I expected this to be faster (due to less allocations and better cache locality), but benchmarked it is not (neither it is slower). Memory usage, however, drops by ~50mb (of `analysis-stats .`). I guess tt construction is just not hot.
This also simplifies using even less memory for token trees by compressing equal span, which I plan to do right after.
Some workflows are more easily expressed with a flat tt, while some are better expressed with a tree. With the right helpers, though (which was mostly a matter of trial and error), even the worst workflows become very easy indeed.
I.e. with `fn foo()`, don't complete at `x.fo|`, but complete (with imports) for `x.foo|`, since this is less likely to have false positives.
I opted to only do that for flyimport, even though for basic imports there can also be snippet completion (completing the params list for a method), since this is less universally applicable and seems not so useful.
To be accurate, only their methods are excluded, the trait themselves are still available.
I also excluded a bunch of std traits by default. Some less opinionated, like `AsRef`, which should never be used directly except in generic scenarios (and won't be excluded there), some more opinionated, like the ops traits, which I know some users sometimes want to use directly. Either way it's configurable.
It should be pretty easy to extend support to excluding only specific methods, but I didn't do that currently.
Traits configured to be excluded are resolved in each completion request from scratch. If this proves too expensive, it is easy enough to cache them in the DB.
Avoid short writes in LineWriter
If the bytes written to `LineWriter` contains at least one new line but doesn't end in a new line (e.g. `"abc\ndef"`) then we:
- write up to the last new line direct to the underlying `Writer`.
- copy as many of the remaining bytes as will fit into our internal buffer.
That last step is inefficient if the remaining bytes are larger than our buffer. It will needlessly split the bytes in two, requiring at least two writes to the underlying `Writer` (one to flush the buffer, one more to write the rest). This PR skips the extra buffering if the remaining bytes are larger than the buffer.
