Exercise: rotational-cipher

config.json

@@ -248,6 +248,19 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "rotational-cipher",
+        "name": "Rotational Cipher",
+        "staus": "beta",
+        "uuid": "139cfa97-ef3a-4f9d-8673-4d525c5c5aa0",
+        "practices": [
+          "conditionals"
+        ],
+        "prerequisites": [
+          "strings"
+        ],
+        "difficulty": 4
+      },
       {
         "slug": "roman-numerals",
         "name": "Roman Numerals",

exercises/practice/rotational-cipher/.docs/instructions.md

@@ -0,0 +1,31 @@
+# Instructions
+
+Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.
+
+The Caesar cipher is a simple shift cipher that relies on
+transposing all the letters in the alphabet using an integer key
+between `0` and `26`. Using a key of `0` or `26` will always yield
+the same output due to modular arithmetic. The letter is shifted
+for as many values as the value of the key.
+
+The general notation for rotational ciphers is `ROT + <key>`.
+The most commonly used rotational cipher is `ROT13`.
+
+A `ROT13` on the Latin alphabet would be as follows:
+
+```text
+Plain:  abcdefghijklmnopqrstuvwxyz
+Cipher: nopqrstuvwxyzabcdefghijklm
+```
+
+It is stronger than the Atbash cipher because it has 27 possible keys, and 25 usable keys.
+
+Ciphertext is written out in the same formatting as the input including spaces and punctuation.
+
+## Examples
+
+- ROT5  `omg` gives `trl`
+- ROT0  `c` gives `c`
+- ROT26 `Cool` gives `Cool`
+- ROT13 `The quick brown fox jumps over the lazy dog.` gives `Gur dhvpx oebja sbk whzcf bire gur ynml qbt.`
+- ROT13 `Gur dhvpx oebja sbk whzcf bire gur ynml qbt.` gives `The quick brown fox jumps over the lazy dog.`

exercises/practice/rotational-cipher/.meta/config.json

@@ -0,0 +1,18 @@
+{
+	"blurb": "Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.",
+	"authors": [
+		"loziniak"
+	],
+	"contributors": [],
+	"files": {
+		"solution": [
+			"rotational-cipher.red"
+		],
+		"test": [
+			"rotational-cipher-test.red"
+		],
+		"example": [
+			".meta/example.red"
+		]
+	}
+}

exercises/practice/rotational-cipher/.meta/example.red

@@ -0,0 +1,28 @@
+Red [
+	description: {"Rotational Cipher" exercise solution for exercism platform}
+	author: "loziniak"
+]
+
+rotation-code: function [start [char!]] [
+	compose/deep [
+		all [c >= (start) c < (start + 26)] [
+			c: c + shiftKey
+			if c >= (start + 26) [c: c - 26]
+			change text c
+		]
+	]
+]
+
+rotate: function [
+	text
+	shiftKey
+] compose/deep [
+	forall text [
+		c: first text
+		case [
+			(rotation-code #"A")
+			(rotation-code #"a")
+		]
+	]
+	text
+]

exercises/practice/rotational-cipher/.meta/tests.toml

@@ -0,0 +1,32 @@
+[canonical-tests]
+
+# rotate a by 0, same output as input
+"74e58a38-e484-43f1-9466-877a7515e10f" = true
+
+# rotate a by 1
+"7ee352c6-e6b0-4930-b903-d09943ecb8f5" = true
+
+# rotate a by 26, same output as input
+"edf0a733-4231-4594-a5ee-46a4009ad764" = true
+
+# rotate m by 13
+"e3e82cb9-2a5b-403f-9931-e43213879300" = true
+
+# rotate n by 13 with wrap around alphabet
+"19f9eb78-e2ad-4da4-8fe3-9291d47c1709" = true
+
+# rotate capital letters
+"a116aef4-225b-4da9-884f-e8023ca6408a" = true
+
+# rotate spaces
+"71b541bb-819c-4dc6-a9c3-132ef9bb737b" = true
+
+# rotate numbers
+"ef32601d-e9ef-4b29-b2b5-8971392282e6" = true
+
+# rotate punctuation
+"32dd74f6-db2b-41a6-b02c-82eb4f93e549" = true
+
+# rotate all letters
+"9fb93fe6-42b0-46e6-9ec1-0bf0a062d8c9" = true
+

