/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2007-2009. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
package com.ericsson.otp.erlang;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
/**
* Provides a Java representation of Erlang bitstrs. An Erlang bitstr is an
* Erlang binary with a length not an integral number of bytes (8-bit). Anything
* can be represented as a sequence of bytes can be made into an Erlang bitstr.
*/
public class OtpErlangBitstr extends OtpErlangObject {
// don't change this!
private static final long serialVersionUID = -3781009633593609217L;
protected byte[] bin;
protected int pad_bits;
/**
* Create a bitstr from a byte array
*
* @param bin
* the array of bytes from which to create the bitstr.
*/
public OtpErlangBitstr(final byte[] bin) {
this.bin = new byte[bin.length];
System.arraycopy(bin, 0, this.bin, 0, bin.length);
pad_bits = 0;
}
/**
* Create a bitstr with pad bits from a byte array.
*
* @param bin
* the array of bytes from which to create the bitstr.
* @param pad_bits
* the number of unused bits in the low end of the last byte.
*/
public OtpErlangBitstr(final byte[] bin, final int pad_bits) {
this.bin = new byte[bin.length];
System.arraycopy(bin, 0, this.bin, 0, bin.length);
this.pad_bits = pad_bits;
check_bitstr(this.bin, this.pad_bits);
}
private void check_bitstr(final byte[] abin, final int a_pad_bits) {
if (a_pad_bits < 0 || 7 < a_pad_bits) {
throw new java.lang.IllegalArgumentException(
"Padding must be in range 0..7");
}
if (a_pad_bits != 0 && abin.length == 0) {
throw new java.lang.IllegalArgumentException(
"Padding on zero length bitstr");
}
if (abin.length != 0) {
// Make sure padding is zero
abin[abin.length - 1] &= ~((1 << a_pad_bits) - 1);
}
}
/**
* Create a bitstr from a stream containing a bitstr encoded in Erlang
* external format.
*
* @param buf
* the stream containing the encoded bitstr.
*
* @exception OtpErlangDecodeException
* if the buffer does not contain a valid external
* representation of an Erlang bitstr.
*/
public OtpErlangBitstr(final OtpInputStream buf)
throws OtpErlangDecodeException {
final int pbs[] = { 0 }; // This is ugly just to get a value-result
// parameter
bin = buf.read_bitstr(pbs);
pad_bits = pbs[0];
check_bitstr(bin, pad_bits);
}
/**
* Create a bitstr from an arbitrary Java Object. The object must implement
* java.io.Serializable or java.io.Externalizable.
*
* @param o
* the object to serialize and create this bitstr from.
*/
public OtpErlangBitstr(final Object o) {
try {
bin = toByteArray(o);
pad_bits = 0;
} catch (final IOException e) {
throw new java.lang.IllegalArgumentException(
"Object must implement Serializable");
}
}
private static byte[] toByteArray(final Object o)
throws java.io.IOException {
if (o == null) {
return null;
}
/* need to synchronize use of the shared baos */
final java.io.ByteArrayOutputStream baos = new ByteArrayOutputStream();
final java.io.ObjectOutputStream oos = new java.io.ObjectOutputStream(
baos);
oos.writeObject(o);
oos.flush();
return baos.toByteArray();
}
private static Object fromByteArray(final byte[] buf) {
if (buf == null) {
return null;
}
try {
final java.io.ByteArrayInputStream bais = new java.io.ByteArrayInputStream(
buf);
final java.io.ObjectInputStream ois = new java.io.ObjectInputStream(
bais);
return ois.readObject();
} catch (final java.lang.ClassNotFoundException e) {
} catch (final java.io.IOException e) {
}
return null;
}
/**
* Get the byte array from a bitstr, padded with zero bits in the little end
* of the last byte.
*
* @return the byte array containing the bytes for this bitstr.
*/
public byte[] binaryValue() {
return bin;
}
/**
* Get the size in whole bytes of the bitstr, rest bits in the last byte not
* counted.
*
* @return the number of bytes contained in the bintstr.
*/
public int size() {
if (pad_bits == 0) {
return bin.length;
}
if (bin.length == 0) {
throw new java.lang.IllegalStateException("Impossible length");
}
return bin.length - 1;
}
/**
* Get the number of pad bits in the last byte of the bitstr. The pad bits
* are zero and in the little end.
*
* @return the number of pad bits in the bitstr.
*/
public int pad_bits() {
return pad_bits;
}
/**
* Get the java Object from the bitstr. If the bitstr contains a serialized
* Java object, then this method will recreate the object.
*
*
* @return the java Object represented by this bitstr, or null if the bitstr
* does not represent a Java Object.
*/
public Object getObject() {
if (pad_bits != 0) {
return null;
}
return fromByteArray(bin);
}
/**
* Get the string representation of this bitstr object. A bitstr is printed
* as #Bin<N>, where N is the number of bytes contained in the object
* or #bin<N-M> if there are M pad bits.
*
* @return the Erlang string representation of this bitstr.
*/
@Override
public String toString() {
if (pad_bits == 0) {
return "#Bin<" + bin.length + ">";
}
if (bin.length == 0) {
throw new java.lang.IllegalStateException("Impossible length");
}
return "#Bin<" + bin.length + "-" + pad_bits + ">";
}
/**
* Convert this bitstr to the equivalent Erlang external representation.
*
* @param buf
* an output stream to which the encoded bitstr should be
* written.
*/
@Override
public void encode(final OtpOutputStream buf) {
buf.write_bitstr(bin, pad_bits);
}
/**
* Determine if two bitstrs are equal. Bitstrs are equal if they have the
* same byte length and tail length, and the array of bytes is identical.
*
* @param o
* the bitstr to compare to.
*
* @return true if the bitstrs contain the same bits, false otherwise.
*/
@Override
public boolean equals(final Object o) {
if (!(o instanceof OtpErlangBitstr)) {
return false;
}
final OtpErlangBitstr that = (OtpErlangBitstr) o;
if (pad_bits != that.pad_bits) {
return false;
}
final int len = bin.length;
if (len != that.bin.length) {
return false;
}
for (int i = 0; i < len; i++) {
if (bin[i] != that.bin[i]) {
return false; // early exit
}
}
return true;
}
@Override
protected int doHashCode() {
final OtpErlangObject.Hash hash = new OtpErlangObject.Hash(15);
hash.combine(bin);
hash.combine(pad_bits);
return hash.valueOf();
}
@Override
public Object clone() {
final OtpErlangBitstr that = (OtpErlangBitstr) super.clone();
that.bin = bin.clone();
that.pad_bits = pad_bits;
return that;
}
}
