path: root/db/mork/src/morkDeque.h

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/*
 * File:      morkDeque.h 
 * Contains:  Ferrum deque (double ended queue (linked list))
 *
 * Copied directly from public domain IronDoc, with minor naming tweaks:
 * Designed and written by David McCusker, but all this code is public domain.
 * There are no warranties, no guarantees, no promises, and no remedies.
 */

#ifndef _MORKDEQUE_
#define _MORKDEQUE_ 1

#ifndef _MORK_
#include "mork.h"
#endif

/*=============================================================================
 * morkNext: linked list node for very simple, singly-linked list
 */

class morkNext /*d*/ {  
public:
  morkNext*  mNext_Link;
  
public:
  explicit morkNext(int inZero) : mNext_Link( 0 ) { }
  
  explicit morkNext(morkNext* ioLink) : mNext_Link( ioLink ) { }
  
  morkNext(); // mNext_Link( 0 ), { }
  
public:
  morkNext*  GetNextLink() const { return mNext_Link; }
  
public: // link memory management methods
  static void* MakeNewNext(size_t inSize, nsIMdbHeap& ioHeap, morkEnv* ev);
  void ZapOldNext(morkEnv* ev, nsIMdbHeap* ioHeap);

public: // link memory management operators
  void* operator new(size_t inSize, nsIMdbHeap& ioHeap, morkEnv* ev) CPP_THROW_NEW
  { return morkNext::MakeNewNext(inSize, ioHeap, ev); }
  
  void operator delete(void* ioAddress) // DO NOT CALL THIS, hope to crash:
  { ((morkNext*) 0)->ZapOldNext((morkEnv*) 0, (nsIMdbHeap*) 0); } // boom
};

/*=============================================================================
 * morkList: simple, singly-linked list
 */

/*| morkList: a list of singly-linked members (instances of morkNext), where
**| the number of list members might be so numerous that we must about cost
**| for two pointer link slots per member (as happens with morkLink).
**|
**|| morkList is intended to support lists of changes in morkTable, where we
**| are worried about the space cost of representing such changes. (Later we
**| can use an array instead, when we get even more worried, to avoid cost
**| of link slots at all, per member).
**|
**|| Do NOT create cycles in links using this list class, since we do not
**| deal with them very nicely.
|*/
class morkList /*d*/  {  
public:
  morkNext*  mList_Head; // first link in the list
  morkNext*  mList_Tail; // last link in the list
  
public:
  morkNext*  GetListHead() const { return mList_Head; }
  morkNext*  GetListTail() const { return mList_Tail; }

  mork_bool IsListEmpty() const { return ( mList_Head == 0 ); }
  mork_bool HasListMembers() const { return ( mList_Head != 0 ); }
  
public:
  morkList(); // : mList_Head( 0 ), mList_Tail( 0 ) { }
  
  void CutAndZapAllListMembers(morkEnv* ev, nsIMdbHeap* ioHeap);
  // make empty list, zapping every member by calling ZapOldNext()

  void CutAllListMembers();
  // just make list empty, dropping members without zapping

public:
  morkNext* PopHead(); // cut head of list
  
  // Note we don't support PopTail(), so use morkDeque if you need that.
  
  void PushHead(morkNext* ioLink); // add to head of list
  void PushTail(morkNext* ioLink); // add to tail of list
};

/*=============================================================================
 * morkLink: linked list node embedded in objs to allow insertion in morkDeques
 */

class morkLink /*d*/ {  
public:
  morkLink*  mLink_Next;
  morkLink*  mLink_Prev;
  
public:
  explicit morkLink(int inZero) : mLink_Next( 0 ), mLink_Prev( 0 ) { }
  
  morkLink(); // mLink_Next( 0 ), mLink_Prev( 0 ) { }
  
public:
  morkLink*  Next() const { return mLink_Next; }
  morkLink*  Prev() const { return mLink_Prev; }
  
  void SelfRefer() { mLink_Next = mLink_Prev = this; }
  void Clear() { mLink_Next = mLink_Prev = 0; }
  
