Preprocessor style comments (lines starting with "//") only seem to work if next character is a space

[RolfSander]

Preprocessor style comments (lines starting with "//") only seem to work if the next character is a space. Otherwise, I get the error message:

Extra parameter on command line

This needs to be fixed, probably in scan.l, where COMMENT2 is defined.

[yantosca]

@RolfSander, is this still an issue or was it addressed in PR #92? Maybe I can take a look if it's still an open issue.

[RolfSander]

The problem still exists :-(

I have created a temporary branch called issue91test with several test cases in the ci-tests/F90_small_strato directory. The issue91test_ok*.kpp files work fine, but the issue91test_err*.kpp files crash. The only difference between them is the location of a comment that starts with // and has no space afterwards.

Can you reproduce the errors?

[yantosca]

Hi @RolfSander, I am finally back after being away for a bit. Yes, I am able to replicate your results on my end. Also, I modified the ok1 case by adding the same comment after #STOICHMAT ON:

//This is a comment without a space after the two slashes
#MODEL      small_strato
#LANGUAGE   Fortran90
#DOUBLE     ON
#INTEGRATOR rosenbrock
#DRIVER     general
#JACOBIAN   SPARSE_LU_ROW
#HESSIAN    ON
#STOICMAT   ON

//This is a comment without a space after the two slashes

{This is the small_strato example from Chapter 2 of the KPP manual}

and I get this error:

KPP is parsing the equation file.Error :issue91test_ok1.kpp:11: Extra parameter on command line '//This'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'is'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'a'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'comment'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'without'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'a'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'space'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'after'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'the'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'two'
Error :issue91test_ok1.kpp:11: Extra parameter on command line 'slashes'

Then I tried:

//This is a comment without a space after the two slashes
#MODEL      small_strato
#LANGUAGE   Fortran90
#DOUBLE     ON
#INTEGRATOR rosenbrock
#DRIVER     general
#JACOBIAN   SPARSE_LU_ROW
#HESSIAN    ON
#STOICMAT   ON

//This is a comment without a space after the two slashes

// This is a comment with a space after the two slashes

{This is the small_strato example from Chapter 2 of the KPP manual}

and I got the same error. I think it because it is expecting a #COMMAND and not finding one, the parsing gets halted. Where in the parser would we look for this?

[RolfSander]

@yantosca, thanks for testing this!

Where in the parser would we look for this?

It is called COMMENT2 in scan.l. I checked the file but couldn't find any requirement for a space after the //.

[yantosca]

@RolfSander: I took a look at scan.l. As is my understanding (and my understanding of Flex isn't that great), the line:

<COMMENT2>[^\n]*        {
                        } 

should ignore zero or more instances of any character except a newline. I tried a couple of other things but they didn't work. I may give up on this for a bit.

[RolfSander]

As we cannot solve this problem, let's change our strategy: It's not a bug, it's a feature! I suggest we simply adjust our documentation accordingly:

Comments are either enclosed between the curly braces { and }, or written in a line starting with two slashes and a space "// ".

[yantosca]

I agree!