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	/*
	* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package javax.swing.text;

	import java.awt.Shape;

	/**
	* <code>NavigationFilter</code> can be used to restrict where the cursor can
	* be positioned. When the default cursor positioning actions attempt to
	* reposition the cursor they will call into the
	* <code>NavigationFilter</code>, assuming
	* the <code>JTextComponent</code> has a non-null
	* <code>NavigationFilter</code> set. In this manner
	* the <code>NavigationFilter</code> can effectively restrict where the
	* cursor can be positioned. Similarly <code>DefaultCaret</code> will call
	* into the <code>NavigationFilter</code> when the user is changing the
	* selection to further restrict where the cursor can be positioned.
	* <p>
	* Subclasses can conditionally call into supers implementation to restrict
	* where the cursor can be placed, or call directly into the
	* <code>FilterBypass</code>.
	*
	* @see javax.swing.text.Caret
	* @see javax.swing.text.DefaultCaret
	* @see javax.swing.text.View
	*
	* @since 1.4
	*/
	public class NavigationFilter {
	/**
	* Invoked prior to the Caret setting the dot. The default implementation
	* calls directly into the <code>FilterBypass</code> with the passed
	* in arguments. Subclasses may wish to conditionally
	* call super with a different location, or invoke the necessary method
	* on the <code>FilterBypass</code>
	*
	* @param fb FilterBypass that can be used to mutate caret position
	* @param dot the position >= 0
	* @param bias Bias to place the dot at
	*/
	public void setDot(FilterBypass fb, int dot, Position.Bias bias) {
	fb.setDot(dot, bias);
	}

	/**
	* Invoked prior to the Caret moving the dot. The default implementation
	* calls directly into the <code>FilterBypass</code> with the passed
	* in arguments. Subclasses may wish to conditionally
	* call super with a different location, or invoke the necessary
	* methods on the <code>FilterBypass</code>.
	*
	* @param fb FilterBypass that can be used to mutate caret position
	* @param dot the position >= 0
	* @param bias Bias for new location
	*/
	public void moveDot(FilterBypass fb, int dot, Position.Bias bias) {
	fb.moveDot(dot, bias);
	}

	/**
	* Returns the next visual position to place the caret at from an
	* existing position. The default implementation simply forwards the
	* method to the root View. Subclasses may wish to further restrict the
	* location based on additional criteria.
	*
	* @param text JTextComponent containing text
	* @param pos Position used in determining next position
	* @param bias Bias used in determining next position
	* @param direction the direction from the current position that can
	* be thought of as the arrow keys typically found on a keyboard.
	* This will be one of the following values:
	* <ul>
	* <li>SwingConstants.WEST
	* <li>SwingConstants.EAST
	* <li>SwingConstants.NORTH
	* <li>SwingConstants.SOUTH
	* </ul>
	* @param biasRet Used to return resulting Bias of next position
	* @return the location within the model that best represents the next
	* location visual position
	* @exception BadLocationException
	* @exception IllegalArgumentException if <code>direction</code>
	* doesn't have one of the legal values above
	*/
	public int getNextVisualPositionFrom(JTextComponent text, int pos,
	Position.Bias bias, int direction,
	Position.Bias[] biasRet)
	throws BadLocationException {
	return text.getUI().getNextVisualPositionFrom(text, pos, bias,
	direction, biasRet);
	}


	/**
	* Used as a way to circumvent calling back into the caret to
	* position the cursor. Caret implementations that wish to support
	* a NavigationFilter must provide an implementation that will
	* not callback into the NavigationFilter.
	* @since 1.4
	*/
	public static abstract class FilterBypass {
	/**
	* Returns the Caret that is changing.
	*
	* @return Caret that is changing
	*/
	public abstract Caret getCaret();

	/**
	* Sets the caret location, bypassing the NavigationFilter.
	*
	* @param dot the position >= 0
	* @param bias Bias to place the dot at
	*/
	public abstract void setDot(int dot, Position.Bias bias);

	/**
	* Moves the caret location, bypassing the NavigationFilter.
	*
	* @param dot the position >= 0
	* @param bias Bias for new location
	*/
	public abstract void moveDot(int dot, Position.Bias bias);
	}
	}

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