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8896 :: To insert a Nim variable into its PCRE regex

• mardiyah (orginal) [2022-02-10T11:07:29+01:00] view original

  How can we insert and interpolate a variable into the regex pattern in procedure re( ... ) just like Perl does with its $variable ?

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• Araq (orginal) [2022-02-10T11:46:06+01:00] view original

  Stop using regexes and use something like "strscans", pegs or a lexer generator:

  https://nim-lang.org/docs/strscans.html

  https://nim-lang.org/docs/parseutils.html

  https://nim-lang.org/docs/pegs.html

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• PMunch (orginal) [2022-02-10T12:04:13+01:00] view original

  Since the re module and re procedure takes a raw string literal you can use fmt from strformat to do this:

  import re, strformat
  
  let
    num = r"\d*"
    wordNum = re(fmt"[a-z]\w*{num}")
    wordNum2 = re"[a-z]\w*\d*"
  
  echo find("hello123", wordNum)
  echo find("hello123", wordNum2)
  
  echo find("       hello123", wordNum)
  echo find("       hello123", wordNum2)
  Run

  Note that the num string needs to be a raw literal as well, or you'd have to escape the backslash.

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• mardiyah (orginal) [2022-02-11T00:27:58+01:00] view original

  then so how to put character {

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• adokitkat (orginal) [2022-02-11T10:35:31+01:00] view original

  To escape { or } you need to double it like {{ / }}.

  It's explained in detail here.

  import re, strformat
  
  let
    num = r"\d*"
    wordNum = re(fmt"[a-z]\w*{num}{{")
  
  echo find("hello123{", wordNum)
  echo find("       hello123{", wordNum)
  
  Run

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• mardiyah (orginal) [2022-02-11T17:21:11+01:00] view original

  simply solved. thanks

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