/***

Overview:

  When printing large objects (such as a Symbol_table) and nested objects
  indentation can be very helpful.

  class Indent provides an easy way to perform indentation

How to use:

  If you include indent.h, you will have access to the global
  variable: Indent indent

  Whenever you start a new line of output, output indent first.
  When you want to increase and decrease the level of intention
  call indent++ or indent--

  Here is some sample code using class Indent

  // indent the following using the "current" indentation level
  os << indent << "Symbol_table" << endl;
  os << indent << "{" << endl;
  indent++; // increase the "current" indentation level
  os << indent << something_goes_here << endl;
  os << indent << something_goes_here << endl;
  os << indent << something_goes_here << endl;
  indent--; // decrease the "current" indentation level
  os << "}" << endl;

  If the entire program shares a single indent object, you can print
  nested structures and the indentation will always be correct.

***/

#ifndef INDENT_H
#define INDENT_H

#include <iostream>

class Indent
{
  friend std::ostream &operator<<(std::ostream &os, const Indent &indent);
  public:
    Indent();

    // overload pre-fix ++ and --
    Indent &operator++() {m_level+=2; return *this;}
    Indent &operator--()
      {m_level-=2; if (m_level < 0) m_level = 0; return *this;}

    // overload post-fix ++ and --
    // this is weird, but putting that int there makes it post-fix
    Indent &operator++(int) {m_level+=2; return *this;}
    Indent &operator--(int)
      {m_level-=2; if (m_level < 0) m_level = 0; return *this;}

    Indent &operator+=(int i) {m_level+=i; return *this;}
    Indent &operator-=(int i)
      {m_level-=i; if (m_level < 0) m_level = 0; return *this;}

  private:
    // disable default copy constructor and default assignment
    // done as a precaution, they should never be called
    Indent(const Indent&);
    const Indent &operator=(const Indent&);

    static int m_count;

    int m_level;
};

std::ostream &operator<<(std::ostream &os, const Indent &indent);

extern Indent indent;

#endif // #ifndef INDENT_H