#!/bin/sh
# This is a shar archive.
# The rest of this file is a shell script which will extract:
#
# 6_3a.c 6_3b.c 6_3c1.c 6_3c2.c 6_3d.c 6_3st1.h makefile substr.h tst.c tst1.c tst1.cmp tst2.cmp tst4.c
#
# 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 23:07:52 EDT 1990
#
echo x - 6_3a.c
sed 's/^X//' > 6_3a.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// substring operator, second version
// exercise 6.3
substring string::operator()(int index, int count)
{
    char *s1 = p->s;
    int s1len = strlen(s1);

    // convert left index, if necessary
    if (index < 0)
	index += s1len;

    // left index past end of string
    else if (index >= s1len)
        {
	substring sst(s1+s1len, 0, this);
	return sst;
	}

    // convert count, if necessary
    int numleft = s1len - index;
    if (count > numleft || count < 0)
	count = numleft;

    // copy the substring
    substring sst(s1+index, count, this);
    return sst;
}

!EOF!
ls -l 6_3a.c
echo x - 6_3b.c
sed 's/^X//' > 6_3b.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// create a string from a substring
string::string(substring& sst)
{
    p = new class srep;
    p->s = new char[ sst.len + 1 ];
    strncpy(p->s, sst.s, sst.len);
    p->s[sst.len] = '\0';
    p->n = 1;
}
!EOF!
ls -l 6_3b.c
echo x - 6_3c1.c
sed 's/^X//' > 6_3c1.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// Assign something to a substring, version 1
// Only allow equal length assignments.
#include <string.h>
#include <string.h>

// substring = char*
substring& substring::operator=(char *cp)
{
    if (len != strlen(cp))
	error("lengths must match for assignment");

    // disconnect string
    if (str->p->n > 1)
	{
	str->p->n--;
	struct srep *oldp = str->p;
	str->p = new struct srep;
	str->p->s = new char[strlen(oldp->s) + 1];
	strcpy(str->p->s, oldp->s);
	str->p->n = 1;
	s = str->p->s + (s - oldp->s);
	}

    if (len > 0)
	memcpy(s, cp, len);

    return *this;
}
!EOF!
ls -l 6_3c1.c
echo x - 6_3c2.c
sed 's/^X//' > 6_3c2.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// substring = string
substring& substring::operator=(string& st)
{
    return *this = st.p->s;
}

// substring = substring
substring& substring::operator=(substring& sst)
{
    string st = sst;
    return *this = st;
}
!EOF!
ls -l 6_3c2.c
echo x - 6_3d.c
sed 's/^X//' > 6_3d.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// assign a string to a substring, version 2
// handling mismatches in lengths
#include <memory.h>
#include <string.h>

// assign a character string to a substring
substring& substring::operator=(char *cp)
{
    // disconnect string
    if (str->p->n > 1)
	{
	str->p->n--;
	struct srep *oldp = str->p;
	str->p = new struct srep;
	str->p->s = new char[strlen(oldp->s) + 1];
	strcpy(str->p->s, oldp->s);
	str->p->n = 1;
	s = str->p->s + (s - oldp->s);
	}

    int stlen = strlen(cp);

    // same size, simply copy data
    if (len == stlen)
	{
	if (len > 0)
	    memcpy(s, cp, len);
	}

    // expand or shrink data area
    else
	{
	// allocate the new data segment
	char *sps = str->p->s;
	const int s1len = s - sps;
	const int s3len = strlen(sps) - len - s1len;
	char *newdata =
	    new char[s1len + stlen + s3len + 1];

	// copy in the data
	if (s1len > 0)
	    memcpy(newdata, sps, s1len);
	if (stlen > 0)
	    memcpy(newdata + s1len, cp, stlen);
	if (s3len > 0)
	    memcpy(newdata + s1len + stlen,
		s + len, s3len);
	newdata[s1len + stlen + s3len]= '\0';

	// replace pointers
	delete str->p->s;
	str->p->s = newdata;
	s = newdata + s1len;
	len = stlen;
	}

    return *this;
}
!EOF!
ls -l 6_3d.c
echo x - 6_3st1.h
sed 's/^X//' > 6_3st1.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
    friend class substring;
    string(substring&);
    substring operator()(int i, int len = -1);
!EOF!
ls -l 6_3st1.h
echo x - makefile
sed 's/^X//' > makefile << '!EOF!'
CC= CC -I. -I../../CC
ERROR= ../../error.o
CFLAGS=

all: tst1 tst2

tst4: tst4.c
	$(CC) +i tst4.c -o tst4

tst1: tst1.c 6_3a.c 6_3b.c 6_3c1.c 6_3c2.c substr.h ../6.1dir/strclass.h 6_3st1.h
	$(CC) $(CFLAGS) -D_6_3 -I../6.1dir tst1.c -o tst1 $(ERROR)

tst2: tst1.c 6_3a.c 6_3b.c 6_3d.c substr.h ../6.1dir/strclass.h 6_3st1.h
	$(CC) $(CFLAGS) -D_6_3 -DTSTD -I../6.1dir tst1.c -o tst2 $(ERROR)

