[clang] [APINotes] Upstream APINotesReader (PR #66769)

[Saleem Abdulrasool via cfe-commits]

================
@@ -0,0 +1,202 @@
+//===--- APINotesReader.h - API Notes Reader --------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the \c APINotesReader class that reads source API notes
+// data providing additional information about source code as a separate input,
+// such as the non-nil/nilable annotations for method parameters.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_APINOTES_READER_H
+#define LLVM_CLANG_APINOTES_READER_H
+
+#include "clang/APINotes/Types.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/VersionTuple.h"
+#include <memory>
+
+namespace clang {
+namespace api_notes {
+
+/// A class that reads API notes data from a binary file that was written by
+/// the \c APINotesWriter.
+class APINotesReader {
+  class Implementation;
+  std::unique_ptr<Implementation> Implementation;
+
+  APINotesReader(llvm::MemoryBuffer *InputBuffer,
+                 llvm::VersionTuple SwiftVersion, bool &Failed);
+
+public:
+  /// Create a new API notes reader from the given member buffer, which
+  /// contains the contents of a binary API notes file.
+  ///
+  /// \returns the new API notes reader, or null if an error occurred.
+  static std::unique_ptr<APINotesReader>
+  get(std::unique_ptr<llvm::MemoryBuffer> InputBuffer,
+      llvm::VersionTuple SwiftVersion);
+
+  ~APINotesReader();
+
+  APINotesReader(const APINotesReader &) = delete;
+  APINotesReader &operator=(const APINotesReader &) = delete;
+
+  /// Captures the completed versioned information for a particular part of
+  /// API notes, including both unversioned API notes and each versioned API
+  /// note for that particular entity.
+  template <typename T> class VersionedInfo {
+    /// The complete set of results.
+    llvm::SmallVector<std::pair<llvm::VersionTuple, T>, 1> Results;
+
+    /// The index of the result that is the "selected" set based on the desired
+    /// Swift version, or \c Results.size() if nothing matched.
+    unsigned Selected;
+
+  public:
+    /// Form an empty set of versioned information.
+    VersionedInfo(std::nullopt_t) : Selected(0) {}
+
+    /// Form a versioned info set given the desired version and a set of
+    /// results.
+    VersionedInfo(
+        llvm::VersionTuple Version,
+        llvm::SmallVector<std::pair<llvm::VersionTuple, T>, 1> Results);
+
+    /// Retrieve the selected index in the result set.
+    std::optional<unsigned> getSelected() const {
+      if (Selected == Results.size())
+        return std::nullopt;
+      return Selected;
+    }
+
+    /// Return the number of versioned results we know about.
+    unsigned size() const { return Results.size(); }
+
+    /// Access all versioned results.
+    const std::pair<llvm::VersionTuple, T> *begin() const {
+      return Results.begin();
+    }
+    const std::pair<llvm::VersionTuple, T> *end() const {
+      return Results.end();
+    }
+
+    /// Access a specific versioned result.
+    const std::pair<llvm::VersionTuple, T> &operator[](unsigned index) const {
+      return Results[index];
+    }
+  };
+
+  /// Look for the context ID of the given Objective-C class.
+  ///
+  /// \param Name The name of the class we're looking for.
+  ///
+  /// \returns The ID, if known.
+  std::optional<ContextID> lookupObjCClassID(llvm::StringRef Name);
+
+  /// Look for information regarding the given Objective-C class.
+  ///
+  /// \param Name The name of the class we're looking for.
+  ///
+  /// \returns The information about the class, if known.
+  VersionedInfo<ObjCContextInfo> lookupObjCClassInfo(llvm::StringRef Name);
+
+  /// Look for the context ID of the given Objective-C protocol.
+  ///
+  /// \param Name The name of the protocol we're looking for.
+  ///
+  /// \returns The ID of the protocol, if known.
+  std::optional<ContextID> lookupObjCProtocolID(llvm::StringRef Name);
+
+  /// Look for information regarding the given Objective-C protocol.
+  ///
+  /// \param Name The name of the protocol we're looking for.
+  ///
+  /// \returns The information about the protocol, if known.
+  VersionedInfo<ObjCContextInfo> lookupObjCProtocolInfo(llvm::StringRef Name);
+
+  /// Look for information regarding the given Objective-C property in
+  /// the given context.
+  ///
+  /// \param CtxID The ID that references the context we are looking for.
+  /// \param Name The name of the property we're looking for.
+  /// \param IsInstance Whether we are looking for an instance property (vs.
+  /// a class property).
+  ///
+  /// \returns Information about the property, if known.
+  VersionedInfo<ObjCPropertyInfo>
+  lookupObjCProperty(ContextID CtxID, llvm::StringRef Name, bool IsInstance);
----------------
compnerd wrote:

Discussed this offline - the idea is to sink the ObjC properties into the `ObjCContextInfo`. This is left as a follow up for now to get the changes in tree first.

https://github.com/llvm/llvm-project/pull/66769