-/* Copyright (C) 1998, 1999 Red Hat, Inc.
+/* DataInput.java -- Interface for reading data from a stream
+ Copyright (C) 1998, 1999, 2001 Free Software Foundation, Inc.
- This file is part of libgcj.
+This file is part of GNU Classpath.
-This software is copyrighted work licensed under the terms of the
-Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
-details. */
+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.
-package java.io;
+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.
-/**
- * @author Warren Levy <warrenl@cygnus.com>
- * @date October 2, 1998.
- */
+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., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+As a special exception, if you link this library with other files to
+produce an executable, this library does not by itself cause the
+resulting executable to be covered by the GNU General Public License.
+This exception does not however invalidate any other reasons why the
+executable file might be covered by the GNU General Public License. */
+
+
+package java.io;
/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
* "The Java Language Specification", ISBN 0-201-63451-1
* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
* Status: Believed complete and correct.
*/
-
+
+/**
+ * This interface is implemented by classes that can data from streams
+ * into Java primitive types.
+ *
+ * @author Aaron M. Renn (arenn@urbanophile.com)
+ * @author Warren Levy <warrenl@cygnus.com>
+ */
public interface DataInput
{
- public boolean readBoolean() throws IOException;
- public byte readByte() throws IOException;
- public char readChar() throws IOException;
- public double readDouble() throws IOException;
- public float readFloat() throws IOException;
- public void readFully(byte[] b)
- throws IOException, NullPointerException;
- public void readFully(byte[] b, int off, int len)
- throws IOException, NullPointerException, IndexOutOfBoundsException;
- public int readInt() throws IOException;
- public String readLine() throws IOException;
- public long readLong() throws IOException;
- public short readShort() throws IOException;
- public int readUnsignedByte() throws IOException;
- public int readUnsignedShort() throws IOException;
- public String readUTF() throws IOException;
- public int skipBytes(int n) throws IOException;
-}
+
+/**
+ * This method reads a Java boolean value from an input stream. It does
+ * so by reading a single byte of data. If that byte is zero, then the
+ * value returned is <code>false</code>. If the byte is non-zero, then
+ * the value returned is <code>true</code>.
+ * <p>
+ * This method can read a <code>boolean</code> written by an object
+ * implementing the <code>writeBoolean()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>boolean</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the boolean
+ * @exception IOException If any other error occurs
+ */
+boolean
+readBoolean() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a Java byte value from an input stream. The value
+ * is in the range of -128 to 127.
+ * <p>
+ * This method can read a <code>byte</code> written by an object
+ * implementing the
+ * <code>writeByte()</code> method in the <code>DataOutput</code> interface.
+ * <p>
+ * @return The <code>byte</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the byte
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+byte
+readByte() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads 8 unsigned bits into a Java <code>int</code> value from
+ * the stream. The value returned is in the range of 0 to 255.
+ * <p>
+ * This method can read an unsigned byte written by an object implementing the
+ * <code>writeUnsignedByte()</code> method in the <code>DataOutput</code>
+ * interface.
+ *
+ * @return The unsigned bytes value read as a Java <code>int</code>.
+ *
+ * @exception EOFException If end of file is reached before reading the value
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+int
+readUnsignedByte() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a Java <code>char</code> value from an input stream.
+ * It operates by reading two bytes from the stream and converting them to
+ * a single 16-bit Java <code>char</code>. The two bytes are stored most
+ * significant byte first (i.e., "big endian") regardless of the native
+ * host byte ordering.
+ * <p>
+ * As an example, if <code>byte1</code> and <code>byte2</code> represent the
+ * first and second byte read from the stream respectively, they will be
+ * transformed to a <code>char</code> in the following manner:
+ * <p>
+ * <code>(char)((byte1 << 8) + byte2)</code>
+ * <p>
+ * This method can read a <code>char</code> written by an object implementing
+ * the
+ * <code>writeChar()</code> method in the <code>DataOutput</code> interface.
+ *
+ * @return The <code>char</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the char
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+char
+readChar() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a signed 16-bit value into a Java in from the stream.
+ * It operates by reading two bytes from the stream and converting them to
+ * a single 16-bit Java <code>short</code>. The two bytes are stored most
+ * significant byte first (i.e., "big endian") regardless of the native
+ * host byte ordering.
+ * <p>
+ * As an example, if <code>byte1</code> and <code>byte2</code> represent the
+ * first and second byte read from the stream respectively, they will be
+ * transformed to a <code>short</code> in the following manner:
+ * <p>
+ * <code>(short)((byte1 << 8) + byte2)</code>
+ * <p>
+ * The value returned is in the range of -32768 to 32767.
+ * <p>
+ * This method can read a <code>short</code> written by an object implementing
+ * the <code>writeShort()</code> method in the <code>DataOutput</code>
+ * interface.
+ *
+ * @return The <code>short</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the value
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+short
+readShort() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads 16 unsigned bits into a Java int value from the stream.
+ * It operates by reading two bytes from the stream and converting them to
+ * a single Java <code>int</code>. The two bytes are stored most
+ * significant byte first (i.e., "big endian") regardless of the native
+ * host byte ordering.