CMP= tst1.cmp tst2.cmp
OUT= tst1.out tst2.out

tst1.out: tst1 ;	tst1 > tst1.out
tst2.out: tst2 ;	tst2 > tst2.out

test: all $(OUT) $(CMP)
	cmp tst1.out tst1.cmp
	cmp tst2.out tst2.cmp
	echo tests done
!EOF!
ls -l makefile
echo x - substr.h
sed 's/^X//' > substr.h << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// <substr.h>, exercise 6.3
// auxiliary substring class for class string
#ifndef SUBSTR_H
# define SUBSTR_H

class substring
{
    friend class string;

    char *s;		// ptr to substring start
    int len;		// length of substring
    string *str;	// ptr to parent string

    substring(char* chptr, int stlen, string* stptr)
    {
	s = chptr;
	len = stlen;
	str = stptr;
    }

public:

    // Do not define a constructor
    // without any initialization.
    // If we did, it would look like this:
    // substring();		// substring x;

    // do define the constructor
    // for use with initialization:
    substring(substring& sst)	// substring x = ...
    {
	s = sst.s;
	len = sst.len;
	str = sst.str;
    }

    substring& operator=(substring &);
    substring& operator=(string &);
    substring& operator=(char *);

    friend ostream& operator<< (ostream& out,
				substring& sst)
	{
	string st = sst;
	return out << st;
	}
};
			// DELETE
#include <6_3a.c>	// DELETE
#include <6_3b.c>	// DELETE
#ifdef TSTD		// DELETE
#include <6_3d.c>	// DELETE
#else			// DELETE
#include <6_3c1.c>	// DELETE
#endif			// DELETE
#include <6_3c2.c>	// DELETE
#endif /* SUBSTR_H */
!EOF!
ls -l substr.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 <string.h>

class string {
    struct srep {
	char *s;
	int n;
    };
    srep *p;

public:
    string(char *);	// string x = "abc"
    string();		// string x;
    string(string&);	// string x = string ...
    string& operator=(char *);
    string& operator=(string &);
    ~string();
    char& operator[](int i);

    friend class substring;
    string(substring&);
};

class substring {
    friend class string;
    char *s;
    int len;
    string *str;

    substring();		// substring x;
    substring(substring&);	// substring x = substring ...

public:
    substring(char* chptr,int len,string* stptr);
    substring& operator=(substring &);
    substring& operator=(string &);
};

string::string(substring& sst)
{
    p = new srep;
    p->s = new char[ sst.len + 1 ];
    strncpy(p->s, sst.s, sst.len);
    p->s[sst.len] = '\0';
    p->n = 1;
}
!EOF!
ls -l tst.c
echo x - tst1.c
sed 's/^X//' > tst1.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#include <strclass.h>
#include <substr.h>

main()
{
    string w = "abcdefghijklmnop";
    string x = "0123456789wxyz";
    cout << "w=" << w;
    cout << "x=" << x;
    cout << "w(5)=" << w(5);
    string y = w(5,3);
    cout << "y=w(5,3)=" << y;
    cout << "x(-5)=" << x(-5);
    cout << "x(-5,3)=" << x(-5,3);
    cout << "x(0)=" << x(0);
    cout << "x(0,2)=" << x(0,2);
    cout << "x(11,8)=" << x(11,8);
    cout << "x(8,4)=" << x(8,4);

    cout << "\nx=" << x;
    x(2,2) = string("$$");
    cout << "x(2,2)='$$'\n";
    cout << "x=" << x << "\n";

    string z = x;
    cout << "\nz=" << z << "x=" << x;
    x(8,4) = string("WXYZ");
    cout << "x(8,4)='WXYZ'\n";
    cout << "x=" << x << "z=" << z << "\n";

#ifdef TSTD
    z = x;
    cout << "\nz=" << z << "x=" << x;
    x(2,6) = string("QQQQ");
    cout << "x(2,6)='QQQQ'\n";
    cout << "x=" << x << "z=" << z << "\n";

    z = x;
    cout << "\nz=" << z << "x=" << x;
    x(8,2) = string("!!!!");
    cout << "x(8,2)='!!!!'\n";
    cout << "x=" << x << "z=" << z << "\n";
#endif
    return 0;
}
!EOF!
ls -l tst1.c
echo x - tst1.cmp
sed 's/^X//' > tst1.cmp << '!EOF!'
w=abcdefghijklmnop [1]
x=0123456789wxyz [1]
w(5)=fghijklmnop [1]
y=w(5,3)=fgh [1]
x(-5)=9wxyz [1]
x(-5,3)=9wx [1]
x(0)=0123456789wxyz [1]
x(0,2)=01 [1]
x(11,8)=xyz [1]
x(8,4)=89wx [1]

x=0123456789wxyz [1]
x(2,2)='$$'
x=01$$456789wxyz [1]


z=01$$456789wxyz [2]
x=01$$456789wxyz [2]
x(8,4)='WXYZ'
x=01$$4567WXYZyz [1]
z=01$$456789wxyz [1]

