In order for an analyzer quick fix to aid the user in correcting
exhaustiveness errors, it needs to know not just the text of the
witness pattern that needs to be inserted, but also which elements are
referenced by the identifiers in that pattern. This will allow it to
add in imports if the user's code doesn't yet import the necessary
library, or insert import prefixes in the case where the user is
already importing the necessary library in a prefixed fashion.
To reduce the effect on the exhaustiveness logic (which was designed
with the intention of building up the witness pattern into a
StringBuffer), we introduce a new type, `DartTemplateBuffer`, which
behaves similarly to StringBuffer but also captures the necessary
semantic information so that the analyzer will be able to fix up
imports in an appropriate way.
This change is mostly isolated to the _fe_analyzer_shared package; it
doesn't add the necessary logic to the analyzer to capture the
elements; it simply plumbs them up to the API boundary between the
packages. Future CLs will add the necessary analyzer logic to make
use of the information.
Change-Id: I7c030fc49a2510acbefd6aeb567e0e7b7102855a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/296385
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Paul Berry
600fccb9bb