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Add rotational-cipher exercise (#73)
* Add rotation-cipher exercise * Tidy up rotational-cipher - Mark second to last tests xtest - Remove unnecessary exp import - Use global constants for "A", "Z", "a" and "z" - Add instructions.append.md
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‎config.json

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"practices": [],
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"prerequisites": [],
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"difficulty": 2
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}, {
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"slug": "rotational-cipher",
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"name": "Rotational Cipher",
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"uuid" : "039a7a86-d954-4bb6-a144-93b2eb17b016",
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"practices" : [],
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"prerequisites": [],
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"difficulty": 4
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}
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]
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},

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

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## Reserved Memory
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Bytes 64-319 of the linear memory are reserved for the input string.
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The input string can be modified in place if desired.

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

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

‎exercises/practice/rotational-cipher/.eslintrc

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{
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"root": true,
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"extends": "@exercism/eslint-config-javascript",
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"env": {
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"jest": true
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},
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"overrides": [
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{
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"files": [
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"*.spec.js"
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],
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"excludedFiles": [
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"custom.spec.js"
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],
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"extends": "@exercism/eslint-config-javascript/maintainers"
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}
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]
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}

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

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{
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"authors": [
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"kahgoh"
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],
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"files": {
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"solution": [
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"rotational-cipher.wat"
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],
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"test": [
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"rotational-cipher.spec.js"
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],
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"example": [
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".meta/proof.ci.wat"
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]
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},
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"blurb": "Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.",
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"source": "Wikipedia",
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"source_url": "https://en.wikipedia.org/wiki/Caesar_cipher",
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"custom": {
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"version.tests.compatibility": "jest-27",
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"flag.tests.task-per-describe": false,
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"flag.tests.may-run-long": false,
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"flag.tests.includes-optional": false
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}
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}

‎exercises/practice/rotational-cipher/.meta/proof.ci.wat

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(module
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(memory (export "mem") 1)
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(global $A i32 (i32.const 65))
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(global $Z i32 (i32.const 90))
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(global $a i32 (i32.const 97))
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(global $z i32 (i32.const 122))
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(func $wrap (param $low i32) (param $high i32) (param $value i32) (param $shiftKey i32) (result i32)
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(local $newValue i32)
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(local.set $newValue (local.get $value))
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(if
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(i32.ge_u
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(local.get $value)
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(local.get $low)
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)
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(then
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(if
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(i32.le_u
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(local.get $value)
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(local.get $high)
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)
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(then
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;; shift the value
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(local.set
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$newValue
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(i32.add
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(local.get $value)
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(local.get $shiftKey)
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)
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)
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;; wrap when value greater than $high
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(if (i32.gt_u (local.get $newValue) (local.get $high))
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(then
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(local.set $newValue
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(i32.sub
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(local.get $newValue)
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(i32.const 26)
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)
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)
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)
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)
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)
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)
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)
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)
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(return (local.get $newValue))
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)
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(func (export "rotate") (param $textOffset i32) (param $textLength i32) (param $shiftKey i32) (result i32 i32)
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(local $index i32)
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(local $stop i32)
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(local $value i32)
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(local.set $index (local.get $textOffset))
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(local.set $stop
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(i32.add
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(local.get $textOffset)
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(local.get $textLength)
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)
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)
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(loop $process
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;; shift upper case
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(local.set $value
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(call $wrap
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(global.get $A)
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(global.get $Z)
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(i32.load8_u (local.get $index))
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(local.get $shiftKey)
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)
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)
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;; shift lower case
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(local.set $value
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(call $wrap
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(global.get $a)
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(global.get $z)
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(local.get $value)
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(local.get $shiftKey)
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)
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)
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(i32.store8
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(local.get $index)
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(local.get $value)
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)
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(local.set $index
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(i32.add (local.get $index) (i32.const 1))
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)
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(br_if
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$process
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(i32.lt_u (local.get $index) (local.get $stop))
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)
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)
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(return (local.get $textOffset) (local.get $textLength))
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)
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)

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

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

‎exercises/practice/rotational-cipher/.npmrc

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audit=false

‎exercises/practice/rotational-cipher/LICENSE

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MIT License
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Copyright (c) 2021 Exercism
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.

‎exercises/practice/rotational-cipher/babel.config.js

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export default {
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presets: ["@exercism/babel-preset-javascript"],
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plugins: [],
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};

‎exercises/practice/rotational-cipher/package.json

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{
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"name": "@exercism/wasm-rotational-cipher",
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"description": "Exercism exercises in WebAssembly.",
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"author": "Kah Goh",
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"type": "module",
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"private": true,
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"license": "MIT",
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"repository": {
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"type": "git",
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"url": "https://github.com/exercism/wasm",
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"directory": "exercises/practice/rotational-cipher"
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},
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"jest": {
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"maxWorkers": 1
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},
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"devDependencies": {
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"@babel/core": "^7.20.12",
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"@exercism/babel-preset-javascript": "^0.2.1",
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"@exercism/eslint-config-javascript": "^0.6.0",
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"@types/jest": "^29.4.0",
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"@types/node": "^18.13.0",
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"babel-jest": "^29.4.2",
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"core-js": "^3.27.2",
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"eslint": "^8.34.0",
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"jest": "^29.4.2"
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},
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"dependencies": {
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"@exercism/wasm-lib": "^0.1.0"
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},
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"scripts": {
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"test": "node --experimental-vm-modules node_modules/jest/bin/jest.js ./*",
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"watch": "node --experimental-vm-modules node_modules/jest/bin/jest.js --watch ./*",
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"lint": "eslint ."
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}
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}

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