!EOF!
ls -l tst1.cmp
echo x - tst2.cmp
sed 's/^X//' > tst2.cmp << '!EOF!'
w=abcdefghijklmnop [1]
x=0123456789wxyz [1]
w(5)=fghijklmnop [1]
y=w(5,3)=fgh [1]
x(-5)=9wxyz [1]
x(-5,3)=9wx [1]
x(0)=0123456789wxyz [1]
x(0,2)=01 [1]
x(11,8)=xyz [1]
x(8,4)=89wx [1]

x=0123456789wxyz [1]
x(2,2)='$$'
x=01$$456789wxyz [1]


z=01$$456789wxyz [2]
x=01$$456789wxyz [2]
x(8,4)='WXYZ'
x=01$$4567WXYZyz [1]
z=01$$456789wxyz [1]


z=01$$4567WXYZyz [2]
x=01$$4567WXYZyz [2]
x(2,6)='QQQQ'
x=01QQQQWXYZyz [1]
z=01$$4567WXYZyz [1]


z=01QQQQWXYZyz [2]
x=01QQQQWXYZyz [2]
x(8,2)='!!!!'
x=01QQQQWX!!!!yz [1]
z=01QQQQWXYZyz [1]

!EOF!
ls -l tst2.cmp
echo x - tst4.c
sed 's/^X//' > tst4.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 <string.h>

class substring;

class string {
    struct srep {
	char *s;
	int n;
    };
    srep *p;

public:
    string(char *);	// string x = "abc"
    string();		// string x;
    string(string&);	// string x = string ...
    string& operator=(char *);
    string& operator=(string &);
    ~string();
    char& operator[](int i);

    friend class substring;
    string(substring&);

    friend ostream& operator<<(ostream&, string&);
    friend istream& operator>>(istream&, string&);

    friend int operator==(string &x, char *s)
	{ return strcmp(x.p->s, s) == 0; }

    friend int operator==(string &x, string &y)
	{ return strcmp(x.p->s, y.p->s) == 0; }

    friend int operator!=(string &x, char *s)
	{ return strcmp(x.p->s, s) != 0; }

    friend int operator!=(string &x, string &y)
	{ return strcmp(x.p->s, y.p->s) != 0; }

    substring operator()(int i, int len = -1);

};

string::string()
{
    p = new srep;
    p->s = 0;
    p->n = 1;
}

string::string(char *s)
{
    p = new srep;
    p->s = new char[ strlen(s) + 1 ];
    strcpy(p->s, s);
    p->n = 1;
}

string::string(string& x)
{
    x.p->n++;
    p = x.p;
}

string::~string()
{
    if (--p->n == 0) {
	delete p->s;
	delete p;
    }
}

string& string::operator=(char *s)
{
    if (p->n > 1) {	// disconnect self
	p->n--;
	p = new srep;
    } else if (p->n == 1)
	delete p->s;

    p->s = new char[ strlen(s) +1 ];
    strcpy(p->s, s);
    p->n = 1;
    return *this;
}

string& string::operator=(string& x)
{
    x.p->n++;
    if (--p->n == 0) {
	delete p->s;
	delete p;
    }
    p = x.p;
    return *this;
}

ostream& operator<<(ostream& s, string& x)
{
    return s << x.p->s << " [" << x.p->n << "]\n";
}

istream& operator>>(istream& s, string& x)
{
    char buf[256];
    s >> buf;
    x = buf;
    cout << "echo: " << x << "\n";
    return s;
}

#include <error.h>

char& string::operator[] (int i)
{
    if (i < 0 || strlen(p->s) < i)
	error("index out of range");
    return p->s[i];
}

class substring {
    friend class string;
    char *s;
    int len;
    string *str;

    substring();		// substring x;
    substring(substring&);	// substring x = substring ...

public:
    substring(char* chptr,int len,string* stptr);
    substring& operator=(substring &);
    substring& operator=(string &);

    friend ostream& operator<<(ostream& out, substring& sst)
	{
	string st = sst;
	return out << st;
	}
};

substring::substring(char* chptr, int stlen, string* stptr)
{
    s = chptr;
    len = stlen;
    str = stptr;
}

substring::substring()
{
    s = 0;
    len = 0;
    str = 0;
}

substring::substring(substring& sst)
{
    s = sst.s;
    len = sst.len;
    str = sst.str;
}

// substring operator
// exercise 6.3
substring string::operator()(int index, int count = -1)
{
    char *s1 = p->s;
    int s1len = strlen(s1);

    // convert left index, if necessary
    if (index < 0)
	index += s1len;

    else if (index >= s1len)
        {
	substring sst(s1+s1len, 0, this);
	return sst;
	}

    // convert count, if necessary
    int numleft = s1len - index;
    if (count > numleft || count < 0)
	count = numleft;

    // copy the substring
    substring sst(s1+index, count, this);
    return sst;
}

// create a string from a substring
string::string(substring& sst)
{
    p = new class srep;
//    p = new srep;
    p->s = new char[ sst.len + 1 ];
    strncpy(p->s, sst.s, sst.len);
    p->s[sst.len] = '\0';
    p->n = 1;
}

main()
{}
!EOF!
ls -l tst4.c
# The following exit is to ensure that extra garbage 
# after the end of the shar file will be ignored.
exit 0