user/src/com/google/gwt/view/client/ListDataProvider.java - gwt - Git at Google

 /*
  * Copyright 2010 Google Inc.
  *
  * 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.google.gwt.view.client;

 import com.google.gwt.core.client.Scheduler;
 import com.google.gwt.core.client.Scheduler.ScheduledCommand;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
 import java.util.NoSuchElementException;

 /**
  * A concrete subclass of {@link AbstractDataProvider} that is backed by an
  * in-memory list.
  *
  * <p>
  * Modifications (inserts, removes, sets, etc.) to the list returned by
  * {@link #getList()} will be reflected in the model. However, mutations to the
  * items contained within the list will NOT be reflected in the model. You must
  * call {@link List#set(int, Object)} to update the item within the list and
  * push the change to the display, or call {@link #refresh()} to push all rows
  * to the displays. {@link List#set(int, Object)} performs better because it
  * allows the data provider to push only those rows which have changed, and
  * usually allows the display to re-render only a subset of the rows.
  * </p>
  *
  * <p>
  * <h3>Example</h3> {@example
  * com.google.gwt.examples.view.ListDataProviderExample}
  * </p>
  *
  * @param <T> the data type of the list
  */
 public class ListDataProvider<T> extends AbstractDataProvider<T> {

   /**
    * A wrapper around a list that updates the model on any change.
    */
   private class ListWrapper implements List<T> {

     /**
      * A wrapped ListIterator.
      */
     private final class WrappedListIterator implements ListIterator<T> {

       /**
        * The error message when {@link #add(Object)} or {@link #remove()} is
        * called more than once per call to {@link #next()} or
        * {@link #previous()}.
        */
       private static final String IMPERMEABLE_EXCEPTION =
           "Cannot call add/remove more than once per call to next/previous.";

       /**
        * The index of the object that will be returned by {@link #next()}.
        */
       private int i = 0;

       /**
        * The index of the last object accessed through {@link #next()} or
        * {@link #previous()}.
        */
       private int last = -1;

       private WrappedListIterator() {
       }

       private WrappedListIterator(int start) {
         int size = ListWrapper.this.size();
         if (start < 0 || start > size) {
           throw new IndexOutOfBoundsException(
               "Index: " + start + ", Size: " + size);
         }
         i = start;
       }

       @Override
       public void add(T o) {
         if (last < 0) {
           throw new IllegalStateException(IMPERMEABLE_EXCEPTION);
         }
         ListWrapper.this.add(i++, o);
         last = -1;
       }

       @Override
       public boolean hasNext() {
         return i < ListWrapper.this.size();
       }

       @Override
       public boolean hasPrevious() {
         return i > 0;
       }

       @Override
       public T next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
         return ListWrapper.this.get(last = i++);
       }

       @Override
       public int nextIndex() {
         return i;
       }

       @Override
       public T previous() {
         if (!hasPrevious()) {
           throw new NoSuchElementException();
         }
         return ListWrapper.this.get(last = --i);
       }

       @Override
       public int previousIndex() {
         return i - 1;
       }

       @Override
       public void remove() {
         if (last < 0) {
           throw new IllegalStateException(IMPERMEABLE_EXCEPTION);
         }
         ListWrapper.this.remove(last);
         i = last;
         last = -1;
       }

       @Override
       public void set(T o) {
         if (last == -1) {
           throw new IllegalStateException();
         }
         ListWrapper.this.set(last, o);
       }
     }

     /**
      * The current size of the list.
      */
     private int curSize = 0;

     /**
      * The delegate wrapper.
      */
     private final ListWrapper delegate;

     /**
      * Set to true if the pending flush has been canceled.
      */
     private boolean flushCancelled;

     /**
      * We wait until the end of the current event loop before flushing changes
      * so that we don't spam the displays. This also allows users to clear and
      * replace all of the data without forcing the display back to page 0.
      */
     private ScheduledCommand flushCommand = new ScheduledCommand() {
       @Override
       public void execute() {
         flushPending = false;
         if (flushCancelled) {
           flushCancelled = false;
           return;
         }
         flushNow();
       }
     };

