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/*
* Buffer.java February 2001
*
* Copyright (C) 2001, Niall Gallagher <niallg@users.sf.net>
*
* 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 org.simpleframework.common.buffer;
import java.io.IOException;
import java.io.InputStream;
/**
* The <code>Buffer</code> interface represents a collection of bytes
* that can be written to and later read. This is used to provide a
* region of memory is such a way that the underlying representation
* of that memory is independent of its use. Typically buffers are
* implemented as either allocated byte arrays or files.
*
* @author Niall Gallagher
*
* @see org.simpleframework.common.buffer.Allocator
*/
public interface Buffer {
/**
* This method is used to allocate a segment of this buffer as a
* separate buffer object. This allows the buffer to be sliced in
* to several smaller independent buffers, while still allowing the
* parent buffer to manage a single buffer. This is useful if the
* parent is split in to logically smaller segments.
*
* @return this returns a buffer which is a segment of this buffer
*/
Buffer allocate() throws IOException;
/**
* This method is used so that a buffer can be represented as a
* stream of bytes. This provides a quick means to access the data
* that has been written to the buffer. It wraps the buffer within
* an input stream so that it can be read directly.
*
* @return a stream that can be used to read the buffered bytes
*/
InputStream open() throws IOException;
/**
* This method is used to acquire the buffered bytes as a string.
* This is useful if the contents need to be manipulated as a
* string or transferred into another encoding. If the UTF-8
* content encoding is not supported the platform default is
* used, however this is unlikely as UTF-8 should be supported.
*
* @return this returns a UTF-8 encoding of the buffer contents
*/
String encode() throws IOException;
/**
* This method is used to acquire the buffered bytes as a string.
* This is useful if the contents need to be manipulated as a
* string or transferred into another encoding. This will convert
* the bytes using the specified character encoding format.
*
* @param charset this is the charset to encode the data with
*
* @return this returns the encoding of the buffer contents
*/
String encode(String charset) throws IOException;
/**
* This method is used to append bytes to the end of the buffer.
* This will expand the capacity of the buffer if there is not
* enough space to accommodate the extra bytes.
*
* @param array this is the byte array to append to this buffer
*
* @return this returns this buffer for another operation
*/
Buffer append(byte[] array) throws IOException;
/**
* This method is used to append bytes to the end of the buffer.
* This will expand the capacity of the buffer if there is not
* enough space to accommodate the extra bytes.
*
* @param array this is the byte array to append to this buffer
* @param len the number of bytes to be read from the array
* @param off this is the offset to begin reading the bytes from
*
* @return this returns this buffer for another operation
*/
Buffer append(byte[] array, int off, int len) throws IOException;
/**
* This will clear all data from the buffer. This simply sets the
* count to be zero, it will not clear the memory occupied by the
* instance as the internal buffer will remain. This allows the
* memory occupied to be reused as many times as is required.
*/
void clear() throws IOException;
/**
* This method is used to ensure the buffer can be closed. Once
* the buffer is closed it is an immutable collection of bytes and
* can not longer be modified. This ensures that it can be passed
* by value without the risk of modification of the bytes.
*/
void close() throws IOException;
/**
* This is used to provide the number of bytes that have been
* written to the buffer. This increases as bytes are appended
* to the buffer. if the buffer is cleared this resets to zero.
*
* @return this returns the number of bytes within the buffer
*/
long length();
}
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