  void AddBefore(morkLink* old)
  {
    ((old)->mLink_Prev->mLink_Next = (this))->mLink_Prev = (old)->mLink_Prev;
    ((this)->mLink_Next = (old))->mLink_Prev = this;
  }
  
  void AddAfter(morkLink* old)
  {
    ((old)->mLink_Next->mLink_Prev = (this))->mLink_Next = (old)->mLink_Next;
    ((this)->mLink_Prev = (old))->mLink_Next = this;
  }
  
  void Remove()
  {
    (mLink_Prev->mLink_Next = mLink_Next)->mLink_Prev = mLink_Prev;
  }
  
public: // link memory management methods
  static void* MakeNewLink(size_t inSize, nsIMdbHeap& ioHeap, morkEnv* ev);
  void ZapOldLink(morkEnv* ev, nsIMdbHeap* ioHeap);

public: // link memory management operators
  void* operator new(size_t inSize, nsIMdbHeap& ioHeap, morkEnv* ev) CPP_THROW_NEW
  { return morkLink::MakeNewLink(inSize, ioHeap, ev); }
  
};

/*=============================================================================
 * morkDeque: doubly linked list modeled after VAX queue instructions
 */

class morkDeque /*d*/ {
public:
  morkLink  mDeque_Head;

public: // construction
  morkDeque(); // { mDeque_Head.SelfRefer(); }

public:// methods
  morkLink* RemoveFirst();

  morkLink* RemoveLast();

  morkLink* At(mork_pos index) const ; /* one-based, not zero-based */

  mork_pos IndexOf(const morkLink* inMember) const; 
    /* one-based index ; zero means member is not in deque */

  mork_num Length() const;

  /* the following method is more efficient for long lists: */
  int LengthCompare(mork_num inCount) const;
  /* -1: length < count, 0: length == count,  1: length > count */

public: // inlines

  mork_bool IsEmpty()const 
  { return (mDeque_Head.mLink_Next == (morkLink*) &mDeque_Head); }

  morkLink* After(const morkLink* old) const
  { return (((old)->mLink_Next != &mDeque_Head)?
            (old)->mLink_Next : (morkLink*) 0); }

  morkLink* Before(const morkLink* old) const
  { return (((old)->mLink_Prev != &mDeque_Head)?
            (old)->mLink_Prev : (morkLink*) 0); }

  morkLink*  First() const
  { return ((mDeque_Head.mLink_Next != &mDeque_Head)?
    mDeque_Head.mLink_Next : (morkLink*) 0); }

  morkLink*  Last() const
  { return ((mDeque_Head.mLink_Prev != &mDeque_Head)?
    mDeque_Head.mLink_Prev : (morkLink*) 0); }
    
/*
From IronDoc documentation for AddFirst:
+--------+   +--------+      +--------+   +--------+   +--------+
| h.next |-->| b.next |      | h.next |-->| a.next |-->| b.next |
+--------+   +--------+  ==> +--------+   +--------+   +--------+
| h.prev |<--| b.prev |      | h.prev |<--| a.prev |<--| b.prev |
+--------+   +--------+      +--------+   +--------+   +--------+
*/

  void AddFirst(morkLink* in) /*i*/ 
  {
    ( (mDeque_Head.mLink_Next->mLink_Prev = 
      (in))->mLink_Next = mDeque_Head.mLink_Next, 
        ((in)->mLink_Prev = &mDeque_Head)->mLink_Next = (in) );
  }
/*
From IronDoc documentation for AddLast:
+--------+   +--------+      +--------+   +--------+   +--------+
| y.next |-->| h.next |      | y.next |-->| z.next |-->| h.next |
+--------+   +--------+  ==> +--------+   +--------+   +--------+
| y.prev |<--| h.prev |      | y.prev |<--| z.prev |<--| h.prev |
+--------+   +--------+      +--------+   +--------+   +--------+
*/

  void AddLast(morkLink* in)
  {
    ( (mDeque_Head.mLink_Prev->mLink_Next = 
      (in))->mLink_Prev = mDeque_Head.mLink_Prev, 
        ((in)->mLink_Next = &mDeque_Head)->mLink_Prev = (in) );
  }
};

#endif /* _MORKDEQUE_ */