Implement code completion for tags, e.g., code completion after "enum"
will provide the names of various enumerations currently
visible. Introduced filtering of code-completion results when we build
the result set, so that we can identify just the kinds of declarations
we want.

This implementation is incomplete for C++, since we don't consider
that the token after the tag keyword could start a
nested-name-specifier. 



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82222 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index f08c481..2eccbd0 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -1589,7 +1589,12 @@
 void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
                                 AccessSpecifier AS) {
   // Parse the tag portion of this.
-
+  if (Tok.is(tok::code_completion)) {
+    // Code completion for an enum name.
+    Actions.CodeCompleteTag(CurScope, DeclSpec::TST_enum);
+    ConsumeToken();
+  }
+  
   AttributeList *Attr = 0;
   // If attributes exist after tag, parse them.
   if (Tok.is(tok::kw___attribute))
diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index 671a542..1b82c06 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -527,6 +527,12 @@
     TagType = DeclSpec::TST_union;
   }
 
+  if (Tok.is(tok::code_completion)) {
+    // Code completion for a struct, class, or union name.
+    Actions.CodeCompleteTag(CurScope, TagType);
+    ConsumeToken();
+  }
+  
   AttributeList *Attr = 0;
   // If attributes exist after tag, parse them.
   if (Tok.is(tok::kw___attribute))
diff --git a/lib/Sema/CodeCompleteConsumer.cpp b/lib/Sema/CodeCompleteConsumer.cpp
index 7464bc1..707ad9a 100644
--- a/lib/Sema/CodeCompleteConsumer.cpp
+++ b/lib/Sema/CodeCompleteConsumer.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 #include "clang/Sema/CodeCompleteConsumer.h"
+#include "clang/Parse/Scope.h"
 #include "clang/Lex/Preprocessor.h"
 #include "Sema.h"
 #include "llvm/ADT/STLExtras.h"
@@ -41,11 +42,11 @@
       return;
   }
   
-  ResultSet Results;
+  ResultSet Results(*this);
   unsigned NextRank = 0;
   
   if (const RecordType *Record = BaseType->getAs<RecordType>()) {
-    NextRank = CollectMemberResults(Record->getDecl(), NextRank, Results);
+    NextRank = CollectMemberLookupResults(Record->getDecl(), NextRank, Results);
 
     if (getSema().getLangOptions().CPlusPlus) {
       if (!Results.empty())
@@ -64,6 +65,32 @@
   }
 }
 
+void CodeCompleteConsumer::CodeCompleteTag(Scope *S, ElaboratedType::TagKind TK) {
+  ResultSet::LookupFilter Filter = 0;
+  switch (TK) {
+  case ElaboratedType::TK_enum:
+    Filter = &CodeCompleteConsumer::IsEnum;
+    break;
+    
+  case ElaboratedType::TK_class:
+  case ElaboratedType::TK_struct:
+    Filter = &CodeCompleteConsumer::IsClassOrStruct;
+    break;
+    
+  case ElaboratedType::TK_union:
+    Filter = &CodeCompleteConsumer::IsUnion;
+    break;
+  }
+  
+  ResultSet Results(*this, Filter);
+  CollectLookupResults(S, 0, Results);
+  
+  // FIXME: In C++, we could have the start of a nested-name-specifier.
+  // Add those results (with a poorer rank, naturally).
+  
+  ProcessCodeCompleteResults(Results.data(), Results.size());
+}
+
 void 
 CodeCompleteConsumer::CodeCompleteQualifiedId(Scope *S, 
                                               NestedNameSpecifier *NNS,
@@ -74,8 +101,8 @@
   if (!Ctx)
     return;
   
-  ResultSet Results;
-  unsigned NextRank = CollectMemberResults(Ctx, 0, Results);
+  ResultSet Results(*this);
+  unsigned NextRank = CollectMemberLookupResults(Ctx, 0, Results);
   
   // The "template" keyword can follow "::" in the grammar
   if (!Results.empty())
@@ -92,6 +119,11 @@
   }
   
   // FIXME: Using declarations
+  // FIXME: Separate overload sets
+  
+  // Filter out any unwanted results.
+  if (Filter && !(Completer.*Filter)(R.Declaration))
+    return;
   
   Decl *CanonDecl = R.Declaration->getCanonicalDecl();
   unsigned IDNS = CanonDecl->getIdentifierNamespace();
@@ -164,23 +196,89 @@
   ShadowMaps.pop_back();
 }
 
