kjs/LabelStack.h

   1 // -*- mode: c++; c-basic-offset: 4 -*-
   2 /*
   3  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
   4  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
   5  *  Copyright (C) 2003, 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
   6  *
   7  *  This library is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU Library General Public
   9  *  License as published by the Free Software Foundation; either
  10  *  version 2 of the License, or (at your option) any later version.
  11  *
  12  *  This library is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  *  Library General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU Library General Public License
  18  *  along with this library; see the file COPYING.LIB.  If not, write to
  19  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20  *  Boston, MA 02110-1301, USA.
  21  *
  22  */
  23
  24 #ifndef KJS_LABEL_STACK_H
  25 #define KJS_LABEL_STACK_H
  26
  27 #include "identifier.h"
  28 #include <wtf/Noncopyable.h>
  29
  30 namespace KJS {
  31   /**
  32    * @short The "label set" in Ecma-262 spec
  33    */
  34   class LabelStack : Noncopyable {
  35   public:
  36     LabelStack()
  37       : tos(0)
  38     {
  39     }
  40     ~LabelStack();
  41
  42     /**
  43      * If id is not empty and is not in the stack already, puts it on top of
  44      * the stack and returns true, otherwise returns false
  45      */
  46     bool push(const Identifier &id);
  47     /**
  48      * Is the id in the stack?
  49      */
  50     bool contains(const Identifier &id) const;
  51     /**
  52      * Removes from the stack the last pushed id (what else?)
  53      */
  54     void pop();
  55
  56   private:
  57     struct StackElem {
  58       Identifier id;
  59       StackElem *prev;
  60     };
  61
  62     StackElem *tos;
  63   };
  64
  65 inline LabelStack::~LabelStack()
  66 {
  67     StackElem *prev;
  68     for (StackElem *e = tos; e; e = prev) {
  69         prev = e->prev;
  70         delete e;
  71     }
  72 }
  73
  74 inline void LabelStack::pop()
  75 {
  76     if (StackElem *e = tos) {
  77         tos = e->prev;
  78         delete e;
  79     }
  80 }
  81
  82 }
  83
  84 #endif // KJS_LABEL_STACK_H