// chset.cpp

#include "chset.h"
#include "pmglobs.h"
#include <iostream.h>
#include <string.h>

// constructor:
chset::chset(const char* s) {
   //cout << "in chset constructor\n";
   if (s == NULL) {
      set = NULL;
   } else {
      int i = 0;
      while (s[i] != '\0') i++;  // counts number of chars in s.
      int size = i + 1;          // for space allocation
      char* tempStr = new char[size];  // allocates space to hold s.
      for (int j = 0; j < size; j++) tempStr[j] = '\0'; // initialize
      
      int k = 0; 
      for (j = 0; j < size; j++) {
         if (strchr(tempStr, s[j]) == NULL) {
            tempStr[k] = s[j];
            k++;
         }
      }  // end of for loop.
      tempStr[k] = '\0';  // end string with NULL character.
      char* tempStr2 = new char[k+1]; // alloc space to hold set members
      for (i = 0; i < k + 1; i++) tempStr2[i] = tempStr[i];  // copy.
      tempStr2[k+1] = '\0';
      delete tempStr;
      set = tempStr2;     // pointer assignment. 
   }  // end of if-else.
}  // end of constructor.    

chset::~chset() {         // destructor
   delete set;
   set = NULL;
}

bool chset::in(char ch) const {  // test if char ch in set set.
   return bool(strchr(set, ch) != NULL);
}

void chset::incl(char ch) {  // add char ch into set set.
   if ( !in(ch) ) {
      int k = strlen(set);
      char* tempStr = new char[k+2]; // 1 space for ch and 1 for NULL
      strcpy(tempStr, set);  // copy string set to string tempStr.
      tempStr[k] = ch;       // assign ch to kth position
      tempStr[k+1] = '\0';   // terminate string with NULL.
      delete set;
      set = tempStr;         // reset set to new set.
   }  // end of if.
}  // end of method incl.

void chset::operator<(char ch) {
// not sure what do this method do.
}

chset operator+(const chset& c1, const chset& c2) { // set union.
   int k = strlen(c1.set);
   int j = k;
   for (int i = 0; i < strlen(c2.set); i++) {
      if ( !c1.in(c2.set[i]) ) k++;  // make space for set union.
   }  // end of for loop. 

   char* tempStr = new char[k+1];
   strcpy(tempStr, c1.set);
   for (i = 0; i < strlen(c2.set); i++) {
      if ( !c1.in(c2.set[i]) ) {
         tempStr[j] = c2.set[i];  // add extra elements of c2 to tempStr.
         j++;
      }  // end of if
   }     // enf of for loop.
   tempStr[j] = '\0';             // teinate string with '\0' char.
  
   chset aChset(tempStr);

   return aChset;
}

chset& chset::operator=(const chset& c) {
   set = strdup(c.set);
   return *this;
}

ostream& operator<<(ostream& co, const chset& c) {
   co << "{" << c.set << "}";
   return co;
}