AbsolutePosition being a mutable reference type easily leads to bugs
where an AbsolutePosition is modified. Making it immutable eliminates
this issue. Furthermore, the introduction of SourceLength should allow
easier manipulation of AbsolutePositions on the client side.
We still cannot make AbsolutePosition a value type since it is used
inside AtomicCache, but the immutability gives the same safety.
SourcePresence and ID are already shared between the two node kinds and
the node's length will soon be cached in RawSyntax as well. By making it
a struct, we will be able to compute the node's length when it is being
constructed in the initialiser.
* [SwiftSyntax] Add accessors for source locations and test diagnostic emission
* Add tests for endLocation
* Pre-emptively copy AbsolutePosition to avoid mutating it twice
Although libSyntax is designed in a way that trivia is attached to
tokens, we shouldn't restrict clients to access trivia only from a token.
An example can be doc-comment, which conceptually attaches to a declaration rather
than the start token of a declaration, like at-attributes.
Syntax nodes are designed as reusable blocks to construct Swift source
code. For this reason, we don't track absolute position in each node;
instead, the absolute position should be calculated on the fly when
needed. We recently found absolute positions are useful to bridge with
sourcekitd, which typically speaks in the language of line, column and
offset. Therefore, this patch tries to add a computed
property on SyntaxNode to get its absolute position.
To compute the absolute position of a SyntaxNode from scratch requires tree traversal.
However, getting the absolute position from these added APIs doesn't necessarily
mean we'll traverse since SyntaxData will actively cache the computed position.
Also, since we recursively compute the absolute position, all the position caches
for a SyntaxNode's previous siblings and ancestors will be populated as well during
the calculation of this SyntaxNode.
* Unify the capitalization across all user-visible error messages (fatal errors, assertion failures, precondition failures) produced by the runtime, standard library and the compiler.
* Update some more tests to the new expectations.
* Create Swift libSyntax API
This patch is an initial implementation of the Swift libSyntax API. It
aims to provide all features of the C++ API but exposed to Swift.
It currently resides in SwiftExperimental and will likely exist in a
molten state for a while.
* Only build SwiftSyntax on macOS
