#!/bin/sh
# This is a shar archive.
# The rest of this file is a shell script which will extract:
#
# 7_7.h 7_7_dlink.h 7_7ahere.c 7_7append.c 7_7dlist.h 7_7getnext.c 7_7getprev.c 7_7ihere.c 7_7insert.c 7_7next.c 7_7prev.c all.c makefile 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 23:10:58 EDT 1990
#
echo x - 7_7.h
sed 's/^X//' > 7_7.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// an iterator for a doubly-linked list
class dlist_iterator
{
    dlink *curr;
    dlist *curr_dlist;

public:
    dlist_iterator(dlist &d)
    { curr_dlist = &d; curr = 0; }

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

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

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

    // manipulate around the beginning
    // and end of the list
    void insert(ent e);
    void append(ent e);

    // manipulate around the current entry
    void inserthere(ent e);
    void appendhere(ent e);
};
!EOF!
ls -l 7_7.h
echo x - 7_7_dlink.h
sed 's/^X//' > 7_7_dlink.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
class dlink
{
    friend class dlist;
    friend class dlist_iterator;
    dlink *next;
    dlink *prev;
    ent e;

    dlink(ent a, dlink *n = 0, dlink *p = 0)
    { e = a; next = n; prev = p; }

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

    ~dlink() { remove(); }
};
!EOF!
ls -l 7_7_dlink.h
echo x - 7_7ahere.c
sed 's/^X//' > 7_7ahere.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_iterator::appendhere(ent a)
{
    if (curr)
	curr->append(new dlink(a));

    else
	this->append(a);
}
!EOF!
ls -l 7_7ahere.c
echo x - 7_7append.c
sed 's/^X//' > 7_7append.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_iterator::insert()
// except that dlist_iterator::curr_dlist->last
// is adjusted afterwards.
void dlist_iterator::append(ent a)
{
    this->insert(a);
    curr_dlist->last = curr_dlist->last->next;
}
!EOF!
ls -l 7_7append.c
echo x - 7_7dlist.h
sed 's/^X//' > 7_7dlist.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
class dlist
{
    friend dlist_iterator;
    dlink *last;

public:
    dlist() { last = 0; }
    dlist(ent a)
    {
	last = new dlink(a);
	last->next = last->prev = last;
    }
    int isempty() { return last != 0; }
    void clear();
    ~dlist() { clear(); }
};
!EOF!
ls -l 7_7dlist.h
echo x - 7_7getnext.c
sed 's/^X//' > 7_7getnext.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_iterator::getnext(ent &a)
{
    if (!curr_dlist->last)
	return 0;

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

    else
	f = curr_dlist->last->next;

    a = f->e;

    // remove f from the list
    if (f == curr_dlist->last)
	curr_dlist->last = 0;

    else
	f->remove();

    delete f;
    return 1;
}
!EOF!
ls -l 7_7getnext.c
echo x - 7_7getprev.c
sed 's/^X//' > 7_7getprev.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_iterator::getprev(ent &a)
{
    if (!curr_dlist->last)
	return 0;

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

	else
	    f = curr->prev;

    else
	curr = curr_dlist->last;

    a = f->e;

    // remove f from the list
    if (f == curr_dlist->last)
	curr_dlist->last = 0;

    else
	f->remove();

    delete f;
    return 1;
}
!EOF!
ls -l 7_7getprev.c
echo x - 7_7ihere.c
sed 's/^X//' > 7_7ihere.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_iterator::inserthere(ent a)
{
    if (curr)
	curr->insert(new dlink(a));

    else
	this->insert(a);
}
!EOF!
ls -l 7_7ihere.c
echo x - 7_7insert.c
sed 's/^X//' > 7_7insert.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// insert an entry at the beginning of the list
void dlist_iterator::insert(ent a)
{
    if (curr_dlist->last)
	curr_dlist->last->next->insert(new dlink(a));

    else
	{
	curr_dlist->last = new dlink(a);
	curr_dlist->last->next =
	    curr_dlist->last->prev = curr_dlist->last;
	}
}
!EOF!
ls -l 7_7insert.c
echo x - 7_7next.c
sed 's/^X//' > 7_7next.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,
// moving curr forward.
int dlist_iterator::next(ent &a)
{
    if (!curr_dlist->last)
	return 0;

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

	else
	    curr = curr->next;

    else
	curr = curr_dlist->last->next;

    a = curr->e;
    return 1;
}
!EOF!
ls -l 7_7next.c
echo x - 7_7prev.c
sed 's/^X//' > 7_7prev.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_iterator::prev(ent &a)
{
    if (!curr_dlist->last)
	return 0;

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

	else
	    curr = curr->prev;

    else
	curr = curr_dlist->last;

    a = curr->e;
    return 1;
}
!EOF!
ls -l 7_7prev.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 "7_6a.h"
#include "7_7_dlink.h"
#include "7_7.h"
#include "7_7dlist.h"
#include "7_6c.c"
#include "7_6d.c"
#include "7_6e.c"
#include "7_6_clear.c"
#include "7_7ahere.c"
#include "7_7append.c"
#include "7_7getnext.c"
#include "7_7getprev.c"
#include "7_7ihere.c"
#include "7_7insert.c"
#include "7_7next.c"
#include "7_7prev.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 ../7.6dir/7_6a.h 7_7_dlink.h 7_7dlist.h 7_7.h
	$(CC) -c tst.c

all.o: all.c ../7.6dir/7_6a.h 7_7_dlink.h \
	../7.6dir/7_6c.c ../7.6dir/7_6d.c ../7.6dir/7_6e.c \
	../7.6dir/7_6_clear.c \
	7_7ahere.c 7_7append.c 7_7getnext.c 7_7getprev.c \
	7_7ihere.c 7_7insert.c 7_7next.c 7_7prev.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 - 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 "7_6a.h"
#include "7_7_dlink.h"
#include "7_7.h"
#include "7_7dlist.h"

#include <stream.h>

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

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

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

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