package org.mandarax.zkb;
/*
* Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
import java.util.*;
import javax.sql.DataSource;
import org.mandarax.kernel.*;
/**
* An abstract OPS implementation.
* @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
* @version 3.4 <7 March 05>
* @since 2.2
*/
public abstract class AbstractOPS implements ObjectPersistencyService {
protected Map urisByObject = new IdentityHashMap();
protected Map objectsByUri = new HashMap();
// prefixes for primitives
public static final String BOOLEAN = "boolean:";
public static final String BYTE = "byte:";
public static final String CHAR = "char:";
public static final String DOUBLE = "double:";
public static final String FLOAT = "float:";
public static final String INT = "int:";
public static final String LONG = "long:";
public static final String SHORT = "short:";
public static final String STRING = "string:";
public static final String OBJECT = "object:java:";
/**
* Get the extension of the associated files.
* @return a file extension
*/
public abstract String getExtension() ;
/**
* Generate an URI for an object.
* @param obj an object
* @return an URI
*/
public synchronized String createName(Object obj) {
if (obj instanceof Integer) return INT+String.valueOf(obj);
else if (obj instanceof String) return STRING+obj;
else if (obj instanceof Boolean) return BOOLEAN+String.valueOf(obj);
else if (obj instanceof Character) return CHAR+String.valueOf(obj);
else if (obj instanceof Double) return DOUBLE+String.valueOf(obj);
else if (obj instanceof Float) return FLOAT+String.valueOf(obj);
else if (obj instanceof Long) return LONG+String.valueOf(obj);
else if (obj instanceof Short) return SHORT+String.valueOf(obj);
else if (obj instanceof Byte) return BYTE+String.valueOf(obj);
else {
// old code (prior to 3.2)
/*
StringBuffer buf = new StringBuffer();
buf.append(OBJECT);
buf.append(getExtension());
buf.append(":");
String type = getType(obj);
buf.append(type);
buf.append("/id=");
buf.append(getCounter(type));
return buf.toString();
*/
// changes in 3.2: there have been some problems with inconsistent IDs
// we cannot reproduce them, but for now use less descriptive ids which are
// unique
return new StringBuffer()
.append(OBJECT)
.append(getType(obj))
.append("/id=")
.append(new java.rmi.server.UID())
.toString();
}
}
/**
* Get the type (name) of an object.
* @param obj an object
* @return the type name
*/
private String getType(Object obj) {
if (obj instanceof Predicate) return "predicate";
if (obj instanceof Function) return "function";
if (obj instanceof ConstantTerm) return "constant_term";
if (obj instanceof ComplexTerm) return "complex_term";
if (obj instanceof VariableTerm) return "variable_term";
if (obj instanceof Prerequisite) return "prerequisite";
if (obj instanceof Fact) return"fact";
if (obj instanceof Rule) return "rule";
if (obj instanceof Query) return"query";
if (obj instanceof ClauseSet) return "clause set";
if (obj instanceof DataSource) return "data source";
return obj==null?"null":obj.getClass().getName();
}
/**
* Get the class (name) of an object.
* We return some top-level superclasses in order to improve readability
* of the files.
* @param obj an object
* @return the class
*/
private Class getClass(Object obj) {
if (obj instanceof Predicate) return Predicate.class;
if (obj instanceof Function) return Function.class;
if (obj instanceof ConstantTerm) return ConstantTerm.class;
if (obj instanceof ComplexTerm) return ComplexTerm.class;
if (obj instanceof VariableTerm) return VariableTerm.class;
if (obj instanceof Prerequisite) return Prerequisite.class;
if (obj instanceof Fact) return Fact.class;
if (obj instanceof Rule) return Rule.class;
if (obj instanceof ClauseSet) return ClauseSet.class;
if (obj instanceof DataSource) return DataSource.class;
return obj==null?null:obj.getClass();
}
/**
* Bind an object to a name (uri).
* @param uri an uri
* @param obj an object
*/
public synchronized void bind(String uri,Object obj) {
if (!isPrimitive(obj)) {
objectsByUri.put(uri,obj);
urisByObject.put(obj,uri);
}
}
/**
* Indicates whether an object is primitive.
* @param obj an object.
* @return true if the object is a primitive wrapper or a string
*/
private boolean isPrimitive(Object obj) {
return obj instanceof Number || obj instanceof String || obj instanceof Boolean || obj instanceof Character;
}
/**
* Find an object. If the object is not yet registered, bind it
* using the generated name.
* @param obj an object
*/
public synchronized String findOrBind(Object obj) {
String uri = null;
if ((uri=(String)urisByObject.get(obj))==null) {
uri = createName(obj);
bind(uri,obj);
}
return uri;
}
/**
* Unbind the name (uri).
* @param uri an uri
*/
public synchronized void unbind(String uri) {
Object obj = lookup(uri);
if (obj!=null) urisByObject.remove(obj);
objectsByUri.remove(uri);
}
/**
* Get an object by name.
* @param uri an uri
* @return obj an object
*/
public synchronized Object lookup(String uri){
if (uri.startsWith(OBJECT)) {
// object - proper look up
return objectsByUri.get(uri);
}
else {
// primitive - decode
if (uri.startsWith(INT)) return Integer.valueOf(uri.substring(INT.length()));
else if (uri.startsWith(STRING)) return uri.substring(STRING.length());
else if (uri.startsWith(BOOLEAN)) return Boolean.valueOf(uri.substring(BOOLEAN.length()));
else if (uri.startsWith(CHAR)) return new Character(uri.substring(CHAR.length()).charAt(0));
else if (uri.startsWith(DOUBLE)) return Double.valueOf(uri.substring(DOUBLE.length()));
else if (uri.startsWith(FLOAT)) return Float.valueOf(uri.substring(FLOAT.length()));
else if (uri.startsWith(LONG)) return Long.valueOf(uri.substring(LONG.length()));
else if (uri.startsWith(SHORT)) return Short.valueOf(uri.substring(SHORT.length()));
else if (uri.startsWith(BYTE)) return Byte.valueOf(uri.substring(BYTE.length()));
else return null;
}
}
/**
* Reverse a map (flip keys and values).
* @param originalMap the map to be reversed
* @param reversedMap an empty map
*/
protected synchronized void reverseMap(Map originalMap,Map reversedMap) {
for (Iterator iter = originalMap.entrySet().iterator();iter.hasNext();) {
Map.Entry nextEntry = (Map.Entry)iter.next();
reversedMap.put(nextEntry.getValue(),nextEntry.getKey());
}
}
/**
* Reset the state.
*/
public synchronized void reset() {
urisByObject.clear();
objectsByUri.clear();
}
}
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