// idsymtab.cpp
// implement idSymbolTable class.

#include "idsymtab.h"
#include <iostream.h>
#include <string.h>

idSymbolTable::idSymbolTable() {  // constructor.
   for (int i = 0; i < NUMOFKEYS; i++) idSymTab[i] = NULL; // initialize.
   for (i = 0; i < MAXCHARS; i++) strTab.str[i] = '@'; // initialize.
   strTab.freeIndex = 0;
   idIndex = 0;
}

idSymbolTable::~idSymbolTable() {  // destructor.
   idSymbolNode* p;
   idSymbolNode* q;

   for (int i = 0; i < NUMOFKEYS; i++) {
      p = idSymTab[i];
      while (p != NULL) {
         q = p->link;
         delete p;      // delete all idSymbolNode which are not NULL.
         p = q;
      }  // end of while loop.
   }  // end of for loop.
}  // end of destructor.

int idSymbolTable::idHash(char* w) {   // define hash function.
   const unsigned int MAX=65535 - 127;
   unsigned int sum = 0;
   
   for (int i = 0; i < strlen(w); i++) sum = (sum + w[i]) % MAX;

   return sum % NUMOFKEYS;
}

void idSymbolTable::printStrTab() {
   for (int i = 0; i < strTab.freeIndex; i++) {
      if (strTab.str[i] != '@') 
         cout << strTab.str[i] << " ";
   }
   cout << "\nThe freeIndex of strTab is: " << strTab.freeIndex << endl;
}
 
void idSymbolTable::printIdSymTab() {
   for (int i = 0; i < NUMOFKEYS; i++) {
      if (idSymTab[i] != NULL) {
         cout << "At index: (" << i 
              << "), there are following idSymbolNode(s):" << endl;
         // process linked list using while loop.  Will do later.
      }
   }
}

void idSymbolTable::searchAndMaybeInsert(char* s, int& idIdx, bool& insertOk) {
   bool done = false;
   insertOk = true;
   int k = 0;
   char w[STRSIZE], t[2];
   t[1] = '\0';
   int idHashValue = idHash(s);
   idSymbolNode* p = idSymTab[idHashValue];

   // Process:
   while ( (p != NULL) && (!done) ) {
      w[0] = '\0';
      k = p->firstChar;
      while (k < (p->firstChar + p->length) ) {
         t[0] = strTab.str[k];
         strcat(w, t);
         k++;
      }  // end of inner while loop.
      if (strcmp(w, s) == 0) { // case w == s
         idIdx = p->index;
         done = true;
      } else {
         p = p->link;  // advance the pointer.
      }  // end of if-else.
   }  // end of outer while loop.

   if (p == NULL) {
      int len = strlen(s);
      if ( (strTab.freeIndex + len) >  (MAXCHARS - 1) ) {
         insertOk = false;
         idIdx = 0;
      } else {
         k = 0;
         while (k < len) {
            strTab.str[strTab.freeIndex + k] = s[k];
            k++;
         }  // end of while loop.
         idSymbolNode* q = idSymTab[idHashValue];
         p = new idSymbolNode;
         p->firstChar = strTab.freeIndex;
         p->length = k;
         p->index = idIndex;
         p->link = q;  // advance pointer.
         idSymTab[idHashValue] = p;
         strTab.freeIndex += k;
         idIdx = idIndex;
         idIndex++;
      }  // end if if-else.
   }  // end of outer if.
}  // end of the method searchAndMaybeInsert().