////////////////////////////////////////////////////
// str.cpp - implementation file for string class //
////////////////////////////////////////////////////
#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[s.max];
  if(array==0)
    throw "\n  memory allocation failure\n\n";
  int i;
  for(i=0; i<s.len; i++)
    array[i] = s.array[i];
  array[s.len] = '\0';
  max = s.max;
  len = s.len;
};

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

str::str(const char *s) {

  int length = strlen(s) + 1;
  array = new char[length];
  int i;
  for(i=0; i<length-1; i++)
    array[i] = s[i];
  array[length-1] = '\0';
  len = length-1;
  max = length;
}

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

str::~str() {

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

//

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

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

  if(this == &s) return *this;
  if(max >= s.max) {
    int i;
    for(i=0; i<=s.size(); i++)
      array[i] = s.array[i];
    len = s.len;
    return *this;
  }
  char *temp = new char[s.max + 10];
  int i;
  for(i=0; i<=s.size(); i++)
    temp[i] = s.array[i];
  len = s.len;
  max = s.max + 10;
  delete [] array;
  array = temp;
  return *this;
}

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

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

  return array[n];
}

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

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

  return array[n];
}

//----< return number of chars in str >------------------------

int str::size() const { return len; }

//

//----< 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];
    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];
    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;
}

//

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

#ifdef TEST_STR

void main() {

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

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

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

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

  s2[3] = 'x';
  cout << "  modified str object: " << s2 << endl;
  cout << "\n\n";

  cout << "  appending \'x\' to orignial str object: ";
  s1 += 'x';
  cout << s1 << endl;
  cout << "  size of str object is " << s1.size() << endl;
  cout << "  appending \"yyy\" to modified last str object: ";
  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 << "  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 << "  assigning \"C++ is great!!! \" several times to this string:\n";
  int i;
  for(i=0; i<10; i++) {
    s1 += "C++ is great!!! ";
    s2 = s1;
    cout << "  " << s2 << endl;
    cout << "  size of str object is now " << s2.size() << "\n\n";
  }
}

#endif