211 lines
7.0 KiB
Java
211 lines
7.0 KiB
Java
package org.warp.commonutils.stream;
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/**
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* A {@code FilterInputStream} contains
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* some other input stream, which it uses as
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* its basic source of data, possibly transforming
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* the data along the way or providing additional
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* functionality. The class {@code FilterInputStream}
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* itself simply overrides all methods of
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* {@code InputStream} with versions that
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* pass all requests to the contained input
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* stream. Subclasses of {@code FilterInputStream}
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* may further override some of these methods
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* and may also provide additional methods
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* and fields.
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*
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* @author Jonathan Payne
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* @since 1.0
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*/
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public class SafeFilterInputStream extends SafeInputStream {
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/**
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* The input stream to be filtered.
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*/
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protected volatile SafeInputStream in;
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/**
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* Creates a {@code FilterInputStream}
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* by assigning the argument {@code in}
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* to the field {@code this.in} so as
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* to remember it for later use.
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*
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* @param in the underlying input stream, or {@code null} if
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* this instance is to be created without an underlying stream.
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*/
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protected SafeFilterInputStream(SafeInputStream in) {
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this.in = in;
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}
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/**
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* Reads the next byte of data from this input stream. The value
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* byte is returned as an {@code int} in the range
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* {@code 0} to {@code 255}. If no byte is available
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* because the end of the stream has been reached, the value
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* {@code -1} is returned. This method blocks until input data
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* is available, the end of the stream is detected, or an exception
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* is thrown.
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* <p>
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* This method
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* simply performs {@code in.read()} and returns the result.
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*
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* @return the next byte of data, or {@code -1} if the end of the
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* stream is reached.
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* @see SafeFilterInputStream#in
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*/
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public int read() {
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return in.read();
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}
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/**
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* Reads up to {@code b.length} bytes of data from this
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* input stream into an array of bytes. This method blocks until some
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* input is available.
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* <p>
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* This method simply performs the call
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* {@code read(b, 0, b.length)} and returns
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* the result. It is important that it does
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* <i>not</i> do {@code in.read(b)} instead;
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* certain subclasses of {@code FilterInputStream}
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* depend on the implementation strategy actually
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* used.
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*
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* @param b the buffer into which the data is read.
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* @return the total number of bytes read into the buffer, or
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* {@code -1} if there is no more data because the end of
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* the stream has been reached.
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* @see SafeFilterInputStream#read(byte[], int, int)
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*/
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public int read(byte b[]) {
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return read(b, 0, b.length);
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}
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/**
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* Reads up to {@code len} bytes of data from this input stream
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* into an array of bytes. If {@code len} is not zero, the method
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* blocks until some input is available; otherwise, no
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* bytes are read and {@code 0} is returned.
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* <p>
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* This method simply performs {@code in.read(b, off, len)}
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* and returns the result.
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*
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* @param b the buffer into which the data is read.
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* @param off the start offset in the destination array {@code b}
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* @param len the maximum number of bytes read.
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* @return the total number of bytes read into the buffer, or
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* {@code -1} if there is no more data because the end of
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* the stream has been reached.
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* @throws NullPointerException If {@code b} is {@code null}.
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* @throws IndexOutOfBoundsException If {@code off} is negative,
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* {@code len} is negative, or {@code len} is greater than
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* {@code b.length - off}
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* @see SafeFilterInputStream#in
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*/
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public int read(byte b[], int off, int len) {
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return in.read(b, off, len);
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}
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/**
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* Skips over and discards {@code n} bytes of data from the
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* input stream. The {@code skip} method may, for a variety of
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* reasons, end up skipping over some smaller number of bytes,
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* possibly {@code 0}. The actual number of bytes skipped is
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* returned.
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* <p>
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* This method simply performs {@code in.skip(n)}.
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*
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* @param n the number of bytes to be skipped.
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* @return the actual number of bytes skipped.
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*/
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public long skip(long n) {
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return in.skip(n);
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}
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/**
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* Returns an estimate of the number of bytes that can be read (or
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* skipped over) from this input stream without blocking by the next
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* caller of a method for this input stream. The next caller might be
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* the same thread or another thread. A single read or skip of this
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* many bytes will not block, but may read or skip fewer bytes.
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* <p>
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* This method returns the result of {@link #in in}.available().
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*
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* @return an estimate of the number of bytes that can be read (or skipped
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* over) from this input stream without blocking.
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*/
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public int available() {
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return in.available();
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}
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/**
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* Closes this input stream and releases any system resources
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* associated with the stream.
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* This
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* method simply performs {@code in.close()}.
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*
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* @see SafeFilterInputStream#in
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*/
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public void close() {
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in.close();
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}
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/**
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* Marks the current position in this input stream. A subsequent
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* call to the {@code reset} method repositions this stream at
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* the last marked position so that subsequent reads re-read the same bytes.
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* <p>
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* The {@code readlimit} argument tells this input stream to
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* allow that many bytes to be read before the mark position gets
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* invalidated.
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* <p>
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* This method simply performs {@code in.mark(readlimit)}.
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*
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* @param readlimit the maximum limit of bytes that can be read before
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* the mark position becomes invalid.
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* @see SafeFilterInputStream#in
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* @see SafeFilterInputStream#reset()
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*/
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public synchronized void mark(int readlimit) {
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in.mark(readlimit);
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}
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/**
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* Repositions this stream to the position at the time the
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* {@code mark} method was last called on this input stream.
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* <p>
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* This method
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* simply performs {@code in.reset()}.
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* <p>
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* Stream marks are intended to be used in
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* situations where you need to read ahead a little to see what's in
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* the stream. Often this is most easily done by invoking some
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* general parser. If the stream is of the type handled by the
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* parse, it just chugs along happily. If the stream is not of
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* that type, the parser should toss an exception when it fails.
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* If this happens within readlimit bytes, it allows the outer
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* code to reset the stream and try another parser.
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*
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* @see SafeFilterInputStream#in
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* @see SafeFilterInputStream#mark(int)
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*/
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public synchronized void reset() {
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in.reset();
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}
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/**
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* Tests if this input stream supports the {@code mark}
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* and {@code reset} methods.
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* This method
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* simply performs {@code in.markSupported()}.
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*
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* @return {@code true} if this stream type supports the
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* {@code mark} and {@code reset} method;
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* {@code false} otherwise.
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* @see SafeFilterInputStream#in
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* @see java.io.InputStream#mark(int)
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* @see java.io.InputStream#reset()
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*/
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public boolean markSupported() {
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return in.markSupported();
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}
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}
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