Stream functions for detecting if an int or float is available.

That is, a function like intAvailable() or floatAvailable() that indicates whether or not a call to parseInt() or parseFloat() would succeed given the data currently in the stream's buffer. I'd suggest not applying the timeout to these (i.e. not waiting for additional characters to arrive), because part of the point would be to do other things while waiting for an int or float to arrive on the serial port.

This probably depends on having multi-byte look-ahead / peek (https://github.com/arduino/Arduino/issues/1910), which is a larger issue.

Start by reading the Stream parseInt() and parseFloat() entry points and the multi-byte look-ahead/peek dependency described in issue #1910. Done means availability checks can inspect the current serial buffer without waiting for additional characters, while distinguishing whether parsing an int or float would succeed.

Written by the indexing model from the issue text.