mariadb/sql/sql_list.h

/* Copyright (C) 2000-2003 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

/* mysql standard class memory allocator */

#ifdef SAFEMALLOC
#define TRASH(XX,YY) bfill((XX), (YY), 0x8F)
#else
#define TRASH(XX,YY) /* no-op */
#endif

class Sql_alloc
{
public:
  static void *operator new(size_t size)
  {
    return (void*) sql_alloc((uint) size);
  }
  static void *operator new[](size_t size)
  {
    return (void*) sql_alloc((uint) size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root)
  { return (void*) alloc_root(mem_root, (uint) size); }
  static void operator delete(void *ptr, size_t size) { TRASH(ptr, size); }
  static void operator delete(void *ptr, MEM_ROOT *mem_root)
  { /* never called */ }
  static void operator delete[](void *ptr, size_t size) { TRASH(ptr, size); }
#ifdef HAVE_purify
  bool dummy;
  inline Sql_alloc() :dummy(0) {}
  inline ~Sql_alloc() {}
#else
  inline Sql_alloc() {}
  inline ~Sql_alloc() {}
#endif

};


/*
  Basic single linked list
  Used for item and item_buffs.
  All list ends with a pointer to the 'end_of_list' element, which
  data pointer is a null pointer and the next pointer points to itself.
  This makes it very fast to traverse lists as we don't have to
  test for a specialend condition for list that can't contain a null
  pointer.
*/


/**
  list_node - a node of a single-linked list.
  @note We never call a destructor for instances of this class.
*/

struct list_node :public Sql_alloc
{
  list_node *next;
  void *info;
  list_node(void *info_par,list_node *next_par)
    :next(next_par),info(info_par)
  {}
  list_node()					/* For end_of_list */
  {
    info= 0;
    next= this;
  }
};


extern list_node end_of_list;

class base_list :public Sql_alloc
{
protected:
  list_node *first,**last;

public:
  uint elements;

  inline void empty() { elements=0; first= &end_of_list; last=&first;}
  inline base_list() { empty(); }
  /**
    This is a shallow copy constructor that implicitly passes the ownership
    from the source list to the new instance. The old instance is not
    updated, so both objects end up sharing the same nodes. If one of
    the instances then adds or removes a node, the other becomes out of
    sync ('last' pointer), while still operational. Some old code uses and
    relies on this behaviour. This logic is quite tricky: please do not use
    it in any new code.
  */
  inline base_list(const base_list &tmp) :Sql_alloc()
  {
    elements= tmp.elements;
    first= tmp.first;
    last= elements ? tmp.last : &first;
  }
  /**
    Construct a deep copy of the argument in memory root mem_root.
    The elements themselves are copied by pointer.
  */
  inline base_list(const base_list &rhs, MEM_ROOT *mem_root)
  {
    if (rhs.elements)
    {
      /*
        It's okay to allocate an array of nodes at once: we never
        call a destructor for list_node objects anyway.
      */
      first= (list_node*) alloc_root(mem_root,
                                     sizeof(list_node) * rhs.elements);
      if (first)
      {
        elements= rhs.elements;
        list_node *dst= first;
        list_node *src= rhs.first;
        for (; dst < first + elements - 1; dst++, src= src->next)
        {
          dst->info= src->info;
          dst->next= dst + 1;
        }
        /* Copy the last node */
        dst->info= src->info;
        dst->next= &end_of_list;
        /* Setup 'last' member */
        last= &dst->next;
        return;
      }
    }
    elements= 0;
    first= &end_of_list;
    last= &first;
  }
  inline base_list(bool error) { }
  inline bool push_back(void *info)
  {
    if (((*last)=new list_node(info, &end_of_list)))
    {
      last= &(*last)->next;
      elements++;
      return 0;
    }
    return 1;
  }
  inline bool push_front(void *info)
  {
    list_node *node=new list_node(info,first);
    if (node)
    {
      if (last == &first)
	last= &node->next;
      first=node;
      elements++;
      return 0;
    }
    return 1;
  }
  void remove(list_node **prev)
  {
    list_node *node=(*prev)->next;
    if (&(*prev)->next == last)
    {
      /*
        We're removing the last element from the list. Adjust "last" to point
        to the previous element.
        The other way to fix this would be to change this function to
        remove_next() and have base_list_iterator save ptr to previous node
        (one extra assignment in iterator++) but as the remove() of the last
        element isn't a common operation it's faster to just walk through the
        list from the beginning here.
      */
      list_node *cur= first;
      if (cur == *prev)
      {
        last= &first;
      }
      else
      {
        while (cur->next != *prev)
          cur= cur->next;
        last= &(cur->next);
      }
    }
    delete *prev;
    *prev=node;
    elements--;
  }
  inline void concat(base_list *list)
  {
    if (!list->is_empty())
    {
      *last= list->first;
      last= list->last;
      elements+= list->elements;
    }
  }
  inline void *pop(void)
  {
    if (first == &end_of_list) return 0;
    list_node *tmp=first;
    first=first->next;
    if (!--elements)
      last= &first;
    return tmp->info;
  }
  inline list_node* last_node() { return *last; }
  inline list_node* first_node() { return first;}
  inline void *head() { return first->info; }
  inline void **head_ref() { return first != &end_of_list ? &first->info : 0; }
  inline bool is_empty() { return first == &end_of_list ; }
  inline list_node *last_ref() { return &end_of_list; }
  friend class base_list_iterator;
  friend class error_list;
  friend class error_list_iterator;

