[antlr-interest] Seeking advice - 2 questions using ANTLR (can translate using rewrite?)

[Mark Volkmann]

On Jan 17, 2008 4:27 PM, Frank Font <mrfont at room4me.com> wrote:
> Hi Mark,
>
> Thanks for the sample grammar.
>
> To keep things simple, do you think the entire translation can be done
> via "rewrite=true" setting and then adding things like "->
> template(....)" actions to the relevant rules?

I don't think that's a good approach because I think there is too much
difference between the input and output. I think the rewrite thing is
best used when you're outputting most of the input as-is. Maybe others
will have a different opinion.

I have to admit I haven't used StringTemplate yet. I need to learn that still.

> For example, I'm inclined to add this to the grammar you provided...
>
> ifStatement
>         : 'IF' e1=condition 'THEN' e2=statement ('ELSE' e3=statement)? 'END IF'
>         -> template(e1={$e1.text},e2={$e2.text}) " IF(<e1>,<e2>,<e3>) "
>         ;

Hmm ... that looks much nicer than my string concatenation!

> I started going down the rewrite road with mixed success and I'm not
> sure it is the right road.
>
> Regards,
> Frank Font
>
> PS - Not familiar with the "com.ociweb.accounting" package.  Do I really
> need that installed?

That's just the Java package name I selected. The generated classes
come out with

package com.ociweb.accounting.

You should change that to be a reasonable Java package name for your company.

> Mark Volkmann wrote:
> > Here's a start on your grammar.
> >
> > grammar Accounting;
> >
> > options {
> >   output = template;
> > }
> >
> > @lexer::header { package com.ociweb.accounting; }
> > @parser::header { package com.ociweb.accounting; }
> >
> > start: ifStatement EOF;
> >
> > ifStatement
> >   : 'IF' condition 'THEN' statement ('ELSE' statement)? 'END IF';
> >
> > comparison: expression RELATIONAL_OPERATOR expression;
> >
> > condition: comparison (LOGICAL_OPERATOR comparison)*;
> >
> > expression
> >   : STRING_LITERAL
> >   | value (SIGN value)*;
> >
> > statement: expression | ifStatement;
> >
> > value: NAME | NUMBER;
> >
> > LOGICAL_OPERATOR: 'AND' | 'OR';
> >
> > RELATIONAL_OPERATOR: '<' | '<=' | '=' | '>=' | '>';
> >
> > APOSTROPHE: '\'';
> >
> > NUMBER: INTEGER | FLOAT;
> > fragment FLOAT: INTEGER '.' NATURAL_NUMBER;
> > fragment INTEGER: SIGN? NATURAL_NUMBER;
> > fragment NATURAL_NUMBER: '0' | '1'..'9' '0'..'9'*;
> > SIGN: '+' | '-';
> >
> > NAME: LETTER (LETTER | NUMBER | '_')*;
> >
> > STRING_LITERAL: APOSTROPHE NONCONTROL_CHAR* APOSTROPHE;
> >
> > WHITESPACE: (NEWLINE | SPACE)+ { $channel = HIDDEN; };
> >
> > // Note that NONCONTROL_CHAR does not include the double-quote character.
> > fragment NONCONTROL_CHAR: LETTER | DIGIT | SYMBOL | SPACE;
> > fragment LETTER: LOWER | UPPER;
> > fragment LOWER: 'a'..'z';
> > fragment UPPER: 'A'..'Z';
> > fragment DIGIT: '0'..'9';
> > fragment NEWLINE: '\r'? '\n';
> > fragment SPACE: ' ' | '\t';
> >
> > // Note that SYMBOL does not include the
> > // apostrophe or double-quote characters.
> > fragment SYMBOL: '!' | '#'..'&' | '('..'/' | ':'..'@' | '['..'`' | '{'..'~';
> >
> > It parses your example input except for I changed "H-CAPRESTATE" to
> > "H_CAPRESTATE" to simply things. This way I can use "-" for
> > subtraction. I'm sure there's a way to work this out so you can also
> > use "-" in names.
> >
> > The grammar above doesn't output anything. It just verifies that input conforms.
> >
> > Email me privately if you want the Java code I wrote that uses the
> > generated classes and my Ant build file.
> >
> > On Jan 17, 2008 3:02 PM, Mark Volkmann <r.mark.volkmann at gmail.com> wrote:
> >
> >> On Jan 17, 2008 2:04 PM, Frank Font <mrfont at room4me.com> wrote:
> >>
> >>> Hello,
> >>>
> >>> I purchased the book, read through it, but I have a thick skull.
> >>> Perhaps I can get some advice here on two questions about converting
> >>> formula expressions that look like "basic" syntax...
> >>>
> >>> IF REP_DTE > '2001-01-01' AND ATOTAL>100 THEN
> >>>     H-CAPRESTATE
> >>> ELSE
> >>>     IF REP_DTE < '2001-01-01' THEN
> >>>         ACCTG_CNG + ACCTG_ERR_CRCT
> >>>     END IF
> >>> END IF
> >>>
> >>> Into a flat format that looks like Excel formula syntax...
> >>>
> >>> IF( AND(REP_DTE > '2001-01-01',ATOTAL>100), H-CAPRESTATE, IF(REP_DTE <
> >>> '2001-01-01', ACCTG_CNG + ACCTG_ERR_CRCT))
> >>>
> >>> I tried writing a few grammar files, but all have had various runtime
> >>> issues.
> >>>
> >>> Here are my questions...
> >>>
> >>> 1.  Is ANTLR the right tool for this job?  (I don't have much time.)
> >>>
> >> ANTLR can definitely do this. However, you shouldn't expect the work
> >> to go quickly if this is your first ANTLR grammar. You'll be learning
> >> lots of things along the way.
> >>
> >>
> >>> 2.  If it is the right tool, is there already a grammar that will get me
> >>> most of the way there?
> >>>
> >> I'm not aware of a particular existing grammar that is close to what
> >> you want. Maybe someone else knows of one.
> >>
> >>
> >>
> >>> Thanks in advance for any advice.
> >>>
> >>> Regards,
> >>> Frank Font
> >>>
> >> --
> >> R. Mark Volkmann
> >> Object Computing, Inc.
> >>
> >>
> >
> >
> >
> >
>
>



-- 
R. Mark Volkmann
Object Computing, Inc.