[fpc-pascal] fpc-passrc expression parser (issue #16914)

Paul Nicholls paulfnicholls at gmail.com
Wed Jul 14 03:22:01 CEST 2010

----- Original Message ----- 
From: "Michael Van Canneyt" <michael at freepascal.org>
To: "FPC-Pascal users discussions" <fpc-pascal at lists.freepascal.org>
Sent: Tuesday, July 13, 2010 6:42 PM
Subject: Re: [fpc-pascal] fpc-passrc expression parser (issue #16914)

> On Tue, 13 Jul 2010, dmitry boyarintsev wrote:
>> Hello, Michael Van Canneyt,
>> Sorry, I can't write to the resolved issue (without re-opening) it.
>>> - better class tree (split out binary/unary/primitive operators in 
>>> subclasses)
>>> These may break backwards compatiblity; if you prefer to do them 
>>> yourself, I can say what I have in mind.
>> That's how it was originally written. However, I personally prefer to
>> keep less subclasses.
> I prefer more, with less fields, it saves memory on big expressions :-)
>> I would like to hear your ideas.
> Well, at least I would have expected 4 subclasses:
> TPasExpr
>  +-- TUnaryExpr (field operand)
>  +-- TBinaryExpr (fields left, right)
>  +-- TPrimitiveExpr (field 'value')
>  +-- TFunctionCallExpr (fields value/params)
> I must say that I am not familiar with the parsing style you used. I wrote 
> 2 expression parsers meanwhile, and both used a different style. (see 
> fcl-base/fpexprpars.pp; the other one is in fcl-js. A third will follow in 
> the sql parser I'm about to commit)
>> thanks,
>> dmitry
>> P.S.. the expression parser still doesn't resolve ranges (i.e. in
>> sets), neither simple nor complex, like:
>> Char(6) in [Char(sizeof(Integer))..Char(SizeOf(int64))]
> That should be relatively easy to add, no ?
> Michael.

Hi all,
  I am interested in expression parsers myself :)

Where can I find the code for "fpexprpars.pp" and other fpc parsing code 
like that?

I had bit of a look browsing the SVN online, but no luck...


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