// This may look like C code, but it is really -*- C++ -*-
/* 
Copyright (C) 1988 Free Software Foundation
    written by Doug Lea (dl@rocky.oswego.edu)

This file is part of GNU CC.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY.  No author or distributor
accepts responsibility to anyone for the consequences of using it
or for whether it serves any particular purpose or works at all,
unless he says so in writing.  Refer to the GNU CC General Public
License for full details.

Everyone is granted permission to copy, modify and redistribute
GNU CC, but only under the conditions described in the
GNU CC General Public License.   A copy of this license is
supposed to have been given to you along with GNU CC so you
can know your rights and responsibilities.  It should be in a
file named COPYING.  Among other things, the copyright notice
and this notice must be preserved on all copies.  
*/


#ifndef _<T>List_h
#pragma once
#define _<T>List_h 1

#ifndef _<T>_typedefs
#define _<T>_typedefs 1
typedef void (*<T>Procedure)(<T&>);
typedef <T>  (*<T>Mapper)(<T&>);
typedef <T>  (*<T>Combiner)(<T&>, <T&>);
typedef int  (*<T>Predicate)(<T&>);
typedef int  (*<T>Comparator)(<T&>, <T&>);
#endif

#include <Pix.h>

struct <T>ListNode
{
  <T>ListNode*          tl;
  short                 ref;
  <T>                   hd;
};

extern <T>ListNode Nil<T>ListNode;

inline void reference(<T>ListNode* p)
{
  if (p->ref >= 0) ++p->ref;
}

inline void dereference(<T>ListNode* p)
{
  while (p->ref > 0 && --p->ref == 0)
  {
    <T>ListNode* n = p->tl;
    delete(p);
    p = n;
  }
}


inline <T>ListNode* new<T>ListNode(<T&> h)
{
  <T>ListNode* p = new <T>ListNode;
  p->ref = 1;
  p->hd = h;
  return p;
}

inline <T>ListNode* new<T>ListNode(<T&> h, <T>ListNode* t)
{
  <T>ListNode* p = new <T>ListNode;
  p->ref = 1;
  p->hd = h;
  p->tl = t;
  return p;
}


class <T>List
{
protected:
  <T>ListNode*          P;

                        <T>List(<T>ListNode* p);
public:
                        <T>List();
                        <T>List(<T&> head);
                        <T>List(<T&> head, <T>List& tl);
                        <T>List(<T>List& a);
                        <T>List(Pix p);
                        ~<T>List();

  <T>List&              operator = (<T>List& a);

  int                   null();
  int                   valid();
                        operator const void* ();
  int                   operator ! ();

  int                   length();
  int                   list_length();

  <T>&                  get();
  <T>&                  head();
  <T>&                  operator [] (int n);

  <T>List               nth(int n);
  <T>List               tail();
  <T>List               last();

  <T>List               find(<T&> targ);
  <T>List               find(<T>List& targ);
  int                   contains(<T&> targ);
  int                   contains(<T>List& targ);
  int                   position(<T&> targ);

  friend <T>List        copy(<T>List& a);
  friend <T>List        concat(<T>List& a, <T>List& b);
  friend <T>List        append(<T>List& a, <T>List& b);
  friend <T>List        map(<T>Mapper f, <T>List& a);
  friend <T>List        merge(<T>List& a, <T>List& b, <T>Comparator f);
  friend <T>List        combine(<T>Combiner f, <T>List& a, <T>List& b);
  friend <T>List        reverse(<T>List& a);
  friend <T>List        select(<T>Predicate f, <T>List& a);        
  friend <T>List        remove(<T&> targ, <T>List& a);
  friend <T>List        remove(<T>Predicate f, <T>List& a);
  friend <T>List        subst(<T&> old, <T&> repl, <T>List& a);

  void                  push(<T&> x);
  <T>                   pop();

  void                  set_tail(<T>List& p);
  void                  append(<T>List& p);
  void                  prepend(<T>List& p);
  void                  del(<T&> targ);
  void                  del(<T>Predicate f);
  void                  select(<T>Predicate f);
  void                  subst(<T&> old, <T&> repl);
  void                  reverse();
  void                  sort(<T>Comparator f);

  void                  apply(<T>Procedure f);
  <T>                   reduce(<T>Combiner f, <T&> base);

  friend int            operator == (<T>List& a, <T>List& b);
  friend int            operator != (<T>List& a, <T>List& b);