#ifdef LIST_EXTRA_DEBUG
  /*
    Check list invariants and print results into trace. Invariants are:
      - (*last) points to end_of_list
      - There are no NULLs in the list.
      - base_list::elements is the number of elements in the list.

    SYNOPSIS
      check_list()
        name  Name to print to trace file

    RETURN 
      1  The list is Ok.
      0  List invariants are not met.
  */

  bool check_list(const char *name)
  {
    base_list *list= this;
    list_node *node= first;
    uint cnt= 0;

    while (node->next != &end_of_list)
    {
      if (!node->info)
      {
        DBUG_PRINT("list_invariants",("%s: error: NULL element in the list", 
                                      name));
        return FALSE;
      }
      node= node->next;
      cnt++;
    }
    if (last != &(node->next))
    {
      DBUG_PRINT("list_invariants", ("%s: error: wrong last pointer", name));
      return FALSE;
    }
    if (cnt+1 != elements)
    {
      DBUG_PRINT("list_invariants", ("%s: error: wrong element count", name));
      return FALSE;
    }
    DBUG_PRINT("list_invariants", ("%s: list is ok", name));
    return TRUE;
  }
#endif // LIST_EXTRA_DEBUG

protected:
  void after(void *info,list_node *node)
  {
    list_node *new_node=new list_node(info,node->next);
    node->next=new_node;
    elements++;
    if (last == &(node->next))
      last= &new_node->next;
  }
};


class base_list_iterator
{
protected:
  base_list *list;
  list_node **el,**prev,*current;
  void sublist(base_list &ls, uint elm)
  {
    ls.first= *el;
    ls.last= list->last;
    ls.elements= elm;
  }
public:
  base_list_iterator(base_list &list_par) 
    :list(&list_par), el(&list_par.first), prev(0), current(0)
  {}

  inline void *next(void)
  {
    prev=el;
    current= *el;
    el= &current->next;
    return current->info;
  }
  inline void *next_fast(void)
  {
    list_node *tmp;
    tmp= *el;
    el= &tmp->next;
    return tmp->info;
  }
  inline void rewind(void)
  {
    el= &list->first;
  }
  inline void *replace(void *element)
  {						// Return old element
    void *tmp=current->info;
    DBUG_ASSERT(current->info != 0);
    current->info=element;
    return tmp;
  }
  void *replace(base_list &new_list)
  {
    void *ret_value=current->info;
    if (!new_list.is_empty())
    {
      *new_list.last=current->next;
      current->info=new_list.first->info;
      current->next=new_list.first->next;
      if ((list->last == &current->next) && (new_list.elements > 1))
	list->last= new_list.last;
      list->elements+=new_list.elements-1;
    }
    return ret_value;				// return old element
  }
  inline void remove(void)			// Remove current
  {
    list->remove(prev);
    el=prev;
    current=0;					// Safeguard
  }
  void after(void *element)			// Insert element after current
  {
    list->after(element,current);
    current=current->next;
    el= &current->next;
  }
  inline void **ref(void)			// Get reference pointer
  {
    return &current->info;
  }
  inline bool is_last(void)
  {
    return el == &list->last_ref()->next;
  }
  friend class error_list_iterator;
};

