Re: massive quotes? - Mailing list pgsql-hackers

Andreas Pflug wrote:
> Bruce Momjian wrote:
> 
> >Tom Lane wrote:
> >  
> >
> >>The discussion so far today seems to be entirely a rehash of arguments
> >>already made (and in many cases already rebutted).  Rather than wasting
> >>list bandwidth with this, I think each camp ought to go off and do their
> >>homework.  Give us *details* of how your solution would work.
> >>    
> >>
> >
> >Another idea would be to enable another set of quoting characters, like:
> >
> >    CREATE FUNCTION xx ...
> >    <--
> >        x = 'fred';
> >        ...
> >    -->
> >
> >and have the lexer understand those new quoting characters.  We just use
> >'' too much in function bodies to use that also for quoting the function
> >text.  Of course, '<--' would have no special meaning inside a quoted
> >string, so we are only eliminating their use as custom operators, and I
> >think that is reasonable.
> >
> >Having heard all the other proposals, I think this will be the clearest.
> >
> >  
> >
> This looks quite similar to my proposal. I called it "function body is 
> enclosed in keywords", while Bruce will enclose it in new quote strings. 
> This is obviously very different for the lexer/parser, while identical 
> for the user. Sounds good to me.
> The quoting strings seem a bit suspicious to me, I can imagine comments 
> like this "converting abc --> def", which would certainly break the 
> function definition (I scanned a part of my sources, I found two 
> occurrences of "-->", one of them in SQL code...)
> 
> How about quoting strings that look like keywords, e.g. FUNCTIONBODY and 
> ENDFUNCTIONBODY?
> 
> CREATE FUNCTION foo() RETURNS int4 AS
> FUNCTIONBODY
> DECLARE bar int4;
> BEGIN
>    RETURN bar;
> END;
> ENDFUNCTIONBODY
> LANGUAGE 'plpgsql';

Uh, the problem with long keywords is that you are then requiring the
_parser_ to identify those keywords, and at that point, the entire text
between the keywords has been sliced up by the lexer, which will
certainly make it a mess.  I might be wrong that we can even use more
then two characters for the start of quote string because I don't think
flex supports more than one character of look-ahead.   Again, lookahead
is the key because you have to flag that text as a quoted string before
it gets processed by the lexer.

I was picking <-- --> out of the air.  We would have to choose other
character sequences, and probably only two-character ones.  However,
looking at scan.l, it seems you could try putting a literal keyword in
there.  Of course, it would also match 'identifier' code, but if it is
earlier, I think it gets matched first.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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