/* 

  Substring (Rosetta code) in Picat.

  http://rosettacode.org/wiki/Substring
  """
  In this task display a substring:

   - starting from n characters in and of m length;
   - starting from n characters in, up to the end of the string;
   - whole string minus last character;
   - starting from a known character within the string and of m length;
   - starting from a known substring within the string and of m length. 

  If the program uses UTF-8 or UTF-16, it must work on any valid Unicode code 
  point, whether in the Basic Multilingual Plane or above it. The program must 
  reference logical characters (code points), not 8-bit code units for UTF-8 or 16-bit 
  code units for UTF-16. Programs for other encodings (such as 8-bit ASCII, or EUC-JP) 
  are not required to handle all Unicode characters. 
  """

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


import util.

main => go.


go =>
  S = "Picat is fun",


  N = 3,
  M = 4,
  C = 'i', % must be a char
  SS = "is",
  test(S,N,M,C,SS),
  
  nl.

test(S,N,M,C,SS) =>
  println($test(S,N,M,C,SS)),


  % - starting from n characters in and of m length;
  println(1=slice(S,N,N+M)),
  println(1=S[N..N+M]),  

  % - starting from n characters in, up to the end of the string;
  println(2=S.slice(N)),

  % - whole string minus last character;
  println(3=but_last(S)),
  println(3=S[1..S.len-1]),  

  % - starting from a known character within the string and of m length;
  println(4=substring4(S,C)),

  % - starting from a known substring within the string and of m length. 
  println(5=substring5(S,SS,M)),

  nl.
  
but_last(S) = slice(S,1,S.length-1).

substring4(S,C) = slice(S,S.find_first_of(C)).

substring5(S,SS,M) = slice(S,Start,Start+M) =>  
  % find is non-deterministic, hence the once/1
  once(find(S,SS,Start,_End)).