**** 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) 2009-2010 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) 2009-2010 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.internal;

import org.jruby.Ruby;
import org.jruby.RubyInstanceConfig.CompileMode;
import org.jruby.RubySystemExit;
import org.jruby.ast.Node;
import org.jruby.ast.executable.Script;
import org.jruby.embed.AttributeName;
import org.jruby.embed.EmbedEvalUnit;
import org.jruby.embed.EvalFailedException;
import org.jruby.embed.ScriptingContainer;
import org.jruby.exceptions.RaiseException;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.scope.ManyVarsDynamicScope;

Implementation of org.jruby.javasupport.JavaEmbedUtils.EvalUnit for embeddiing.
This class is created when a Ruby script has been parsed. Once parsed, the script
is ready to run many times without parsing.
Users do not instantiate explicitly. Instead, they can get the instance by parsing Ruby script by parse method of ScriptingContainer. 
Author:
Yoko Harada /**
 * Implementation of org.jruby.javasupport.JavaEmbedUtils.EvalUnit for embeddiing.
 * This class is created when a Ruby script has been parsed. Once parsed, the script
 * is ready to run many times without parsing.
 *
 * <p>Users do not instantiate explicitly. Instead, they can get the instance by parsing
 * Ruby script by parse method of {@link ScriptingContainer}.
 *
 * @author Yoko Harada <yokolet@gmail.com>
 */
public class EmbedEvalUnitImpl implements EmbedEvalUnit {

    private final ScriptingContainer container;
    private final Node node;
    private final ManyVarsDynamicScope scope;
    private final Script script;

    public EmbedEvalUnitImpl(ScriptingContainer container, Node node, ManyVarsDynamicScope scope) {
        this(container, node, scope, null);
    }

    public EmbedEvalUnitImpl(ScriptingContainer container, Node node, ManyVarsDynamicScope scope, Script script) {
        this.container = container;
        this.node = node;
        this.scope = scope;
        this.script = script;
    }

    
Returns a root node of parsed Ruby script.
Returns:
a root node of parsed Ruby script/**
     * Returns a root node of parsed Ruby script.
     *
     * @return a root node of parsed Ruby script
     */
    public Node getNode() {
        return node;
    }

    
Returns a ManyVarsDynamicScope used to parse a script. A returned value
is used to inject Ruby's local variable when script is evaluated.
Returns:
a scope to refer local variables/**
     * Returns a ManyVarsDynamicScope used to parse a script. A returned value
     * is used to inject Ruby's local variable when script is evaluated.
     *
     * @return a scope to refer local variables
     */
    public ManyVarsDynamicScope getScope() {
        return scope;
    }

    
Evaluates a Ruby script, which has been parsed before.
Returns:
results of executing this evaluation unit/**
     * Evaluates a Ruby script, which has been parsed before.
     *
     * @return results of executing this evaluation unit
     */
    public IRubyObject run() {
        if (node == null && script == null) {
            return null;
        }
        final Ruby runtime = container.getProvider().getRuntime();
        final BiVariableMap vars = container.getVarMap();
        final boolean sharing_variables = isSharingVariables();

        // Keep reference to current context to prevent it being collected.
        final ThreadContext threadContext = runtime.getCurrentContext();
        if (sharing_variables) {
            vars.inject(scope, 0, null);
            threadContext.pushScope(scope);
        }
        try {
            final IRubyObject ret;
            CompileMode mode = runtime.getInstanceConfig().getCompileMode();
            if (mode == CompileMode.FORCE) {
                ret = runtime.runScriptBody(script);
            } else {
                ret = runtime.runInterpreter(node);
            }
            if (sharing_variables) {
                vars.retrieve(ret);
            }
            return ret;
        }
        catch (RaiseException e) {
            // handle exits as simple script termination
            if ( e.getException() instanceof RubySystemExit ) {
                return ((RubySystemExit) e.getException()).status();
            }
            runtime.printError(e.getException());
            throw new EvalFailedException(e.getMessage(), e);
        }
        catch (StackOverflowError soe) {
            throw runtime.newSystemStackError("stack level too deep", soe);
        }
        catch (Throwable e) {
            throw new EvalFailedException(e);
        }
        finally {
            if (sharing_variables) {
                threadContext.popScope();
            }
            vars.terminate();
            /* Below lines doesn't work. Neither does classCache.flush(). How to clear cache?
            ClassCache classCache = JavaEmbedUtils.createClassCache(getRuntime().getClassLoader());
            getRuntime().getInstanceConfig().setClassCache(classCache);
            */
        }
    }

    private boolean isSharingVariables() {
        final Object sharing = container.getAttribute(AttributeName.SHARING_VARIABLES);
        if ( sharing != null && sharing instanceof Boolean &&
                ((Boolean) sharing).booleanValue() == false ) {
            return false;
        }
        return true;
    }

}