[Grammatica-users] GetParent question

[Luc Morin]

Hi,

I'm trying to create an Analyzer for the following simple grammar:

/*-------------------------------------------------------------------*/

%header%

GRAMMARTYPE = "LL"
DESCRIPTION = "A grammar for Eplan 21 Format Strings."

AUTHOR      = "Luc Morin"
VERSION     = "1.0"
DATE        = "9 December 2003"

%tokens%

LEFT_BRACKET                 = "<"
RIGHT_BRACKET                = ">"
SPACE                        = <<[ ]+>>
NUMBER                       = <<[0-9]+>>
WHITESPACE                   = <<[\t\n\r]+>>    %error unexpected token%
ALPHA                                            = <<[a-zA-Z]+>>        %error 
unexpected token%

%productions%

Property = LEFT_BRACKET NUMBER [Index] [IndirectProperty] RIGHT_BRACKET ;

Index = SPACE NUMBER ;

IndirectProperty = Property ;

/*-----------------------------------------------------------------------*/


I'm overriding some of the Exit functions in my own Analyzer, for example 
ExitProperty(Production node).

Here's a printout of the parse tree for the input string "<5<10>>"


Property(2001)
  LEFT_BRACKET(1001): "<", line: 1, col: 1
  NUMBER(1004): "5", line: 1, col: 2
  IndirectProperty(2003)
    Property(2001)
      LEFT_BRACKET(1001): "<", line: 1, col: 3
      NUMBER(1004): "10", line: 1, col: 4
      RIGHT_BRACKET(1002): ">", line: 1, col: 6
  RIGHT_BRACKET(1002): ">", line: 1, col: 7


I need to know if a property(2001) has an IndirectProperty(2003) parent, as the 
treatment is different. The problem is that within ExitProperty(), the 
Production cannot access its parent node. A call to node.GetParent() always 
returns null.

Is this a normal behavior?

How can I access the parent node of a Production ?

Thanks

Luc Morin
 
Electrical Designer
Wulftec / M.J. Maillis Group
Ph.: (819) 838-4232 ext. 232
Fx.: (819) 838-5539
 
www.wulftec.com
www.maillis.gr
 
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