| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. The ASF licenses this file to You |
| * 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. For additional information regarding |
| * copyright in this work, please see the NOTICE file in the top level |
| * directory of this distribution. |
| */ |
| package org.apache.abdera2.common.io; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.PushbackInputStream; |
| |
| /** |
| * PushbackInputStream implementation that performs dynamic resizing of the unread buffer |
| */ |
| public class DynamicPushbackInputStream extends PushbackInputStream { |
| |
| private final int origsize; |
| |
| public DynamicPushbackInputStream(InputStream in) { |
| super(in); |
| this.origsize = 1; |
| } |
| |
| public DynamicPushbackInputStream(InputStream in, int initialSize) { |
| super(in, initialSize); |
| this.origsize = initialSize; |
| } |
| |
| /** |
| * Clear the buffer |
| */ |
| public int clear() { |
| int m = buf.length; |
| buf = new byte[origsize]; |
| pos = origsize; |
| return m; |
| } |
| |
| /** |
| * Shrink the buffer. This will reclaim currently unused space in the buffer, reducing memory but potentially |
| * increasing the cost of resizing the buffer |
| */ |
| public int shrink() { |
| byte[] old = buf; |
| if (pos == 0) |
| return 0; // nothing to do |
| int n = old.length - pos; |
| int m, p, s, l; |
| if (n < origsize) { |
| buf = new byte[origsize]; |
| p = pos; |
| s = origsize - n; |
| l = old.length - p; |
| m = old.length - origsize; |
| pos = s; |
| } else { |
| buf = new byte[n]; |
| p = pos; |
| s = 0; |
| l = n; |
| m = old.length - l; |
| pos = 0; |
| } |
| System.arraycopy(old, p, buf, s, l); |
| return m; |
| } |
| |
| private void resize(int len) { |
| byte[] old = buf; |
| buf = new byte[old.length + len]; |
| System.arraycopy(old, 0, buf, len, old.length); |
| } |
| |
| public void unread(byte[] b, int off, int len) throws IOException { |
| if (len > pos && pos + len > buf.length) { |
| resize(len - pos); |
| pos += len - pos; |
| } |
| super.unread(b, off, len); |
| } |
| |
| public void unread(int b) throws IOException { |
| if (pos == 0) { |
| resize(1); |
| pos++; |
| } |
| super.unread(b); |
| } |
| |
| public int read() throws IOException { |
| int m = super.read(); |
| if (pos >= buf.length && buf.length > origsize) |
| shrink(); |
| return m; |
| } |
| |
| public int read(byte[] b, int off, int len) throws IOException { |
| this.available(); // workaround for a problem in PushbackInputStream, without this, the amount of bytes read |
| // from some streams will be incorrect |
| int r = super.read(b, off, len); |
| if (pos >= buf.length && buf.length > origsize) |
| shrink(); |
| return r; |
| } |
| |
| public long skip(long n) throws IOException { |
| long r = super.skip(n); |
| if (pos >= buf.length && buf.length > origsize) |
| shrink(); |
| return r; |
| } |
| } |