+// Find the next outer declaration context corresponding to this scope.
+static DeclContext *findOuterContext(Scope *S) {
+  for (S = S->getParent(); S; S = S->getParent())
+    if (S->getEntity())
+      return static_cast<DeclContext *>(S->getEntity())->getPrimaryContext();
+  
+  return 0;
+}
+
+/// \brief Collect the results of searching for declarations within the given
+/// scope and its parent scopes.
+///
+/// \param S the scope in which we will start looking for declarations.
+///
+/// \param InitialRank the initial rank given to results in this scope.
+/// Larger rank values will be used for results found in parent scopes.
+unsigned CodeCompleteConsumer::CollectLookupResults(Scope *S, 
+                                                    unsigned InitialRank,
+                                                    ResultSet &Results) {
+  if (!S)
+    return InitialRank;
+  
+  // FIXME: Using directives!
+  
+  unsigned NextRank = InitialRank;
+  Results.EnterNewScope();
+  if (S->getEntity() && 
+      !((DeclContext *)S->getEntity())->isFunctionOrMethod()) {
+    // Look into this scope's declaration context, along with any of its
+    // parent lookup contexts (e.g., enclosing classes), up to the point
+    // where we hit the context stored in the next outer scope.
+    DeclContext *Ctx = (DeclContext *)S->getEntity();
+    DeclContext *OuterCtx = findOuterContext(S);
+    
+    for (; Ctx && Ctx->getPrimaryContext() != OuterCtx;
+         Ctx = Ctx->getLookupParent()) {
+      if (Ctx->isFunctionOrMethod())
+        continue;
+      
+      NextRank = CollectMemberLookupResults(Ctx, NextRank + 1, Results);
+    }
+  } else if (!S->getParent()) {
+    // Look into the translation unit scope. We walk through the translation
+    // unit's declaration context, because the Scope itself won't have all of
+    // the declarations if 
+    NextRank = CollectMemberLookupResults(
+                                    getSema().Context.getTranslationUnitDecl(), 
+                                          NextRank + 1, Results);
+  } else {
+    // Walk through the declarations in this Scope.
+    for (Scope::decl_iterator D = S->decl_begin(), DEnd = S->decl_end();
+         D != DEnd; ++D) {
+      if (NamedDecl *ND = dyn_cast<NamedDecl>((Decl *)((*D).get())))
+        Results.MaybeAddResult(Result(ND, NextRank));        
+    }
+    
+    NextRank = NextRank + 1;
+  }
+  
+  // Lookup names in the parent scope.
+  NextRank = CollectLookupResults(S->getParent(), NextRank, Results);
+  Results.ExitScope();
+  
+  return NextRank;
+}
+
 /// \brief Collect the results of searching for members within the given
 /// declaration context.
 ///
 /// \param Ctx the declaration context from which we will gather results.
 ///
-/// \param InitialRank the initial rank given to results in this tag
-/// declaration. Larger rank values will be used for, e.g., members found
-/// in base classes.
+/// \param InitialRank the initial rank given to results in this declaration
+/// context. Larger rank values will be used for, e.g., members found in
+/// base classes.
 ///
 /// \param Results the result set that will be extended with any results
 /// found within this declaration context (and, for a C++ class, its bases).
 ///
 /// \returns the next higher rank value, after considering all of the
 /// names within this declaration context.
-unsigned CodeCompleteConsumer::CollectMemberResults(DeclContext *Ctx, 
-                                                    unsigned InitialRank,
-                                                    ResultSet &Results) {
+unsigned CodeCompleteConsumer::CollectMemberLookupResults(DeclContext *Ctx, 
+                                                          unsigned InitialRank,
+                                                          ResultSet &Results) {
   // Enumerate all of the results in this context.
   Results.EnterNewScope();
   for (DeclContext *CurCtx = Ctx->getPrimaryContext(); CurCtx; 
@@ -188,10 +286,8 @@
     for (DeclContext::decl_iterator D = CurCtx->decls_begin(), 
                                  DEnd = CurCtx->decls_end();
          D != DEnd; ++D) {
-      if (NamedDecl *ND = dyn_cast<NamedDecl>(*D)) {
-        // FIXME: Apply a filter to the results
+      if (NamedDecl *ND = dyn_cast<NamedDecl>(*D))
         Results.MaybeAddResult(Result(ND, InitialRank));
-      }
     }
   }
   
@@ -235,9 +331,9 @@
       
       // Collect results from this base class (and its bases).
       NextRank = std::max(NextRank, 
-                          CollectMemberResults(Record->getDecl(), 
-                                               InitialRank + 1, 
-                                               Results));
+                          CollectMemberLookupResults(Record->getDecl(), 
+                                                     InitialRank + 1, 
+                                                     Results));
     }
   }
   