     /**
      * Set to true if a flush is pending.
      */
     private boolean flushPending;

     /**
      * The list that backs the wrapper.
      */
     private List<T> list;

     /**
      * If this is a sublist, the offset it the index relative to the main list.
      */
     private final int offset;

     /**
      * If modified is true, the smallest modified index.
      */
     private int maxModified = Integer.MIN_VALUE;

     /**
      * If modified is true, one past the largest modified index.
      */
     private int minModified = Integer.MAX_VALUE;

     /**
      * True if the list data has been modified.
      */
     private boolean modified;

     public ListWrapper(List<T> list) {
       this(list, null, 0);

       // Initialize the data size based on the size of the input list.
       updateRowCount(list.size(), true);
     }

     /**
      * Construct a new {@link ListWrapper} that delegates flush calls to the
      * specified delegate.
      *
      * @param list the list to wrap
      * @param delegate the delegate
      * @param offset the offset of this list
      */
     private ListWrapper(List<T> list, ListWrapper delegate, int offset) {
       this.list = list;
       this.delegate = delegate;
       this.offset = offset;
     }

     @Override
     public void add(int index, T element) {
       try {
         list.add(index, element);
         minModified = Math.min(minModified, index);
         maxModified = size();
         modified = true;
         flush();
       } catch (IndexOutOfBoundsException e) {
         throw new IndexOutOfBoundsException(e.getMessage());
       }
     }

     @Override
     public boolean add(T e) {
       boolean toRet = list.add(e);
       minModified = Math.min(minModified, size() - 1);
       maxModified = size();
       modified = true;
       flush();
       return toRet;
     }

     @Override
     public boolean addAll(Collection<? extends T> c) {
       minModified = Math.min(minModified, size());
       boolean toRet = list.addAll(c);
       maxModified = size();
       modified = true;
       flush();
       return toRet;
     }

     @Override
     public boolean addAll(int index, Collection<? extends T> c) {
       try {
         boolean toRet = list.addAll(index, c);
         minModified = Math.min(minModified, index);
         maxModified = size();
         modified = true;
         flush();
         return toRet;
       } catch (IndexOutOfBoundsException e) {
         throw new IndexOutOfBoundsException(e.getMessage());
       }
     }

     @Override
     public void clear() {
       list.clear();
       minModified = maxModified = 0;
       modified = true;
       flush();
     }

     @Override
     public boolean contains(Object o) {
       return list.contains(o);
     }

     @Override
     public boolean containsAll(Collection<?> c) {
       return list.containsAll(c);
     }

     @Override
     public boolean equals(Object o) {
       return list.equals(o);
     }

     @Override
     public T get(int index) {
       return list.get(index);
     }

     @Override
     public int hashCode() {
       return list.hashCode();
     }

     @Override
     public int indexOf(Object o) {
       return list.indexOf(o);
     }

     @Override
     public boolean isEmpty() {
       return list.isEmpty();
     }

     @Override
     public Iterator<T> iterator() {
       return listIterator();
     }

     @Override
     public int lastIndexOf(Object o) {
       return list.lastIndexOf(o);
     }

     @Override
     public ListIterator<T> listIterator() {
       return new WrappedListIterator();
     }

     @Override
     public ListIterator<T> listIterator(int index) {
       return new WrappedListIterator(index);
     }

     @Override
     public T remove(int index) {
       try {
         T toRet = list.remove(index);
         minModified = Math.min(minModified, index);
         maxModified = size();
         modified = true;
         flush();
         return toRet;
       } catch (IndexOutOfBoundsException e) {
         throw new IndexOutOfBoundsException(e.getMessage());
       }
     }

     @Override
     public boolean remove(Object o) {
       int index = indexOf(o);
       if (index == -1) {
         return false;
       }
       remove(index);
       return true;
     }

     @Override
     public boolean removeAll(Collection<?> c) {
       boolean toRet = list.removeAll(c);
       minModified = 0;
       maxModified = size();
       modified = true;
       flush();
       return toRet;
     }