template <class T> class List :public base_list
{
public:
  inline List() :base_list() {}
  inline List(const List<T> &tmp) :base_list(tmp) {}
  inline List(const List<T> &tmp, MEM_ROOT *mem_root) :
    base_list(tmp, mem_root) {}
  inline bool push_back(T *a) { return base_list::push_back(a); }
  inline bool push_front(T *a) { return base_list::push_front(a); }
  inline T* head() {return (T*) base_list::head(); }
  inline T** head_ref() {return (T**) base_list::head_ref(); }
  inline T* pop()  {return (T*) base_list::pop(); }
  void delete_elements(void)
  {
    list_node *element,*next;
    for (element=first; element != &end_of_list; element=next)
    {
      next=element->next;
      delete (T*) element->info;
    }
    empty();
  }
};


template <class T> class List_iterator :public base_list_iterator
{
public:
  List_iterator(List<T> &a) : base_list_iterator(a) {}
  inline T* operator++(int) { return (T*) base_list_iterator::next(); }
  inline T *replace(T *a)   { return (T*) base_list_iterator::replace(a); }
  inline T *replace(List<T> &a) { return (T*) base_list_iterator::replace(a); }
  inline void after(T *a)   { base_list_iterator::after(a); }
  inline T** ref(void)	    { return (T**) base_list_iterator::ref(); }
};


template <class T> class List_iterator_fast :public base_list_iterator
{
protected:
  inline T *replace(T *a)   { return (T*) 0; }
  inline T *replace(List<T> &a) { return (T*) 0; }
  inline void remove(void)  { }
  inline void after(T *a)   { }
  inline T** ref(void)	    { return (T**) 0; }

public:
  inline List_iterator_fast(List<T> &a) : base_list_iterator(a) {}
  inline T* operator++(int) { return (T*) base_list_iterator::next_fast(); }
  inline void rewind(void)  { base_list_iterator::rewind(); }
  void sublist(List<T> &list_arg, uint el_arg)
  {
    base_list_iterator::sublist(list_arg, el_arg);
  }
};


/*
  A simple intrusive list which automaticly removes element from list
  on delete (for THD element)
*/

struct ilink
{
  struct ilink **prev,*next;
  static void *operator new(size_t size)
  {
    return (void*)my_malloc((uint)size, MYF(MY_WME | MY_FAE));
  }
  static void operator delete(void* ptr_arg, size_t size)
  {
     my_free((gptr)ptr_arg, MYF(MY_WME|MY_ALLOW_ZERO_PTR));
  }

  inline ilink()
  {
    prev=0; next=0;
  }
  inline void unlink()
  {
    /* Extra tests because element doesn't have to be linked */
    if (prev) *prev= next;
    if (next) next->prev=prev;
    prev=0 ; next=0;
  }
  virtual ~ilink() { unlink(); }		/*lint -e1740 */
};


template <class T> class I_List_iterator;

class base_ilist
{
  public:
  struct ilink *first,last;
  inline void empty() { first= &last; last.prev= &first; }
  base_ilist() { empty(); }
  inline bool is_empty() {  return first == &last; }
  inline void append(ilink *a)
  {
    first->prev= &a->next;
    a->next=first; a->prev= &first; first=a;
  }
  inline void push_back(ilink *a)
  {
    *last.prev= a;
    a->next= &last;
    a->prev= last.prev;
    last.prev= &a->next;
  }
  inline struct ilink *get()
  {
    struct ilink *first_link=first;
    if (first_link == &last)
      return 0;
    first_link->unlink();			// Unlink from list
    return first_link;
  }
  inline struct ilink *head()
  {
    return (first != &last) ? first : 0;
  }
  friend class base_list_iterator;
};


class base_ilist_iterator
{
  base_ilist *list;
  struct ilink **el,*current;
public:
  base_ilist_iterator(base_ilist &list_par) :list(&list_par),
    el(&list_par.first),current(0) {}
  void *next(void)
  {
    /* This is coded to allow push_back() while iterating */
    current= *el;
    if (current == &list->last) return 0;
    el= &current->next;
    return current;
  }
};


template <class T>
class I_List :private base_ilist
{
public:
  I_List() :base_ilist()	{}
  inline void empty()		{ base_ilist::empty(); }
  inline bool is_empty()        { return base_ilist::is_empty(); } 
  inline void append(T* a)	{ base_ilist::append(a); }
  inline void push_back(T* a)	{ base_ilist::push_back(a); }
  inline T* get()		{ return (T*) base_ilist::get(); }
  inline T* head()		{ return (T*) base_ilist::head(); }
#ifndef _lint
  friend class I_List_iterator<T>;
#endif
};


template <class T> class I_List_iterator :public base_ilist_iterator
{
public:
  I_List_iterator(I_List<T> &a) : base_ilist_iterator(a) {}
  inline T* operator++(int) { return (T*) base_ilist_iterator::next(); }
};