Find the index store path by searching through the command-line
arguments, and if found, also provide a default database path next to
the index store. Also add command-line arguments so that either of these
can be overridden. We could also easily add these as initialization
options if an LSP client wanted to provide them in the future.
URL can in fact store URIs, it just doesn't have a very nice API to
interact with them. As long as we only operate on absoluteString, we
should be fine though. So instead of implementing the logic for
detecting file URLs ourselves, we can just use a URL as storage for
DocumentURI.
According to the LSP specification, arbitrary URIs can be used as
document identifiers. Instead of internally assuming that all URIs are
URLs, use a DocumentURI enum to represent URIs. These can either be file
URLs or other URIs whose value as treated as an opaque string.
We will be able to split the LSP modules off later. These LSP modules
will provide the ability to write custom LSP servers and clients in
Swift. The sourcekit-lsp repository will build on top of this new
package to provide an LSP implementation that creates a language server
for Swift and C-based-languages.
`SourceKitServer` now talks to the `SwiftLanguageServer` and
`ClangLanguageServerShim` directly through the `ToolchainLanguageServer`
protocol.
Each individual `ToolchainLanguageServer` manages its own threading.
Change-Id: I77aa5468f1486bd4e6e6fdb732c6a051ee05c6d1