+ * <p>
+ * As an example, if <code>byte1</code> and <code>byte2</code> represent the
+ * first and second byte read from the stream respectively, they will be
+ * transformed to an <code>int</code> in the following manner:
+ * <p>
+ * <code>(int)((byte1 << 8) + byte2)</code>
+ * <p>
+ * The value returned is in the range of 0 to 65535.
+ * <p>
+ * This method can read an unsigned short written by an object implementing
+ * the <code>writeUnsignedShort()</code> method in the <code>DataOutput</code>
+ * interface.
+ *
+ * @return The unsigned short value read as a Java <code>int</code>.
+ *
+ * @exception EOFException If end of file is reached before reading the value
+ * @exception IOException If any other error occurs
+ */
+int
+readUnsignedShort() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a Java <code>int</code> value from an input stream
+ * It operates by reading four bytes from the stream and converting them to
+ * a single Java <code>int</code>. The bytes are stored most
+ * significant byte first (i.e., "big endian") regardless of the native
+ * host byte ordering.
+ * <p>
+ * As an example, if <code>byte1</code> through <code>byte4</code> represent
+ * the first four bytes read from the stream, they will be
+ * transformed to an <code>int</code> in the following manner:
+ * <p>
+ * <code>(int)((byte1 << 24) + (byte2 << 16) + (byte3 << 8) + byte4))</code>
+ * <p>
+ The value returned is in the range of -2147483648 to 2147483647.
+ * <p>
+ * This method can read an <code>int</code> written by an object implementing
+ * the <code>writeInt()</code> method in the <code>DataOutput</code> interface.
+ *
+ * @return The <code>int</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the int
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+int
+readInt() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a Java <code>long</code> value from an input stream
+ * It operates by reading eight bytes from the stream and converting them to
+ * a single Java <code>long</code>. The bytes are stored most
+ * significant byte first (i.e., "big endian") regardless of the native
+ * host byte ordering.
+ * <p>
+ * As an example, if <code>byte1</code> through <code>byte8</code> represent
+ * the first eight bytes read from the stream, they will be
+ * transformed to an <code>long</code> in the following manner:
+ * <p>
+ * <code>(long)((byte1 << 56) + (byte2 << 48) + (byte3 << 40) +
+ * (byte4 << 32) + (byte5 << 24) + (byte6 << 16) + (byte7 << 8) + byte9))
+ * </code>
+ * <p>
+ * The value returned is in the range of -9223372036854775808 to
+ * 9223372036854775807.
+ * <p>
+ * This method can read an <code>long</code> written by an object implementing
+ * the <code>writeLong()</code> method in the <code>DataOutput</code>
+ * interface.
+ *
+ * @return The <code>long</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the long
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+long
+readLong() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a Java float value from an input stream. It operates
+ * by first reading an <code>int</code> value from the stream by calling the
+ * <code>readInt()</code> method in this interface, then converts that
+ * <code>int</code> to a <code>float</code> using the
+ * <code>intBitsToFloat</code> method in the class
+ * <code>java.lang.Float</code>.
+ * <p>
+ * This method can read a <code>float</code> written by an object implementing
+ * the <code>writeFloat()</code> method in the <code>DataOutput</code>
+ * interface.
+ *
+ * @return The <code>float</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the float
+ * @exception IOException If any other error occurs
+ *
+ * @see java.lang.Float
+ * @see DataOutput
+ */
+float
+readFloat() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a Java double value from an input stream. It operates
+ * by first reading a <code>long</code> value from the stream by calling the
+ * <code>readLong()</code> method in this interface, then converts that
+ * <code>long</code> to a <code>double</code> using the
+ * <code>longBitsToDouble</code> method in the class
+ * <code>java.lang.Double</code>.
+ * <p>
+ * This method can read a <code>double</code> written by an object
+ * implementing the <code>writeDouble()</code> method in the
+ * <code>DataOutput</code> interface.
+ *
+ * @return The <code>double</code> value read
+ *
+ * @exception EOFException If end of file is reached before reading the double
+ * @exception IOException If any other error occurs
+ *
+ * @see java.lang.Double
+ * @see DataOutput
+ */
+double
+readDouble() throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads the next line of text data from an input stream.
+ * It operates by reading bytes and converting those bytes to <code>char</code>
+ * values by treating the byte read as the low eight bits of the
+ * <code>char</code> and using 0 as the high eight bits. Because of this,
+ * it does not support the full 16-bit Unicode character set.
+ * <P>
+ * The reading of bytes ends when either the end of file or a line terminator
+ * is encountered. The bytes read are then returned as a <code>String</code>.
+ * A line terminator is a byte sequence consisting of either
+ * <code>\r</code>, <code>\n</code> or <code>\r\n</code>. These termination
+ * charaters are discarded and are not returned as part of the string.
+ * <p>
+ * This method can read data that was written by an object implementing the
+ * <code>writeLine()</code> method in <code>DataOutput</code>.
