AroundBlockScan started as a utility class that was meant to be used as a DSL for scanning and making new blocks. As logic got added to this class it became hard to reason about what exactly is being mutated when. I pulled the scanning logic out into it's own class which gives us a clean separation of concerns. This allowed me to remove a lot of accessors that aren't core to the logic provided by AroundBlockScan.
In addition to this refactor the ScanHistory class can snapshot a scan. This allows us to be more aggressive with scans in the future as we can now snapshot and rollback if it didn't turn out the way we wanted.
The change comes with a minor perf impact:
before: 5.092678 0.104299 5.196977 ( 5.226494)
after: 5.128536 0.099871 5.228407 ( 5.249542)
This represents a 0.996x change in speed (where 1x would be no change and 2x would be twice as fast). This is a 0.38% decrease in performance which is negligible. It's likely coming from the extra blocks being created while scanning. This is negligible and if the history feature works well we might be able to make better block decisions which is means fewer calls to ripper which is the biggest bottleneck.
While this doesn't fix https://github.com/ruby/syntax_suggest/issues/187 it's a good intermediate step that will hopefully make working on that issue easier.
ad8487d8aa
I previously left a comment stating I didn't know why a certain method existed. In investigating the code in `CaptureCodeContext#capture_before_after_kws` I found that it was added as to give a slightly less noisy output.
The docs for AroundBlockScan#capture_neighbor_context only describe keywords as being a primary concern. I modified that code to only include lines that are keywords or ends. This reduces the output noise even more.
This allows me to remove that `start_at_next_line` method.
One weird side effect of the prior logic is it would cause this code to produce this output:
```
class OH
def hello
def hai
end
end
```
```
1 class OH
> 2 def hello
4 def hai
5 end
6 end
```
But this code to produce this output:
```
class OH
def hello
def hai
end
end
```
```
1 class OH
> 2 def hello
4 end
5 end
```
Note the missing `def hai`. The only difference between them is that space.
With this change, they're now both consistent.
4a54767a3e
