/* * $Id$ * Copyright (C) 2001 The Apache Software Foundation. All rights reserved. * For details on use and redistribution please refer to the * LICENSE file included with these sources. */ package org.apache.fop.layoutmgr; import java.util.Iterator; import java.util.NoSuchElementException; public abstract class PositionIterator implements Iterator { Iterator parentIter; Object nextObj; LayoutManager childLM; boolean bHasNext; PositionIterator(Iterator pIter) { parentIter = pIter; lookAhead(); //checkNext(); } public LayoutManager getNextChildLM() { // Move to next "segment" of iterator, ie: new childLM if (childLM == null && nextObj != null) { childLM = getLM(nextObj); bHasNext = true; } return childLM; } protected abstract LayoutManager getLM(Object nextObj); protected abstract Position getPos(Object nextObj); private void lookAhead() { if (parentIter.hasNext()) { bHasNext = true; nextObj = parentIter.next(); } else { endIter(); } } protected boolean checkNext() { LayoutManager lm = getLM(nextObj); if (childLM == null) { childLM = lm; } else if (childLM != lm) { // End of this sub-sequence with same child LM bHasNext = false; childLM = null; return false; } return true; } protected void endIter() { bHasNext = false; nextObj = null; childLM = null; } public boolean hasNext() { return (bHasNext && checkNext()); } public Object next() throws NoSuchElementException { if (bHasNext) { Object retObj = getPos(nextObj); lookAhead(); return retObj; } else { throw new NoSuchElementException("PosIter"); } } protected Object peekNext() { return nextObj; } public void remove() throws UnsupportedOperationException { throw new UnsupportedOperationException("PositionIterator doesn't support remove"); } }