@@ -247,6 +343,46 @@
   return NextRank;
 }
 
+/// \brief Determines whether the given declaration is suitable as the 
+/// start of a C++ nested-name-specifier, e.g., a class or namespace.
+bool CodeCompleteConsumer::IsNestedNameSpecifier(NamedDecl *ND) const {
+  // Allow us to find class templates, too.
+  if (ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(ND))
+    ND = ClassTemplate->getTemplatedDecl();
+  
+  return getSema().isAcceptableNestedNameSpecifier(ND);
+}
+
+/// \brief Determines whether the given declaration is an enumeration.
+bool CodeCompleteConsumer::IsEnum(NamedDecl *ND) const {
+  return isa<EnumDecl>(ND);
+}
+
+/// \brief Determines whether the given declaration is a class or struct.
+bool CodeCompleteConsumer::IsClassOrStruct(NamedDecl *ND) const {
+  // Allow us to find class templates, too.
+  if (ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(ND))
+    ND = ClassTemplate->getTemplatedDecl();
+  
+  if (RecordDecl *RD = dyn_cast<RecordDecl>(ND))
+    return RD->getTagKind() == TagDecl::TK_class ||
+           RD->getTagKind() == TagDecl::TK_struct;
+  
+  return false;
+}
+
+/// \brief Determines whether the given declaration is a union.
+bool CodeCompleteConsumer::IsUnion(NamedDecl *ND) const {
+  // Allow us to find class templates, too.
+  if (ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(ND))
+    ND = ClassTemplate->getTemplatedDecl();
+
+  if (RecordDecl *RD = dyn_cast<RecordDecl>(ND))
+    return RD->getTagKind() == TagDecl::TK_union;
+  
+  return false;
+}
+
 namespace {
   struct VISIBILITY_HIDDEN SortCodeCompleteResult {
     typedef CodeCompleteConsumer::Result Result;
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 915a859..2952c84 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -2083,6 +2083,7 @@
   virtual CXXScopeTy *ActOnCXXGlobalScopeSpecifier(Scope *S,
                                                    SourceLocation CCLoc);
 
+  bool isAcceptableNestedNameSpecifier(NamedDecl *SD);
   NamedDecl *FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS);
 
 
@@ -3635,6 +3636,8 @@
                                                SourceLocation OpLoc,
                                                bool IsArrow);
   
+  virtual void CodeCompleteTag(Scope *S, unsigned TagSpec);
+
   virtual void CodeCompleteQualifiedId(Scope *S, const CXXScopeSpec &SS,
                                        bool EnteringContext);
   //@}
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index 759b56c..60661f1 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -260,7 +260,7 @@
 
 /// \brief Determines whether the given declaration is an valid acceptable
 /// result for name lookup of a nested-name-specifier.
-bool isAcceptableNestedNameSpecifier(ASTContext &Context, NamedDecl *SD) {
+bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD) {
   if (!SD)
     return false;
 
@@ -307,7 +307,7 @@
   assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
 
   NamedDecl *Result = Found;
-  if (isAcceptableNestedNameSpecifier(Context, Result))
+  if (isAcceptableNestedNameSpecifier(Result))
     return Result;
 
   return 0;
@@ -406,7 +406,7 @@
 
   // FIXME: Deal with ambiguities cleanly.
   NamedDecl *SD = Found;
-  if (isAcceptableNestedNameSpecifier(Context, SD)) {
+  if (isAcceptableNestedNameSpecifier(SD)) {
     if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) {
       // C++ [basic.lookup.classref]p4:
       //   [...] If the name is found in both contexts, the
@@ -425,7 +425,7 @@
 
       // FIXME: Handle ambiguities in FoundOuter!
       NamedDecl *OuterDecl = FoundOuter;
-      if (isAcceptableNestedNameSpecifier(Context, OuterDecl) &&
+      if (isAcceptableNestedNameSpecifier(OuterDecl) &&
           OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
           (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
            !Context.hasSameType(
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 2183cfa..bfee4d8 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -34,6 +34,35 @@
   CodeCompleter->CodeCompleteMemberReferenceExpr(S, BaseType, IsArrow);
 }
 
+void Sema::CodeCompleteTag(Scope *S, unsigned TagSpec) {
+  if (!CodeCompleter)
+    return;
+  
+  TagDecl::TagKind TK;
+  switch ((DeclSpec::TST)TagSpec) {
+  case DeclSpec::TST_enum:
+    TK = TagDecl::TK_enum;
+    break;
+    
+  case DeclSpec::TST_union:
+    TK = TagDecl::TK_union;
+    break;
+    
+  case DeclSpec::TST_struct:
+    TK = TagDecl::TK_struct;
+    break;
+
+  case DeclSpec::TST_class:
+    TK = TagDecl::TK_class;
+    break;
+    
+  default:
+    assert(false && "Unknown type specifier kind in CodeCompleteTag");
+    return;
+  }
+  CodeCompleter->CodeCompleteTag(S, TK);
+}
+
 void Sema::CodeCompleteQualifiedId(Scope *S, const CXXScopeSpec &SS,
                                    bool EnteringContext) {
   if (!SS.getScopeRep() || !CodeCompleter)