[antlr-interest] Tree Evaluation with Logical Operators (AND and OR)

[Oliver Zeigermann]

You could return a set of elements that make the - local - expression
false from each expression and modify this list with each logical
operator like AND/OR.

Maybe like:

set1 AND set2 => union set1 set2
set1 OR set2 => intersection set1 set2

Your final set is the one of the top level expression.

Have you thought about NOT, by the way?

-Oliver

2009/1/22 Priolo, Scott <spriolo at walkerinfo.com>:
> I see the recursion now.  Thanks for point that out.
>
> It just dawned on me that I'm trying to "set" the flag isLowScore on the
> elements which cause the Boolean expression to be false.
>
> a=1
> b=3
> c=1
>
> So in the expression (a < 3) or (b < 3) or ((b = 3) AND (c < 3))
>
> I need to mark b and c as the elements that caused the expression to be
> false.  I can't figure out the action of the AND.
>
> Thanks for your help.
>
> -----Original Message-----
> From: Oliver Zeigermann [mailto:oliver.zeigermann at gmail.com]
> Sent: Thursday, January 22, 2009 8:07 AM
> To: Priolo, Scott
> Cc: shmuel siegel; antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Tree Evaluation with Logical Operators
> (AND and OR)
>
> That looks good. What is the problem with it?
>
> Note that both precedence and part/whole relation is composed into the
> tree structure.
>
> -Oliver
>
> 2009/1/22 Priolo, Scott <spriolo at walkerinfo.com>:
>> This is what I have so far.  ID is converted to an INT. Variable are
>> pulled out of a memory map that is preloaded prior to processing.
>>
>> I will try | ^(AND|OR expr expr) but it seems like there should be
> more
>> of a recursive nature to "and, or"  operators.
>>
>> expr returns [int value]
>>    :   ^(GT a=expr b=expr)   {
>>                               $value = (a>b)?1:0;
>>                               le.isLowScore((a>b));
>>                               System.out.println("(GT " + a + " " + b
> +
>> ") bool:" + (a>b));
>>                               }
>>    |   ^(GTEQ a=expr b=expr) {
>>                                $value = (a>=b)?1:0;
>>                                le.isLowScore((a>=b));
>>                                System.out.println("(GTEQ " + a + " " +
>> b + ") bool:" + (a>=b));
>>                              }
>>    |   ^(LT a=expr b=expr)   {
>>                                $value = (a<b)?1:0;
>>                                le.isLowScore((a<b));
>>                                System.out.println("(LT " + a + " " + b
>> + ") bool:" + (a<b));
>>                              }
>>    |   ^(LTEQ a=expr b=expr) {
>>                                $value = (a<=b)?1:0;
>>                                le.isLowScore((a<=b));
>>                                System.out.println("(LTEQ " + a + " " +
>> b + ") bool:" + (a<=b));
>>                              }
>>    |   ^(EQ a=expr b=expr)   {
>>                                $value = (a==b)?1:0;
>>                                le.isLowScore((a==b));
>>                                System.out.println("(EQ " + a + " " + b
>> + ") bool:" + (a==b));
>>                              }
>>    |   ^(NEQ a=expr b=expr)  {
>>                                $value = (a!=b)?1:0;
>>                                le.isLowScore((a!=b));
>>                                System.out.println("(NEQ " + a + " " +
> b
>> + ") bool:" + (a!=b));
>>                              }
>>    |   ^(OR a=expr b=expr)   {
>>                                // WHAT TO DO HERE
>>                                //System.out.println("(OR " + a + " " +
>> b + ") bool:" + (a|b));
>>                              }
>>    |   ^(AND a=expr b=expr)  {
>>                                // WHAT TO DO HERE
>>                                //System.out.println("(AND " + a + " "
> +
>> b + ") bool:" + (a&b));
>>                              }
>>    |   ID
>>        {
>>        try {
>>                //pull value out of map if this is an id "Q22_B"
>>                PgmQuestionsEntry q =
>> (PgmQuestionsEntry)variableMap.get(($ID.text).toLowerCase());
>>                if ( q!=null ) {
>>                        int idvalue = (int) q.getResponseNumber();
>>                        $value = idvalue;
>>                        System.out.println("=> Parsing ID = " +
> $ID.text
>> + " value = " + idvalue);
>>                } else System.err.println("undefined variable
>> "+$ID.text);
>>        } catch (Exception e)
>>        {
>>                e.printStackTrace();
>>        }
>>        }
>>    |   INT
>>        // when token matches an INT pattern convert it to int.
>>        {$value = Integer.valueOf($INT.text);}
>>    ;
>>
>> -----Original Message-----
>> From: shmuel siegel [mailto:antlr at shmuelhome.mine.nu]
>> Sent: Thursday, January 22, 2009 7:39 AM
>> To: Oliver Zeigermann
>> Cc: Priolo, Scott; antlr-interest at antlr.org
>> Subject: Re: [antlr-interest] Tree Evaluation with Logical Operators
>> (AND and OR)
>>
>> Oliver Zeigermann wrote:
>>> OK, so you need a tree grammar that can parse complex boolean
>>> expressions, right?
>>>
>>> expression
>>>   : ^((AND|OR) expression expression)
>>>   | ^(('<'|'>'|'='|'!=') expression expression)
>>>   | ^(('+'|'-'|'*'|'/') expression expression)
>>>   | ID
>>>   | literal
>>>   ;
>>>
>>> Would that work?
>>>
>>> -Oliver
>>>
>>>
>> This grammar is not syntactically restrictive since it allows ^(AND 3
>> 4). This will cause problems if you want to evaluate the tree since
> you
>> won't know the type of the return value of expression. It is better to
>> separate out arithmetic and logical expressions. Care must be taken to
>> establish if ID is arithmetic or logical.
>>
>>
>