CDE

Task/Caesar-cipher/Elena/caesar-cipher.elena

@@ -0,0 +1,59 @@
+#define std'dictionary'*.
+#define std'basic'*.
+#define std'patterns'*.
+#define std'routines'strings'*.
+
+#define math'* = std'math'*.
+
+// --- subjects ---
+#subject cipher_key.
+
+#symbol Letters    = "abcdefghijklmnopqrstuvwxyz".
+#symbol BigLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".
+#symbol TestText   = "Pack my box with five dozen liquor jugs.".
+#symbol Key = 12.
+
+#symbol EEncrypt : aKey =
+{
+    eval : aChar
+    [
+        #var anIndex := Letters~eliteralop first_occ'find:aChar.
+        #if (-1) ifless:anIndex
+        [
+            $next eval:(Letters @ (aKey + anIndex)~math'eops math'modulus:26).
+        ]
+        | [
+            anIndex := BigLetters~eliteralop first_occ'find:aChar.
+            #if (-1) ifless:anIndex
+            [
+                $next eval:(BigLetters @ (aKey + anIndex)~math'eops math'modulus:26).
+            ]
+            | [
+                $next eval:aChar.
+            ].
+        ].
+    ]
+}.
+
+#symbol Encrypted &literal:aLiteral &cipher_key:aKey
+    = __group(EEncrypt::aKey, Summing::String) start:Scan::aLiteral.
+
+#symbol Decrypted &literal:aLiteral &cipher_key:aKey
+    = __group(EEncrypt::(26 - aKey), Summing::String) start:Scan::aLiteral.
+
+#symbol Program =
+[
+    #var anS := TestText.
+
+    'program'output << "Original text :" << anS << "%n".
+
+    anS := Encrypted &&literal:anS &cipher_key:Key.
+
+    'program'output << "Encrypted text:" << anS << "%n".
+
+    anS := Decrypted &&literal:anS &cipher_key:Key.
+
+    'program'output << "Decrypted text:" << anS << "%n".
+
+    'program'input get.
+].