[clangd] Implement GetEligiblePoints

Summary:
This is an helper for incoming move definition out-of-line action to
figure out possible insertion locations for definition of a qualified name.

Reviewers: hokein, ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68024

1 files changed, 21 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/SourceCode.h b/clang-tools-extra/clangd/SourceCode.h
index 3017746c17e..a05d8adf923 100644
--- a/clang-tools-extra/clangd/SourceCode.h
+++ b/clang-tools-extra/clangd/SourceCode.h
@@ -262,6 +262,27 @@ llvm::StringSet<> collectWords(llvm::StringRef Content);
 std::vector<std::string> visibleNamespaces(llvm::StringRef Code,
                                            const format::FormatStyle &Style);
 
+/// Represents locations that can accept a definition.
+struct EligibleRegion {
+  /// Namespace that owns all of the EligiblePoints, e.g.
+  /// namespace a{ namespace b {^ void foo();^} }
+  /// It will be “a::b” for both carrot locations.
+  std::string EnclosingNamespace;
+  /// Offsets into the code marking eligible points to insert a function
+  /// definition.
+  std::vector<Position> EligiblePoints;
+};
+
+/// Returns most eligible region to insert a definition for \p
+/// FullyQualifiedName in the \p Code.
+/// Pseudo parses \pCode under the hood to determine namespace decls and
+/// possible insertion points. Choses the region that matches the longest prefix
+/// of \p FullyQualifiedName. Returns EOF if there are no shared namespaces.
+/// \p FullyQualifiedName should not contain anonymous namespaces.
+EligibleRegion getEligiblePoints(llvm::StringRef Code,
+                                 llvm::StringRef FullyQualifiedName,
+                                 const format::FormatStyle &Style);
+
 struct DefinedMacro {
   llvm::StringRef Name;
   const MacroInfo *Info;