ilya-biryukov added inline comments.
================
Comment at: unittests/clangd/SyncAPI.h:1
+//===--- SyncAPI.h - Sync version of ClangdServer's API ----------*-
C++-*-===//
+//
----------------
sammccall wrote:
> Being able to call synchronously is really nice for tests.
> It's a bit unfortunate that to do this for each function we want to call
> synchronously (giving them a name, writing some boilerplate that repeats the
> args a few times).
>
> It would be nice if we had a primitive we could compose.
>
> Here's an idea that might work:
>
> ```Tagged<CompletionList> CompletionResults;
> Server.codeComplete(File, Pos, Opts, capture(CompletionResults),
> OverriddenContents);```
>
> `capture()` returns a callback that writes into CompletionResults. It also
> magically causes the call to block!
>
> (brief pause for you to consider the API before I suggest a shameful
> implementation)
>
> Actually capture() returns a proxy object that converts to UniqueFunction.
> The proxy object itself has a destructor that blocks on the UF being invoked.
> The proxy will be destroyed at the end of the full-expression, i.e. the line.
> e.g.
>
> ```template <typename T> struct CaptureProxy {
> T &Target;
> std::promise<T> Promise;
> std::future<T> Future;
> CaptureProxy(T &Target) : Target(Target) {}
> operator UniqueFunction<void(T)>() {
> return BindWithForward([](T Value, std::promise<T> Promise) {
> Promise.set_value(std::move(Value));
> }, std::move(Promise));
> }
> ~CaptureProxy() { Target = Future.get(); }
> };
> template <typename T> CaptureProxy<T> capture(T &Target) {
> return CaptureProxy<T>(Target);
> }```
>
> This is a little bit magic, but it's just for tests :-)
>
> (One caveat - this needs the return value to be default-constructible. We
> could easily use Optional instead, but these are default-constructible in
> practice)
As discussed offline, I've opted for both:
- implementing the helper to allow reusing the future/promise code
- providing a function that actually returns the value synchronously.
This approach writing a small amount of wrapper code for each of the LSP
methods in ClangdServer, but it, arguably, makes the test code nicer.
Repository:
rL LLVM
https://reviews.llvm.org/D43068
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