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/ Netscape Plug-Ins Developer's Kit / Netscape_Plug-Ins_Developers_Kit.iso / source / Chap02 / queue / queue.cpp < prev    next >
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C/C++ Source or Header  |  1996-10-24  |  1.6 KB  |  73 lines
  1. #include "queue.h"
  2. #include <assert.h>
  3.  
  4. charQueue::listNode* charQueue::listNode::kNull = (  listNode*) 0;
  5.  
  6. charQueue:: charQueue()
  7. {
  8.     fHead = fTail = listNode::kNull;
  9. }
  10. charQueue::~charQueue()
  11. {
  12.     if (listNode::kNull != fTail)
  13.     {
  14.         listNode* aPointerFromTail = fTail;
  15.         while (listNode::kNull != aPointerFromTail->fNext)
  16.         {
  17.             aPointerFromTail = aPointerFromTail->fNext;
  18.             assert (listNode::kNull != aPointerFromTail->fPrevious);
  19.             delete aPointerFromTail->fPrevious;
  20.         }
  21.         assert (listNode::kNull != aPointerFromTail);
  22.         delete aPointerFromTail;
  23.         fTail = fHead = listNode::kNull;
  24.     }
  25. }
  26. void charQueue::add(char aChar)
  27. {
  28.     if (listNode::kNull == fTail)
  29.     {
  30.         fTail = new listNode();
  31.         fTail->fChar = aChar;
  32.         fHead = fTail;
  33.     }
  34.     else
  35.     {
  36.         listNode* aPointerFromHead = fHead;
  37.         while (listNode::kNull != aPointerFromHead->fPrevious)
  38.         {
  39.             aPointerFromHead = aPointerFromHead->fPrevious;
  40.         }
  41.         aPointerFromHead->fPrevious = new listNode();
  42.         aPointerFromHead->fPrevious->fChar = aChar;
  43.         aPointerFromHead->fPrevious->fNext = aPointerFromHead;
  44.         fTail = aPointerFromHead;
  45.     }
  46. }
  47.  
  48. char charQueue::remove()
  49. {
  50.     char theResult;
  51.     if (listNode::kNull != fHead)
  52.     {
  53.         theResult = fHead->fChar;
  54.         listNode* thePreviousNode = fHead->fPrevious;
  55.         if (listNode::kNull != thePreviousNode)
  56.             thePreviousNode->fNext = listNode::kNull;
  57.         else
  58.             fTail = listNode::kNull;
  59.         delete fHead;
  60.         fHead = thePreviousNode;
  61.     }
  62.     else
  63.     {
  64.         throw QueueEmpty();
  65.     }
  66.     return theResult;
  67. }
  68.  
  69. charQueue::listNode::listNode()
  70. {
  71.     fPrevious = fNext = kNull;
  72. }
  73.