     @Override
     public boolean retainAll(Collection<?> c) {
       boolean toRet = list.retainAll(c);
       minModified = 0;
       maxModified = size();
       modified = true;
       flush();
       return toRet;
     }

     @Override
     public T set(int index, T element) {
       T toRet = list.set(index, element);
       minModified = Math.min(minModified, index);
       maxModified = Math.max(maxModified, index + 1);
       modified = true;
       flush();
       return toRet;
     }

     @Override
     public int size() {
       return list.size();
     }

     @Override
     public List<T> subList(int fromIndex, int toIndex) {
       return new ListWrapper(list.subList(fromIndex, toIndex), this, fromIndex);
     }

     @Override
     public Object[] toArray() {
       return list.toArray();
     }

     @Override
     public <C> C[] toArray(C[] a) {
       return list.toArray(a);
     }

     /**
      * Flush the data to the model.
      */
     private void flush() {
       // Defer to the delegate.
       if (delegate != null) {
         delegate.minModified = Math.min(
             minModified + offset, delegate.minModified);
         delegate.maxModified = Math.max(
             maxModified + offset, delegate.maxModified);
         delegate.modified = modified || delegate.modified;
         delegate.flush();
         return;
       }

       flushCancelled = false;
       if (!flushPending) {
         flushPending = true;
         Scheduler.get().scheduleFinally(flushCommand);
       }
     }

     /**
      * Flush pending list changes to the displays. By default,
      */
     private void flushNow() {
       // Cancel any pending flush command.
       if (flushPending) {
         flushCancelled = true;
       }

       // Early exit if this list has been replaced in the data provider.
       if (listWrapper != this) {
         return;
       }

       int newSize = list.size();
       if (curSize != newSize) {
         curSize = newSize;
         updateRowCount(curSize, true);
       }

       if (modified) {
         updateRowData(minModified, list.subList(minModified, maxModified));
         modified = false;
       }
       minModified = Integer.MAX_VALUE;
       maxModified = Integer.MIN_VALUE;
     }
   }

   /**
    * The wrapper around the actual list.
    */
   private ListWrapper listWrapper;

   /**
    * Creates an empty model.
    */
   public ListDataProvider() {
     this(new ArrayList<T>(), null);
   }

   /**
    * Creates a list model that wraps the given list.
    *
    * <p>
    * The wrapped list should no longer be modified as the data provider cannot
    * detect changes to the wrapped list. Instead, call {@link #getList()} to
    * retrieve a wrapper that can be modified and will correctly forward changes
    * to displays.
    *
    * @param listToWrap the List to be wrapped
    */
   public ListDataProvider(List<T> listToWrap) {
     this(listToWrap, null);
   }

   /**
    * Creates an empty list model that wraps the given collection.
    *
    * @param keyProvider an instance of ProvidesKey<T>, or null if the record
    *        object should act as its own key
    */
   public ListDataProvider(ProvidesKey<T> keyProvider) {
     this(new ArrayList<T>(), keyProvider);
   }

   /**
    * Creates a list model that wraps the given list.
    *
    * <p>
    * The wrapped list should no longer be modified as the data provider cannot
    * detect changes to the wrapped list. Instead, call {@link #getList()} to
    * retrieve a wrapper that can be modified and will correctly forward changes
    * to displays.
    *
    * @param listToWrap the List to be wrapped
    * @param keyProvider an instance of ProvidesKey<T>, or null if the record
    *        object should act as its own key
    */
   public ListDataProvider(List<T> listToWrap, ProvidesKey<T> keyProvider) {
     super(keyProvider);
     listWrapper = new ListWrapper(listToWrap);
   }

   /**
    * Flush pending list changes to the displays. By default, displays are
    * informed of modifications to the underlying list at the end of the current
    * event loop, which makes it possible to perform multiple operations
    * synchronously without repeatedly refreshing the displays. This method can
    * be called to flush the changes immediately instead of waiting until the end
    * of the current event loop.
    */
   public void flush() {
     listWrapper.flushNow();
   }

