Create an `InputBuffer` over a `Reader`?

[fge]

The InputBuffer is basically the character sequence used in a parsing run. Parboiled could build such buffers from plain Strings or char arrays.

Grappa added one for CharSequences (which basically obsoletes the runs over Strings since String implements CharSequence).

What about creating an InputBuffer over a Reader? And even from an InputStream (but then the encoding would be required to be specified)?