implementation module MatchStrings

import StdEnv

head				:: String -> Char
head ""				= abort "head uitgevoerd op lege string"
head s				= s.[0]

tail				:: String -> String
tail ""				= abort "tail uitgevoerd op lege string"
tail s				= s % (1, size s - 1)

is_gelijk			:: String String -> Bool
is_gelijk "" ""		= True
is_gelijk a ""		= False
is_gelijk "" b 		= False
is_gelijk a b		= (head a == head b) && (is_gelijk (tail a) (tail b))

is_deelstring		:: String String -> Bool
is_deelstring "" b	= True
is_deelstring a ""	= False
is_deelstring a b	= is_gelijk a (b % (0, size a - 1)) || is_deelstring a (tail b)

is_deel				:: String String -> Bool
is_deel "" b		= True
is_deel a ""		= False
is_deel a b			= head a == head b && is_deel (tail a) (tail b) || is_deel a (tail b)

is_match			:: String String -> Bool
is_match "" ""		= True
is_match "" b		= False
is_match "*" ""		= True
is_match a ""		= False
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)

//Start				= (head pink_floyd, tail pink_floyd)
//Start				= is_gelijk     "" " "
//Start				= is_deelstring "there"          pink_floyd
//Start				= is_deelstring "there"          marillion
//Start				= is_deel       "there"          marillion
//Start				= is_deel       "she and her"    pink_floyd
//Start				= is_deel       radiohead        pink_floyd
//Start				= is_match      "*.here*.here*." pink_floyd
//Start				= is_match      ".here.here."    pink_floyd

pink_floyd			= "Is there anybody in there?"
marillion			= "Just for the record"
radiohead			= "There there"