   /**
    * Get the list that backs this model. Changes to the list will be reflected
    * in the model.
    *
    * <p>
    * NOTE: Mutations to the items contained within the list will NOT be
    * reflected in the model. You must call {@link List#set(int, Object)} to
    * update the item within the list and push the change to the display, or call
    * {@link #refresh()} to push all rows to the displays.
    * {@link List#set(int, Object)} performs better because it allows the data
    * provider to push only those rows which have changed, and usually allows the
    * display to re-render only a subset of the rows.
    *
    * @return the list
    *
    * @see #setList(List)
    */
   public List<T> getList() {
     return listWrapper;
   }

   /**
    * Refresh all of the displays listening to this adapter.
    *
    * <p>
    * Use {@link #refresh()} to push mutations to the underlying data items
    * contained within the list. The data provider cannot detect changes to data
    * objects within the list, so you must call this method if you modify items.
    *
    * <p>
    * This is a shortcut for calling {@link List#set(int, Object)} on every item
    * that you modify, but note that calling {@link List#set(int, Object)}
    * performs better because the data provider knows which rows were modified
    * and can push only the modified rows the displays.
    */
   public void refresh() {
     updateRowData(0, listWrapper);
   }

   /**
    * Replace this model's list with the specified list.
    *
    * <p>
    * The wrapped list should no longer be modified as the data provider cannot
    * detect changes to the wrapped list. Instead, call {@link #getList()} to
    * retrieve a wrapper that can be modified and will correctly forward changes
    * to displays.
    *
    * @param listToWrap the model's new list
    *
    * @see #getList()
    */
   public void setList(List<T> listToWrap) {
     listWrapper = new ListWrapper(listToWrap);
     listWrapper.minModified = 0;
     listWrapper.maxModified = listWrapper.size();
     listWrapper.modified = true;
     flush();
   }

   @Override
   protected void onRangeChanged(HasData<T> display) {
     int size = listWrapper.size();
     if (size > 0) {
       // Do not push data if the data set is empty.
       updateRowData(display, 0, listWrapper);
     }
   }
 }
	/*
	* Copyright 2010 Google Inc.
	*
	* 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.google.gwt.view.client;

	import com.google.gwt.core.client.Scheduler;
	import com.google.gwt.core.client.Scheduler.ScheduledCommand;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Iterator;
	import java.util.List;
	import java.util.ListIterator;
	import java.util.NoSuchElementException;

	/**
	* A concrete subclass of {@link AbstractDataProvider} that is backed by an
	* in-memory list.
	*
	* <p>
	* Modifications (inserts, removes, sets, etc.) to the list returned by
	* {@link #getList()} will be reflected in the model. However, mutations to the
	* items contained within the list will NOT be reflected in the model. You must
	* call {@link List#set(int, Object)} to update the item within the list and
	* push the change to the display, or call {@link #refresh()} to push all rows
	* to the displays. {@link List#set(int, Object)} performs better because it
	* allows the data provider to push only those rows which have changed, and
	* usually allows the display to re-render only a subset of the rows.
	* </p>
	*
	* <p>
	* <h3>Example</h3> {@example
	* com.google.gwt.examples.view.ListDataProviderExample}
	* </p>
	*
	* @param <T> the data type of the list
	*/
	public class ListDataProvider<T> extends AbstractDataProvider<T> {

	/**
	* A wrapper around a list that updates the model on any change.
	*/
	private class ListWrapper implements List<T> {

	/**
	* A wrapped ListIterator.
	*/
	private final class WrappedListIterator implements ListIterator<T> {

	/**
	* The error message when {@link #add(Object)} or {@link #remove()} is
	* called more than once per call to {@link #next()} or
	* {@link #previous()}.
	*/
	private static final String IMPERMEABLE_EXCEPTION =
	"Cannot call add/remove more than once per call to next/previous.";

	/**
	* The index of the object that will be returned by {@link #next()}.
	*/
	private int i = 0;

	/**
	* The index of the last object accessed through {@link #next()} or
	* {@link #previous()}.
	*/
	private int last = -1;

	private WrappedListIterator() {
	}

	private WrappedListIterator(int start) {
	int size = ListWrapper.this.size();
	if (start < 0 \|\| start > size) {
	throw new IndexOutOfBoundsException(
	"Index: " + start + ", Size: " + size);
	}
	i = start;
	}

