IteratorSeq.java

import java.io.IOException;
import java.io.NotSerializableException;
import java.util.Iterator;
import clojure.lang.ASeq;
import clojure.lang.ISeq;
import clojure.lang.IPersistentMap;
 
public class IteratorSeq extends ASeq{
final Iterator iter;
final State state;
 
    static class State{
    volatile Object val;
    volatile Object _rest;
}
 
public static IteratorSeq create(Iterator iter){
    if(iter.hasNext())
        return new IteratorSeq(iter);
    return null;
}
 
public IteratorSeq(Iterator iter){
    this.iter = iter;
    state = new State();
    this.state.val = state;
    this.state._rest = state;
}
 
public IteratorSeq(IPersistentMap meta, Iterator iter, State state){
    super(meta);
    this.iter = iter;
    this.state = state;
}
 
public Object first() { 
  if(state.val == state) synchronized(state) { 
    if(state.val == state) state.val = iter.next(); 
  } 
  return state.val; 
}
 
public ISeq next(){
  if(state._rest == state) {
    synchronized(state) {
      if(state._rest == state) {
        first();
        state._rest = iter.hasNext() ? new IteratorSeq(iter) : null;
      }
    }
  }
  return (ISeq) state._rest;
}
 
public IteratorSeq withMeta(IPersistentMap meta){
    return new IteratorSeq(meta, iter, state);
}
 
private void writeObject (java.io.ObjectOutputStream out) throws IOException {
    throw new NotSerializableException(getClass().getName());
}
}