week1/camil/2.3/MatchStrings.icl

   1 implementation module MatchStrings
   2
   3 import StdEnv
   4
   5 head                            :: String -> Char
   6 head ""                         = abort "head uitgevoerd op lege string"
   7 head s                          = s.[0]
   8
   9 tail                            :: String -> String
  10 tail ""                         = abort "tail uitgevoerd op lege string"
  11 tail s                          = s % (1, size s - 1)
  12
  13 is_gelijk                       :: String String -> Bool
  14 is_gelijk "" ""         = True
  15 is_gelijk a ""          = False
  16 is_gelijk "" b          = False
  17 is_gelijk a b           = (head a == head b) && (is_gelijk (tail a) (tail b))
  18
  19 is_deelstring           :: String String -> Bool
  20 is_deelstring "" b      = True
  21 is_deelstring a ""      = False
  22 is_deelstring a b       = is_gelijk a (b % (0, size a - 1)) || is_deelstring a (tail b)
  23
  24 is_deel                         :: String String -> Bool
  25 is_deel "" b            = True
  26 is_deel a ""            = False
  27 is_deel a b                     = head a == head b && is_deel (tail a) (tail b) || is_deel a (tail b)
  28
  29 is_match                        :: String String -> Bool
  30 is_match "" ""          = True
  31 is_match "" b           = False
  32 is_match "*" ""         = True
  33 is_match a ""           = False
  34 is_match a b            = (head a == '.' || head a == head b) && is_match (tail a) (tail b) || head a == '*' && (is_match a (tail b) || is_match (tail a) b)
  35
  36 //Start                         = (head pink_floyd, tail pink_floyd)
  37 //Start                         = is_gelijk     "" " "
  38 //Start                         = is_deelstring "there"          pink_floyd
  39 //Start                         = is_deelstring "there"          marillion
  40 //Start                         = is_deel       "there"          marillion
  41 //Start                         = is_deel       "she and her"    pink_floyd
  42 //Start                         = is_deel       radiohead        pink_floyd
  43 //Start                         = is_match      "*.here*.here*." pink_floyd
  44 //Start                         = is_match      ".here.here."    pink_floyd
  45
  46 pink_floyd                      = "Is there anybody in there?"
  47 marillion                       = "Just for the record"
  48 radiohead                       = "There there"