	@Override
	public void add(T o) {
	if (last < 0) {
	throw new IllegalStateException(IMPERMEABLE_EXCEPTION);
	}
	ListWrapper.this.add(i++, o);
	last = -1;
	}

	@Override
	public boolean hasNext() {
	return i < ListWrapper.this.size();
	}

	@Override
	public boolean hasPrevious() {
	return i > 0;
	}

	@Override
	public T next() {
	if (!hasNext()) {
	throw new NoSuchElementException();
	}
	return ListWrapper.this.get(last = i++);
	}

	@Override
	public int nextIndex() {
	return i;
	}

	@Override
	public T previous() {
	if (!hasPrevious()) {
	throw new NoSuchElementException();
	}
	return ListWrapper.this.get(last = --i);
	}

	@Override
	public int previousIndex() {
	return i - 1;
	}

	@Override
	public void remove() {
	if (last < 0) {
	throw new IllegalStateException(IMPERMEABLE_EXCEPTION);
	}
	ListWrapper.this.remove(last);
	i = last;
	last = -1;
	}

	@Override
	public void set(T o) {
	if (last == -1) {
	throw new IllegalStateException();
	}
	ListWrapper.this.set(last, o);
	}
	}

	/**
	* The current size of the list.
	*/
	private int curSize = 0;

	/**
	* The delegate wrapper.
	*/
	private final ListWrapper delegate;

	/**
	* Set to true if the pending flush has been canceled.
	*/
	private boolean flushCancelled;

	/**
	* We wait until the end of the current event loop before flushing changes
	* so that we don't spam the displays. This also allows users to clear and
	* replace all of the data without forcing the display back to page 0.
	*/
	private ScheduledCommand flushCommand = new ScheduledCommand() {
	@Override
	public void execute() {
	flushPending = false;
	if (flushCancelled) {
	flushCancelled = false;
	return;
	}
	flushNow();
	}
	};

	/**
	* Set to true if a flush is pending.
	*/
	private boolean flushPending;

	/**
	* The list that backs the wrapper.
	*/
	private List<T> list;

	/**
	* If this is a sublist, the offset it the index relative to the main list.
	*/
	private final int offset;

	/**
	* If modified is true, the smallest modified index.
	*/
	private int maxModified = Integer.MIN_VALUE;

	/**
	* If modified is true, one past the largest modified index.
	*/
	private int minModified = Integer.MAX_VALUE;

	/**
	* True if the list data has been modified.
	*/
	private boolean modified;

	public ListWrapper(List<T> list) {
	this(list, null, 0);

	// Initialize the data size based on the size of the input list.
	updateRowCount(list.size(), true);
	}

	/**
	* Construct a new {@link ListWrapper} that delegates flush calls to the
	* specified delegate.
	*
	* @param list the list to wrap
	* @param delegate the delegate
	* @param offset the offset of this list
	*/
	private ListWrapper(List<T> list, ListWrapper delegate, int offset) {
	this.list = list;
	this.delegate = delegate;
	this.offset = offset;
	}

	@Override
	public void add(int index, T element) {
	try {
	list.add(index, element);
	minModified = Math.min(minModified, index);
	maxModified = size();
	modified = true;
	flush();
	} catch (IndexOutOfBoundsException e) {
	throw new IndexOutOfBoundsException(e.getMessage());
	}
	}

	@Override
	public boolean add(T e) {
	boolean toRet = list.add(e);
	minModified = Math.min(minModified, size() - 1);
	maxModified = size();
	modified = true;
	flush();
	return toRet;
	}

	@Override
	public boolean addAll(Collection<? extends T> c) {
	minModified = Math.min(minModified, size());
	boolean toRet = list.addAll(c);
	maxModified = size();
	modified = true;
	flush();
	return toRet;
	}

