Insert formatted text into VIM for every letter of alphabet - bash

Question

In VIM, for every letter of the English alphabet, I want to insert a line in the following format:
fragment {upper(letter)}: '{lower(letter)}' | '{upper(letter)'};
So, for example, for the letter a, it would be:
fragment A: 'a' | 'A';
Writing 26 lines like this is tedious, and you shouldn't repeat yourself. How can I do that?

Answer 1

In vim:
for i in range(65,90) " ASCII codes
let c = nr2char(i) " Character
echo "fragment" c ": '"tolower(c)"' | '" c "';"
endfor
Or as a oneliner:
:for i in range(65,90) | let c = nr2char(i) | echo "fragment" c ": '"tolower(c)"' | '" c "';" | endfor
fragment A : ' a ' | ' A ';
fragment B : ' b ' | ' B ';
fragment C : ' c ' | ' C ';
...
fragment X : ' x ' | ' X ';
fragment Y : ' y ' | ' Y ';
fragment Z : ' z ' | ' Z ';
Use :redir #a to copy that output to register a.

Answer 2

Here's one way.
First, I'm gonna create the text in bash with a single command, then I'll tell VIM to insert the output of that command into the file.
I need to iterate through English alphabets, and for every letter, echo one line in the specified format. So at first, let's just echo each letter in a single line (By using a for loop):
❯ alphabets="abcdefghijklmnopqrstuvwxyz"
❯ for ((i=0; i<${#alphabets}; i++)); do echo "${alphabets:$i:1}"; done
a
b
...
z
The way this works is:
${#alphabets} is equal to the length of the variable alphabets.
${alphabets:$i:1} extracts the letter at position i from the variable alphabets (zero-based).
Now we need to convert these letters to upper case. Here's one way we can achieve this:
❯ echo "a" | tr a-z A-Z
A
Now if we apply this to the for loop we had, we get this:
❯ for ((i=0; i<${#alphabets}; i++)); do echo "${alphabets:$i:1}" | tr a-z A-Z; done
A
B
...
Z
From here, it's quite easy to produce the text we wanted:
❯ for ((i=0; i<${#alphabets}; i++)); do c="${alphabets:$i:1}"; cap=$(echo "${c}" | tr a-z A-Z); echo "fragment ${cap}: '${c}' | '${cap}';"; done
fragment A: 'a' | 'A';
fragment B: 'b' | 'B';
...
fragment Z: 'z' | 'Z';
Now that we generated the text, we can simply use :r !command to insert the text into vim:
:r !alphabets="abcdefghijklmnopqrstuvwxyz"; for ((i=0; i<${\#alphabets}; i++)); do c="${alphabets:$i:1}"; cap=$(echo "${c}" | tr a-z A-Z); echo "fragment ${cap}: '${c}' | '${cap}';"; done
Note that # is a special character in vim and should be spaced using \.
Here's another one-liner that does the same thing, and I believe is more intuitive:
for c in {a..z}; do u=$(echo ${c} | tr a-z A-Z); echo "fragment ${u}: '${c}' | '${u}';"; done