[PATCH] Added code-completion results to override virtual methods from base class

[Sergey Shambir]

Hi rsmith,

Inside C++ class definition, QtCreator adds virtual methods from base class to completion list. The patch ports such feature to clang.

http://llvm-reviews.chandlerc.com/D622

Files:
  lib/Sema/SemaCodeComplete.cpp
  include/clang/Sema/CodeCompleteConsumer.h

Index: lib/Sema/SemaCodeComplete.cpp
===================================================================
--- lib/Sema/SemaCodeComplete.cpp
+++ lib/Sema/SemaCodeComplete.cpp
@@ -1259,12 +1259,55 @@
       bool Accessible = true;
       if (Ctx)
         Accessible = Results.getSema().IsSimplyAccessible(ND, Ctx);
-      
       ResultBuilder::Result Result(ND, Results.getBasePriority(ND), 0, false,
                                    Accessible);
       Results.AddResult(Result, CurContext, Hiding, InBaseClass);
     }
   };
+
+  /// \brief Visible declaration consumer that adds a code-completion result
+  /// for each C++ non-final virtual method.
+  /// Works in two passes: 1. ban unsuitable methods and 2. collect suitable
+  class OverridableMethodDeclConsumer : public VisibleDeclConsumer {
+    ResultBuilder &Results;
+    DeclContext *CurContext;
+    llvm::StringSet<> ConsumedMethods;
+    bool IsCollectPass;
+
+  public:
+    OverridableMethodDeclConsumer(ResultBuilder &Results, DeclContext *CurContext)
+      : Results(Results), CurContext(CurContext), IsCollectPass(false) { }
+
+    void StartCollectPass()
+    {
+        IsCollectPass = true;
+    }
+
+    virtual void FoundDecl(NamedDecl *ND, NamedDecl *,
+                           DeclContext *Ctx, bool InBaseClass) {
+      const CXXMethodDecl *MD = dyn_cast<const CXXMethodDecl>(ND);
+      if (!MD || isa<CXXDestructorDecl>(ND) || !MD->isVirtual())
+        return;
+
+      if (!IsCollectPass) {
+          if (MD->getAttr<FinalAttr>() || !InBaseClass)
+            ConsumedMethods.insert(MD->getName());
+          return;
+      }
+
+      if (0 == ConsumedMethods.count(ND->getName())) {
+        ConsumedMethods.insert(MD->getName());
+        unsigned priority = CCP_MemberDeclaration;
+        if (MD->isPure())
+          priority /= CCF_OverridePureVirtual;
+        bool Accessible = true;
+        if (Ctx)
+          Accessible = Results.getSema().IsSimplyAccessible(ND, Ctx);
+        ResultBuilder::Result Result(ND, priority, 0, false, Accessible);
+        Results.AddResult(Result);
+      }
+    }
+  };
 }
 
 /// \brief Add type specifiers for the current language as keyword results.
@@ -3227,7 +3270,6 @@
   // only allowed where we can have an expression.
   switch (CompletionContext) {
   case PCC_Namespace:
-  case PCC_Class:
   case PCC_ObjCInterface:
   case PCC_ObjCImplementation:
   case PCC_ObjCInstanceVariableList:
@@ -3238,6 +3280,16 @@
     Results.setFilter(&ResultBuilder::IsOrdinaryNonValueName);
     break;
 
+  case PCC_Class: {
+      // Collect non-final virtual methods from base classes
+      OverridableMethodDeclConsumer Consumer(Results, CurContext);
+      LookupVisibleDecls(S, LookupMemberName, Consumer, false);
+      Consumer.StartCollectPass();
+      LookupVisibleDecls(S, LookupMemberName, Consumer, false);
+      Results.setFilter(&ResultBuilder::IsOrdinaryNonValueName);
+  }
+      break;
+
   case PCC_Statement:
   case PCC_ParenthesizedExpression:
   case PCC_Expression:
Index: include/clang/Sema/CodeCompleteConsumer.h
===================================================================
--- include/clang/Sema/CodeCompleteConsumer.h
+++ include/clang/Sema/CodeCompleteConsumer.h
@@ -99,7 +99,10 @@
   /// \brief Divide by this factor when a code-completion result's type is
   /// similar to the type we expect (e.g., both arithmetic types, both
   /// Objective-C object pointer types).
-  CCF_SimilarTypeMatch = 2
+  CCF_SimilarTypeMatch = 2,
+  /// \brief Divide by this factor when a code-completion will override
+  /// pure virtual method rather than just virtual
+  CCF_OverridePureVirtual = 2
 };
 
 /// \brief A simplified classification of types used when determining
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