	@Override
	public boolean addAll(int index, Collection<? extends T> c) {
	try {
	boolean toRet = list.addAll(index, c);
	minModified = Math.min(minModified, index);
	maxModified = size();
	modified = true;
	flush();
	return toRet;
	} catch (IndexOutOfBoundsException e) {
	throw new IndexOutOfBoundsException(e.getMessage());
	}
	}

	@Override
	public void clear() {
	list.clear();
	minModified = maxModified = 0;
	modified = true;
	flush();
	}

	@Override
	public boolean contains(Object o) {
	return list.contains(o);
	}

	@Override
	public boolean containsAll(Collection<?> c) {
	return list.containsAll(c);
	}

	@Override
	public boolean equals(Object o) {
	return list.equals(o);
	}

	@Override
	public T get(int index) {
	return list.get(index);
	}

	@Override
	public int hashCode() {
	return list.hashCode();
	}

	@Override
	public int indexOf(Object o) {
	return list.indexOf(o);
	}

	@Override
	public boolean isEmpty() {
	return list.isEmpty();
	}

	@Override
	public Iterator<T> iterator() {
	return listIterator();
	}

	@Override
	public int lastIndexOf(Object o) {
	return list.lastIndexOf(o);
	}

	@Override
	public ListIterator<T> listIterator() {
	return new WrappedListIterator();
	}

	@Override
	public ListIterator<T> listIterator(int index) {
	return new WrappedListIterator(index);
	}

	@Override
	public T remove(int index) {
	try {
	T toRet = list.remove(index);
	minModified = Math.min(minModified, index);
	maxModified = size();
	modified = true;
	flush();
	return toRet;
	} catch (IndexOutOfBoundsException e) {
	throw new IndexOutOfBoundsException(e.getMessage());
	}
	}

	@Override
	public boolean remove(Object o) {
	int index = indexOf(o);
	if (index == -1) {
	return false;
	}
	remove(index);
	return true;
	}

	@Override
	public boolean removeAll(Collection<?> c) {
	boolean toRet = list.removeAll(c);
	minModified = 0;
	maxModified = size();
	modified = true;
	flush();
	return toRet;
	}

	@Override
	public boolean retainAll(Collection<?> c) {
	boolean toRet = list.retainAll(c);
	minModified = 0;
	maxModified = size();
	modified = true;
	flush();
	return toRet;
	}

	@Override
	public T set(int index, T element) {
	T toRet = list.set(index, element);
	minModified = Math.min(minModified, index);
	maxModified = Math.max(maxModified, index + 1);
	modified = true;
	flush();
	return toRet;
	}

	@Override
	public int size() {
	return list.size();
	}

	@Override
	public List<T> subList(int fromIndex, int toIndex) {
	return new ListWrapper(list.subList(fromIndex, toIndex), this, fromIndex);
	}

	@Override
	public Object[] toArray() {
	return list.toArray();
	}

	@Override
	public <C> C[] toArray(C[] a) {
	return list.toArray(a);
	}

	/**
	* Flush the data to the model.
	*/
	private void flush() {
	// Defer to the delegate.
	if (delegate != null) {
	delegate.minModified = Math.min(
	minModified + offset, delegate.minModified);
	delegate.maxModified = Math.max(
	maxModified + offset, delegate.maxModified);
	delegate.modified = modified \|\| delegate.modified;
	delegate.flush();
	return;
	}

	flushCancelled = false;
	if (!flushPending) {
	flushPending = true;
	Scheduler.get().scheduleFinally(flushCommand);
	}
	}

	/**
	* Flush pending list changes to the displays. By default,
	*/
	private void flushNow() {
	// Cancel any pending flush command.
	if (flushPending) {
	flushCancelled = true;
	}

	// Early exit if this list has been replaced in the data provider.
	if (listWrapper != this) {
	return;
	}

	int newSize = list.size();
	if (curSize != newSize) {
	curSize = newSize;
	updateRowCount(curSize, true);
	}

	if (modified) {
	updateRowData(minModified, list.subList(minModified, maxModified));
	modified = false;
	}
	minModified = Integer.MAX_VALUE;
	maxModified = Integer.MIN_VALUE;
	}
	}

