Accept keystrokes and modify the val field of the event. Also accept InputNote.NoteOn or InputNote.Control msgs and enter a value based on their velocity or value, respectively. So you can use a MIDI knob to set arbitrary control values.

Since control vals are typically normalized between 0 and 1, this accepts hexadecimal higits and modifies the event text with modify_hex. However, not all tracks are normalized, so this only happens if infer_normalized thinks that it's normalized.

The ' key will enter a ' call, which repeats the last value. This is useful to extend a constant pitch value to the desired breakpoint.

Editing a tempo track is just like editing a normal control track, except that it doesn't do the hex entry thing.

Try to figure out where the note part is in event text and modify that with the given function.

If the val was hex, keep it hex.

Partially-parse event text into method, val, and args. Method is actually the call, val is the first argument to the calll, and args are the remaining arguments. Control calls have a convention where the first argument is the value to set. I separate it out so I can replace just that value while leaving any arguments intact. E.g., exponential interpolation might look like e 0 3, where 0 is the destination and 3 is the exponent. Or e (4c) 3 in the case of pitches. If I press a MIDI key I want to replace just the 4c.

The "method" terminology dates from back before calls existed. Nowadays it's just a call, but for that matter so are numeric literals, so I need something to differentiate 1 from i 1.

Try to figure out the call part of the expression and split it from the rest.

I use a trailing space to tell the difference between a method and a val.