Add support for retrieving the Doxygen comment associated with a given

declaration in the AST. 

The new ASTContext::getCommentForDecl function searches for a comment
that is attached to the given declaration, and returns that comment, 
which may be composed of several comment blocks.

Comments are always available in an AST. However, to avoid harming
performance, we don't actually parse the comments. Rather, we keep the
source ranges of all of the comments within a large, sorted vector,
then lazily extract comments via a binary search in that vector only
when needed (which never occurs in a "normal" compile).

Comments are written to a precompiled header/AST file as a blob of
source ranges. That blob is only lazily loaded when one requests a
comment for a declaration (this never occurs in a "normal" compile). 

The indexer testbed now supports comment extraction. When the
-point-at location points to a declaration with a Doxygen-style
comment, the indexer testbed prints the associated comment
block(s). See test/Index/comments.c for an example.

Some notes:
  - We don't actually attempt to parse the comment blocks themselves,
  beyond identifying them as Doxygen comment blocks to associate them
  with a declaration.
  - We won't find comment blocks that aren't adjacent to the
  declaration, because we start our search based on the location of
  the declaration.
  - We don't go through the necessary hops to find, for example,
  whether some redeclaration of a declaration has comments when our
  current declaration does not. Similarly, we don't attempt to
  associate a \param Foo marker in a function body comment with the
  parameter named Foo (although that is certainly possible).
  - Verification of my "no performance impact" claims is still "to be
  done".



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74704 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index f229881bfc..6d5ed72455 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -26,6 +26,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/Support/Allocator.h"
+#include <vector>
 
 namespace clang {
   
@@ -35,6 +36,7 @@ class FileEntry;
 class HeaderSearch;
 class PragmaNamespace;
 class PragmaHandler;
+class CommentHandler;
 class ScratchBuffer;
 class TargetInfo;
 class PPCallbacks;
@@ -109,6 +111,10 @@ class Preprocessor {
   /// with this preprocessor.
   PragmaNamespace *PragmaHandlers;
   
+  /// \brief Tracks all of the comment handlers that the client registered 
+  /// with this preprocessor.
+  std::vector<CommentHandler *> CommentHandlers;
+  
   /// CurLexer - This is the current top of the stack that we're lexing from if
   /// not expanding a macro and we are lexing directly from source code.
   ///  Only one of CurLexer, CurPTHLexer, or CurTokenLexer will be non-null.
@@ -301,6 +307,14 @@ public:
   /// to remove a handler that has not been registered.
   void RemovePragmaHandler(const char *Namespace, PragmaHandler *Handler);
 
+  /// \brief Add the specified comment handler to the preprocessor.
+  void AddCommentHandler(CommentHandler *Handler);
+  
+  /// \brief Remove the specified comment handler.
+  ///
+  /// It is an error to remove a handler that has not been registered.
+  void RemoveCommentHandler(CommentHandler *Handler);
+  
   /// EnterMainSourceFile - Enter the specified FileID as the main source file,
   /// which implicitly adds the builtin defines etc.
   void EnterMainSourceFile();  
@@ -791,6 +805,7 @@ public:
   void HandlePragmaSystemHeader(Token &SysHeaderTok);
   void HandlePragmaDependency(Token &DependencyTok);
   void HandlePragmaComment(Token &CommentTok);
+  void HandleComment(SourceRange Comment);
 };
 
 /// PreprocessorFactory - A generic factory interface for lazily creating
@@ -801,6 +816,15 @@ public:
   virtual Preprocessor* CreatePreprocessor() = 0;  
 };
   
+/// \brief Abstract base class that describes a handler that will receive 
+/// source ranges for each of the comments encountered in the source file.
+class CommentHandler {
+public:
+  virtual ~CommentHandler();
+  
+  virtual void HandleComment(Preprocessor &PP, SourceRange Comment) = 0;
+};
+  
 }  // end namespace clang
 
 #endif