#ifndef _STRINGTAB
#define _STRINGTAB
/*
 * StringTab and Symbol interface file
 *      created by CMB  8/04
 *
 *
 *  MOD 3/21/06 by CMB
 *    changed << operator on pointer to take pointer to const object
 *
 *  MOD 9/28/04 by CMB
 *    added << operator on Symbol & for printing symbol table
 *      to interface file.
 *
 *  MOD 9/21/04 by CMB
 *    added << operator on Symbol * useful for printing ASTs
 *    also changed getName to return const-ref (so it doesn't copy it)
 *
 *  MOD 9/15/04 by CMB
 *    added #include <iostream> to get it to compile with g++ version 3
 *
 *
 *   StringTab class:
 *   The StringTab class is for storing the strings used while compiling.
 *         (e.g., string constants or identifiers from the source code)
 *     It stores the strings uniquely.  E.g., if you insert the same string
 *         a second time, it returns the first one in the table
 *         (using a Symbol*).
 *
 *   Member functions:
 ***   StringTable st;
 *        Creates an empty StringTable.
 *
 *     Symbol *sym;
 ***   sym = st.addString(someString);
 *         Adds someString to the StringTable st.  
 *         If someString is already present in the table, returns a pointer 
 *             to the existing symbol instance.
 *         Once we add a string to the table, we access the string
 *         via a Symbol pointer (sym).
 *
 ***  st.dumpStringTab(myOStream);
 *        Prints the strings in the table to myOStream, one per line.
 *
 *
 *  Symbol class:
 *
 *     Since Symbols are unique if they are created via the same StringTab
 *          object, we can compare two Symbol *pointers* find out if they
 *          are the same symbol.  (but not if they are from different 
 *          StringTabs)
 *
 *     One may not create Symbol objects outside of a StringTable.
 *
 *     Symbol *sym;
 *
 ***   sym->getName();
 *          Get the string itself
 *
 *     o << sym;
 *          Print out the sym
 *
 */


#include <map>
#include <string>
#include <iostream>
using namespace std;

class Symbol;

class StringTab {
 private:
  typedef map<string, Symbol *> StrTabMap;
  StrTabMap tab;
  
 public:

  Symbol *addString(string newId);

  void dumpStringTab(ostream &o);

};


class Symbol {
 public:
  const string &getName() const { return id; }
  
 private:
  string id;
  friend class StringTab;
      // constructor is private: only allow StringTab to create symbols
  Symbol(string newId) : id(newId) { }   

};


ostream& operator<<(ostream& o, const Symbol *symPtr);
ostream& operator<<(ostream& o, const Symbol& symbol) ;


#endif