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/*
* Copyright 2000-2014 Vaadin Ltd.
*
* Licensed 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.
*/
package com.vaadin.client.widget.escalator;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import com.google.gwt.dom.client.TableRowElement;
/**
* An internal implementation of the {@link Row} interface.
*
* There is only one instance per Escalator. This is designed to be re-used when
* rendering rows.
*
* @since 7.4
* @author Vaadin Ltd
* @see Escalator.AbstractRowContainer#refreshRow(Node, int)
*/
public class FlyweightRow implements Row {
static class CellIterator implements Iterator {
/** A defensive copy of the cells in the current row. */
private final ArrayList cells;
private final boolean cellsAttached;
private int cursor = 0;
private int skipNext = 0;
/**
* Creates a new iterator of attached flyweight cells. A cell is
* attached if it has a corresponding {@link FlyweightCell#getElement()
* DOM element} attached to the row element.
*
* @param cells
* the collection of cells to iterate
*/
public static CellIterator attached(
final Collection cells) {
return new CellIterator(cells, true);
}
/**
* Creates a new iterator of unattached flyweight cells. A cell is
* unattached if it does not have a corresponding
* {@link FlyweightCell#getElement() DOM element} attached to the row
* element.
*
* @param cells
* the collection of cells to iterate
*/
public static CellIterator unattached(
final Collection cells) {
return new CellIterator(cells, false);
}
private CellIterator(final Collection cells,
final boolean attached) {
this.cells = new ArrayList(cells);
cellsAttached = attached;
}
@Override
public boolean hasNext() {
return cursor + skipNext < cells.size();
}
@Override
public FlyweightCell next() {
// if we needed to skip some cells since the last invocation.
for (int i = 0; i < skipNext; i++) {
cells.remove(cursor);
}
skipNext = 0;
final FlyweightCell cell = cells.get(cursor++);
cell.setup(this);
return cell;
}
@Override
public void remove() {
throw new UnsupportedOperationException(
"Cannot remove cells via iterator");
}
/**
* Sets the number of cells to skip when {@link #next()} is called the
* next time. Cell hiding is also handled eagerly in this method.
*
* @param colspan
* the number of cells to skip on next invocation of
* {@link #next()}
*/
public void setSkipNext(final int colspan) {
assert colspan > 0 : "Number of cells didn't make sense: "
+ colspan;
skipNext = colspan;
}
/**
* Gets the next n cells in the iterator, ignoring any
* possibly spanned cells.
*
* @param n
* the number of next cells to retrieve
* @return A list of next n cells, or less if there aren't
* enough cells to retrieve
*/
public List rawPeekNext(final int n) {
final int from = Math.min(cursor, cells.size());
final int to = Math.min(cursor + n, cells.size());
List nextCells = cells.subList(from, to);
for (FlyweightCell cell : nextCells) {
cell.setup(this);
}
return nextCells;
}
public boolean areCellsAttached() {
return cellsAttached;
}
}
private static final int BLANK = Integer.MIN_VALUE;
private int row;
private TableRowElement element;
private double[] columnWidths = null;
private final List cells = new ArrayList();
public void setup(final TableRowElement e, final int row,
double[] columnWidths) {
element = e;
this.row = row;
this.columnWidths = columnWidths;
}
/**
* Tear down the state of the Row.
*
* This is an internal check method, to prevent retrieving uninitialized
* data by calling {@link #getRow()}, {@link #getElement()} or
* {@link #getCells()} at an improper time.
*
* This should only be used with asserts ("
* assert flyweightRow.teardown() ") so that the code is never
* run when asserts aren't enabled.
*
* @return always true
*/
public boolean teardown() {
element = null;
row = BLANK;
columnWidths = null;
for (final FlyweightCell cell : cells) {
assert cell.teardown();
}
return true;
}
@Override
public int getRow() {
assertSetup();
return row;
}
@Override
public TableRowElement getElement() {
assertSetup();
return element;
}
public void addCells(final int index, final int numberOfColumns) {
for (int i = 0; i < numberOfColumns; i++) {
final int col = index + i;
cells.add(col, new FlyweightCell(this, col));
}
updateRestOfCells(index + numberOfColumns);
}
public void removeCells(final int index, final int numberOfColumns) {
cells.subList(index, index + numberOfColumns).clear();
updateRestOfCells(index);
}
private void updateRestOfCells(final int startPos) {
// update the column number for the cells to the right
for (int col = startPos; col < cells.size(); col++) {
cells.set(col, new FlyweightCell(this, col));
}
}
/**
* Returns flyweight cells for the client code to render. The cells get
* their associated {@link FlyweightCell#getElement() elements} from the row
* element.
*
* Precondition: each cell has a corresponding element in the row
*
* @return an iterable of flyweight cells
*
* @see #setup(Element, int, int[])
* @see #teardown()
*/
public Iterable getCells() {
return getCells(0, cells.size());
}
/**
* Returns a subrange of flyweight cells for the client code to render. The
* cells get their associated {@link FlyweightCell#getElement() elements}
* from the row element.
*
* Precondition: each cell has a corresponding element in the row
*
* @param offset
* the index of the first cell to return
* @param numberOfCells
* the number of cells to return
* @return an iterable of flyweight cells
*/
public Iterable getCells(final int offset,
final int numberOfCells) {
assertSetup();
assert offset >= 0 && offset + numberOfCells <= cells.size() : "Invalid range of cells";
return new Iterable() {
@Override
public Iterator iterator() {
return CellIterator.attached(cells.subList(offset, offset
+ numberOfCells));
}
};
}
/**
* Returns a subrange of unattached flyweight cells. Unattached cells do not
* have {@link FlyweightCell#getElement() elements} associated. Note that
* FlyweightRow does not keep track of whether cells in actuality have
* corresponding DOM elements or not; it is the caller's responsibility to
* invoke this method with correct parameters.
*
* Precondition: the range [offset, offset + numberOfCells) must be valid
*
* @param offset
* the index of the first cell to return
* @param numberOfCells
* the number of cells to return
* @return an iterable of flyweight cells
*/
public Iterable getUnattachedCells(final int offset,
final int numberOfCells) {
assertSetup();
assert offset >= 0 && offset + numberOfCells <= cells.size() : "Invalid range of cells";
return new Iterable() {
@Override
public Iterator iterator() {
return CellIterator.unattached(cells.subList(offset, offset
+ numberOfCells));
}
};
}
/**
* Asserts that the flyweight row has properly been set up before trying to
* access any of its data.
*/
private void assertSetup() {
assert element != null && row != BLANK && columnWidths != null : "Flyweight row was not "
+ "properly initialized. Make sure the setup-method is "
+ "called before retrieving data. This is either a bug "
+ "in Escalator, or the instance of the flyweight row "
+ "has been stored and accessed.";
}
double getColumnWidth(int column) {
assertSetup();
return columnWidths[column];
}
}