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.
This split allows future maintainers (i.e: me) to quickly know whether a
function handles the conversion of bytes into tokens -- scan_* function
family -- or handles updating the Scanner's state -- the fetch_*
function family.
Typically one might thing of the call stack as:
1. a Scanner
2. fetches a token
3. by scanning the byte stream
and refactor out the scanning code into scan_directive which is called
from the relevant Scanner method. This makes directive scanning more
consistent with the other scanning functions
Split out the _massive_ tests module into smaller focused modules, one
per area, explained below:
- anchor | For anchor '&' and alias '*' node tags
- collection | For flow and block collections
- complex | For interactions between token types
- directive | For directives '%'
- document | For doc starts '---' and endings '...'
- key | For mapping keys explicit and implicit
- tag | For node type tags '!!', '!'
- whitespace | For whitespace chomping between tokens
This vastly reduces the size of lib/scanner's file leading to notably
better performance by rustfmt and rustanalyzer
Paul Stemmet