	/**
	* The wrapper around the actual list.
	*/
	private ListWrapper listWrapper;

	/**
	* Creates an empty model.
	*/
	public ListDataProvider() {
	this(new ArrayList<T>(), null);
	}

	/**
	* Creates a list model that wraps the given list.
	*
	* <p>
	* The wrapped list should no longer be modified as the data provider cannot
	* detect changes to the wrapped list. Instead, call {@link #getList()} to
	* retrieve a wrapper that can be modified and will correctly forward changes
	* to displays.
	*
	* @param listToWrap the List to be wrapped
	*/
	public ListDataProvider(List<T> listToWrap) {
	this(listToWrap, null);
	}

	/**
	* Creates an empty list model that wraps the given collection.
	*
	* @param keyProvider an instance of ProvidesKey<T>, or null if the record
	* object should act as its own key
	*/
	public ListDataProvider(ProvidesKey<T> keyProvider) {
	this(new ArrayList<T>(), keyProvider);
	}

	/**
	* Creates a list model that wraps the given list.
	*
	* <p>
	* The wrapped list should no longer be modified as the data provider cannot
	* detect changes to the wrapped list. Instead, call {@link #getList()} to
	* retrieve a wrapper that can be modified and will correctly forward changes
	* to displays.
	*
	* @param listToWrap the List to be wrapped
	* @param keyProvider an instance of ProvidesKey<T>, or null if the record
	* object should act as its own key
	*/
	public ListDataProvider(List<T> listToWrap, ProvidesKey<T> keyProvider) {
	super(keyProvider);
	listWrapper = new ListWrapper(listToWrap);
	}

	/**
	* Flush pending list changes to the displays. By default, displays are
	* informed of modifications to the underlying list at the end of the current
	* event loop, which makes it possible to perform multiple operations
	* synchronously without repeatedly refreshing the displays. This method can
	* be called to flush the changes immediately instead of waiting until the end
	* of the current event loop.
	*/
	public void flush() {
	listWrapper.flushNow();
	}

	/**
	* Get the list that backs this model. Changes to the list will be reflected
	* in the model.
	*
	* <p>
	* NOTE: Mutations to the items contained within the list will NOT be
	* reflected in the model. You must call {@link List#set(int, Object)} to
	* update the item within the list and push the change to the display, or call
	* {@link #refresh()} to push all rows to the displays.
	* {@link List#set(int, Object)} performs better because it allows the data
	* provider to push only those rows which have changed, and usually allows the
	* display to re-render only a subset of the rows.
	*
	* @return the list
	*
	* @see #setList(List)
	*/
	public List<T> getList() {
	return listWrapper;
	}

	/**
	* Refresh all of the displays listening to this adapter.
	*
	* <p>
	* Use {@link #refresh()} to push mutations to the underlying data items
	* contained within the list. The data provider cannot detect changes to data
	* objects within the list, so you must call this method if you modify items.
	*
	* <p>
	* This is a shortcut for calling {@link List#set(int, Object)} on every item
	* that you modify, but note that calling {@link List#set(int, Object)}
	* performs better because the data provider knows which rows were modified
	* and can push only the modified rows the displays.
	*/
	public void refresh() {
	updateRowData(0, listWrapper);
	}

	/**
	* Replace this model's list with the specified list.
	*
	* <p>
	* The wrapped list should no longer be modified as the data provider cannot
	* detect changes to the wrapped list. Instead, call {@link #getList()} to
	* retrieve a wrapper that can be modified and will correctly forward changes
	* to displays.
	*
	* @param listToWrap the model's new list
	*
	* @see #getList()
	*/
	public void setList(List<T> listToWrap) {
	listWrapper = new ListWrapper(listToWrap);
	listWrapper.minModified = 0;
	listWrapper.maxModified = listWrapper.size();
	listWrapper.modified = true;
	flush();
	}

	@Override
	protected void onRangeChanged(HasData<T> display) {
	int size = listWrapper.size();
	if (size > 0) {
	// Do not push data if the data set is empty.
	updateRowData(display, 0, listWrapper);
	}
	}
	}