General use case

I am trying to implement a basic shell.

Description

I need to read user input until some delimiters are pressed so a corresponding action can be performed. Those delimiter could be a single 'a', a single 'b' or a single 'c'.

An input example would look like this (where > is the shell prompt):

> 111-222-333-444a
Ok, '111-222-333-444' entered

Why do I want inline delimiter instead of 'new-line' delimiter?

Because I would like to listen to keyboard event such as 'up-arrow' to erase the current command and print the last command (implementing a history feature).

Because I would like to listen to keyboard event such as 'tabulation' to automaticly complete the current command (implementing auto-completion feature).

What I have so far

Up to now, my code looks like this:

bool done = false;
char c;
while (!done && std::cin.get(c))
{   
    switch (c)
    {
    case 'a':
        // Do something corresponding to 'a'
        done = true;
        break;

    case 'b':
        // Do something corresponding to 'b'
        done = true;
        break;

    case 'c':
        // Do something corresponding to 'c'
        done = true;
        break;

    default:
        // buffer input until a delimiter is pressed
        break;
    }
}

However, the loop seem to be executed only after the 'new-line' key have been pressed. This behaviour kill the interactive essence of the user input.

What is the question?

I know std::ostream is buffered so content is not write to disk until some event occured but what about std::istream. Is it buffered? If yes, how is it and what are my option to bypass this behaviour?

Also, I've tagged this question as 'homework' because, event if it is not a school exercice, it is an exercise I am trying to do by myself and I do not want to only pick a libra