+ *
+ * @return The line read as a <code>String</code>
+ *
+ * @exception IOException If an error occurs
+ *
+ * @see DataOutput
+ */
+String
+readLine() throws IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads a <code>String</code> from an input stream that is
+ * encoded in a modified UTF-8 format. This format has a leading two byte
+ * sequence that contains the remaining number of bytes to read. This two byte
+ * sequence is read using the <code>readUnsignedShort()</code> method of this
+ * interface.
+ *
+ * After the number of remaining bytes have been determined, these bytes
+ * are read an transformed into <code>char</code> values. These
+ * <code>char</code> values are encoded in the stream using either a one, two,
+ * or three byte format.
+ * The particular format in use can be determined by examining the first
+ * byte read.
+ * <p>
+ * If the first byte has a high order bit of 0, then
+ * that character consists on only one byte. This character value consists
+ * of seven bits that are at positions 0 through 6 of the byte. As an
+ * example, if <code>byte1</code> is the byte read from the stream, it would
+ * be converted to a <code>char</code> like so:
+ * <p>
+ * <code>(char)byte1</code>
+ * <p>
+ * If the first byte has 110 as its high order bits, then the
+ * character consists of two bytes. The bits that make up the character
+ * value are in positions 0 through 4 of the first byte and bit positions
+ * 0 through 5 of the second byte. (The second byte should have
+ * 10 as its high order bits). These values are in most significant
+ * byte first (i.e., "big endian") order.
+ * <p>
+ * As an example, if <code>byte1</code> and <code>byte2</code> are the first
+ * two bytes read respectively, and the high order bits of them match the
+ * patterns which indicate a two byte character encoding, then they would be
+ * converted to a Java <code>char</code> like so:
+ * <p>
+ * <code>(char)(((byte1 & 0x1F) << 6) + (byte2 & 0x3F))</code>
+ * <p>
+ * If the first byte has a 1110 as its high order bits, then the
+ * character consists of three bytes. The bits that make up the character
+ * value are in positions 0 through 3 of the first byte and bit positions
+ * 0 through 5 of the other two bytes. (The second and third bytes should
+ * have 10 as their high order bits). These values are in most
+ * significant byte first (i.e., "big endian") order.
+ * <p>
+ * As an example, if <code>byte1</code>, <code>byte2</code>, and
+ * <code>byte3</code> are the three bytes read, and the high order bits of
+ * them match the patterns which indicate a three byte character encoding,
+ * then they would be converted to a Java <code>char</code> like so:
+ *
+ * <code>
+ * (char)(((byte1 & 0x0F) << 12) + ((byte2 & 0x3F) + (byte3 & 0x3F))
+ * </code>
+ *
+ * Note that all characters are encoded in the method that requires the
+ * fewest number of bytes with the exception of the character with the
+ * value of <code>\<llll>u0000</code> which is encoded as two bytes. This is
+ * a modification of the UTF standard used to prevent C language style
+ * <code>NUL</code> values from appearing in the byte stream.
+ * <p>
+ * This method can read data that was written by an object implementing the
+ * <code>writeUTF()</code> method in <code>DataOutput</code>.
+ *
+ * @returns The <code>String</code> read
+ *
+ * @exception EOFException If end of file is reached before reading the String
+ * @exception UTFDataFormatException If the data is not in UTF-8 format
+ * @exception IOException If any other error occurs
+ *
+ * @see DataOutput
+ */
+String
+readUTF() throws EOFException, UTFDataFormatException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads raw bytes into the passed array until the array is
+ * full. Note that this method blocks until the data is available and
+ * throws an exception if there is not enough data left in the stream to
+ * fill the buffer
+ *
+ * @param buf The buffer into which to read the data
+ *
+ * @exception EOFException If end of file is reached before filling the buffer
+ * @exception IOException If any other error occurs
+ */
+void
+readFully(byte[] buf) throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method reads raw bytes into the passed array <code>buf</code> starting
+ * <code>offset</code> bytes into the buffer. The number of bytes read will be
+ * exactly <code>len</code>. Note that this method blocks until the data is
+ * available and * throws an exception if there is not enough data left in
+ * the stream to read <code>len</code> bytes.
+ *
+ * @param buf The buffer into which to read the data
+ * @param offset The offset into the buffer to start storing data
+ * @param len The number of bytes to read into the buffer
+ *
+ * @exception EOFException If end of file is reached before filling the buffer
+ * @exception IOException If any other error occurs
+ */
+void
+readFully(byte[] buf, int offset, int len) throws EOFException, IOException;
+
+/*************************************************************************/
+
+/**
+ * This method skips and discards the specified number of bytes in an
+ * input stream
+ *
+ * @param num_bytes The number of bytes to skip
+ *
+ * @return The number of bytes actually skipped, which will always be
+ * <code>num_bytes</code>
+ *
+ * @exception EOFException If end of file is reached before all bytes can be
+ * skipped
+ * @exception IOException If any other error occurs
+ */
+int
+skipBytes(int n) throws EOFException, IOException;
+
+} // interface DataInput
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