vuepress-plugin-code-switcher

This is the demo page for the vuepress-plugin-code-switcher. Please refer to the Readme on its GitHub Repository (opens new window) for more information regarding how to use it.

All examples shown are taken from Rosetta Code (opens new window).

Synchronised switchers

These two switchers are synchronized by default, no additional settings needed to be made.

Longest Common Substring

• Julia
• Kotlin
• Perl

function lcs(s1::AbstractString, s2::AbstractString)
    l, r = 1, 0
    sub_len = 0
    for i in 1:length(s1)
        for j in i:length(s1)
            if !contains(s2, SubString(s1, i, j)) break
            elseif sub_len < j - i
                l, r = i, j
                sub_len = j - i
            end
        end
    end 
    s1[l:r] 
end
 
@show lcs("thisisatest", "testing123testing")

fun lcs(a: String, b: String): String {
    if (a.length > b.length) return lcs(b, a)
    var res = ""
    for (ai in 0 until a.length) {
        for (len in a.length - ai downTo 1) {
            for (bi in 0 until b.length - len) {
                if (a.regionMatches(ai, b, bi,len) && len > res.length) {
                    res = a.substring(ai, ai + len)
                }
            }
        }
    }
    return res
}
 
fun main(args: Array<String>) = println(lcs("testing123testing", "thisisatest"))

#!/usr/bin/perl
use strict ;
use warnings ;
 
sub longestCommonSubstr {
   my $first = shift ;
   my $second = shift ;
   my %firstsubs = findSubstrings ( $first );
   my %secondsubs = findSubstrings ( $second ) ;
   my @commonsubs ;
   foreach my $subst ( keys %firstsubs ) {
      if ( exists $secondsubs{ $subst } ) {
	 push ( @commonsubs , $subst ) ;
      }
   }
   my @sorted = sort { length $b <=> length $a } @commonsubs ;
   return $sorted[0] ;
}
 
sub findSubstrings {
   my $string = shift ;
   my %substrings ;
   my $l = length $string ;
   for ( my $start = 0 ; $start < $l ; $start++ ) {
      for ( my $howmany = 1 ; $howmany < $l - $start + 1 ; $howmany++) {
	 $substrings{substr( $string , $start , $howmany) } = 1 ;
      }
   }
   return %substrings ;
}
 
my $longest = longestCommonSubstr( "thisisatest" ,"testing123testing" ) ;
print "The longest common substring of <thisisatest> and <testing123testing> is $longest !\n" ; 

Palindrome Detection

• Julia
• Kotlin
• Perl

function palindrome(s)
    len = length(s)
    if(len==0 || len==1)
        return true
    end
    if(s[1] == s[len])
        return palindrome(SubString(s,2,len-1))
    end
    return false
end

fun isExactPalindrome(s: String) = (s == s.reversed())
 
fun isInexactPalindrome(s: String): Boolean {
    var t = ""
    for (c in s) if (c.isLetterOrDigit()) t += c
    t = t.toLowerCase()
    return t == t.reversed()
}

# Palindrome.pm
package Palindrome;
 
use strict;
use warnings;
 
use Exporter 'import';
our @EXPORT = qw(palindrome palindrome_c palindrome_r palindrome_e);
 
sub palindrome
{
    my $s = (@_ ? shift : $_);
    return $s eq reverse $s;
}
 
sub palindrome_c
{
    my $s = (@_ ? shift : $_);
    for my $i (0 .. length($s) >> 1)
    {
        return 0 unless substr($s, $i, 1) eq substr($s, -1 - $i, 1);
    }
    return 1;
}
 
sub palindrome_r
{
    my $s = (@_ ? shift : $_);
    if (length $s <= 1) { return 1; }
    elsif (substr($s, 0, 1) ne substr($s, -1, 1)) { return 0; }
    else { return palindrome_r(substr($s, 1, -1)); }
}

sub palindrome_e
{
    (@_ ? shift : $_) =~ /^(.?|(.)(?1)\2)$/ + 0
}

Isolated Switchers

The following two switchers are isolated. They do not listen to any of the other switchers being changed.

