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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/io/LineNumberInputStream.java
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+/* LineNumberInputStream.java -- An input stream which counts line numbers
+ Copyright (C) 1998, 1999, 2002, 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package java.io;
+
+/**
+ * This class functions like a standard <code>InputStream</code>
+ * except that it counts line numbers, and canonicalizes newline
+ * characters. As data is read, whenever the byte sequences "\r",
+ * "\n", or "\r\n" are encountered, the running line count is
+ * incremeted by one. Additionally, the whatever line termination
+ * sequence was encountered will be converted to a "\n" byte. Note
+ * that this class numbers lines from 0. When the first line
+ * terminator is encountered, the line number is incremented to 1, and
+ * so on.
+ * <p>
+ * This class counts only line termination characters. If the last line
+ * read from the stream does not end in a line termination sequence, it
+ * will not be counted as a line.
+ * <p>
+ * Note that since this class operates as a filter on an underlying
+ * stream, it has the same mark/reset functionality as the underlying
+ * stream. The <code>mark()</code> and <code>reset()</code> methods
+ * in this class handle line numbers correctly. Calling
+ * <code>reset()</code> resets the line number to the point at which
+ * <code>mark()</code> was called if the subordinate stream supports
+ * that functionality.
+ * <p>
+ * @deprecated This class is deprecated in favor if
+ * <code>LineNumberReader</code> because it operates on ASCII bytes
+ * instead of an encoded character stream. This class is for backward
+ * compatibility only and should not be used in new applications.
+ *
+ * @author Aaron M. Renn (arenn@urbanophile.com)
+ * @author Warren Levy (warrenl@cygnus.com)
+ */
+public class LineNumberInputStream extends FilterInputStream
+{
+ /** The current line number. */
+ private int lineNumber = 0;
+
+ /** The line number when the stream was marked. */
+ private int markLineNumber = 0;
+
+ /** Flag to indicate a '\r' was just read so that an immediately
+ * subsequent '\n' can be ignored. */
+ private boolean justReadReturnChar = false;
+
+ /**
+ * Create a new <code>LineNumberInputStream</code> that reads from the
+ * specified subordinate <code>InputStream</code>
+ *
+ * @param in The subordinate <code>InputStream</code> to read from
+ */
+ public LineNumberInputStream(InputStream in)
+ {
+ super(in);
+ }
+
+ /**
+ * This method returns the number of bytes that can be read from the
+ * stream before the stream can block. This method is tricky
+ * because the subordinate <code>InputStream</code> might return
+ * only "\r\n" characters, which are replaced by a single "\n"
+ * character by the <code>read()</code> method of this class. So
+ * this method can only guarantee that <code>in.available() /
+ * 2</code> bytes can actually be read before blocking. In
+ * practice, considerably more bytes might be read before blocking
+ * <p>
+ * Note that the stream may not block if additional bytes beyond the count
+ * returned by this method are read.
+ *
+ * @return The number of bytes that can be read before blocking could occur
+ *
+ * @exception IOException If an error occurs
+ */
+ public int available() throws IOException
+ {
+ // We can only guarantee half the characters that might be available
+ // without blocking because "\r\n" is treated as a single character.
+ return in.available() / 2;
+ }
+
+ /**
+ * This method returns the current line number
+ *
+ * @return The current line number
+ */
+ public int getLineNumber()
+ {
+ return lineNumber;
+ }
+
+ /**
+ * This method marks a position in the input to which the stream can
+ * be "reset" byte calling the <code>reset()</code> method. The
+ * parameter <code>readlimit</code> is the number of bytes that can
+ * be read from the stream after setting the mark before the mark
+ * becomes invalid. For example, if <code>mark()</code> is called
+ * with a read limit of 10, then when 11 bytes of data are read from
+ * the stream before the <code>reset()</code> method is called, then
+ * the mark is invalid and the stream object instance is not
+ * required to remember the mark.
+ * <p>
+ * In this class, this method will remember the current line number
+ * as well as the current position in the stream. When the
+ * <code>reset()</code> method is called, the line number will be
+ * restored to the saved line number in addition to the stream
+ * position.
+ * <p>
+ * This method only works if the subordinate stream supports mark/reset
+ * functionality.
+ *
+ * @param readlimit The number of bytes that can be read before the
+ * mark becomes invalid
+ */
+ public void mark(int readlimit)
+ {
+ in.mark(readlimit);
+ markLineNumber = lineNumber;
+ }
+
+ /**
+ * This method reads an unsigned byte from the input stream and returns it
+ * as an int in the range of 0-255. This method will return -1 if the
+ * end of the stream has been reached.
