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4674 :: std::pair, std::make_pair, std::find, std::distance in Nim?

• r3c (orginal) [2019-02-23T00:23:20+01:00] view original

  Hi, I have block of code in C++ like this:

  ++
  std::vector<std::pair<int, int>> TL;
  int texture, lightmap;
  
  auto p = std::make_pair(texture, lightmap); // make pair
  auto it = std::find(TL.begin(), TL.end(), p);    // iterator
  int pos = std::distance(TL.begin(), it);           // the distance from the first pair
  
  if (it != texturePairs.TL.end())
  {
      doSomething(pos);
  }
  Run

  Basicly, I take two ints, make pair out of them, then i search for that pair in a vector of pairs, if the pair is found, doSomething(pos) runs.

  How do i make this in Nim? I looked for pairs, but in Nim they are similar to enumerations. https://forum.nim-lang.org/t/3570

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• mashingan (orginal) [2019-02-23T06:00:53+01:00] view original

  You can iterate and check manually like

  var
    intpair = newseq[(int, int)]()
    texture: int
    lightmap: int
  
  for thepair in intpair:
    if thepair[0] == texture and thepair[1] == lightmap:
      doSomething((texture, lightmap))
  Run

  or you can use define

  type
    IntPair = tuple
      a: int
      b: int
  
  proc `==`(a, b: IntPair): bool =
    a.a == b.a and a.b == b.b
  
  var
    texture: int
    lightmap: int
    intpairs = newseq[IntPair]()
    thepair = (texture, lightmap)
    pos = intpairs.find thepair
  
  if pos != -1: doSomething(thepair)
  Run

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• Araq (orginal) [2019-02-23T10:37:19+01:00] view original

  A pair would be a tuple with two components, std:find is system.find and Nim tends to use integer indexes instead of pointers because they are much easier to prove correct or check at runtime.

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• r3c (orginal) [2019-02-23T15:44:28+01:00] view original

  Thanks, it works!

  In my case, i dont need std::distance, because system.find does the job. Can it be implemented with slice maybe?

  Another question, is there something similar to std::map in Nim? https://thispointer.com/stdmap-tutorial-part-1-usage-detail-with-examples/

  For example, if you have

  var s = newSeq[seq[uint32]]()
  Run

  you cant do s[42].add(5) for example, with map you can do that.

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• miran (orginal) [2019-02-23T15:58:22+01:00] view original

  is there something similar to std::map in Nim?

  (from the link): std::map is an associative container that store elements in key-value pair.

  https://nim-lang.github.io/Nim/tables.html ?

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