#!/bin/sh
# This is a shar archive.
# The rest of this file is a shell script which will extract:
#
# 7_9.h 7_9_app.c 7_9_apph.c 7_9_clear.c 7_9_cons.c 7_9_dlist.h 7_9_getn.c 7_9_getp.c 7_9_ins.c 7_9_insh.c 7_9_next.c 7_9_prev.c all.c makefile nlink.h tst.c tst.cmp
#
# To extract the files from this shell archive file simply
# create a directory for this file, move the archive file
# to it and enter the command
#
#	sh filename
# 
# The files will be extracted automatically.
# Note: Do not use csh.
#
# Archive created: Mon Jul 30 23:11:14 EDT 1990
#
echo x - 7_9.h
sed 's/^X//' > 7_9.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Exercise 7.9
// A link class from which objects can be derived
class dlink
{
    friend class dlist;
    dlink *next;
    dlink *prev;

public:
    dlink(dlink *n = 0, dlink *p = 0)
    { next = n; prev = p; }

    dlink(dlink &)
    { next = prev = 0; }

    void operator=(dlink &)
    { next = prev = 0; }

    void insert(dlink *);
    void append(dlink *);
    void remove();

    ~dlink() { remove(); }
    friend ostream &operator<<(ostream &out, dlink*n);	// DELETE
};
							// DELETE
inline ostream &operator<<(ostream &out, dlink*n)	// DELETE
{							// DELETE
    out << form("%#x", (long)n) << "\t" <<		// DELETE
           form("n: %#x", (long)(n->next)) << "\t" <<	// DELETE
           form("p: %#x", (long)(n->prev));		// DELETE
    return out;						// DELETE
}							// DELETE
!EOF!
ls -l 7_9.h
echo x - 7_9_app.c
sed 's/^X//' > 7_9_app.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Append an entry at the end of the list.
// This is the same as dlist::insert() except
// that dlist::last is adjusted afterwards.
void dlist::append(dlink *a)
{
    this->insert(a);
    last = last->next;
}
!EOF!
ls -l 7_9_app.c
echo x - 7_9_apph.c
sed 's/^X//' > 7_9_apph.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Append an entry after the
// current location of the list.
// If curr is not set, append at
// the end of the list.
void dlist::appendhere(dlink *a)
{
    if (curr)
	curr->append(a);

    else
	this->append(a);
}
!EOF!
ls -l 7_9_apph.c
echo x - 7_9_clear.c
sed 's/^X//' > 7_9_clear.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// clear the list
void dlist::clear()
{
    dlink *l = last;
    if (!l) return;

    do  {
	dlink *ll = l;
	l = l->next;
	ll->next = ll->prev = 0;
    } while (l != last);

    last = 0;
}
!EOF!
ls -l 7_9_clear.c
echo x - 7_9_cons.c
sed 's/^X//' > 7_9_cons.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
dlist::dlist(dlink *a)
{
    curr = 0;
    last = a;
    last->next = last->prev = last;
}
!EOF!
ls -l 7_9_cons.c
echo x - 7_9_dlist.h
sed 's/^X//' > 7_9_dlist.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// manage a doubly-linked list
class dlist
{
    dlink *last;
    dlink *curr;

public:
    dlist();
    dlist(dlink*);
    ~dlist();
    int isempty() { return last != 0; }
    void clear();

    // set current pointer to the ends of the list
    void reset() { curr = 0; }

    // move around the list, leaving the links there
    int next(dlink *&e);
    int prev(dlink *&e);

    // move around the list, removing the links
    int getnext(dlink *&e);
    int getprev(dlink *&e);

    // manipulate around the beginning
    // and end of the list
    void insert(dlink*);
    void append(dlink*);

    // manipulate around the current entry
    void inserthere(dlink*);
    void appendhere(dlink*);
};
!EOF!
ls -l 7_9_dlist.h
echo x - 7_9_getn.c
sed 's/^X//' > 7_9_getn.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Get the next entry from a list,
// removing it afterwards.
// curr is left alone.
int dlist::getnext(dlink *&a)
{
    if (!last)
	return 0;

    // choose the link to remove
    if (curr)
        if (curr == last)
	    {
	    curr = 0;
	    return 0;
	    }
	
	else
	    a = curr->next;

    else
	a = last->next;

    // remove a from the list
    if (a == last)
	last = 0;

    else
	a->remove();
    return 1;
}
!EOF!
ls -l 7_9_getn.c
echo x - 7_9_getp.c
sed 's/^X//' > 7_9_getp.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Get the previous entry from a list,
// removing it afterwards
int dlist::getprev(dlink *&a)
{
    if (!last)
	return 0;

    // choose the link to remove
    if (curr)
	if (curr == last->prev)
	    {
	    curr = 0;
	    return 0;
	    }

	else
	    a = curr->prev;

    else
	a = curr = last;

    // remove f from the list
    if (a == last)
	last = 0;

    else
	a->remove();
    return 1;
}
!EOF!
ls -l 7_9_getp.c
echo x - 7_9_ins.c
sed 's/^X//' > 7_9_ins.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// DELETE #include "nlink.h"
// insert an entry at the beginning of the list
void dlist::insert(dlink *a)
{
// DELETE    cout << "dlist::insert(" << (char*)(((nlink*)a)->x) << ")\n";
    if (last)
	last->next->insert(a);

    else
	{
	last = a;
	last->next = last->prev = last;
	}
//DELETE
//DELETE    cout << "\tlast: " << (nlink*)last;
//DELETE    cout << "\tfrom last->next\n";
//DELETE    for (a = last->next; a != last; a = a->next)
//DELETE	cout << "\tnext: " << (nlink*)a;
}
!EOF!
ls -l 7_9_ins.c
echo x - 7_9_insh.c
sed 's/^X//' > 7_9_insh.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Insert an entry before the
// current location of the list.
// If curr is not set, insert at
// the beginning of the list.
void dlist::inserthere(dlink *a)
{
    if (curr)
	curr->insert(a);

    else
	this->insert(a);
}
!EOF!
ls -l 7_9_insh.c
echo x - 7_9_next.c
sed 's/^X//' > 7_9_next.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#include <stream.h>
// Get the next entry from a list,
// moving curr forward.
int dlist::next(dlink *&a)
{
    if (!last)
	return 0;

