[antlr-interest] Issues with Tree Grammar

[Ney, Richard]

I have an existing tree grammar that I have to modify to handle a slight
modification. Currently as shown in the listed grammer the
groupExpression is based off of the mathExpression.

 

selectColumn

      : #(SELECT_COLUMN (column = groupExpression a = objectAlias))

      | #(SELECT_STAR STAR)

      ;

      

objectAlias

      : a:ALIAS

      | /* empty */

      ;

      

distinct

      : "distinct"

      | /* empty */

      ;     

      

groupExpression

      : #("avg" column = mathExpression)

      | #("sum" column = mathExpression)

      | #("count" dist = distinct (column = fieldName | STAR))

      | #("max" column = mathExpression)

      | #("min" column = mathExpression)

      | column = mathExpression

      ;

 

mathExpression

      : #(PLUS left = mathExpression right = mathExpression)

      | #(MINUS left = mathExpression right = mathExpression)

      | #(STAR left = mathExpression right = mathExpression)

      | #(DIV left = mathExpression right = mathExpression)

      | #(MOD left = mathExpression right = mathExpression)

      | result = expression

      ;

 

expression

      :     result = fieldName

      |     node = unaryExpression

      ;     

 

Now based on a change in requirements I now need to be able to form a
mathExpression that has the left or right sides as a groupExpression
trees. Can someone recommend a simple way to modify the grammar to add
this support while avoiding the recursive grammar?

 

 

Richard Ney                                                         

Principal Software Engineer

Aspect Communications

1310 Ridder Park Drive

San Jose, CA 95131-2313

 

916.797.9602          Home Office

408.325.2464       SJ Office

www.aspect.com

 

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