mirror of
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368 lines
8.9 KiB
Java
368 lines
8.9 KiB
Java
/* Buffer.java --
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Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.nio;
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import gnu.gcj.RawData;
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/**
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* @since 1.4
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*/
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public abstract class Buffer
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{
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private final int cap;
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int limit;
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int pos;
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int mark;
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final RawData address;
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/**
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* Creates a new Buffer.
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*
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* Should be package private.
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*/
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Buffer (int capacity, int limit, int position, int mark,
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RawData address)
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{
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if (capacity < 0)
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throw new IllegalArgumentException ();
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this.address = address;
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cap = capacity;
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limit (limit);
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position (position);
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if (mark >= 0)
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{
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if (mark > pos)
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throw new IllegalArgumentException ();
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this.mark = mark;
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}
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else
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{
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this.mark = -1;
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}
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}
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/**
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* Retrieves the capacity of the buffer.
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*
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* @return the capacity of the buffer
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*/
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public final int capacity ()
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{
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return cap;
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}
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/**
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* Clears the buffer.
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*
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* @return this buffer
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*/
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public final Buffer clear ()
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{
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limit = cap;
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pos = 0;
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mark = -1;
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return this;
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}
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/**
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* Flips the buffer.
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*
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* @return this buffer
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*/
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public final Buffer flip ()
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{
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limit = pos;
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pos = 0;
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mark = -1;
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return this;
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}
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/**
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* Tells whether the buffer has remaining data to read or not.
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*
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* @return true if the buffer contains remaining data to read,
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* false otherwise
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*/
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public final boolean hasRemaining ()
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{
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return remaining() > 0;
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}
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/**
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* Tells whether this buffer is read only or not.
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*
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* @return true if the buffer is read only, false otherwise
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*/
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public abstract boolean isReadOnly ();
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/**
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* Retrieves the current limit of the buffer.
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*
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* @return the limit of the buffer
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*/
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public final int limit ()
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{
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return limit;
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}
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/**
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* Sets this buffer's limit.
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*
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* @param newLimit The new limit value; must be non-negative and no larger
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* than this buffer's capacity.
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*
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* @return this buffer
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*
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* @exception IllegalArgumentException If the preconditions on newLimit
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* do not hold.
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*/
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public final Buffer limit (int newLimit)
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{
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if ((newLimit < 0) || (newLimit > cap))
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throw new IllegalArgumentException ();
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if (newLimit < mark)
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mark = -1;
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if (pos > newLimit)
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pos = newLimit;
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limit = newLimit;
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return this;
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}
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/**
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* Sets this buffer's mark at its position.
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*
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* @return this buffer
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*/
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public final Buffer mark ()
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{
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mark = pos;
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return this;
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}
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/**
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* Retrieves the current position of this buffer.
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*
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* @return the current position of this buffer
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*/
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public final int position ()
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{
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return pos;
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}
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/**
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* Sets this buffer's position. If the mark is defined and larger than the
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* new position then it is discarded.
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*
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* @param newPosition The new position value; must be non-negative and no
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* larger than the current limit.
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*
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* @return this buffer
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*
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* @exception IllegalArgumentException If the preconditions on newPosition
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* do not hold
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*/
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public final Buffer position (int newPosition)
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{
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if ((newPosition < 0) || (newPosition > limit))
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throw new IllegalArgumentException ();
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if (newPosition <= mark)
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mark = -1;
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pos = newPosition;
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return this;
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}
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/**
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* Returns the number of elements between the current position and the limit.
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*
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* @return the number of remaining elements
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*/
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public final int remaining()
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{
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return limit - pos;
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}
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/**
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* Resets this buffer's position to the previously-marked position.
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*
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* @return this buffer
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*
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* @exception InvalidMarkException If the mark has not been set.
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*/
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public final Buffer reset()
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{
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if (mark == -1)
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throw new InvalidMarkException ();
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pos = mark;
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return this;
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}
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/**
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* Rewinds this buffer. The position is set to zero and the mark
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* is discarded.
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*
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* @return this buffer
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*/
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public final Buffer rewind()
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{
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pos = 0;
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mark = -1;
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return this;
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}
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/**
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* Checks for underflow. This method is used internally to check
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* whether a buffer has enough elements left to satisfy a read
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* request.
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*
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* @exception BufferUnderflowException If there are no remaining
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* elements in this buffer.
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*/
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final void checkForUnderflow()
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{
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if (!hasRemaining())
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throw new BufferUnderflowException();
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}
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/**
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* Checks for underflow. This method is used internally to check
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* whether a buffer has enough elements left to satisfy a read
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* request for a given number of elements.
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*
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* @param length The length of a sequence of elements.
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*
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* @exception BufferUnderflowException If there are not enough
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* remaining elements in this buffer.
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*/
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final void checkForUnderflow(int length)
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{
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if (remaining() < length)
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throw new BufferUnderflowException();
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}
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/**
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* Checks for overflow. This method is used internally to check
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* whether a buffer has enough space left to satisfy a write
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* request.
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*
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* @exception BufferOverflowException If there is no remaining
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* space in this buffer.
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*/
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final void checkForOverflow()
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{
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if (!hasRemaining())
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throw new BufferOverflowException();
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}
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/**
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* Checks for overflow. This method is used internally to check
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* whether a buffer has enough space left to satisfy a write
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* request for a given number of elements.
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*
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* @param length The length of a sequence of elements.
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*
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* @exception BufferUnderflowException If there is not enough
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* remaining space in this buffer.
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*/
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final void checkForOverflow(int length)
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{
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if (remaining() < length)
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throw new BufferOverflowException();
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}
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/**
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* Checks if index is negative or not smaller than the buffer's
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* limit. This method is used internally to check whether
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* an indexed request can be fulfilled.
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*
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* @param index The requested position in the buffer.
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*
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* @exception IndexOutOfBoundsException If index is negative or not smaller
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* than the buffer's limit.
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*/
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final void checkIndex(int index)
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{
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if (index < 0
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|| index >= limit ())
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throw new IndexOutOfBoundsException ();
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}
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/**
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* Checks if buffer is read-only. This method is used internally to
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* check if elements can be put into a buffer.
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*
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* @exception ReadOnlyBufferException If this buffer is read-only.
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*/
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final void checkIfReadOnly()
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{
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if (isReadOnly())
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throw new ReadOnlyBufferException ();
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}
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/**
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* Checks whether an array is large enough to hold the given number of
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* elements at the given offset. This method is used internally to
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* check if an array is big enough.
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*
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* @param arraylength The length of the array.
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* @param offset The offset within the array of the first byte to be read;
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* must be non-negative and no larger than arraylength.
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* @param length The number of bytes to be read from the given array;
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* must be non-negative and no larger than arraylength - offset.
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*
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* @exception IndexOutOfBoundsException If the preconditions on the offset
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* and length parameters do not hold
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*/
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static final void checkArraySize(int arraylength, int offset, int length)
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{
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if ((offset < 0) ||
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(length < 0) ||
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(arraylength < length + offset))
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throw new IndexOutOfBoundsException ();
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}
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}
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