+ * <p>
+ * Note that if a line termination sequence is encountered (ie, "\r",
+ * "\n", or "\r\n") then that line termination sequence is converted to
+ * a single "\n" value which is returned from this method. This means
+ * that it is possible this method reads two bytes from the subordinate
+ * stream instead of just one.
+ * <p>
+ * Note that this method will block until a byte of data is available
+ * to be read.
+ *
+ * @return The byte read or -1 if end of stream
+ *
+ * @exception IOException If an error occurs
+ */
+ public int read() throws IOException
+ {
+ // Treat "\r\n" as a single character. A '\r' may have been read by
+ // a previous call to read so we keep an internal flag to avoid having
+ // to read ahead.
+
+ int ch = in.read();
+
+ if (ch == '\n')
+ if (justReadReturnChar)
+ {
+ ch = in.read();
+ justReadReturnChar = false;
+ }
+ else
+ lineNumber++;
+ else if (ch == '\r')
+ {
+ ch = '\n';
+ justReadReturnChar = true;
+ lineNumber++;
+ }
+ else
+ justReadReturnChar = false;
+
+ return ch;
+ }
+
+ /**
+ * This method reads bytes from a stream and stores them into a caller
+ * supplied buffer. It starts storing data at index <code>offset</code> into
+ * the buffer and attemps to read <code>len</code> bytes. This method can
+ * return before reading the number of bytes requested. The actual number
+ * of bytes read is returned as an int. A -1 is returned to indicated the
+ * end of the stream.
+ * <p>
+ * This method will block until some data can be read.
+ * <p>
+ * Note that if a line termination sequence is encountered (ie, "\r",
+ * "\n", or "\r\n") then that line termination sequence is converted to
+ * a single "\n" value which is stored in the buffer. Only a single
+ * byte is counted towards the number of bytes read in this case.
+ *
+ * @param b The array into which the bytes read should be stored
+ * @param off The offset into the array to start storing bytes
+ * @param len The requested number of bytes to read
+ *
+ * @return The actual number of bytes read, or -1 if end of stream
+ *
+ * @exception IOException If an error occurs.
+ */
+ public int read(byte[] b, int off, int len) throws IOException
+ {
+ if (off < 0 || len < 0 || off + len > b.length)
+ throw new ArrayIndexOutOfBoundsException();
+
+ // This case always succeeds.
+ if (len == 0)
+ return 0;
+
+ // The simplest, though not necessarily the most time efficient thing
+ // to do is simply call read(void) len times. Since this is a deprecated
+ // class, that should be ok.
+ final int origOff = off;
+ while (len-- > 0)
+ {
+ int ch = read();
+ if (ch < 0)
+ break;
+
+ b[off++] = (byte) ch;
+ }
+
+ // This is safe since we already know that some bytes were
+ // actually requested.
+ return off == origOff ? -1 : off - origOff;
+ }
+
+ /**
+ * This method resets a stream to the point where the
+ * <code>mark()</code> method was called. Any bytes that were read
+ * after the mark point was set will be re-read during subsequent
+ * reads.
+ * <p>
+ * In this class, this method will also restore the line number that was
+ * current when the <code>mark()</code> method was called.
+ * <p>
+ * This method only works if the subordinate stream supports mark/reset
+ * functionality.
+ *
+ * @exception IOException If an error occurs
+ */
+ public void reset() throws IOException
+ {
+ in.reset();
+ lineNumber = markLineNumber;
+ justReadReturnChar = false;
+ }
+
+ /**
+ * This method sets the current line number to the specified value.
+ *
+ * @param lineNumber The new line number
+ */
+ public void setLineNumber(int lineNumber)
+ {
+ this.lineNumber = lineNumber;
+ }
+
+ /**
+ * This method skips up to the requested number of bytes in the
+ * input stream. The actual number of bytes skipped is returned. If the
+ * desired number of bytes to skip is negative, no bytes are skipped.
+ *
+ * @param n requested number of bytes to skip.
+ *
+ * @return The actual number of bytes skipped.
+ *
+ * @exception IOException If an error occurs.
+ */
+ public long skip(long n) throws IOException
+ {
+ if (n <= 0)
+ return 0L;
+
+ final long origN = n;
+
+ do
+ {
+ int ch = read();
+ if (ch < 0)
+ break;
+ if (ch == '\n' || ch == '\r')
+ lineNumber++;
+ }
+ while (--n > 0);
+
+ return origN - n;
+ }
+}