Add workspace/symbols support

[literalpie]

https://bugs.swift.org/browse/SR-10806

Feedback welcome!

This branch builds on changes made in this PR of indexstore-db

This is the feature that is activated in VSCode with CMD+T

[literalpie]

Much of the other functionality seems to be done in SwiftLanguageServer, but I think I need to do this here to have access to index. Is that correct?

[benlangmuir]

Yep, this is the right place for it. Language-agnostic functionality belongs here, which is why we also implement e.g. jump to definition here.

[literalpie]

I would like some guidance on how to get kind, detail, and containerName.

[benlangmuir]

• kind: We have a symbol kind in the index that we should expose on class Symbol. Then we can convert it to an LSP SymbolKind here.

• detail: This isn't a field on SymbolInformation AFAICT. Did you mix it up with DocumentSymbol?

• containerName: Ah didn't realize we'd need this. For this we would need to expose the SymbolOccurrence's relations in the index. The C++ version of this is SymbolOccurrence::getRelations, we just need to thread it through the C and Swift interfaces. Since you already have the canonical occurrence, you would find the related symbol that has relation role childOf and use that symbol's name.

[literalpie]

You are correct that detail came from DocumentSymbol.

for containerName, it looks like I will have to pass an ArrayPointer to Swift, which I can't find a good example of. Maybe I could use unsafeBufferPointer as mentioned here, but it looks like that involves copying which I think we want to avoid. is there a better way to do this?

[benlangmuir]

Copying should be fine, since the number of relations for a single occurrence will generally be small, and we can do the copy lazily only when you ask for related symbols. Here's a sketch of the C API I would start with. We can always optimize this later if needed.

typedef void *indexstoredb_symbol_relation_t;

...

INDEXSTOREDB_PUBLIC uint64_t
indexstoredb_symbol_relation_get_roles(_Nonnull  indexstoredb_symbol_relation_t);

INDEXSTOREDB_PUBLIC indexstoredb_symbol_t
indexstoredb_symbol_relation_get_symbol(_Nonnull indexstoredb_symbol_relation_t);

/// The relations are owned by the occurrence and shall not be used after the occurrence is freed.
INDEXSTOREDB_PUBLIC bool
indexstoredb_symbol_occurrence_relations(_Nonnull indexstoredb_occurrence_t,
                      bool(^applier)(indexstoredb_symbol_relation_t));

On the Swift side, this can lazily create an array from the occurrence.

[literalpie]

I'm not sure what roles should be included. I've excluded accessorOf because otherwise getters and setters of variables were returned in addition to the variable itself.