/* Copyright (c) 1992 by AT&T Bell Laboratories. */
/* Advanced C++ Programming Styles and Idioms */
/* James O. Coplien */
/* All rights reserved. */

#include <stdlib.h>
#include <string.h>

class StringRep {
friend String;
private:
    StringRep(const char *s) {
       ::strcpy(rep = new char[::strlen(s)+1], s);
       count = 1;
    }
    ~StringRep() { delete[] rep; }
private:
    char *rep;
    int count;
};

class String {
public:
    String()                     { rep = new StringRep(""); }
    String(const String& s)      { rep = s.rep; rep->count++; }
    String& operator=(const String& s) {
        s.rep->count++;
        if (--rep->count <= 0) delete rep;
        rep = s.rep;
        return *this;
    }
    ~String() {
        if (--rep->count <= 0) delete rep;
    }
    String(const char *s)        { rep = new StringRep(s); }
    String operator+(const String&) const;
    int length() const           { return ::strlen(rep->rep); }
private:
    StringRep *rep;
};

String String::operator+(const String& s) const
{
    char *buf = new char[s.length() + length() + 1];
    ::strcpy(buf, rep->rep);
    ::strcat(buf, s.rep->rep);
    String retval( buf );
    delete[] buf;         // get rid of temporary storage
    return retval;
}