/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2000-2009. All Rights Reserved.
*
* Licensed 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.
*
* %CopyrightEnd%
*/
package com.ericsson.otp.erlang;
/**
* Provides a Java representation of Erlang refs. There are two styles of Erlang
* refs, old style (one id value) and new style (array of id values). This class
* manages both types.
*/
public class OtpErlangRef extends OtpErlangObject {
// don't change this!
private static final long serialVersionUID = -7022666480768586521L;
private final int tag;
private final String node;
private final int creation;
// old style refs have one 18-bit id
// r6 "new" refs have array of ids, first one is only 18 bits however
// 19 "newer" refs have full 32-bits for creation and for ids[0]
private int ids[] = null;
/**
* Create a unique Erlang ref belonging to the local node.
*
* @param self
* the local node.
*
* @deprecated use OtpLocalNode:createRef() instead
*/
@Deprecated
public OtpErlangRef(final OtpLocalNode self) {
final OtpErlangRef r = self.createRef();
tag = r.tag;
ids = r.ids;
creation = r.creation;
node = r.node;
}
/**
* Create an Erlang ref from a stream containing a ref encoded in Erlang
* external format.
*
* @param buf
* the stream containing the encoded ref.
*
* @exception OtpErlangDecodeException
* if the buffer does not contain a valid external
* representation of an Erlang ref.
*/
public OtpErlangRef(final OtpInputStream buf)
throws OtpErlangDecodeException {
final OtpErlangRef r = buf.read_ref();
tag = r.tag;
node = r.node();
creation = r.creation();
ids = r.ids();
}
/**
* Create an old style Erlang ref from its components.
*
* @param node
* the nodename.
*
* @param id
* an arbitrary number. Only the low order 18 bits will be used.
*
* @param creation
* another arbitrary number.
*/
public OtpErlangRef(final String node, final int id, final int creation) {
this.tag = OtpExternal.newRefTag;
this.node = node;
ids = new int[1];
ids[0] = id & 0x3ffff; // 18 bits
this.creation = creation & 0x03; // 2 bits
}
/**
* Create a new style Erlang ref from its components.
*
* @param node
* the nodename.
*
* @param ids
* an array of arbitrary numbers. Only the low order 18 bits of
* the first number will be used. If the array contains only one
* number, an old style ref will be written instead. At most
* three numbers will be read from the array.
*
* @param creation
* another arbitrary number. Only the low order 2 bits will be
* used.
*/
public OtpErlangRef(final String node, final int[] ids, final int creation) {
this(OtpExternal.newRefTag, node, ids, creation);
}
/**
* Create a new(er) style Erlang ref from its components.
*
* @param tag
* the external format to be compliant with.
* OtpExternal.newRefTag where only a subset of the bits are used (see other constructor)
* OtpExternal.newerRefTag where all bits of ids and creation are used.
* newerPortTag can only be decoded by OTP-19 and newer.
*
* @param node
* the nodename.
*
* @param ids
* an array of arbitrary numbers. At most three numbers
* will be read from the array.
*
* @param creation
* another arbitrary number.
*/
public OtpErlangRef(final int tag, final String node, final int[] ids,
final int creation) {
this.tag = tag;
this.node = node;
// use at most 3 words
int len = ids.length;
this.ids = new int[3];
this.ids[0] = 0;
this.ids[1] = 0;
this.ids[2] = 0;
if (len > 3) {
len = 3;
}
System.arraycopy(ids, 0, this.ids, 0, len);
if (tag == OtpExternal.newRefTag) {
this.creation = creation & 0x3;
this.ids[0] &= 0x3ffff; // only 18 significant bits in first number
}
else {
this.creation = creation;
}
}
protected int tag() {
return tag;
}
/**
* Get the id number from the ref. Old style refs have only one id number.
* If this is a new style ref, the first id number is returned.
*
* @return the id number from the ref.
*/
public int id() {
return ids[0];
}
/**
* Get the array of id numbers from the ref. If this is an old style ref,
* the array is of length 1. If this is a new style ref, the array has
* length 3.
*
* @return the array of id numbers from the ref.
*/
public int[] ids() {
return ids;
}
/**
* Determine whether this is a new style ref.
*
* @return true if this ref is a new style ref, false otherwise.
*/
public boolean isNewRef() {
return ids.length > 1;
}
/**
* Get the creation number from the ref.
*
* @return the creation number from the ref.
*/
public int creation() {
return creation;
}
/**
* Get the node name from the ref.
*
* @return the node name from the ref.
*/
public String node() {
return node;
}
/**
* Get the string representation of the ref. Erlang refs are printed as
* #Ref<node.id>
*
* @return the string representation of the ref.
*/
@Override
public String toString() {
String s = "#Ref<" + node;
for (int i = 0; i < ids.length; i++) {
s += "." + ids[i];
}
s += ">";
return s;
}
/**
* Convert this ref to the equivalent Erlang external representation.
*
* @param buf
* an output stream to which the encoded ref should be written.
*/
@Override
public void encode(final OtpOutputStream buf) {
buf.write_ref(this);
}
/**
* Determine if two refs are equal. Refs are equal if their components are
* equal. New refs and old refs are considered equal if the node, creation
* and first id numnber are equal.
*
* @param o
* the other ref to compare to.
*
* @return true if the refs are equal, false otherwise.
*/
@Override
public boolean equals(final Object o) {
if (!(o instanceof OtpErlangRef)) {
return false;
}
final OtpErlangRef ref = (OtpErlangRef) o;
if (!(node.equals(ref.node()) && creation == ref.creation())) {
return false;
}
if (isNewRef() && ref.isNewRef()) {
return ids[0] == ref.ids[0] && ids[1] == ref.ids[1]
&& ids[2] == ref.ids[2];
}
return ids[0] == ref.ids[0];
}
/**
* Compute the hashCode value for a given ref. This function is compatible
* with equal.
*
* @return the hashCode of the node.
**/
@Override
protected int doHashCode() {
final OtpErlangObject.Hash hash = new OtpErlangObject.Hash(7);
hash.combine(creation, ids[0]);
if (isNewRef()) {
hash.combine(ids[1], ids[2]);
}
return hash.valueOf();
}
@Override
public Object clone() {
final OtpErlangRef newRef = (OtpErlangRef) super.clone();
newRef.ids = ids.clone();
return newRef;
}
}
