I identified a pattern among rules that create results with adjacent
results, so I created a method that abstracts that. I did have to
compromise with the DateTimeDiff, having to escape the input instead of
using the name itself, but that seems like a good trade-off.
I've also renamed "Subsequent" to "Adjacent" because it sounded better.
This is the second time I've renamed this concept, and I hope it will be
the last.
With this change, any rule can be used as a PHP attribute. I have wanted
to implement this feature for a while, as it allows you to bind the
validation to a specific property and just validate the object
afterwards.
In some cases, "DateTimeImmutable" will throw an exception because it
cannot parse the date. In those cases, we shouldn't throw an exception,
but instead return a specific result that tells what happened.
Since I updated the validation engine[1], it became possible to create
results with siblings. This commit changes the "DateTimeDiff", allowing
it to create a result with a sibling when possible. That will improve
the clarity of the error messages.
While at it, I noticed that we were not translating the type of
interval, so I fixed that and improved the documentation.
[1]: 238f2d506a
Besides the interface's name, everything already calls this type "Rule",
not "Validatable." This commit puts a stone on it and renames the
interface for better naming.
