**** 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) 2009-2012 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) 2009-2012 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 java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import org.jruby.Ruby;
import org.jruby.RubyObject;
import org.jruby.embed.internal.BiVariableMap;
import org.jruby.internal.runtime.GlobalVariables;
import org.jruby.runtime.builtin.IRubyObject;

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

    private static final String VALID_NAME = "\\$(([a-zA-Z]|_|\\d)*|-[a-zA-Z]|[!-~&&[^#%()-\\{\\}\\[\\]\\|\\^]])";

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

    protected GlobalVariable(RubyObject receiver, String name, Object... javaObjects) {
        super(receiver, name, false);
        updateByJavaObject(receiver.getRuntime(), javaObjects);
    }

    
A constructor used when global variables are retrieved from Ruby.
Params:
name – the global variable name
irubyObject – Ruby global object/**
     * A constructor used when global variables are retrieved from Ruby.
     *
     * @param name the global variable name
     * @param irubyObject Ruby global object
     */
    GlobalVariable(RubyObject receiver, String name, IRubyObject irubyObject) {
        super(receiver, name, true, irubyObject);
    }

    
Retrieves global variables from Ruby after the evaluation.
Params:
runtime – Ruby runtime
receiver – receiver object returned when a script is evaluated.
vars – map to save retrieved global variables./**
     * Retrieves global 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 global variables.
     */
    public static void retrieve(IRubyObject receiver, BiVariableMap vars) {
        if ( vars.isLazy() ) return;

        GlobalVariables globalVars = receiver.getRuntime().getGlobalVariables();
        for ( final String name : globalVars.getNames() ) {
            if ( isPredefined(name) ) continue;
            IRubyObject value = globalVars.get(name);
            // receiver of gvar should to topSelf always
            updateGlobalVar(vars, getTopSelf(receiver), name, value);
        }
    }

    private static void updateGlobalVar(final BiVariableMap vars,
            final RubyObject receiver, final String name, final IRubyObject value) {
        BiVariable var = vars.getVariable(receiver, name);
        if (var != null) {
            var.setRubyObject(value);
        } else {
            var = new GlobalVariable(receiver, name, value);
            vars.update(name, var);
        }
    }

    
Retrieves a global variable by key from Ruby after the evaluation.
Params:
runtime – Ruby runtime
receiver – receiver object returned when a script is evaluated.
vars – map to save a retrieved global variable.
key – name of the global variable/**
     * Retrieves a global variable by key from Ruby after the evaluation.
     *
     * @param runtime Ruby runtime
     * @param receiver receiver object returned when a script is evaluated.
     * @param vars map to save a retrieved global variable.
     * @param key name of the global variable
     */
    public static void retrieveByKey(Ruby runtime, BiVariableMap vars, String key) {
        GlobalVariables globalVars = runtime.getGlobalVariables();
        // if the specified key doesn't exist, this method is called before the
        // evaluation. Don't update value in this case.
        if ( ! globalVars.getNames().contains(key) ) return;

        // the specified key is found, so let's update
        IRubyObject value = globalVars.get(key);
        updateGlobalVar(vars, (RubyObject) runtime.getTopSelf(), key, value);
    }

    private static final String[] PREDEFINED_PATTERNS = {
        "\\$([\\u0021-\\u0040]|\\u005c|[\\u005e-\\u0060]|\\u007e)",
        "\\$-(\\d|[A-z])"
    };
    private static final Set<String> PREDEFINED_NAMES = new HashSet<String>();

    static {
        final String[] NAMES = {
            "$DEBUG", "$F", "$FILENAME", "$KCODE", "$LOAD_PATH", "$SAFE", "$VERBOSE", "$CLASSPATH", "$LOADED_FEATURES",
            "$PROGRAM_NAME", "$FIELD_SEPARATOR", "$ERROR_POSITION", "$DEFAULT_OUTPUT", "$PREMATCH", "$RS", "$MATCH",
            "$LAST_READ_LINE", "$FS", "$INPUT_RECORD_SEPARATOR", "$PID", "$NR", "$ERROR_INFO", "$PROCESS_ID",
            "$OUTPUT_RECORD_SEPARATOR", "$INPUT_LINE_NUMBER", "$LAST_PAREN_MATCH", "$LAST_MATCH_INFO", "$CHILD_STATUS",
            "$IGNORECASE", "$DEFAULT_INPUT", "$OFS", "$OUTPUT_FIELD_SEPARATOR", "$POSTMATCH", "$ORS",
            "$configure_args", "$deferr", "$defout", "$expect_verbose", "$stderr", "$stdin", "$stdout"
        };
        PREDEFINED_NAMES.addAll(Arrays.asList(NAMES));
    }

    protected static boolean isPredefined(final String name) {
        for ( String pattern : PREDEFINED_PATTERNS ) {
            if ( name.matches(pattern) ) return true;
        }
        return GlobalVariable.PREDEFINED_NAMES.contains(name);
    }

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

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

    
Sets a Java object and its Ruby type as a value of this object.
At the same time, sets Ruby object to Ruby runtime.
Params:
runtime – is used to convert a Java object to Ruby object.
javaObject – is a variable value to be set./**
     * Sets a Java object and its Ruby type as a value of this object.
     * At the same time, sets Ruby object to Ruby runtime.
     *
     * @param runtime is used to convert a Java object to Ruby object.
     * @param javaObject is a variable value to be set.
     */
    @Override
    public void setJavaObject(Ruby runtime, Object javaObject) {
        updateByJavaObject(runtime, javaObject);
        tryEagerInjection(runtime, null);
    }

    
A global variable is injected when it is set. This method does nothing.
Instead injection is done by tryEagerInjection.
/**
     * A global variable is injected when it is set. This method does nothing.
     * Instead injection is done by tryEagerInjection.
     */
    @Override
    public void inject() {
        // do nothing
    }

    @Deprecated
    public void tryEagerInjection(Ruby runtime, IRubyObject receiver) {
        tryEagerInjection(receiver);
    }

    
Injects a global 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 global 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.
     */
    public void tryEagerInjection(final IRubyObject receiver) {
        // wreckages of global local vars might remain on runtime, which may cause
        // assertion error since those names doesn't start from "$"
        final String name = this.name.startsWith("$") ? this.name : ('$' + this.name);
        synchronized (getRuntime()) {
            getRuntime().getGlobalVariables().set(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() {
        synchronized (getRuntime()) {
            getRuntime().getGlobalVariables().clear(name);
        }
    }

    
Returns true if a given receiver is identical to the receiver this object has.
Returns:
true always/**
     * Returns true if a given receiver is identical to the receiver this object has.
     *
     * @return true always
     */
    @Override
    public boolean isReceiverIdentical(RubyObject recv) {
        return true;
    }

}