dom/xslt/base/txStack.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef txStack_h___
   7 #define txStack_h___
   8
   9 #include "nsTArray.h"
  10
  11 class txStack : private nsTArray<void*> {
  12  public:
  13   /**
  14    * Returns the specified object from the top of this stack,
  15    * without removing it from the stack.
  16    *
  17    * @return a pointer to the object that is the top of this stack.
  18    */
  19   inline void* peek() {
  20     NS_ASSERTION(!isEmpty(), "peeking at empty stack");
  21     return !isEmpty() ? ElementAt(Length() - 1) : nullptr;
  22   }
  23
  24   /**
  25    * Adds the specified object to the top of this stack.
  26    *
  27    * @param obj a pointer to the object that is to be added to the
  28    * top of this stack.
  29    */
  30   inline void push(void* aObject) { AppendElement(aObject); }
  31
  32   /**
  33    * Removes and returns the specified object from the top of this
  34    * stack.
  35    *
  36    * @return a pointer to the object that was the top of this stack.
  37    */
  38   inline void* pop() {
  39     void* object = nullptr;
  40     NS_ASSERTION(!isEmpty(), "popping from empty stack");
  41     if (!isEmpty()) {
  42       object = PopLastElement();
  43     }
  44     return object;
  45   }
  46
  47   /**
  48    * Returns true if there are no objects in the stack.
  49    *
  50    * @return true if there are no objects in the stack.
  51    */
  52   inline bool isEmpty() { return IsEmpty(); }
  53
  54   /**
  55    * Returns the number of elements in the Stack.
  56    *
  57    * @return the number of elements in the Stack.
  58    */
  59   inline int32_t size() { return Length(); }
  60
  61  private:
  62   friend class txStackIterator;
  63 };
  64
  65 class txStackIterator {
  66  public:
  67   /**
  68    * Creates an iterator for the given stack.
  69    *
  70    * @param aStack the stack to create an iterator for.
  71    */
  72   inline explicit txStackIterator(txStack* aStack)
  73       : mStack(aStack), mPosition(0) {}
  74
  75   /**
  76    * Returns true if there is more objects on the stack.
  77    *
  78    * @return .
  79    */
  80   inline bool hasNext() { return (mPosition < mStack->Length()); }
  81
  82   /**
  83    * Returns the next object pointer from the stack.
  84    *
  85    * @return .
  86    */
  87   inline void* next() {
  88     if (mPosition == mStack->Length()) {
  89       return nullptr;
  90     }
  91     return mStack->ElementAt(mPosition++);
  92   }
  93
  94  private:
  95   txStack* mStack;
  96   uint32_t mPosition;
  97 };
  98
  99 #endif /* txStack_h___ */