**** BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
The contents of this file are subject to the Eclipse Public
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.eclipse.org/legal/epl-v20.html
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.
Copyright (C) 2009-2011 Yoko Harada 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
 **** END LICENSE BLOCK *****
/**
 * **** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * 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.
 *
 * Copyright (C) 2009-2011 Yoko Harada <yokolet@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 * **** END LICENSE BLOCK *****
 */
package org.jruby.embed.variable;

import org.jruby.embed.internal.BiVariableMap;
import org.jruby.RubyClass;
import org.jruby.RubyModule;
import org.jruby.RubyObject;
import org.jruby.runtime.builtin.IRubyObject;

An implementation of BiVariable for a Ruby class variable.
Author:
Yoko Harada /**
 * An implementation of BiVariable for a Ruby class variable.
 *
 * @author Yoko Harada <yokolet@gmail.com>
 */
public class ClassVariable extends AbstractVariable {

    private static final String VALID_NAME = "@@([a-zA-Z]|_)([a-zA-Z]|_|\\d)*";

    
Returns an instance of this class. This factory method is used when a class variables is put in BiVariableMap. This variable is originated from Java. 
Params:
runtime – 
name – a variable name
javaObject – Java object that should be assigned to.
Returns:
the instance of ClassVariable/**
     * Returns an instance of this class. This factory method is used when a class
     * variables is put in {@link BiVariableMap}. This variable is originated from Java.
     *
     * @param runtime
     * @param name a variable name
     * @param javaObject Java object that should be assigned to.
     * @return the instance of ClassVariable
     */
    public static BiVariable getInstance(RubyObject receiver, String name, Object... javaObject) {
        if (name.matches(VALID_NAME)) {
            return new ClassVariable(receiver, name, javaObject);
        }
        return null;
    }

    
Constructor when the variable is originated from Java
Params:
receiver – 
name – 
javaObject – /**
     * Constructor when the variable is originated from Java
     *
     * @param receiver
     * @param name
     * @param javaObject
     */
    private ClassVariable(RubyObject receiver, String name, Object... javaObjects) {
        super(receiver, name, false);
        updateByJavaObject(receiver.getRuntime(), javaObjects);
    }

    
A constructor used when this variable is retrieved from Ruby.
Params:
receiver – a receiver object that this variable/constant is originally in. When
       the variable/constant is originated from Ruby, receiver may not be null.
name – the class variable name
irubyObject – Ruby class variable object/**
     * A constructor used when this variable is retrieved from Ruby.
     *
     * @param receiver a receiver object that this variable/constant is originally in. When
     *        the variable/constant is originated from Ruby, receiver may not be null.
     * @param name the class variable name
     * @param irubyObject Ruby class variable object
     */
    ClassVariable(RubyObject receiver, String name, IRubyObject irubyObject) {
        super(receiver, name, true, irubyObject);
    }

    
Retrieves class variables from Ruby after the evaluation.
Params:
runtime – Ruby runtime
receiver – receiver object returned when a script is evaluated.
vars – map to save retrieved class variables./**
     * Retrieves class variables from Ruby after the evaluation.
     *
     * @param runtime Ruby runtime
     * @param receiver receiver object returned when a script is evaluated.
     * @param vars map to save retrieved class variables.
     */
    public static void retrieve(final RubyObject receiver, final BiVariableMap vars) {
        if ( vars.isLazy() ) return;
        // trying to get variables from receiver;
        updateClassVar(receiver, vars);
        // trying to get variables from topself.
        updateClassVar(getTopSelf(receiver), vars);
    }

    private static void updateClassVar(final RubyObject receiver, final BiVariableMap vars) {
        for ( final String name : receiver.getMetaClass().getClassVariableNameList() ) {
            final IRubyObject value = receiver.getMetaClass().getClassVar(name);
            vars.updateVariable(receiver, name, value, ClassVariable.class);
        }
    }

    
Retrieves a class variable by key from Ruby runtime after the evaluation.
This method is used when eager retrieval is off.
Params:
receiver – receiver object returned when a script is evaluated.
vars – map to save retrieved instance variables.
name – instace varible name/**
     * Retrieves a class variable by key from Ruby runtime after the evaluation.
     * This method is used when eager retrieval is off.
     *
     * @param receiver receiver object returned when a script is evaluated.
     * @param vars map to save retrieved instance variables.
     * @param name instace varible name
     */
    public static void retrieveByKey(final RubyObject receiver,
        final BiVariableMap vars, final String name) {
        final RubyClass klazz = receiver.getMetaClass();
        IRubyObject value = null;
        if ( receiver == receiver.getRuntime().getTopSelf() &&
             klazz.getClassVariableNameList().contains(name) ) {
            value = klazz.getClassVar(name);
        }
        else {
            if ( klazz.hasClassVariable(name) ) {
                value = klazz.getClassVar(name);
            }
        }
        if ( value == null ) return;

        vars.updateVariable(receiver, name, value, ClassVariable.class);
    }

    
Returns enum type of this variable defined in BiVariable. 
Returns:
this enum type, BiVariable.Type.ClassVariable./**
     * Returns enum type of this variable defined in {@link BiVariable}.
     *
     * @return this enum type, BiVariable.Type.ClassVariable.
     */
    @Override
    public Type getType() {
        return Type.ClassVariable;
    }

    
Returns true if the given name is a decent Ruby class variable. Unless
returns false.
Params:
name – is a name to be checked.
Returns:
true if the given name is of a Ruby class variable./**
     * Returns true if the given name is a decent Ruby class variable. Unless
     * returns false.
     *
     * @param name is a name to be checked.
     * @return true if the given name is of a Ruby class variable.
     */
    public static boolean isValidName(Object name) {
        return isValidName(VALID_NAME, name);
    }

    
Injects a class variable value to a parsed Ruby script. This method is
invoked during EvalUnit#run() is executed.
Params:
runtime – is environment where a variable injection occurs
receiver – is the instance that will have variable injection./**
     * Injects a class variable value to a parsed Ruby script. This method is
     * invoked during EvalUnit#run() is executed.
     *
     * @param runtime is environment where a variable injection occurs
     * @param receiver is the instance that will have variable injection.
     */
    @Override
    public void inject() {
        RubyModule rubyClass = getRubyClass(receiver.getRuntime());
        rubyClass.setClassVar(name, rubyObject);
    }

    
Attempts to remove this variable from top self or receiver.
/**
     * Attempts to remove this variable from top self or receiver.
     *
     */
    @Override
    public void remove() {
        RubyModule rubyClass = getRubyClass(receiver.getRuntime());
        rubyClass.removeClassVariable(name);
    }
}