/*
    $Id: misc.cc 1109 2007-04-17 00:04:26Z rvernica $

    Copyright (C) 2007 by The Regents of the University of California

    Redistribution of this file is permitted under the terms of the
    GNU Public License (GPL).

    Date: 01/30/2007
    Author: Rares Vernica <rvernica@ics.uci.edu>
*/

#include "misc.h"

#include <iostream>
#include <sstream>

unsigned pow(unsigned x, unsigned y) 
{
  unsigned r = 1;
  while (y > 0) {
    r *= x;
    y--;
  }
  return r;
}

vector<vector<unsigned> > subsets(unsigned n, unsigned k) 
{
  if (k == 0) {
    cerr << "subsets: k cannot be 0" << endl;
    exit(EXIT_FAILURE);
  }
  vector<vector<unsigned> > subs;
  vector<unsigned> sub(k);

  unsigned i;
  for (i = 0; i < k; i++)
    sub[i] = i;
  subs.push_back(sub);

  while (sub[0] < n - k) {
    for (i = 0; i < k; i++)
      if (sub[k - i - 1] < n - i - 1)
        break;
    i = k - i - 1;
    sub[i]++;
    i++;
    for (; i < k; i++)
      sub[i] = sub[i - 1] + 1;
    subs.push_back(sub);
  }

  return subs;
}

string utos(unsigned i) 
{
  stringstream s;
  s << i;
  return s.str();
}

string utosh(unsigned i) 
{
  string str;
  if (i < 1000)
    str = utos(i);
  else
    str = utos(i / 1000) + "k";
  return str;
}

UnsignedSeq::UnsignedSeq(unsigned initialValue): value(initialValue)
{
}

unsigned UnsignedSeq::operator() ()
{
  return value++;
}

string removeExt(const string filename)
{
  const string exts[] = {"txt", "bin"};
  for (unsigned i = 0; i < sizeof(exts) / sizeof(string); i++)
    if (filename.substr(filename.size() - 4) == "." + exts[i])
      return filename.substr(0, filename.size() - 4);
  return filename;
}

void writeerror(const string filename) 
{
  cerr << "can't write to file \"" << filename << "\"" << endl;
  exit(EXIT_FAILURE);
}

void readerror(const string filename) 
{
  cerr << "can't read from file \"" << filename << "\"" << endl;
  exit(EXIT_FAILURE);
}