[clangd] Implement "textDocument/documentLink" protocol support

Summary:
This adds an implementation for the "textDocument/documentLink" LSP request.

It returns links for all `#include` directives to the resolved target files.

Fixes https://github.com/clangd/clangd/issues/217.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70872

1 files changed, 33 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/Protocol.h b/clang-tools-extra/clangd/Protocol.h
index f110292b091..1ccfa587bf8 100644
--- a/clang-tools-extra/clangd/Protocol.h
+++ b/clang-tools-extra/clangd/Protocol.h
@@ -1250,6 +1250,39 @@ struct SelectionRange {
 };
 llvm::json::Value toJSON(const SelectionRange &);
 
+/// Parameters for the document link request.
+struct DocumentLinkParams {
+  /// The document to provide document links for.
+  TextDocumentIdentifier textDocument;
+};
+bool fromJSON(const llvm::json::Value &, DocumentLinkParams &);
+
+/// A range in a text document that links to an internal or external resource,
+/// like another text document or a web site.
+struct DocumentLink {
+  /// The range this link applies to.
+  Range range;
+
+  /// The uri this link points to. If missing a resolve request is sent later.
+  URIForFile target;
+
+  // TODO(forster): The following optional fields defined by the language
+  // server protocol are unsupported:
+  //
+  // data?: any - A data entry field that is preserved on a document link
+  //              between a DocumentLinkRequest and a
+  //              DocumentLinkResolveRequest.
+
+  friend bool operator==(const DocumentLink &LHS, const DocumentLink &RHS) {
+    return LHS.range == RHS.range && LHS.target == RHS.target;
+  }
+
+  friend bool operator!=(const DocumentLink &LHS, const DocumentLink &RHS) {
+    return !(LHS == RHS);
+  }
+};
+llvm::json::Value toJSON(const DocumentLink &DocumentLink);
+
 } // namespace clangd
 } // namespace clang