In essence, this allows us to test the Scanner's ability to handle
chunked byte streams, hooking directly into the existing test suite.
It has three levels large, medium and small where large is probably the
smallest buffer size + increment that could be considered reasonable
(4k/64), with the smaller two testing absurd buffers (8/8 and 1/1).
this simply prevents state corruption in the Scanner by waiting to make
the changes until _after_ any errors would have been returned.
While this works, its not immediately obvious in the code why the
operations are ordered the way they are. I should document this
probably.
before there was a subtle error when eating whitespace wherein the
whitespace could be eaten twice, which corrupts the Scanner.stats.
Now we ensure that any movement is captured before returning the error
to the caller
cache! allows the Scanner to state that it requires 'N' more codepoints
before it can correctly process the byte stream.
Its primary purpose is its interaction with O_EXTENDABLE, which allows
the caller to hint to the Scanner that the buffer could grow, likewise
cache! returns an error that hints to the caller that they should extend
the byte stream before calling the Scanner again -- or pass opts without
O_EXTENDABLE.
This struct is a C style bitflag container, which controls various
aspects of Scanner functionality.
The initial flags available are O_ZEROED, O_EXTENDABLE and O_LAZY. Read
each's documentation for an explanation.
Paul Stemmet