* [SwiftSyntax] Add SyntaxRewriter.visitAny(_:)
This function, when overridden, allows Syntax rewriters to perform custom dynamic visitation behavior. If a user wanted to, say, store a series of transformations accessible by metatype, they can override visitAny and do their own runtime dispatch.
If a non-nil result is returned from visitAny, the original specialized visitors are skipped.
The sourcekitd client library provides parsing APIs for SwiftSyntax users.
The internal use of sourcekit service is an implementation detail that end users
shouldn't worry about.
When using SwiftSyntax as a standalone tool, we invoke Swiftc
internally to get serialized syntax trees. This is not ideal for
several reasons: (1) we have to hard-code the relative path of swiftc
to invoke it; (2) we have to rely on standard input/output to pass the
tree across the process boundaries; and (3) we have to maintain two
different ways to get syntax tree (swiftc and sourcekitd).
This patch attempts to teach SwiftSyntax to use SourceKitd to get the
tree just like other clients. We first add a SourceKitd client library
written in Swift; and next teach SwiftSyntax to adopt this SourceKitd
client-side library. For platforms other than MacOS, we still use Swiftc
to get syntax trees. This client library also allows us to add
SourceKitd tests in Swift.
This patch also re-enables several flaky tests.
Based on the feedbacks from our early adopters, separating syntax tree analysis
with transformation is a common pattern. Thus, we introduce a read-only
syntax tree visitor to help the analysis phase. This visitor never alters the
content of a tree being visited, in contrast to SyntaxRewriter which always does.
