Zig: completed Rotational Cipher

zig/rotational-cipher/.exercism/config.json

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+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "rotational_cipher.zig"
+    ],
+    "test": [
+      "test_rotational_cipher.zig"
+    ],
+    "example": [
+      ".meta/example.zig"
+    ]
+  },
+  "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"
+}

zig/rotational-cipher/.exercism/metadata.json

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+{"track":"zig","exercise":"rotational-cipher","id":"febb4070e9eb44dabea37232f64c12c6","url":"https://exercism.org/tracks/zig/exercises/rotational-cipher","handle":"Chomp1295","is_requester":true,"auto_approve":false}

zig/rotational-cipher/HELP.md

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+# Help
+
+## Running the tests
+
+Write your code in `<exercise_name>.zig`.
+
+To run the tests for an exercise, run:
+
+```bash
+zig test test_exercise_name.zig
+```
+
+in the exercise's root directory (replacing `exercise_name` with the name of the exercise).
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit rotational_cipher.zig` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Zig track's documentation](https://exercism.org/docs/tracks/zig)
+- The [Zig track's programming category on the forum](https://forum.exercism.org/c/programming/zig)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+- [The Zig Programming Language Documentation][documentation] is a great overview of all of the language features that Zig provides to those who use it.
+- [Zig Guide][zig-guide] is an excellent primer that explains the language features that Zig has to offer.
+- [Ziglings][ziglings] is highly recommended.
+  Learn Zig by fixing tiny broken programs.
+- [The Zig Programming Language Discord][discord-zig] is the main [Discord][discord].
+  It provides a great way to get in touch with the Zig community at large, and get some quick, direct help for any Zig related problem.
+- [#zig][irc] on irc.freenode.net is the main Zig IRC channel.
+- [/r/Zig][reddit] is the main Zig subreddit.
+- [Stack Overflow][stack-overflow] can be used to discover code snippets and solutions to problems that may have already asked and maybe solved by others.
+
+[discord]: https://discordapp.com
+[discord-zig]: https://discord.com/invite/gxsFFjE
+[documentation]: https://ziglang.org/documentation/master
+[irc]: https://webchat.freenode.net/?channels=%23zig
+[reddit]: https://www.reddit.com/r/Zig
+[stack-overflow]: https://stackoverflow.com/questions/tagged/zig
+[zig-guide]: https://zig.guide/
+[ziglings]: https://codeberg.org/ziglings/exercises

zig/rotational-cipher/README.md

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+# Rotational Cipher
+
+Welcome to Rotational Cipher on Exercism's Zig Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## 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.`
+
+## Source
+
+### Created by
+
+- @keiravillekode
+
+### Based on
+
+Wikipedia - https://en.wikipedia.org/wiki/Caesar_cipher

zig/rotational-cipher/rotational_cipher.zig

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+const std = @import("std");
+const mem = std.mem;
+
+pub fn rotate(allocator: mem.Allocator, text: []const u8, shiftKey: u5) mem.Allocator.Error![]u8 {
+    const result = try allocator.alloc(u8, text.len);
+
+    for (text, 0..) |c, i| {
+        result[i] = switch(c) {
+            'a'...'z' => (c - 'a' + shiftKey) % 26 + 'a',
+            'A'...'Z' => (c - 'A' + shiftKey) % 26 + 'A',
+            else => c,
+        };
+    }
+
+    return result;
+}

zig/rotational-cipher/test_rotational_cipher.zig

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+const std = @import("std");
+const testing = std.testing;
+
+const rotational_cipher = @import("rotational_cipher.zig");
+
+test "rotate a by 0, same output as input" {
+    const expected: []const u8 = "a";
+    const actual = try rotational_cipher.rotate(testing.allocator, "a", 0);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate a by 1" {
+    const expected: []const u8 = "b";
+    const actual = try rotational_cipher.rotate(testing.allocator, "a", 1);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate a by 26, same output as input" {
+    const expected: []const u8 = "a";
+    const actual = try rotational_cipher.rotate(testing.allocator, "a", 26);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate m by 13" {
+    const expected: []const u8 = "z";
+    const actual = try rotational_cipher.rotate(testing.allocator, "m", 13);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate n by 13 with wrap around alphabet" {
+    const expected: []const u8 = "a";
+    const actual = try rotational_cipher.rotate(testing.allocator, "n", 13);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate capital letters" {
+    const expected: []const u8 = "TRL";
+    const actual = try rotational_cipher.rotate(testing.allocator, "OMG", 5);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate spaces" {
+    const expected: []const u8 = "T R L";
+    const actual = try rotational_cipher.rotate(testing.allocator, "O M G", 5);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate numbers" {
+    const expected: []const u8 = "Xiwxmrk 1 2 3 xiwxmrk";
+    const actual = try rotational_cipher.rotate(testing.allocator, "Testing 1 2 3 testing", 4);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate punctuation" {
+    const expected: []const u8 = "Gzo'n zvo, Bmviyhv!";
+    const actual = try rotational_cipher.rotate(testing.allocator, "Let's eat, Grandma!", 21);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "rotate all letters" {
+    const expected: []const u8 = "Gur dhvpx oebja sbk whzcf bire gur ynml qbt.";
+    const actual = try rotational_cipher.rotate(testing.allocator, "The quick brown fox jumps over the lazy dog.", 13);
+    defer testing.allocator.free(actual);
+    try testing.expectEqualStrings(expected, actual);
+}