#include <string>
#include <setjmp.h>
#include "token.h"
#include "node.h"
#include "hashtable.h"
#include "lexan.h"
#include "world.h"

int world::evaluate(node * n)
{ node_type t = n->gettype();
  if (t == terror)
  { cerr << "Error! " << n->getstring() << "\n";
    return 0; }

  else if (t == tnumber)
    return n->getvalue();

  else if (t == tvariable)
  { int * p = mem.find(n->getstring());
    if (p == NULL)
    { cerr << "Error! undefined variable " << n->getstring() << "\n";
      longjmp(error_go, 254); }
    return * p; }

  else if (t == toperator)
  { int L = evaluate(n->getlink(0));
    int R = evaluate(n->getlink(1));
    char c = n->getstring()[0];
    switch (c)
    { case '+': return L + R;
      case '-': return L - R;
      case '*': return L * R;
      case '/': { if (R == 0)     
                  { cout << "division by zero!\n";
                    longjmp(error_go, 234); }
                  return L / R; }
      case '^': return power(L, R);
      default: { cout << "error operator '" << c << "'\n";
                 return 0; } } }  

  else
  { cerr << "Error evaluate node type " << n->gettype() << "\n";
    return 0; } }

int world::main_evaluate(node * n)
{ int a = setjmp(error_go);
  if (a != 0)
    return 0;
  return evaluate(n); }

void world::setvar(string name, int value)
{ mem.set(name, value); }

int world::power(int a, int b)
{ if (b == 0)
  { if (a == 0)
    { cout << "Error! 0^0\n";
      longjmp(error_go, 241); }
    return 1; }
  if (b < 0)
  { if (a == 0)
    { cout << "Error! 0^negative\n";
      longjmp(error_go, 242); }
    if (a == 1)
      return 1;
    if (a == -1)
    { if (b & 1)
        return -1;
      return 1; }
    return 0; }
  int p = 1;
  int m = a;
  while (b > 0)
  { if (b & 1)
      p *= m;
    m *= m;
    b >>= 1; }
  return p; }