Data commit

Task/Rot-13/Smalltalk/rot-13.st

@@ -0,0 +1,74 @@
+"1. simple approach"
+rot13 := [ :string |
+  string collect: [ :each | | index |
+    index := 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
+      indexOf: each ifAbsent: [ 0 ]. "Smalltalk uses 1-based indexing"
+        index isZero
+          ifTrue: [ each ]
+          ifFalse: [ 'nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM' at:
+            index ] ] ].
+
+(rot13 value: 'Test123') printNl "gives 'Grfg123'"
+
+"2. extending built-in classes"
+Character extend [
+  + inc [
+     (inc isKindOf: Character)
+     ifTrue: [
+        ^ ( Character value: ((self asInteger) + (inc asInteger)) )
+     ] ifFalse: [
+       ^ ( Character value: ((self asInteger) + inc) )
+     ]
+  ]
+  - inc [
+    ^ ( self + (inc asInteger negated) )
+  ]
+  trFrom: map1 to: map2 [
+     (map1 includes: self) ifTrue: [
+        ^ map2 at: (map1 indexOf: self)
+     ] ifFalse: [ ^self ]
+  ]
+].
+
+String extend [
+  rot: num [ |s|
+    s := String new.
+    self do: [ :c |
+         ((c asLowercase) between: $a and: $z)
+	   ifTrue: [ |c1|
+              c1 := ( $a + ((((c asLowercase) - $a + num) asInteger) rem:26)).
+              (c isLowercase) ifFalse: [ c1 := c1 asUppercase ].
+              s := s, (c1 asString)
+           ]
+           ifFalse: [
+	      s := s, (c asString)
+           ]
+     ].
+     ^s
+  ]
+].
+
+('abcdefghijklmnopqrstuvwxyz123!' rot: 13) displayNl.
+(('abcdefghijklmnopqrstuvwxyz123!' rot: 13) rot: 13) displayNl.
+
+
+
+"2. using a 'translation'. Not very idiomatic Smalltalk code"
+rotThirteen := [ :s | |m1 m2 r|
+  r := String new.
+  m1 := OrderedCollection new.
+  0 to: 25 do: [ :i | m1 add: ($a + i) ].
+  m2 := OrderedCollection new.
+  0 to: 25 do: [ :i | m2 add: ($a + ((i+13) rem: 26)) ].
+  s do: [ :c |
+    (c between: $a and: $z) | (c between: $A and: $Z)
+      ifTrue: [ | a |
+        a := (c asLowercase) trFrom: m1 to: m2.
+        (c isUppercase) ifTrue: [ a := a asUppercase ].
+        r := r, (a asString)]
+      ifFalse: [ r := r, (c asString) ]
+  ].
+  r
+].
+
+(rotThirteen value: 'abcdefghijklmnopqrstuvwxyz123!') displayNl.