gistnode.h

一个俄国人写的内存数据库系统

// -*- Mode: C++ -*-

//         GiSTnode.h
//
// Copyright (c) 1996, Regents of the University of California
// $Header: /usr/local/devel/GiST/libGiST/libGiST/GiSTnode.h,v 1.1.1.1 1996/08/06 23:47:21 jmh Exp $
#ifndef GISTNODE_H
#define GISTNODE_H

#include "GiSTentry.h"
#include "GiSTpredicate.h"
#include "GiSTpath.h"
#include "GiSTstore.h"
class GiST;

// Type of line table element
typedef unsigned short GiSTlte;

// Page header
struct GiSTheader
{
  int level;
  int numEntries;
  GiSTpage parent;
  GiSTpage sibling;
};

// Entry pointer, with some handy operators 
class GiSTentryptr
{
  public:
    GiSTentryptr() { ptr = NULL; }
    operator GiSTentry* () const { return ptr; }
    operator GiSTentry& () const { return *ptr; }
    GiSTentry* operator->() const { return ptr; }
    GiSTentryptr& operator = (GiSTentry* ptr) { this->ptr = ptr; return *this; }
    GiSTentryptr& operator = (GiSTentryptr& ptr) { this->ptr = ptr.ptr; return *this; }
    GiSTentry* Ptr() const { return ptr; }
  private:
    GiSTentry *ptr;
};

#define GIST_PAGE_HEADER_SIZE sizeof(GiSTheader)

// The GiST node class.
class GiSTnode : public GiSTobject
{
public:
  GiSTnode();
  GiSTnode(const GiSTnode& node);

  GiSTobjid IsA() const { return GISTNODE_CLASS; }
#ifdef PRINTING_OBJECTS
  virtual void Print(ostream& os) const;
#endif
  // Operations on the entry array
  GiSTentryptr& operator [] (int index);
  const GiSTentryptr& operator [] (int index) const;

  void Expand(int index);
  int NumEntries() const { return numEntries; }
  void SetNumEntries(int num) { numEntries = num; }

  // Search methods
  virtual GiSTentry* SearchPtr(GiSTpage ptr) const;
  virtual GiSTpage   SearchMinPenalty(const GiSTentry& entry) const;
  virtual GiSTpage   SearchNeighbors(GiSTpage ptr) const;
  virtual GiSTlist<GiSTentry*>   Search(const GiSTpredicate &query) const;

  // Insertion and deletion
  virtual void Insert(const GiSTentry &entry);
  virtual void InsertBefore(const GiSTentry &entry, int index);
  virtual void DeleteEntry(int index);
  virtual void DeleteBulk(int vec[], int veclen);

  // Pack/unpack disk representation
  virtual void Pack(char *page) const;
  virtual void Unpack(const char *page);

  // two of the basic GiST methods
  // Returns the Union of all entries
  virtual GiSTentry* Union() const = 0;
  // Splitting
  virtual GiSTnode *PickSplit();

  // required support methods
  virtual GiSTentry* CreateEntry() const = 0;
  virtual int FixedLength() const { return 0; }

  virtual GiSTcompressedEntry Entry(int entryPos) const;

  //coalescing
  virtual void Coalesce(const GiSTnode &node, const GiSTentry& entry);

  // access to the private members
  GiSTpage Sibling()    const { return sibling; }
  void SetSibling(GiSTpage p) { sibling = p; }
  int IsLeaf() const { return level == 0; }
  int Level() const { return level; }
  void SetLevel(int l) { level = l; }

  virtual int IsOverFull(const GiSTstore &store) const;
  virtual int IsUnderFull(const GiSTstore &store) const;

  ~GiSTnode();

  virtual int Size() const;

  GiST *Tree() const { return tree; }
  void SetTree(GiST *t) { tree = t; }

  GiSTpath& Path() { return path; }

private:
  void Reset();
  GiSTpath path;
  GiSTentryptr *entries;
  char *packedNode;
  GiSTpage sibling;
  int level;
  int numEntries, maxEntries;
  GiST *tree;
};

#endif