[Grammatica-users] Simple question

[Luc Morin]

Hi all,

 

Is it possible to have certain tokens to be part of a production, but not to be included in the parse tree ?

 

For example, I want to create a parse tree from the following line:

 

 

<5 1> = "allo" ? <6> : <7<8 1>>

 

Which is a conditional _expression_. I "need" the < and > tokens to be compatible with some third party software, but I don't want to clutter the parse tree with them.

 

I'd also like to get rid of the =, ? and : tokens

 

I find that if I use the %ignore% directive for those tokens, I get parse errors because of unreckognized tokens.

 

Right now the parse tree looks like this:

 

File(2001)
  _expression_(2002)
    Property(2004)
      SMALLER_THAN(1005): "<", line: 1, col: 1
      Propnum(2005)
        NUMBER(1007): "5", line: 1, col: 2
      Index(2006)
        NUMBER(1007): "1", line: 1, col: 4
      GREATER_THAN(1004): ">", line: 1, col: 5
    CondStatement(2003)
      EQUAL(1003): "=", line: 1, col: 7
      QUOTED_STRING(1006): ""allo"", line: 1, col: 9
      Q_MARK(1001): "?", line: 1, col: 16
      Property(2004)
        SMALLER_THAN(1005): "<", line: 1, col: 18
        Propnum(2005)
          NUMBER(1007): "6", line: 1, col: 19
        GREATER_THAN(1004): ">", line: 1, col: 20
      COLON(1002): ":", line: 1, col: 22
      Property(2004)
        SMALLER_THAN(1005): "<", line: 1, col: 24
        Propnum(2005)
          NUMBER(1007): "7", line: 1, col: 25
        Property(2004)
          SMALLER_THAN(1005): "<", line: 1, col: 26
          Propnum(2005)
            NUMBER(1007): "8", line: 1, col: 27
          Index(2006)
            NUMBER(1007): "1", line: 1, col: 29
          GREATER_THAN(1004): ">", line: 1, col: 30
        GREATER_THAN(1004): ">", line: 1, col: 31

 

 

I'd like it to look like this:

 

 

File(2001)
  _expression_(2002)
    Property(2004)
      Propnum(2005)
        NUMBER(1007): "5", line: 1, col: 2
      Index(2006)
        NUMBER(1007): "1", line: 1, col: 4
    CondStatement(2003)
      QUOTED_STRING(1006): ""allo"", line: 1, col: 9
      Property(2004)
        Propnum(2005)
          NUMBER(1007): "6", line: 1, col: 19
      Property(2004)
        Propnum(2005)
          NUMBER(1007): "7", line: 1, col: 25
        Property(2004)
          Propnum(2005)
            NUMBER(1007): "8", line: 1, col: 27
          Index(2006)
            NUMBER(1007): "1", line: 1, col: 29

 

 

 

Here's the grammar:

 

------------------------8<----------------------------

 

%header%

GRAMMARTYPE = "LL"

DESCRIPTION = "A grammar for a new form generator."

AUTHOR = "Luc Morin"

VERSION = "1.0"

DATE = "10 march 2005"

 

%tokens%

Q_MARK = "?"

COLON = ":"

EQUAL = "="

GREATER_THAN = ">"

SMALLER_THAN = "<"

QUOTED_STRING = <<"[^"]*">>

NUMBER = <<[0-9]+>>

WHITESPACE = <<[ \t\n\r]+>> %ignore%

 

%productions%

File = _expression_+ ;

_expression_ = Property [CondStatement] ;

CondStatement = EQUAL QUOTED_STRING Q_MARK Property COLON Property ;

Property = SMALLER_THAN Propnum [Index] [Property] GREATER_THAN ;

Propnum = NUMBER ;

Index = NUMBER ;

 

 

------------------------8<----------------------------

 

 

 

Is that at all possible ? I find that it makes "navigating" the tree easier.

 

Regards,

 

 

Luc Morin

 

Electrical Designer

Wulftec / M.J. Maillis Group

address@hidden

Ph.: (819) 838-4232 ext. 232

Fx.: (819) 838-5539

 

www.wulftec.com

www.maillis.gr

 

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