Letter Frequency

• Kotlin
• Ruby

import java.io.File
 
fun main(args: Array<String>) {
    val text = File("input.txt").readText().toLowerCase()
    val letterMap = text.filter { it in 'a'..'z' }.groupBy { it }.toSortedMap()
    for (letter in letterMap) println("${letter.key} = ${letter.value.size}")
    val sum = letterMap.values.sumBy { it.size }
    println("\nTotal letters = $sum")
}

def letter_frequency(file)
  letters = 'a' .. 'z'
  File.read(file) .
       split(//) .
       group_by {|letter| letter.downcase} .
       select   {|key, val| letters.include? key} .
       collect  {|key, val| [key, val.length]} 
end
 
letter_frequency(ARGV[0]).sort_by {|key, val| -val}.each {|pair| p pair}

Rot-13

• Kotlin
• Ruby

import java.io.*
 
fun String.rot13() = map {
    when {
        it.isUpperCase() -> { val x = it + 13; if (x > 'Z') x - 26 else x }
        it.isLowerCase() -> { val x = it + 13; if (x > 'z') x - 26 else x }
        else -> it
    } }.toCharArray()
 
fun InputStreamReader.println() =
        try { BufferedReader(this).forEachLine { println(it.rot13()) } }
        catch (e: IOException) { e.printStackTrace() }
 
fun main(args: Array<String>) {
    if (args.any())
        args.forEach { FileReader(it).println() }
    else
        InputStreamReader(System.`in`).println()
}

# Returns a copy of _s_ with rot13 encoding.
def rot13(s)
  s.tr('A-Za-z', 'N-ZA-Mn-za-m')
end
 
# Perform rot13 on files from command line, or standard input.
while line = ARGF.gets
  print rot13(line)
end

Multiple Switcher Groups

The following switchers are in different groups. Even though they show the same languages, they might not be thematically related, so only some code blocks switch, while the others stay the same.

Group 1: FizzBuzz

• Nim
• OCaml

for i in 1..100:
  if i mod 15 == 0:
    echo("FizzBuzz")
  elif i mod 3 == 0:
    echo("Fizz")
  elif i mod 5 == 0:
    echo("Buzz")
  else:
    echo(i)

let fizzbuzz i =
  match i mod 3, i mod 5 with
    0, 0 -> "FizzBuzz"
  | 0, _ -> "Fizz"
  | _, 0 -> "Buzz"
  | _    -> string_of_int i
 
let _ =
  for i = 1 to 100 do print_endline (fizzbuzz i) done

Group 1: Hello world

• Nim
• OCaml

echo("Hello world!")

print_endline "Hello world!"

Group 2: String case

• Nim
• OCaml

import strutils
 
var s: string = "alphaBETA_123"
echo s," as upper case: ", toUpper(s)
echo s," as lower case: ", toLower(s)
echo s," as Capitalized: ", capitalize(s)
echo s," as normal case: ", normalize(s)  # remove underscores, toLower

let () =
  let str = "alphaBETA" in
  print_endline (String.uppercase_ascii str); (* ALPHABETA *)
  print_endline (String.lowercase_ascii str); (* alphabeta *)
 
  print_endline (String.capitalize_ascii str); (* AlphaBETA *)
;;

Group 2: Strip whitespace

• Nim
• OCaml

import strutils
 
let s = " \t \n String with spaces  \t  \n  "
echo "'", s, "'"
echo "'", s.strip(trailing = false), "'"
echo "'", s.strip(leading = false), "'"
echo "'", s.strip(), "'"

let left_pos s len =
  let rec aux i =
    if i >= len then None
    else match s.[i] with
    | ' ' | '\n' | '\t' | '\r' -> aux (succ i)
    | _ -> Some i
  in
  aux 0
 
let right_pos s len =
  let rec aux i =
    if i < 0 then None
    else match s.[i] with
    | ' ' | '\n' | '\t' | '\r' -> aux (pred i)
    | _ -> Some i
  in
  aux (pred len)
 
let trim s =
  let len = String.length s in
  match left_pos s len, right_pos s len with
  | Some i, Some j -> String.sub s i (j - i + 1)
  | None, None -> ""
  | _ -> assert false
 
let ltrim s =
  let len = String.length s in
  match left_pos s len with
  | Some i -> String.sub s i (len - i)
  | None -> ""
 
let rtrim s =
  let len = String.length s in
  match right_pos s len with
  | Some i -> String.sub s 0 (i + 1)
  | None -> ""