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5085 :: Reading a file line by line at compile time

• jyapayne (orginal) [2019-08-10T02:06:19+02:00] view original

  Is there a way to read a file line by line at compile time?

  My use case is that I want to process an input file and produce Nim code via macros, but have no trace of the input file in the resulting binary. Basically, I just want to iterate over the lines and throw them away after the VM has read them.

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• gemath (orginal) [2019-08-10T08:36:46+02:00] view original

  Like this:

  import strutils
  
  macro r: untyped =
    for l in "input".slurp.splitLines:
      # process a line
      echo l
  
  r()
  Run

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• jyapayne (orginal) [2019-08-10T15:21:53+02:00] view original

  Huh, interesting. That works! I was more looking for something that wouldn't read everything into memory at once (kind of like memfiles), but this works for now. Thank you!

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• cdome (orginal) [2019-08-12T12:17:47+02:00] view original

  Line by lines is not support at compile time. One more option: readLines("input",3) reads first 3 lines of file, works at compile time. Useful if you need to parse a header in the beginning of the file.

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