// @(#)$Id: BlankReader.java 1199 2009-02-17 19:42:32Z smshaner $

// Copyright (C) 2003 Iowa State University

// This file is part of JML

// JML is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.

// JML is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with JML; see the file COPYING.  If not, write to
// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.


package org.jmlspecs.samples.reader;

/** A reader that delivers a stream of blanks.
 * @author Arnd Poetzsch-Heffter
 *         from an example by K. Rustan M. Leino and Greg Nelson, in
 *         Data abstraction and information hiding,
 *         ACM Transactions on Programming Languages and Systems,
 *         Volume 24, number 5, pp. 491-553, September 2002.
 */
public class BlankReader extends BufferedReader
{
  private int num;
  //@           in state, svalid;

  //@ private represents svalid <- hi <= num ;

  /*@ public normal_behavior
    @   requires    0 <= n;
    @   assignable  valid, state;
    @   ensures     valid && svalid;
    @*/
  public BlankReader( int n ) {
    num  = n;
    buff = new char[ Math.min(n,8192) ];
    lo  = 0;
    cur = 0;
    hi  = buff.length;
    for( int i = 0; i < hi; i++ ) {
      buff[i] = 32;
    }
  }

  public void refill() {
    lo = cur;
    hi = Math.min( lo+buff.length, num );
  }

  public void close() {}

}