///////////////////////////////////////////////////////////////
//  str.cpp - implementation file for string class           //
//  ver 1.4                                                  //
//                                                           //
//  Language:     Visual C++, ver 6.0                        //
//  Platform:     Micron Dual Pentium Pro 200, Win NT 4.0    //
//  Application:  ECS500 Example                             //
//  Author:       Jim Fawcett, ECS500 Instructor             //
//                Syracuse University, CST 2-187             //
//                fawcett@ecs.syr.edu, (315) 443-3948        //
///////////////////////////////////////////////////////////////

#include <iostream>
#include <cstring>
#include "str.h"
using namespace std;

//----< sized constructor >------------------------------------

str::str(int n) {

  array = new char[n];
  if(array==0)
    throw "\n  memory allocation failure\n\n";
  max = n;
  len = 0;
}

//----<copy constructor >--------------------------------------

str::str(const str &s) {

  array = new char[max = s.max];
  if(array==0)
    throw "\n  memory allocation failure\n\n";
  len = s.len;
  int i;
  for(i=0; i<=len; i++)
    array[i] = s.array[i];
};

//----< promotion constructor >--------------------------------

str::str(const char *s) {

  len = strlen(s);
  max = len+1;
  array = new char[len+1];
  if(array == NULL)
    throw "\n  memory allocation failure\n\n";
  int i;
  for(i=0; i<=len; i++)
    array[i] = s[i];
}

//

//----< destructor >-------------------------------------------

str::~str() {

  delete [] array;
  max = len = 0;
}

//----< assignment operator >----------------------------------

str& str::operator=(const str &s) {

  if(this == &s) return *this;
  if(max >= s.len+1) {
    len = s.len;
    int i;
    for(i=0; i<=len; i++)
      array[i] = s.array[i];
    return *this;
  }
  delete [] array;
  array = new char[max = s.max + 10];
  if(array == NULL)
    throw "\n  memory allocation failure\n\n";
  int i;
  len = s.len;
  for(i=0; i<=len; i++)
    array[i] = s.array[i];
  return *this;
}

//---< index operator >----------------------------------------

char& str::operator[](int n) {

  static char safe = '?';
  if(n<0 || len<=n) {
    cout << "\n  index out of bounds in operator[]\n\n";
    return safe;
  }
  return array[n];
}

//----< index operator for const str >-------------------------

char str::operator[](int n) const {

  char safe = '?';
  if(n<0 || len<=n) {
    cout << "\n  index out of bounds in operator[]\n\n";
    return safe;
  }
  return array[n];
}

//

//----< append char to string >--------------------------------

void str::operator+=(char ch) {

  if(len < max-1) {
    array[len] = ch;
    array[len+1] = '\0';
    len++;
  }
  else {
    max *= 2;   // multiply by 2
    char *temp = new char[max];
    if(temp == NULL)
      throw "\n  memory allocation failure\n\n";
    int i;
    for(i=0; i<len; i++)
      temp[i] = array[i];
    temp[len] = ch;
    temp[len+1] = '\0';
    len++;
    delete [] array;
    array = temp;
  }
}

//----< append string to string >------------------------------

void str::operator+=(const str &s) {

  if(len < max-s.size()) {
    int i;
    for(i=0; i<=s.len; i++)
      array[len+i] = s[i];
    len += s.size();
  }
  else {
    max += max + s.size();
    char *temp = new char[max];
    int i;
    for(i=0; i<len; i++)
      temp[i] = array[i];
    for(i=0; i<s.size(); i++)
      temp[len+i] = s[i];
    temp[len+s.size()] = '\0';
    len += s.size();
    delete [] array;
    array = temp;
  }
}

//

//----< insertion operator >-----------------------------------

ostream& operator<<(ostream &out, const str &s) {

  int i;
  for(i=0; i<s.size(); i++)
    out << s[i];
  return out;
}

//----< extraction operator >----------------------------------

istream& operator>>(istream &in, str &s) {

  char ch;
  s.flush();
  in >> ch;
  while((ch != '\n') && in.good()) {
    s += ch;
    in.get(ch);
  }
  return in;
}

//

//----< test stub >--------------------------------------------

#ifdef TEST_STR

#include <fstream>

void main() {

  cout << "\n  Testing str class "
       << "\n ===================\n";

  cout << "\n  testing promotion constructor "
       << "\n -------------------------------\n";

  str s1 = "this is a string";   // calls str(const char *s)
  cout << "  new str object: " << s1 << endl;

  cout << "\n  testing copy constructor "
       << "\n --------------------------\n";

  str s2 = s1;                   // calls str(const str &s)
  cout << "  copy of original:    " << s2 << endl;

  cout << "\n  testing index operator "
       << "\n ------------------------\n";

  char ch = s1[1];
  cout << "  second character is: " << ch << endl;

  s2[3] = 'x';
  cout << "  modifying fourth character: " << s2 << endl;

  cout << "\n  testing appends "
       << "\n -----------------\n";

  cout << "  appending vowel characters:\n";
  s1 += 'a';
  cout << "  " << s1 << endl;
  s1 += 'e';
  cout << "  " << s1 << endl;
  s1 += 'i';
  cout << "  " << s1 << endl;
  s1 += 'o';
  cout << "  " << s1 << endl;
  s1 += 'u';
  cout << "  " << s1 << endl;
  cout << "  size of str object is " << s1.size() << endl;
  
  cout << "\n  appending string \"yyy\": ";
  s1 += "yyy";
  cout << s1 << endl;
  cout << "  size of str object is now " << s1.size() << endl; 

  cout << "  appending a long string to str object:\n  ";
  s1 += " and the rain in Spain falls mainly on the plain";
  cout << s1 << endl;
  cout << "  size of str object is now " << s1.size() << "\n\n";

//

  cout << "\n  testing assignment operator "
       << "\n -----------------------------\n";

  cout << "  assigning the original's copy to this string: ";
  s1 = s2;
  cout << s2 << endl;
  cout << "  size of str object is now " << s1.size() << "\n\n";

  cout << "\n  testing memory resizing by multiple appends "
       << "\n ---------------------------------------------\n";  
  cout << "  appending \"C++ is great!!! \" several times to this string:\n\n";
  int i;
  for(i=0; i<5; i++) {
    s1 += "C++ is great!!! ";
    s2 = s1;
    cout << "  " << s2 << endl;
    cout << "  size of str object is now " << s2.size() << "\n\n";
  }

  cout << "\n  testing insertion and extraction operators "
       << "\n --------------------------------------------\n";

  ofstream out("test.dat");
  if(!out.good()) {
    cout << "\n  can't open file for writing strings\n\n";
    return;
  }
  str insert1 = "Now is the time for all good men ";
  insert1 += "to come to the aid of their country";
  out << insert1 << endl;

  str insert2 = "The rain in Spain falls mainly on the plain";
  out << insert2 << endl;

  str insert3 = "This is the last line";
  out << insert3 << endl;

  out.close();
  ifstream in("test.dat");
  if(!in.good()) {
    cout << "\n  can't open file test.dat for input\n\n";
    return;
  }

  str extract;
  while(in.good()) {
    in >> extract;
    cout << "  " << extract << endl;
  }
  cout << endl;
}

#endif