & ~ 6;
    ERROR:  Unable to identify a right operator '&' for type 'int4'
            You may need to add parentheses or an explicit cast
    test=> select 5 & (~ 6);
     ?column?
    ----------
            1
    (1 row)

> This patch was installed, with xor as "#".  The parser still needs work.
> Besides the known issue of "|", this also parses funny:
>
> => select 5 & ~ 6;
> ERROR:  Unable to identify a right operator '&' for type 'int4'
>
>
> Marko Kreen writes:
>
> > Here is my next take on binary operators for integers.
> > It implements the following operators for int2/int4/int8:
> >
> >  ~ - not
> >  & - and
> >  ^ - xor
> >  | - or
> >  << - shift left
> >  >> - shift right
> >
> > Notes:
> >
> > * My original choice for xor was '#' because the '^' operator conflicts
> >   with power operator on floats but Tom Lane said:
> >
> > > Well, you *could* use '^' since there's no definition of it for integer
> > > operands.  But that would mean that something like '4^2', which was
> > > formerly implicitly coerced to float and interpreted as floating
> > > power function, would suddenly mean something different.  Again a
> > > serious risk of silently breaking applications.  This doesn't apply to
> > > '|' though, since it has no numeric interpretation at all right now.
> >
> >   As the bit-string uses '^' too for xor-ing it would be nice to be
> >   consistent.  I am quite unsure on this matter.  The patch now seems
> >   otherwise sane to me, this is the only issue left.
> >
> > * On << and >> the second argument is always int32 as this seems
> >   to be the 'default' int type in PostgreSQL.
> >
> > * Oids used are 1874 - 1909.
> >
> > Comments?
> >
> > Patch is against current CVS.
> >
> >
>
> --
> Peter Eisentraut      peter_e@gmx.net       http://yi.org/peter-e/
>
>


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