follow deno styleguide

main.ts → mod.ts

@@ -1,54 +1,68 @@
-'use strict';
+/** This module is browser compatible. */
 
-type char = string;
+'use strict';
 
 const ALPHABET = 'abcdefghijklmnopqrstuvwxyz';
 const ALL_LOWER_CASE = /[a-z]/g;
 const ENTIRELY_LOWER_CASE = /^[a-z]*$/;
 
-export const validate = (...args: string[]): void => {
+/** Throw an error if any string argument is not a lower-case ASCII letter string. */
+export function validate(...args: string[]): void {
   args.forEach((s: string) => {
     if (!ENTIRELY_LOWER_CASE.test(s))
       throw new Error(`String must consist of lowercase letters only. Received ${JSON.stringify(s)}.`);
   });
 }
 
-export const mod = (n: number, m: number): number => ((n % m) + m) % m;
+/** Alternative to `%` that works on negative numbers. */
+export function mod(n: number, m: number): number {
+  return ((n % m) + m) % m;
+}
 
-export const rotate = (s: string): string => {
-  const [c]: char = s;
+/** Shift each character in a string to the right, wrapping around. */
+export function rotate(s: string): string {
+  const [c]: string = s;
   const sliced: string = s.slice(1);
   const rotated: string = sliced.concat(c);
   return rotated;
 }
 
-export const swap = (s: string, i: number, j: number): string => {
+/** Swap a pair of characters in a string. */
+export function swap(s: string, i: number, j: number): string {
   let a: string[] = [...s];
   [a[i], a[j]] = [a[j], a[i]];
   const swapped: string = a.join('');
   return swapped;
 }
 
-const nothingIfIn = (set: Set<char>) => (c: char): string => set.has(c) ? '' : c;
+/** Returns a closure which returns an empty string if the given `Set` contains the given `string`. */
+function nothingIfIn(set: Set<string>) {
+  return (c: string): string => set.has(c) ? '' : c;
+}
 
-export const permutate = (key: string): string => {
-  const set: Set<char> = new Set(key);
+/** Returns the alphabet with all `key` letters moved to the beginning. */
+export function permutate(key: string): string {
+  const set: Set<string> = new Set(key);
   const uniques: string = [...set].join('');
   const diff: string = ALPHABET.replace(ALL_LOWER_CASE, nothingIfIn(set));
   const perm: string = uniques.concat(diff);
   return perm;
 }
 
-export const encrypt = (pt: string, pw: string, k: string, ct = '', perm: string = permutate(k)): string => {
+/** Encrypts a string using the provided password and key, all of which must consist of characters in the range `[a-z]`.
+ *
+ *      const ciphertext = encrypt('helloworld', 'foo', 'bar');
+ */
+export function encrypt(pt: string, pw: string, k: string, ct = '', perm: string = permutate(k)): string {
   validate(pt, pw, k, ct, perm);
-  const [pwC]: char = pw;
+  const [pwC]: string = pw;
   const pwC_i: number = ALPHABET.indexOf(pwC);
-  const [permC]: char = perm;
+  const [permC]: string = perm;
   const permC_i: number = ALPHABET.indexOf(permC);
   const shift: number = (pwC_i + permC_i + 2);
-  const [ptC]: char = pt;
+  const [ptC]: string = pt;
   const ctC_i: number = (shift + perm.indexOf(ptC)) % ALPHABET.length;
-  const ctC: char = perm[ctC_i];
+  const ctC: string = perm[ctC_i];
   const ptC_i: number = perm.indexOf(ptC);
 
   const ptSlice: string = pt.slice(1);
@@ -59,16 +73,17 @@ export const encrypt = (pt: string, pw: string, k: string, ct = '', perm: string
   return (pt.length === 0) ? ct : encrypt(ptSlice, pwRotated, k, ctNew, permSwapped);
 }
 
-export const decrypt = (ct: string, pw: string, k: string, pt = '', perm: string = permutate(k)): string => {
+/** Decrypts a string consisting only of characters in the range `[a-z]`. */
+export function decrypt(ct: string, pw: string, k: string, pt = '', perm: string = permutate(k)): string {
   validate(pt, pw, k, ct, perm);
-  const [pwC]: char = pw; 
+  const [pwC]: string = pw;
   const pwC_i: number = ALPHABET.indexOf(pwC);
-  const [permC]: char = perm;
+  const [permC]: string = perm;
   const permC_i: number = ALPHABET.indexOf(permC);
   const shift: number = -(pwC_i + permC_i + 2);
-  const [ctC]: char = ct;
+  const [ctC]: string = ct;
   const ptC_i: number = mod((shift + perm.indexOf(ctC)), ALPHABET.length);
-  const ptC: char = perm[ptC_i];
+  const ptC: string = perm[ptC_i];
   const ctC_i: number = perm.indexOf(ctC);
 
   const ctSlice: string = ct.slice(1);

test.ts → mod_test.ts

@@ -1,7 +1,7 @@
 'use strict';
 
 import { assertEquals } from 'https://deno.land/[email protected]/testing/asserts.ts';
-import { encrypt, decrypt, permutate, swap, rotate, mod, validate } from './main.ts';
+import { encrypt, decrypt, permutate, swap, rotate, mod, validate } from './mod.ts';
 
 Deno.test('validate', () => {
   try {