//===--- Scope.h - Scope interface ------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the Scope interface.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_PARSE_SCOPE_H
#define LLVM_CLANG_PARSE_SCOPE_H

#include "clang/Parse/Action.h"
#include "llvm/ADT/SmallPtrSet.h"

namespace clang {

/// 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,
    
    /// HasBreak - This flag is set on 'BreakScope' scopes, when they actually
    /// do contain a break stmt.
    HasBreak      = 0x08,
    
    /// HasContinue - This flag is set on 'ContinueScope' scopes, when they
    /// actually do contain a continue stmt.
    HasContinue   = 0x10
  };
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 Depth : 16;
  
  /// Flags - This contains a set of ScopeFlags, which indicates how the scope
  /// interrelates with other control flow statements.
  unsigned Flags : 8;
  
  /// 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 immediately
  /// preceeding BreakParent/ContinueParent if this scope is not one, or null if
  /// there is no containing break/continue scope.
  Scope *BreakParent, *ContinueParent;
  
  /// 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<Action::DeclTy*, 32> DeclSetTy;
  DeclSetTy DeclsInScope;
  
public:
  Scope(Scope *Parent, unsigned ScopeFlags) {
    Init(Parent, ScopeFlags);
  }
  
  /// getParent - Return the scope that this is nested in.
  ///
  Scope *getParent() const { return AnyParent; }
  
  /// getContinueParent - Return the closest scope that a continue statement
  /// would be affected by.
  Scope *getContinueParent() const {
    return ContinueParent;
  }
  
  /// getBreakParent - Return the closest scope that a break statement
  /// would be affected by.
  Scope *getBreakParent() const {
    return BreakParent;
  }
  
  
  typedef DeclSetTy::iterator decl_iterator;
  decl_iterator decl_begin() const { return DeclsInScope.begin(); }
  decl_iterator decl_end()   const { return DeclsInScope.end(); }

  void AddDecl(Action::DeclTy *D) {
    DeclsInScope.insert(D);
  }
  
  /// isDeclScope - Return true if this is the scope that the specified decl is
  /// declared in.
  bool isDeclScope(Action::DeclTy *D) {
    return DeclsInScope.count(D) != 0;
  }
  
  /// Init - This is used by the parser to implement scope caching.
  ///
  void Init(Scope *Parent, unsigned ScopeFlags) {
    assert((ScopeFlags & (HasBreak|HasContinue)) == 0 &&
           "These flags can't be set in ctor!");
    AnyParent = Parent;
    Depth = AnyParent ? AnyParent->Depth+1 : 0;
    Flags = ScopeFlags;
    
    if (AnyParent) {
      FnParent       = AnyParent->FnParent;
      BreakParent    = AnyParent->BreakParent;
      ContinueParent = AnyParent->ContinueParent;
    } else {
      FnParent = BreakParent = ContinueParent = 0;
    }
    
    // If this scope is a function or contains breaks/continues, remember it.
    if (Flags & FnScope)       FnParent = this;
    if (Flags & BreakScope)    BreakParent = this;
    if (Flags & ContinueScope) ContinueParent = this;
    
    DeclsInScope.clear();
  }      
};
    
}  // end namespace clang

#endif
