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517 :: c2nim and ##

• julien (orginal) [2014-08-07T07:16:58+02:00] view original

  I'm trying to wrap fftw3: https://github.com/FFTW/fftw3/blob/master/api/fftw3.h

  It relies extensively on using the concatenation operator ##.

  In the c2nim manual it clearly states "c2nim cannot translate any macro that contains the ## token concatenation operator."

  However, it is not clear whether it should be able to handle it if using the "def" directive. E.g. in the source of c2nim when handling "def":

  of pxDirConc:
    # just ignore this token: this implements token merging correctly
    discard
  Run

  I tried c2nim and using def on a test file but it did not work (complains about a missing semicolon): https://gist.github.com/anonymous/dc5af36f040b5e99325f

  I probably have two options: a) manage the ## manually to prepare the fftw3.h file... b) fix c2nim to handle it.

  I am very new to nimrod, but if someone could point out a path to fix ## operator support in c2nim, perhaps I could give it a try.

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• Araq (orginal) [2014-08-07T13:31:34+02:00] view original

  The comment is wrong, it has to implemented completely differently:

  • Keep the pxDirConc token as is in the macro.
  • During macro expansion handle pxDirConc in a special way, so that the surrounding tokens get merged, this likely requires to re-run parts of the lexer so that the resulting token is classified properly. That said, I don't think it's ever used for anything else than identifier construction, so you can cheat here.

  BTW a##b could be supported in #define too; it can be translated to `a b` (note the backticks).

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• Araq (orginal) [2014-08-08T10:27:48+02:00] view original

  I've implemented this feature and it turned out to be exactly as simple as described here. ;-) Unfortunately there was another hard to track down bug that caused wrong macro expansions if the macro uses some of its parameters multiple times. That was fixed too.

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