text: //===--- Scope.h - Scope interface ------------------------------*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file defines the Scope interface.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_CLANG_SEMA_SCOPE_H
  #define LLVM_CLANG_SEMA_SCOPE_H
  
  #include "clang/Basic/Diagnostic.h"
  #include "llvm/ADT/SmallPtrSet.h"
  #include "llvm/ADT/SmallVector.h"
  
  namespace clang {
  
  class Decl;
  class UsingDirectiveDecl;
  
  /// Scope - A scope is a transient data structure that is used while parsing the
  /// program.  It assists with resolving identifiers to the appropriate
  /// declaration.
  ///
  class Scope {
  public:
    /// ScopeFlags - These are bitfields that are or'd together when creating a
    /// scope, which defines the sorts of things the scope contains.
    enum ScopeFlags {
      /// FnScope - This indicates that the scope corresponds to a function, which
      /// means that labels are set here.
      FnScope       = 0x01,
  
      /// BreakScope - This is a while,do,switch,for, etc that can have break
      /// stmts embedded into it.
      BreakScope    = 0x02,
  
      /// ContinueScope - This is a while,do,for, which can have continue
      /// stmt embedded into it.
      ContinueScope = 0x04,
  
      /// DeclScope - This is a scope that can contain a declaration.  Some scopes
      /// just contain loop constructs but don't contain decls.
      DeclScope = 0x08,
  
      /// ControlScope - The controlling scope in a if/switch/while/for statement.
      ControlScope = 0x10,
  
      /// ClassScope - The scope of a struct/union/class definition.
      ClassScope = 0x20,
  
      /// BlockScope - This is a scope that corresponds to a block/closure object.
      /// Blocks serve as top-level scopes for some objects like labels, they
      /// also prevent things like break and continue.  BlockScopes always have
      /// the FnScope and DeclScope flags set as well.
      BlockScope = 0x40,
  
      /// TemplateParamScope - This is a scope that corresponds to the
      /// template parameters of a C++ template. Template parameter
      /// scope starts at the 'template' keyword and ends when the
      /// template declaration ends.
      TemplateParamScope = 0x80,
  
      /// FunctionPrototypeScope - This is a scope that corresponds to the
      /// parameters within a function prototype.
      FunctionPrototypeScope = 0x100,
  
      /// AtCatchScope - This is a scope that corresponds to the Objective-C
      /// \@catch statement.
      AtCatchScope = 0x200,
      
      /// ObjCMethodScope - This scope corresponds to an Objective-C method body.
      /// It always has FnScope and DeclScope set as well.
      ObjCMethodScope = 0x400,
  
      /// SwitchScope - This is a scope that corresponds to a switch statement.
      SwitchScope = 0x800,
  
      /// TryScope - This is the scope of a C++ try statement.
      TryScope = 0x1000
    };
  private:
    /// The parent scope for this scope.  This is null for the translation-unit
    /// scope.
    Scope *AnyParent;
  
    /// Depth - This is the depth of this scope.  The translation-unit scope has
    /// depth 0.
    unsigned short Depth;
  
    /// Flags - This contains a set of ScopeFlags, which indicates how the scope
    /// interrelates with other control flow statements.
    unsigned short Flags;
  
    /// PrototypeDepth - This is the number of function prototype scopes
    /// enclosing this scope, including this scope.
    unsigned short PrototypeDepth;
  
    /// PrototypeIndex - This is the number of parameters currently
    /// declared in this scope.
    unsigned short PrototypeIndex;
  
    /// FnParent - If this scope has a parent scope that is a function body, this
    /// pointer is non-null and points to it.  This is used for label processing.
    Scope *FnParent;
  
    /// BreakParent/ContinueParent - This is a direct link to the innermost
    /// BreakScope/ContinueScope which contains the contents of this scope
    /// for control flow purposes (and might be this scope itself), or null
    /// if there is no such scope.
    Scope *BreakParent, *ContinueParent;
  
    /// BlockParent - This is a direct link to the immediately containing
    /// BlockScope if this scope is not one, or null if there is none.
    Scope *BlockParent;
  
    /// TemplateParamParent - This is a direct link to the
    /// immediately containing template parameter scope. In the
    /// case of nested templates, template parameter scopes can have
    /// other template parameter scopes as parents.
    Scope *TemplateParamParent;
  
    /// DeclsInScope - This keeps track of all declarations in this scope.  When
    /// the declaration is added to the scope, it is set as the current
    /// declaration for the identifier in the IdentifierTable.  When the scope is
    /// popped, these declarations are removed from the IdentifierTable's notion
    /// of current declaration.  It is up to the current Action implementation to
    /// implement these semantics.
    typedef llvm::SmallPtrSet<Decl *, 32> DeclSetTy;
    DeclSetTy DeclsInScope;
  
    /// Entity - The entity with which this scope is associated. For
    /// example, the entity of a class scope is the class itself, the
    /// entity of a function scope is a function, etc. This field is
    /// maintained by the Action implementation.
    void *Entity;
  
    typedef SmallVector<UsingDirectiveDecl *, 2> UsingDirectivesTy;
    UsingDirectivesTy UsingDirectives;
  
    /// \brief Used to determine if errors occurred in this scope.
    DiagnosticErrorTrap ErrorTrap;
    
  public:
    Scope(Scope *Parent, unsigned ScopeFlags, DiagnosticsEngine &Diag)
      : ErrorTrap(Diag) {
      Init(Parent, ScopeFlags);
    }
  
    /// getFlags - Return the flags for this scope.
    ///
    unsigned getFlags() const { return Flags; }
    void setFlags(unsigned F) { Flags = F; }
  
