package fcm;

import java.io.BufferedReader;
import java.io.Reader;
import java.io.FileReader;
import java.io.File;
import java.io.IOException;

public class IOClosureTest {

  public interface ReaderCallback {
    
    public void doWithReader(Reader reader) throws IOException;
    
  }
  
  public static void doWithFile(File file, ReaderCallback callback) throws IOException {
    Reader reader = null;
    boolean done = false;
    try {
      reader = new FileReader(file);
      callback.doWithReader(reader);
      done = true;
    } finally {
      if (reader != null) {
        try {
          reader.close();
        } catch (IOException e) {
          if (done) throw e;
        }
      }
    }
  }
  
  public interface LineCallback {
    public void doForLine(String line) throws IOException;
  }
  
  public static void forEachLine(File file, final LineCallback lineCallback) throws IOException {
    doWithFile(file, #(Reader reader) {
      BufferedReader bufferedReader = new BufferedReader(reader);
      String line;
      while ( (line = bufferedReader.readLine()) != null) {
        lineCallback.doForLine(line);
      }
    });
  }
  
  
  public static void main(String[] args) throws IOException {
    forEachLine(new File(args[0]), #(String line) {
      System.out.println("This is a line:" + line);
    });
  }

  public static void theOldWay(String[] args) throws IOException {
    BufferedReader reader = null;
    boolean done = false;
    try {
      reader = new BufferedReader(new FileReader(new File(args[0])));
      String line;
      while ( (line = reader.readLine()) != null) {
        System.out.println("This is a line:" + line);
      }
      done = true;
    } finally {
      if (reader != null) {
        try {
          reader.close();
        } catch (IOException e) {
          if (done) throw e;
        }
      }
    }
    
  }

  
  
}