  Pix                   first();
  void                  next(Pix& p);
  Pix                   seek(<T&> item);
  <T>&                  operator () (Pix p);
  int                   owns(Pix p);

  void                  error(const char*);
  int                   OK();
};


inline <T>List::~<T>List()
{
  dereference(P);
}

inline <T>List::<T>List()
{
  P = &Nil<T>ListNode;
}

inline <T>List::<T>List(<T>ListNode* p)
{
  P = p;
}

inline <T>List::<T>List(<T&> head)
{
  P = new<T>ListNode(head);
  P->tl = &Nil<T>ListNode;
}

inline <T>List::<T>List(<T&> head, <T>List& tl)
{
  P = new<T>ListNode(head, tl.P);
  reference(P->tl);
}

inline <T>List::<T>List(<T>List& a)
{
  reference(a.P);
  P = a.P;
}


inline <T>List& <T>List::operator = (<T>List& a)
{
  reference(a.P);
  dereference(P);
  P = a.P;
  return *this;
}


inline <T>& <T>List::get()
{
  return P->hd;
}

inline <T>& <T>List::head()
{
  return P->hd;
}


inline <T>List <T>List::tail()
{
  reference(P->tl);
  return <T>List(P->tl);
}


inline void <T>List::set_tail(<T>List& a)
{
  reference(a.P);
  dereference(P->tl);
  P->tl = a.P;
}


inline int <T>List::null()
{
  return P == &Nil<T>ListNode;
}

inline int <T>List::valid()
{
  return P != &Nil<T>ListNode;
}

inline <T>List::operator const void* ()
{
  return (P == &Nil<T>ListNode)? 0 : this;
}

inline int <T>List::operator ! ()
{
  return (P == &Nil<T>ListNode);
}


inline <T>List <T>List::nth(int n)
{
  for (<T>ListNode* p = P; n-- > 0; p = p->tl);
  reference(p);
  return <T>List(p);
}

inline <T>&  <T>List::operator [] (int n)
{
  for (<T>ListNode* p = P; n-- > 0; p = p->tl);
  return (p->hd);
}

inline <T>List <T>List::last()
{
  <T>ListNode* p = P;
  if (p != &Nil<T>ListNode) while (p->tl != &Nil<T>ListNode) p = p->tl;
  reference(p);
  return <T>List(p);
}

inline void <T>List::push(<T&> head)
{
  <T>ListNode* oldp = P;
  P = new<T>ListNode(head, oldp);
}

inline <T> <T>List::pop()
{
  <T> res = P->hd;
  reference(P->tl);
  dereference(P);
  P = P->tl;
  return res;
}

inline void <T>List::append(<T>List& l)
{
  <T>ListNode* p = P;
  <T>ListNode* a = l.P;
  reference(a);
  if (p != &Nil<T>ListNode)
  {
    while (p->tl != &Nil<T>ListNode) p = p->tl;
    p->tl = a;
  }
  else
    P = a;
}

inline int <T>List::length()
{
  int l = 0;
  for (<T>ListNode* p = P; p != &Nil<T>ListNode; p = p->tl) ++l;
  return l;
}

inline int operator != (<T>List& x, <T>List& y)
{
  return !(x == y);
}

inline Pix <T>List::first()
{
  return (P == &Nil<T>ListNode)? 0 : Pix(P);
}

inline <T>& <T>List::operator () (Pix p)
{
  return ((<T>ListNode*)p)->hd;
}

inline void <T>List::next(Pix& p)
{
  if (p != 0)
  {
    p = Pix(((<T>ListNode*)p)->tl);
    if (p == &Nil<T>ListNode) p = 0;
  }
}

inline <T>List::<T>List(Pix p)
{
  P = (<T>ListNode*)p;
  reference(P);
}

#endif