    /// isBlockScope - Return true if this scope correspond to a closure.
    bool isBlockScope() const { return Flags & BlockScope; }
  
    /// getParent - Return the scope that this is nested in.
    ///
    const Scope *getParent() const { return AnyParent; }
    Scope *getParent() { return AnyParent; }
  
    /// getFnParent - Return the closest scope that is a function body.
    ///
    const Scope *getFnParent() const { return FnParent; }
    Scope *getFnParent() { return FnParent; }
  
    /// getContinueParent - Return the closest scope that a continue statement
    /// would be affected by.
    Scope *getContinueParent() {
      return ContinueParent;
    }
  
    const Scope *getContinueParent() const {
      return const_cast<Scope*>(this)->getContinueParent();
    }
  
    /// getBreakParent - Return the closest scope that a break statement
    /// would be affected by.
    Scope *getBreakParent() {
      return BreakParent;
    }
    const Scope *getBreakParent() const {
      return const_cast<Scope*>(this)->getBreakParent();
    }
  
    Scope *getBlockParent() { return BlockParent; }
    const Scope *getBlockParent() const { return BlockParent; }
  
    Scope *getTemplateParamParent() { return TemplateParamParent; }
    const Scope *getTemplateParamParent() const { return TemplateParamParent; }
  
    /// Returns the number of function prototype scopes in this scope
    /// chain.
    unsigned getFunctionPrototypeDepth() const {
      return PrototypeDepth;
    }
  
    /// Return the number of parameters declared in this function
    /// prototype, increasing it by one for the next call.
    unsigned getNextFunctionPrototypeIndex() {
      assert(isFunctionPrototypeScope());
      return PrototypeIndex++;
    }
  
    typedef DeclSetTy::iterator decl_iterator;
    decl_iterator decl_begin() const { return DeclsInScope.begin(); }
    decl_iterator decl_end()   const { return DeclsInScope.end(); }
    bool decl_empty()          const { return DeclsInScope.empty(); }
  
    void AddDecl(Decl *D) {
      DeclsInScope.insert(D);
    }
  
    void RemoveDecl(Decl *D) {
      DeclsInScope.erase(D);
    }
  
    /// isDeclScope - Return true if this is the scope that the specified decl is
    /// declared in.
    bool isDeclScope(Decl *D) {
      return DeclsInScope.count(D) != 0;
    }
  
    void* getEntity() const { return Entity; }
    void setEntity(void *E) { Entity = E; }
  
    bool hasErrorOccurred() const { return ErrorTrap.hasErrorOccurred(); }
                             
    /// isClassScope - Return true if this scope is a class/struct/union scope.
    bool isClassScope() const {
      return (getFlags() & Scope::ClassScope);
    }
  
    /// isInCXXInlineMethodScope - Return true if this scope is a C++ inline
    /// method scope or is inside one.
    bool isInCXXInlineMethodScope() const {
      if (const Scope *FnS = getFnParent()) {
        assert(FnS->getParent() && "TUScope not created?");
        return FnS->getParent()->isClassScope();
      }
      return false;
    }
    
    /// isInObjcMethodScope - Return true if this scope is, or is contained in, an
    /// Objective-C method body.  Note that this method is not constant time.
    bool isInObjcMethodScope() const {
      for (const Scope *S = this; S; S = S->getParent()) {
        // If this scope is an objc method scope, then we succeed.
        if (S->getFlags() & ObjCMethodScope)
          return true;
      }
      return false;
    }
  
    /// isTemplateParamScope - Return true if this scope is a C++
    /// template parameter scope.
    bool isTemplateParamScope() const {
      return getFlags() & Scope::TemplateParamScope;
    }
  
    /// isFunctionPrototypeScope - Return true if this scope is a
    /// function prototype scope.
    bool isFunctionPrototypeScope() const {
      return getFlags() & Scope::FunctionPrototypeScope;
    }
  
    /// isAtCatchScope - Return true if this scope is \@catch.
    bool isAtCatchScope() const {
      return getFlags() & Scope::AtCatchScope;
    }
  
    /// isSwitchScope - Return true if this scope is a switch scope.
    bool isSwitchScope() const {
      for (const Scope *S = this; S; S = S->getParent()) {
        if (S->getFlags() & Scope::SwitchScope)
          return true;
        else if (S->getFlags() & (Scope::FnScope | Scope::ClassScope |
                                  Scope::BlockScope | Scope::TemplateParamScope |
                                  Scope::FunctionPrototypeScope |
                                  Scope::AtCatchScope | Scope::ObjCMethodScope))
          return false;
      }
      return false;
    }
    
    /// \brief Determine whether this scope is a C++ 'try' block.
    bool isTryScope() const { return getFlags() & Scope::TryScope; }
  
    /// containedInPrototypeScope - Return true if this or a parent scope
    /// is a FunctionPrototypeScope.
    bool containedInPrototypeScope() const;
  
    typedef UsingDirectivesTy::iterator udir_iterator;
    typedef UsingDirectivesTy::const_iterator const_udir_iterator;
  
    void PushUsingDirective(UsingDirectiveDecl *UDir) {
      UsingDirectives.push_back(UDir);
    }
  
    udir_iterator using_directives_begin() {
      return UsingDirectives.begin();
    }
  
    udir_iterator using_directives_end() {
      return UsingDirectives.end();
    }
  
    const_udir_iterator using_directives_begin() const {
      return UsingDirectives.begin();
    }
  
    const_udir_iterator using_directives_end() const {
      return UsingDirectives.end();
    }
  
    /// Init - This is used by the parser to implement scope caching.
    ///
    void Init(Scope *parent, unsigned flags);
  };
  
  }  // end namespace clang
  
  #endif
  