    // move curr forward, possibly to
    // the beginning or end of the list.
    if (curr)
	if (curr == last)
	    {
	    curr = 0;
	    return 0;
	    }

	else
	    curr = curr->next;

    else
	curr = last->next;

    a = curr;
    return 1;
}
!EOF!
ls -l 7_9_next.c
echo x - 7_9_prev.c
sed 's/^X//' > 7_9_prev.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Get the previous entry from a list,
// moving curr backwards.
int dlist::prev(dlink *&a)
{
    if (!last)
	return 0;

    // move curr backwards, possibly to
    // the beginning or end of the list.
    if (curr)
	if (curr == last->next)
	    {
	    curr = 0;
	    return 0;
	    }

	else
	    curr = curr->prev;

    else
	curr = last;

    a = curr;
    return 1;
}
!EOF!
ls -l 7_9_prev.c
echo x - all.c
sed 's/^X//' > all.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#include <stream.h>

#include "7_9.h"
#include "nlink.h"
#include "7_9_dlist.h"

#include "7_6e.c"	/* dlink::remove() */
#include "7_9_app.c"	/* dlist::append() */
#include "7_6_cons1.c"	/* dlist() */
#include "7_6_dest.c"	/* ~dlist() */
#include "7_6c.c"	/* dlink::insert() */
#include "7_6d.c"	/* dlink::append() */
#include "7_9_apph.c"
#include "7_9_clear.c"
#include "7_9_cons.c"
#include "7_9_getn.c"
#include "7_9_getp.c"
#include "7_9_ins.c"
#include "7_9_insh.c"
#include "7_9_next.c"
#include "7_9_prev.c"
!EOF!
ls -l all.c
echo x - makefile
sed 's/^X//' > makefile << '!EOF!'
CC= CC -I. -I../7.6dir -I../../CC
CFLAGS=

all: tst

tst: tst.o all.o
	$(CC) -o tst tst.o all.o

tst.o: tst.c 7_9.h 7_9_dlist.h nlink.h
	$(CC) -c tst.c

all.o: all.c 7_9.h 7_9_dlist.h nlink.h \
	7_9_apph.c 7_9_clear.c 7_9_cons.c 7_9_getn.c 7_9_getp.c \
	7_9_ins.c 7_9_insh.c 7_9_next.c 7_9_prev.c 7_9_app.c
	$(CC) -c all.c

CMP= tst.cmp
OUT= tst.out

tst.out: tst ; tst > tst.out

test: all $(CMP) $(OUT)
	cmp tst.out tst.cmp
	@echo test done
!EOF!
ls -l makefile
echo x - nlink.h
sed 's/^X//' > nlink.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#ifndef NLINK_H
#define NLINK_H
class nlink : public dlink {
public:
	void *x;
	nlink(char*nx) { x = nx; }
};

inline ostream &operator<<(ostream &out, nlink*n)
{
    out << (dlink*)n << "\t" << (char*)(n->x) << "\n";
    return out;
}
#endif
!EOF!
ls -l nlink.h
echo x - tst.c
sed 's/^X//' > tst.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#include <stream.h>

#include "7_9.h"
#include "nlink.h"
#include "7_9_dlist.h"

main()
{
    dlist xdlist;

/*
    nlink i1("ins 1");
    xdlist.insert(&i1);
    nlink a1("app 1");
    xdlist.append(&a1);

    nlink i2("ins 2");
    xdlist.insert(&i2);
    nlink a2("app 2");
    xdlist.append(&a2);
*/

    nlink hello("hello");
    xdlist.insert(&hello);
    nlink there("there");
    xdlist.insert(&there);
    nlink how("how");
    xdlist.insert(&how);
    nlink are("are");
    xdlist.insert(&are);
    nlink you("you");
    xdlist.append(&you);
    nlink today("today");
    xdlist.insert(&today);

    nlink *x;
    cout << "forwards\n";
    while (xdlist.next(x))
	cout << "'" << (char*)x->x << "'\n";
    cout << "\nbackwards\n";
    while (xdlist.prev(x))
	cout << "'" << (char*)x->x << "'\n";
    xdlist.next(x);
    xdlist.next(x);
    nlink Beep("Beep");
    xdlist.inserthere(&Beep);
    nlink Boop("Boop");
    xdlist.appendhere(&Boop);
    xdlist.reset();
    cout << "\nforwards, removing\n";
    while (xdlist.getnext(x))
	cout << "'" << (char*)x->x << "'\n";
    cout << "\nbackwards\n";
    while (xdlist.getprev(x))
	cout << "'" << (char*)x->x << "'\n";
    return 0;
}
!EOF!
ls -l tst.c
echo x - tst.cmp
sed 's/^X//' > tst.cmp << '!EOF!'
forwards
'today'
'are'
'how'
'there'
'hello'
'you'

backwards
'you'
'hello'
'there'
'how'
'are'
'today'

forwards, removing
'today'
'Beep'
'are'
'Boop'
'how'
'there'
'hello'
'you'

backwards
!EOF!
ls -l tst.cmp
# The following exit is to ensure that extra garbage 
# after the end of the shar file will be ignored.
exit 0