path: root/comm/mailnews/db/mork/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) noexcept(true) {
    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) noexcept(true) {
    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_ */