exercises/practice/rotational-cipher/rotational-cipher-test.red

@@ -0,0 +1,137 @@
+Red [
+	description: {Tests for Rotational Cipher Exercism exercise}
+	author: "loziniak"
+]
+
+exercise-slug: "rotational-cipher"
+ignore-after: 1
+
+
+canonical-cases: [#(
+    description: "rotate a by 0, same output as input"
+    input: #(
+        text: "a"
+        shiftKey: 0
+    )
+    expected: "a"
+    function: "rotate"
+    uuid: "74e58a38-e484-43f1-9466-877a7515e10f"
+) #(
+    description: "rotate a by 1"
+    input: #(
+        text: "a"
+        shiftKey: 1
+    )
+    expected: "b"
+    function: "rotate"
+    uuid: "7ee352c6-e6b0-4930-b903-d09943ecb8f5"
+) #(
+    description: "rotate a by 26, same output as input"
+    input: #(
+        text: "a"
+        shiftKey: 26
+    )
+    expected: "a"
+    function: "rotate"
+    uuid: "edf0a733-4231-4594-a5ee-46a4009ad764"
+) #(
+    description: "rotate m by 13"
+    input: #(
+        text: "m"
+        shiftKey: 13
+    )
+    expected: "z"
+    function: "rotate"
+    uuid: "e3e82cb9-2a5b-403f-9931-e43213879300"
+) #(
+    description: "rotate n by 13 with wrap around alphabet"
+    input: #(
+        text: "n"
+        shiftKey: 13
+    )
+    expected: "a"
+    function: "rotate"
+    uuid: "19f9eb78-e2ad-4da4-8fe3-9291d47c1709"
+) #(
+    description: "rotate capital letters"
+    input: #(
+        text: "OMG"
+        shiftKey: 5
+    )
+    expected: "TRL"
+    function: "rotate"
+    uuid: "a116aef4-225b-4da9-884f-e8023ca6408a"
+) #(
+    description: "rotate spaces"
+    input: #(
+        text: "O M G"
+        shiftKey: 5
+    )
+    expected: "T R L"
+    function: "rotate"
+    uuid: "71b541bb-819c-4dc6-a9c3-132ef9bb737b"
+) #(
+    description: "rotate numbers"
+    input: #(
+        text: "Testing 1 2 3 testing"
+        shiftKey: 4
+    )
+    expected: "Xiwxmrk 1 2 3 xiwxmrk"
+    function: "rotate"
+    uuid: "ef32601d-e9ef-4b29-b2b5-8971392282e6"
+) #(
+    description: "rotate punctuation"
+    input: #(
+        text: "Let's eat, Grandma!"
+        shiftKey: 21
+    )
+    expected: "Gzo'n zvo, Bmviyhv!"
+    function: "rotate"
+    uuid: "32dd74f6-db2b-41a6-b02c-82eb4f93e549"
+) #(
+    description: "rotate all letters"
+    input: #(
+        text: "The quick brown fox jumps over the lazy dog."
+        shiftKey: 13
+    )
+    expected: "Gur dhvpx oebja sbk whzcf bire gur ynml qbt."
+    function: "rotate"
+    uuid: "9fb93fe6-42b0-46e6-9ec1-0bf0a062d8c9"
+)]
+
+
+
+print ["Testing" ignore-after "cases…"]
+
+cases: copy/deep/part canonical-cases ignore-after
+foreach test-case cases [
+	result: context load to file!
+		rejoin [exercise-slug %.red]
+	;	%.meta/example.red						; test example solution
+
+	; function name
+	result-execution: reduce [
+		make path! reduce [
+			'result
+			to word! test-case/function
+		]
+	]
+	; arguments
+	append result-execution values-of test-case/input
+
+	result: do result-execution
+
+	print [
+		pad/with test-case/description 30 #"."
+		either result = test-case/expected [
+			"✓"
+		] [
+			rejoin [{FAILED. Expected: "} test-case/expected {", but got "} result {"}]
+		]
+	]
+]
+
+print [
+	(length? canonical-cases) - ignore-after
+	"cases ignored."
+]

exercises/practice/rotational-cipher/rotational-cipher.red

@@ -0,0 +1,12 @@
+Red [
+	description: {"Rotational Cipher" exercise solution for exercism platform}
+	author: "" ; you can write your name here, in quotes
+]
+
+rotate: function [
+	text
+	shiftKey
+] [
+	cause-error 'user 'message ["You need to implement this function."]
+]
+