Moves in squared strings (I)

Moves in squared strings (I)

This kata is the first of a sequence of four about "Squared Strings".

You are given a string of n lines, each substring being n characters long: For example:

s = "abcd\nefgh\nijkl\nmnop"

We will study some transformations of this square of strings.

• Vertical mirror:

  vert_mirror (or vertMirror or vert-mirror)

  vert_mirror(s) => "dcba\nhgfe\nlkji\nponm"

• Horizontal mirror:

  hor_mirror (or horMirror or hor-mirror)

  hor_mirror(s) => "mnop\nijkl\nefgh\nabcd"

or printed:

vertical mirror   |horizontal mirror   
abcd --> dcba     |abcd --> mnop 
efgh     hgfe     |efgh     ijkl 
ijkl     lkji     |ijkl     efgh 
mnop     ponm     |mnop     abcd

Task:

• Write these two functions

and

• high-order function oper(fct, s) where

  • fct is the function of one variable f to apply to the string s

    (fct will be one of vertMirror, horMirror)

Examples:

s = "abcd\nefgh\nijkl\nmnop"
oper(vert_mirror, s) => "dcba\nhgfe\nlkji\nponm"
oper(hor_mirror, s) => "mnop\nijkl\nefgh\nabcd"

Note:

The form of the parameter fct in oper changes according to the language. You can see each form according to the language in "Sample Tests".

Bash Note:

The input strings are separated by , instead of \n. The output strings should be separated by \r instead of \n. See "Sample Tests".

Forthcoming katas will study other transformations.

Solutions

💲 Shell

#!/bin/bash

#will set internal field separator (IFS) to ','
IFS=','

vertMirror()
{
    arr=() #bash array
    for field 
    do
      arr+=( $(rev <<< $field) )
    done

    str=""
    for (( i=0; i < ${#arr[*]}; ++i))
    do
      str+=${arr[$i]}
      str+=$'\r'
    done

    echo $str
}

horMirror()
{
    arr=("$@") #bash array

    str=""
    for (( i=${#arr[*]}-1; i >= 0; --i))
    do
      str+=${arr[$i]}
      str+=$'\r'
    done

    echo $str
}

oper()
{
  $1 "${@:2}"
}

oper $1 $2
IFS=' '