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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id$ */
package org.apache.fop.layoutmgr;
import org.apache.fop.util.ListUtil;
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
/**
* Represents a list of Knuth elements.
*/
public abstract class KnuthSequence extends ArrayList {
/**
* Creates a new and empty list.
*/
public KnuthSequence() {
super();
}
/**
* Creates a new list from an existing list.
* @param list The list from which to create the new list.
*/
public KnuthSequence(List list) {
super(list);
}
/**
* Marks the start of the sequence.
*/
public void startSequence() {
}
/**
* Finalizes a Knuth sequence.
* @return a finalized sequence.
*/
public abstract KnuthSequence endSequence();
/**
* Can sequence be appended to this sequence?
* @param sequence The sequence that may be appended.
* @return whether the sequence can be appended to this sequence.
*/
public abstract boolean canAppendSequence(KnuthSequence sequence);
/**
* Append sequence to this sequence if it can be appended.
* @param sequence The sequence that is to be appended.
* @param keepTogether Whether the two sequences must be kept together.
* @param breakElement The BreakElement that may be inserted between the two sequences.
* @return whether the sequence was succesfully appended to this sequence.
*/
public abstract boolean appendSequence(KnuthSequence sequence, boolean keepTogether,
BreakElement breakElement);
/**
* Append sequence to this sequence if it can be appended.
* @param sequence The sequence that is to be appended.
* @return whether the sequence was succesfully appended to this sequence.
*/
public abstract boolean appendSequence(KnuthSequence sequence);
/**
* Append sequence to this sequence if it can be appended.
* If that is not possible, close this sequence.
* @param sequence The sequence that is to be appended.
* @return whether the sequence was succesfully appended to this sequence.
*/
public boolean appendSequenceOrClose(KnuthSequence sequence) {
if (!appendSequence(sequence)) {
endSequence();
return false;
} else {
return true;
}
}
/**
* Append sequence to this sequence if it can be appended.
* If that is not possible, close this sequence.
* @param sequence The sequence that is to be appended.
* @param keepTogether Whether the two sequences must be kept together.
* @param breakElement The BreakElement that may be inserted between the two sequences.
* @return whether the sequence was succesfully appended to this sequence.
*/
public boolean appendSequenceOrClose(KnuthSequence sequence, boolean keepTogether,
BreakElement breakElement) {
if (!appendSequence(sequence, keepTogether, breakElement)) {
endSequence();
return false;
} else {
return true;
}
}
/**
* Wrap the Positions of the elements of this sequence in a Position for LayoutManager lm.
* @param lm The LayoutManager for the Positions that will be created.
*/
public void wrapPositions(LayoutManager lm) {
ListIterator listIter = listIterator();
ListElement element;
while (listIter.hasNext()) {
element = (ListElement) listIter.next();
element.setPosition
(lm.notifyPos(new NonLeafPosition(lm, element.getPosition())));
}
}
/**
* @return the last element of this sequence.
*/
public ListElement getLast() {
return (isEmpty()
? null
: (ListElement) ListUtil.getLast(this));
}
/**
* Remove the last element of this sequence.
* @return the removed element.
*/
public ListElement removeLast() {
return (isEmpty()
? null
: (ListElement) ListUtil.removeLast(this));
}
/**
* @param index The index of the element to be returned
* @return the element at index index.
*/
public ListElement getElement(int index) {
return (index >= size() || index < 0)
? null
: (ListElement) get(index);
}
/** @return the position index of the first box in this sequence */
protected int getFirstBoxIndex() {
if (isEmpty()) {
return -1;
} else {
return getFirstBoxIndex(0);
}
}
/**
* Get the position index of the first box in this sequence,
* starting at the given index. If there is no box after the
* passed {@code startIndex}, the starting index itself is returned.
* @param startIndex the starting index for the lookup
* @return the absolute position index of the next box element
*/
protected int getFirstBoxIndex(int startIndex) {
if (isEmpty() || startIndex < 0 || startIndex >= size()) {
return -1;
} else {
ListElement element = null;
int posIndex = startIndex;
int lastIndex = size();
while (posIndex < lastIndex
&& !(element = getElement(posIndex)).isBox()) {
posIndex++;
}
if (posIndex != startIndex
&& element.isBox()) {
return posIndex - 1;
} else {
return startIndex;
}
}
}
/**
* Is this an inline or a block sequence?
* @return true if this is an inline sequence
*/
public abstract boolean isInlineSequence();
/** {@inheritDoc} */
public String toString() {
return "<KnuthSequence " + super.toString() + ">";
}
}
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