Add rotational-cipher

config.json

@@ -625,6 +625,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 2
+      },
+      {
+        "slug": "rotational-cipher",
+        "name": "rotational cipher",
+        "uuid": "14c90535-2be7-438b-b3af-80fc84336e89",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
       }
     ]
   },

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

@@ -0,0 +1,29 @@
+# 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 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "rotational_cipher.bal"
+    ],
+    "test": [
+      "tests/rotational_cipher_test.bal"
+    ],
+    "example": [
+      ".meta/reference/rotational_cipher.bal"
+    ]
+  },
+  "blurb": "Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Caesar_cipher"
+}

exercises/practice/rotational-cipher/.meta/reference/rotational_cipher.bal

@@ -0,0 +1,25 @@
+# Encodes the input text using the rotational cipher technique
+#
+# + text - the text to encode
+# + shiftKey - the number of positions to shift each alphabetic character
+# + return - the encoded text
+function rotate(string text, int shiftKey) returns string {
+    string result = "";
+    foreach string:Char chr in text {
+        int codePoint = chr.toCodePointInt();
+        int newCodePoint = codePoint;
+
+        if codePoint >= 65 && codePoint <= 90 {
+            newCodePoint = 65 + (codePoint - 65 + shiftKey) % 26;
+        }
+        else if codePoint >= 97 && codePoint <= 122 {
+            newCodePoint = 97 + (codePoint - 97 + shiftKey) % 26;
+        }
+
+        // Checkpanic since this shouldn't return an error
+        string rotated = checkpanic string:'fromCodePointInt(newCodePoint);
+        result += rotated;
+    }
+
+    return result;
+}

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

@@ -0,0 +1,40 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[74e58a38-e484-43f1-9466-877a7515e10f]
+description = "rotate a by 0, same output as input"
+
+[7ee352c6-e6b0-4930-b903-d09943ecb8f5]
+description = "rotate a by 1"
+
+[edf0a733-4231-4594-a5ee-46a4009ad764]
+description = "rotate a by 26, same output as input"
+
+[e3e82cb9-2a5b-403f-9931-e43213879300]
+description = "rotate m by 13"
+
+[19f9eb78-e2ad-4da4-8fe3-9291d47c1709]
+description = "rotate n by 13 with wrap around alphabet"
+
+[a116aef4-225b-4da9-884f-e8023ca6408a]
+description = "rotate capital letters"
+
+[71b541bb-819c-4dc6-a9c3-132ef9bb737b]
+description = "rotate spaces"
+
+[ef32601d-e9ef-4b29-b2b5-8971392282e6]
+description = "rotate numbers"
+
+[32dd74f6-db2b-41a6-b02c-82eb4f93e549]
+description = "rotate punctuation"
+
+[9fb93fe6-42b0-46e6-9ec1-0bf0a062d8c9]
+description = "rotate all letters"

exercises/practice/rotational-cipher/Ballerina.toml

@@ -0,0 +1,5 @@
+[package]
+org = "ballerina_exercism"
+name = "rotational_cipher"
+version = "0.1.0"
+distribution = "2201.5.0"

exercises/practice/rotational-cipher/Dependencies.toml

@@ -0,0 +1,38 @@
+# AUTO-GENERATED FILE. DO NOT MODIFY.
+
+# This file is auto-generated by Ballerina for managing dependency versions.
+# It should not be modified by hand.
+
+[ballerina]
+dependencies-toml-version = "2"
+distribution-version = "2201.5.0"
+
+[[package]]
+org = "ballerina"
+name = "jballerina.java"
+version = "0.0.0"
+scope = "testOnly"
+
+[[package]]
+org = "ballerina"
+name = "test"
+version = "0.0.0"
+scope = "testOnly"
+dependencies = [
+	{org = "ballerina", name = "jballerina.java"}
+]
+modules = [
+	{org = "ballerina", packageName = "test", moduleName = "test"}
+]
+
+[[package]]
+org = "ballerina_exercism"
+name = "rotational_cipher"
+version = "0.1.0"
+dependencies = [
+	{org = "ballerina", name = "test"}
+]
+modules = [
+	{org = "ballerina_exercism", packageName = "rotational_cipher", moduleName = "rotational_cipher"}
+]
+

exercises/practice/rotational-cipher/rotational_cipher.bal

@@ -0,0 +1,8 @@
+# Encodes the input text using the rotational cipher technique
+#
+# + text - the text to encode
+# + shiftKey - the number of positions to shift each alphabetic character
+# + return - the encoded text
+function rotate(string text, int shiftKey) returns string {
+    // TODO: implement this function
+}

exercises/practice/rotational-cipher/tests/rotational_cipher_test.bal

@@ -0,0 +1,74 @@
+
+import ballerina/test;
+
+
+@test:Config {}
+function testRotateABy0SameOutputAsInput() {
+    test:assertEquals(rotate("a", 0), "a");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateABy1() {
+    test:assertEquals(rotate("a", 1), "b");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateABy26SameOutputAsInput() {
+    test:assertEquals(rotate("a", 26), "a");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateMBy13() {
+    test:assertEquals(rotate("m", 13), "z");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateNBy13WithWrapAroundAlphabet() {
+    test:assertEquals(rotate("n", 13), "a");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateCapitalLetters() {
+    test:assertEquals(rotate("OMG", 5), "TRL");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateSpaces() {
+    test:assertEquals(rotate("O M G", 5), "T R L");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateNumbers() {
+    test:assertEquals(rotate("Testing 1 2 3 testing", 4), "Xiwxmrk 1 2 3 xiwxmrk");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotatePunctuation() {
+    test:assertEquals(rotate("Let's eat, Grandma!", 21), "Gzo'n zvo, Bmviyhv!");
+}
+
+@test:Config {
+    enable: false
+}
+function testRotateAllLetters() {
+    string text = "The quick brown fox jumps over the lazy dog.";
+    int shift = 13;
+    string expected = "Gur dhvpx oebja sbk whzcf bire gur ynml qbt.";
+    test:assertEquals(rotate(text, shift), expected);
+}