I’m trying to make a textx grammar that will include a the ability to have single line comments like a c/c++ source file. e.g.

//this is a comment

This is the grammar I have developed to test this. Eventually ‘Entry’ will contain more than just comment.

Ledger:entries+=Entry;

Entry: Comment;

Comment:///.*$/;

However when I try to parse the following file

//comment 1
//comment 2

I get this error

textx.exceptions.TextXSyntaxError: file.txt:3:1: Expected Comment => 'omment 2 *'

This is the debug output of the parser

*** PARSING MODEL ***
>> Matching rule Model=Sequence at position 0 => *//comment
   >> Matching rule Ledger=Sequence in Model at position 0 => *//comment
      >> Matching rule __asgn_oneormore=OneOrMore[entries] in Ledger at position 0 => *//comment
         ?? Try match rule Comment=RegExMatch(//.*$) in __asgn_oneormore at position 0 => *//comment
         ?? Try match rule Comment=RegExMatch(//.*$) in __asgn_oneormore at position 0 => *//comment
' at 0 => '*//comment 1*'ent 1
         ?? Try match rule Comment=RegExMatch(//.*$) in __asgn_oneormore at position 13 => omment 1 *//comment
' at 13 => 'omment 1 *//comment 2*'
         ?? Try match rule Comment=RegExMatch(//.*$) in __asgn_oneormore at position 26 => omment 2 *
         -- NoMatch at 26
         -- NoMatch at 26
      <<- Not matched rule __asgn_oneormore=OneOrMore[entries] in __asgn_oneormore at position 0 => *//comment
   <<- Not matched rule Ledger=Sequence in Ledger at position 0 => *//comment
<<- Not matched rule Model=Sequence in Model at position 0 => *//comment

If I add another option to the Entry rule e.g.

Ledger:entries+=Entry;

Entry: Comment | FLOAT;

Comment:///.*$/;

and add that entry to the file e.g.

//comment 1
//comment 2
7

Then I don’t get an exception thrown but comments aren’t parsed ( they don’t show up in my model). Parser debug output is as follows.

>> Matching rule Model=Sequence at position 0 => *//comment
   >> Matching rule Ledger=Sequence in Model at position 0 => *//comment
      >> Matching rule __asgn_oneormore=OneOrMore[entries] in Ledger at position 0 => *//comment
         >> Matching rule Entry=OrderedChoice in __asgn_oneormore at position 0 => *//comment
            ?? Try match rule Comment=RegExMatch(//.*$) in Entry at position 0 => *//comment
            ?? Try match rule Comment=RegExMatch(//.*$) in Entry at position 0 => *//comment
' at 0 => '*//comment 1*'omment 1
            ?? Try match rule Comment=RegExMatch(//.*$) in Entry at position 13 => omment 1 *//comment
' at 13 => 'omment 1 *//comment 2*'
            ?? Try match rule Comment=RegExMatch(//.*$) in Entry at position 26 => omment 2 *7
            -- NoMatch at 26
            -- NoMatch at 26
            ?? Try match rule FLOAT=RegExMatch([+-]?(d+(.d*)?|.d+)([eE][+-]?d+)?(?<=[w.])(?![w.])) in Entry at position 0 => *//comment
            ++ Match '7' at 26 => 'omment 2 *7*'
         <<+ Matched rule Entry=OrderedChoice in Entry at position 27 => mment 2 7*
         >> Matching rule Entry=OrderedChoice in __asgn_oneormore at position 27 => mment 2 7*
            ?? Try match rule Comment=RegExMatch(//.*$) in Entry at position 27 => mment 2 7*
            ?? Try match rule Comment=RegExMatch(//.*$) in Entry at position 27 => mment 2 7*
            -- NoMatch at 27
            -- NoMatch at 27
            ?? Try match rule FLOAT=RegExMatch([+-]?(d+(.d*)?|.d+)([eE][+-]?d+)?(?<=[w.])(?![w.])) in Entry at position 27 => mment 2 7*
            -- NoMatch at 27
         <<- Not matched rule Entry=OrderedChoice in Entry at position 27 => mment 2 7*
      <<+ Matched rule __asgn_oneormore=OneOrMore[entries] in __asgn_oneormore at position 27 => mment 2 7*
   <<+ Matched rule Ledger=Sequence in Ledger at position 27 => mment 2 7*
   ?? Try match rule EOF in Model at position 27 => mment 2 7*
<<+ Matched rule Model=Sequence in Model at position 27 => mment 2 7*

Can anyone help me add c style comments to my grammar that end up in the model?
Thanks!