Fixing keyboard layout switching errors (snoop)

Purpose

Sometimes programmers have to simultaneously use two keyboard layouts: English and Russian. (I prefer to write comments in Russian. Also, where it is possible, I try to write code in Russian). In the case often it occures that a large piece of the entered text has wrong layout. The above script in the AutoHotKey language saves me a lot of time, because it allows me to quickly fix the layout of the selected text in any text editor. To convert the text from wrong layout just select the text and press the Break key. There are also additional options for transcoding the selected text (case change, etc.). Here is the complete list of transformations:

keyboard shortcut	action
Break	replace all English characters with Cyrillic characters and vice versa; set correct layout
Ctrl-Shift-PageUp	change the case of each character to the opposite
Win-PageUp	change all characters to uppercase; set CapsLock on
Win-PageDown	change all characters to lowercase; set CapsLock off
Alt-Shift-\	in the text, replace all right slashes (/) with left slashes (\)
Alt-Shift-]	remove all square brackets ([ and ]) in the text

Story

I have got a peek at the original idea in the "Misprint by Dr. Golomin" utility. I used this utility for about 18 years (2001-2018), for which I am very grateful to the author, Evgeny Golomin. His utility was called SNOOP, so I kept the name.

How does it work

Once you find that the entered text is in the wrong encoding, you need to (1) highlight the "wrong" text and (2) press the Break button. The script (1) recodes all characters and (2) detects the input layout (from the first highlighted character) and changes it to an alternative one (if the first character of the selected text was English, then the Russian layout will be activated, and vice versa). The lookup tables are very simple:

1. line f contains all the characters of the English keyboard in the order they appear on a simple sequential press, if you start from the upper left corner of the QWERTY and move along the lines towards the lower right corner; first all uppercase characters are listed, then all lowercase characters;
2. line g lists the symbols of the Russian layout in the same order.
3. let us concatenate the first array to the second one (fg=f+g) and the second one to the first one (gf=g+f), then there will always be antagonist characters in the same places; therefore for recoding we look for the place of the replaced character in the first array fg and, using the obtained index, we get the replacement character from the second array gf.

static f := "QWERTYUIOP{}ASDFGHJKL:""|ZXCVBNM<>?qwertyuiop[]asdfghjkl;'\zxcvbnm,./``~!@#$`%^&"
static g := "ЙЦУКЕНГШЩЗХЪФЫВАПРОЛДЖЭ/ЯЧСМИТЬБЮ,йцукенгшщзхъфывапролджэ\ячсмитьбю.ёЁ!""№;`%:?"
fg = %f%%g%
gf = %g%%f%

Restrictions

In the repository the AHK file is laid out in utf-8 encoding. In the script, all symbols of the national (Russian) layout are listed explicitly, so for the script to be compiled correctly it must be converted to ANSI encoding. (The github repository requires text files to be converted to utf-8, otherwise they will not display correctly in the Internet browser). I have cp-1251 encoding as ANSI on my Windows system. For proper download/conversion, you can use the iconv utility (https://mlocati.github.io/articles/gettext-iconv-windows.html). I have a filter configured for the repository in the .git\config file:

[filter "wincp1251"]
        clean = iconv -f windows-1251 -t utf-8
        smudge = iconv -f utf-8 -t windows-1251
        required

and the usage of the filter in the .gitattributes file:

*.ahk filter=wincp1251

Customization options

Other languages

I suspect that the script with minimal modifications can be used not only for Russian, but also for any other additional language (Ukrainian, French, German, etc.). For this you need:

1. Before compiling, be sure to convert the script to proper Windows encoding (cp-1251, cp-1252, etc.);
2. fix the corresponding line g in the script so that it displays the characters of the national alphabet in correct order (As far as I understand, for Ukrainian and Belarusian Windows uses the same cp-1251, but with a different arrangement of characters on the keyboard.);
3. replace the parameters in the layout change code with the ones corresponding to the required alphabet (see code lines with SendMessage, 0x50).

Other keyboard shortcuts

Of course, this is easy to do. Look for the right keycodes for AHK. I selected the codes for my convenience.

Other actions

Using the method described you can make any tabular recoding you need (see examples with case substitution in the code), as well as some exotic operation of substitution or omission of characters (I often need to replace direct slashes with backslashes in file paths, as well as "cleaning" SQL text from square brackets).