path: root/lib/Sema/SemaLookup.cpp

//===--------------------- SemaLookup.cpp - Name Lookup  ------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements name lookup for C, C++, Objective-C, and
//  Objective-C++.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "SemaInherit.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Parse/DeclSpec.h"
#include "clang/Basic/LangOptions.h"
#include "llvm/ADT/STLExtras.h"
#include <set>

using namespace clang;

/// MaybeConstructOverloadSet - Name lookup has determined that the
/// elements in [I, IEnd) have the name that we are looking for, and
/// *I is a match for the namespace. This routine returns an
/// appropriate Decl for name lookup, which may either be *I or an
/// OverloadeFunctionDecl that represents the overloaded functions in
/// [I, IEnd). 
///
/// The existance of this routine is temporary; LookupDecl should
/// probably be able to return multiple results, to deal with cases of
/// ambiguity and overloaded functions without needing to create a
/// Decl node.
template<typename DeclIterator>
static Decl *
MaybeConstructOverloadSet(ASTContext &Context, 
                          DeclIterator I, DeclIterator IEnd) {
  assert(I != IEnd && "Iterator range cannot be empty");
  assert(!isa<OverloadedFunctionDecl>(*I) && 
         "Cannot have an overloaded function");

  if (isa<FunctionDecl>(*I)) {
    // If we found a function, there might be more functions. If
    // so, collect them into an overload set.
    DeclIterator Last = I;
    OverloadedFunctionDecl *Ovl = 0;
    for (++Last; Last != IEnd && isa<FunctionDecl>(*Last); ++Last) {
      if (!Ovl) {
        // FIXME: We leak this overload set. Eventually, we want to
        // stop building the declarations for these overload sets, so
        // there will be nothing to leak.
        Ovl = OverloadedFunctionDecl::Create(Context, 
                                         cast<ScopedDecl>(*I)->getDeclContext(),
                                             (*I)->getDeclName());
        Ovl->addOverload(cast<FunctionDecl>(*I));
      }
      Ovl->addOverload(cast<FunctionDecl>(*Last));
    }
    
    // If we had more than one function, we built an overload
    // set. Return it.
    if (Ovl)
      return Ovl;
  }
  
  return *I;
}

/// @brief Constructs name lookup criteria.
///
/// @param K The kind of name that we're searching for.
///
/// @param RedeclarationOnly If true, then name lookup will only look
/// into the current scope for names, not in parent scopes. This
/// option should be set when we're looking to introduce a new
/// declaration into scope.
///
/// @param CPlusPlus Whether we are performing C++ name lookup or not.
Sema::LookupCriteria::LookupCriteria(NameKind K, bool RedeclarationOnly,
                                     bool CPlusPlus)  
  : Kind(K), AllowLazyBuiltinCreation(K == Ordinary), 
    RedeclarationOnly(RedeclarationOnly) { 
  switch (Kind) {
  case Ordinary:
    IDNS = Decl::IDNS_Ordinary;
    if (CPlusPlus)
      IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member;
    break;

  case Tag:
    IDNS = Decl::IDNS_Tag;
    break;

  case Member:
    IDNS = Decl::IDNS_Member;
    if (CPlusPlus)
      IDNS |= Decl::IDNS_Tag | Decl::IDNS_Ordinary;    
    break;

  case NestedNameSpecifier:
  case Namespace:
    IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member;
    break;
  }
}

/// isLookupResult - Determines whether D is a suitable lookup result
/// according to the lookup criteria.
bool Sema::LookupCriteria::isLookupResult(Decl *D) const {
  switch (Kind) {
  case Ordinary:
  case Tag:
  case Member:
    return D->isInIdentifierNamespace(IDNS);

  case NestedNameSpecifier:
    return isa<TypedefDecl>(D) || D->isInIdentifierNamespace(Decl::IDNS_Tag);

  case Namespace:
    return isa<NamespaceDecl>(D);
  }

  assert(false && "isLookupResult always returns before this point");
  return false;
}

/// @brief Moves the name-lookup results from Other to the
/// newly-constructed LookupResult.
Sema::LookupResult::LookupResult(const LookupResult& Other) 
  : StoredKind(Other.StoredKind), First(Other.First), Last(Other.Last),
    Context(Other.Context) {
  Other.StoredKind = Dead;
}

/// @brief Moves the name-lookup results from Other to this LookupResult.
Sema::LookupResult::LookupResult(ASTContext &Context, 
                                 IdentifierResolver::iterator F, 
                                 IdentifierResolver::iterator L)
  : Context(&Context) {
  if (F != L && isa<FunctionDecl>(*F)) {
    IdentifierResolver::iterator Next = F;
    ++Next;
    if (Next != L && isa<FunctionDecl>(*Next)) {
      StoredKind = OverloadedDeclFromIdResolver;
      First = F.getAsOpaqueValue();
      Last = L.getAsOpaqueValue();
      return;
    }
  } 
    
  StoredKind = SingleDecl;
  First = reinterpret_cast<uintptr_t>(*F);
  Last = 0;
}

Sema::LookupResult::LookupResult(ASTContext &Context, 
                                 DeclContext::lookup_iterator F, 
                                 DeclContext::lookup_iterator L)
  : Context(&Context) {
  if (F != L && isa<FunctionDecl>(*F)) {
    DeclContext::lookup_iterator Next = F;
    ++Next;
    if (Next != L && isa<FunctionDecl>(*Next)) {
      StoredKind = OverloadedDeclFromDeclContext;
      First = reinterpret_cast<uintptr_t>(F);
      Last = reinterpret_cast<uintptr_t>(L);
      return;
    }
  }
  
  StoredKind = SingleDecl;
  First = reinterpret_cast<uintptr_t>(*F);
  Last = 0;
}

Sema::LookupResult::~LookupResult() {
  if (StoredKind == AmbiguousLookup)
    delete getBasePaths();
}

Sema::LookupResult& Sema::LookupResult::operator=(const LookupResult& Other) {
  if (StoredKind == AmbiguousLookup)
    delete getBasePaths();

  StoredKind = Other.StoredKind;
  First = Other.First;
  Last = Other.Last;
  Context = Other.Context;

  Other.StoredKind = Dead;
  return *this;
}


/// @brief Determine the result of name lookup.
Sema::LookupResult::LookupKind Sema::LookupResult::getKind() const {
  switch (StoredKind) {
  case SingleDecl:
    return (reinterpret_cast<Decl *>(First) != 0)? Found : NotFound;

  case OverloadedDeclFromIdResolver:
  case OverloadedDeclFromDeclContext:
    return FoundOverloaded;

  case AmbiguousLookup:
    return Last? AmbiguousBaseSubobjectTypes : AmbiguousBaseSubobjects;

  case Dead:
    assert(false && "Attempt to look at a dead LookupResult");
    break;
  }

  // We can't ever get here.
  return NotFound;
}

/// @brief Converts the result of name lookup into a single (possible
/// NULL) pointer to a declaration.
///
/// The resulting declaration will either be the declaration we found
/// (if only a s