Re: Re: [PATCHES] Select parser at runtime

Ian Lance Taylor wrote:
> Along these lines, I don't think Bruce's suggestion of modifications
> to the Postgres gram.y is a good idea, because it causes the Oracle
> parser to add an ongoing cost to the Postgres parser.

    Bruce,  Tom  and  I discussed these issues during our time in
    San Diego last month.

    If we want to have both parsers available at runtime we  need
    to  replace the YY (case-insensitive) prefix in the generated
    files per parser and call the right one from tcop.   Now  for
    some flex/bison combo's at least the prefix switches (to have
    something different than YY) don't work reliable. There  will
    be  some  global  YY-objects  left, causing linkage problems.
    That's why PL/pgSQL's scanner/parser's C-code is run  through
    sed(1).

    If  Bruce's  suggestion  of having both parsers in one source
    with #ifdef, #else, #endif is better  than  separate  sources
    depends  mainly  on  how big the differences finally will be.
    Doesn't really  bother  me.  Maybe  we  could  start  with  a
    combined  one  and  separate  later if it turns out that they
    drift apart too much?


Jan

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