Escape non-printing characters

[xjunior]

Escape non-printing characters to avoid weird behavior when colors are used.

According to https://superuser.com/questions/301353/escape-non-printing-characters-in-a-function-for-a-bash-prompt

From lib/readline/display.c:243 in bash source code:

243 /* Current implementation:
244         \001 (^A) start non-visible characters
245         \002 (^B) end non-visible characters
246    all characters except \001 and \002 (following a \001) are copied to
247    the returned string; all characters except those between \001 and
248    \002 are assumed to be `visible'. */

Closes #493

[xjunior]

This is usually not a problem when it's just printing lines, but it becomes an issue if the text color helpers are used to produce a nice prompt. Also, this conforms to the readline spec for scaping non-visible characters.

[kyrylo]

Could you provide a before/after example?

[xjunior]

@kyrylo this solves the issue discussed here: #493

Here's an example of it breaking:

.pryrc

Pry.config.prompt_name = Pry::Helpers::Text.green("MAKE IT LONG")

Screen.Recording.2020-12-31.at.18.29.03.mov

Here is with the fix:
.pryrc

Pry.config.prompt_name = "\001\033[0;32m\002MAKE IT LONG\001\033[0m\002"

Screen.Recording.2020-12-31.at.18.33.10.mov

As you can see, it will start breaking as you navigate through the history and edit the line, especially if you navigate through big lines that span more than one line on your terminal.

[kyrylo]

Thanks for the extra info!