smart tab

[zhaojiangbin]

What would it take to have a command for the Tab key to do the following:

1. If more than one character is selected, try to indent the lines overlapping the region; Otherwise,
2. If cursor follows a token (symbol/word/operator/etc.) and there are completion candidates to that token, try to complete it; Otherwise,
3. Try to indent the current line; Otherwise (i.e. the current line is already at the correct indentation),
4. If in the insert mode, insert spaces according the current tab width (or insert a tab If tabs are preferred).

#1209 discusses the "tab out" feature in auto-pairs. In vscode, the Tab key also moves cursor from one formal function parameter to the next (S-Tab moves backward) as part of code completion.

In Emacs, key mappings like this are sometimes called DWIM (do what I mean).