Data commit

Task/Caesar-cipher/Picat/caesar-cipher.picat

@@ -0,0 +1,23 @@
+main =>
+  S = "All human beings are born free and equal in dignity and rights.",
+  println(S),
+  println(caesar(S,5)),
+  println(caesar(caesar(S,5),-5)),
+  nl.
+
+caesar(String, N) = Cipher =>
+  Lower = [chr(I): I in 97..122],
+  Upper = [chr(I): I in 65..90],
+  M = create_map(Lower, Upper, N),
+  % If a char is not in a..zA..z then show it as it is.
+  Cipher := [M.get(C,C) : C in String].
+
+create_map(Lower,Upper, N) = M =>
+  M = new_map(),
+  Len = Lower.length,
+  foreach(I in 1..Len)
+    II = (N+I) mod Len,
+    if II == 0 then II := Len end, % Adjust for 1 based
+    M.put(Upper[I],Upper[II]),
+    M.put(Lower[I],Lower[II])
+  end.