Package org.springmodules.template.engine.velocity.extended

Source Code of org.springmodules.template.engine.velocity.extended.ExtendedRuntimeInstance

package org.springmodules.template.engine.velocity.extended;

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you 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.
*/

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.*;

import org.apache.commons.collections.ExtendedProperties;
import org.apache.velocity.Template;
import org.apache.velocity.app.event.*;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.log.Log;
import org.apache.velocity.runtime.log.LogManager;
import org.apache.velocity.runtime.parser.ParseException;
import org.apache.velocity.runtime.parser.Parser;
import org.apache.velocity.runtime.parser.node.SimpleNode;
import org.apache.velocity.runtime.resource.ContentResource;
import org.apache.velocity.runtime.resource.ResourceManager;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.VelocimacroFactory;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.ParserPool;
import org.apache.velocity.util.ClassUtils;
import org.apache.velocity.util.RuntimeServicesAware;
import org.apache.velocity.util.StringUtils;
import org.apache.velocity.util.introspection.Introspector;
import org.apache.velocity.util.introspection.Uberspect;
import org.apache.velocity.util.introspection.UberspectLoggable;

/**
* This is the Runtime system for Velocity. It is the
* single access point for all functionality in Velocity.
* It adheres to the mediator pattern and is the only
* structure that developers need to be familiar with
* in order to get Velocity to perform.
* <p/>
* The Runtime will also cooperate with external
* systems like Turbine. Runtime properties can
* set and then the Runtime is initialized.
* <p/>
* Turbine, for example, knows where the templates
* are to be loaded from, and where the Velocity
* log file should be placed.
* <p/>
* So in the case of Velocity cooperating with Turbine
* the code might look something like the following:
* <p/>
* <blockquote><code><pre>
* ri.setProperty(Runtime.FILE_RESOURCE_LOADER_PATH, templatePath);
* ri.setProperty(Runtime.RUNTIME_LOG, pathToVelocityLog);
* ri.init();
* </pre></code></blockquote>
* <p/>
* <pre>
* -----------------------------------------------------------------------
* N O T E S  O N  R U N T I M E  I N I T I A L I Z A T I O N
* -----------------------------------------------------------------------
* init()
* <p/>
* If init() is called by itself the RuntimeInstance will initialize
* with a set of default values.
* -----------------------------------------------------------------------
* init(String/Properties)
* <p/>
* In this case the default velocity properties are layed down
* first to provide a solid base, then any properties provided
* in the given properties object will override the corresponding
* default property.
* -----------------------------------------------------------------------
* </pre>
*
* @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
* @author <a href="mailto:jlb@houseofdistraction.com">Jeff Bowden</a>
* @author <a href="mailto:geirm@optonline.net">Geir Magusson Jr.</a>
* @version $Id: ExtendedRuntimeInstance.java,v 1.1 2007/06/24 00:47:13 hueboness Exp $
*/
public class ExtendedRuntimeInstance implements RuntimeConstants, RuntimeServices {

    /**
     * VelocimacroFactory object to manage VMs
     */
    private VelocimacroFactory vmFactory = null;

    /**
     * The Runtime logger.  We start with an instance of
     * a 'primordial logger', which just collects log messages
     * then, when the log system is initialized, all the
     * messages get dumpted out of the primordial one into the real one.
     */
    private Log log = new Log();

    /**
     * The Runtime parser pool
     */
    private ParserPool parserPool;

    /**
     * Indicate whether the Runtime is in the midst of initialization.
     */
    private boolean initializing = false;

    /**
     * Indicate whether the Runtime has been fully initialized.
     */
    private boolean initialized = false;

    /**
     * These are the properties that are laid down over top
     * of the default properties when requested.
     */
    private ExtendedProperties overridingProperties = null;

    /**
     * This is a hashtable of initialized directives.
     * The directives that populate this hashtable are
     * taken from the RUNTIME_DEFAULT_DIRECTIVES
     * property file. This hashtable is passed
     * to each parser that is created.
     */
    private Hashtable runtimeDirectives;

    /**
     * Object that houses the configuration options for
     * the velocity runtime. The ExtendedProperties object allows
     * the convenient retrieval of a subset of properties.
     * For example all the properties for a resource loader
     * can be retrieved from the main ExtendedProperties object
     * using something like the following:
     * <p/>
     * ExtendedProperties loaderConfiguration =
     * configuration.subset(loaderID);
     * <p/>
     * And a configuration is a lot more convenient to deal
     * with then conventional properties objects, or Maps.
     */
    private ExtendedProperties configuration = new ExtendedProperties();

    private ResourceManager resourceManager = null;

    /**
     * This stores the engine-wide set of event handlers.  Event handlers for
     * each specific merge are stored in the context.
     */
    private EventCartridge eventCartridge = null;

    /*
     *  Each runtime instance has it's own introspector
     *  to ensure that each instance is completely separate.
     */
    private Introspector introspector = null;

    /*
    *  Opaque reference to something specificed by the
    *  application for use in application supplied/specified
    *  pluggable components
    */
    private Map applicationAttributes = null;

    private Uberspect uberSpect;

    /**
     * Creates a new RuntimeInstance object.
     */
    public ExtendedRuntimeInstance(ResourceManager resourceManager) {
        /*
         *  create a VM factory, introspector, and application attributes
         */
        vmFactory = new VelocimacroFactory(this);

        /*
         *  make a new introspector and initialize it
         */
        introspector = new Introspector(getLog());

        /*
         * and a store for the application attributes
         */
        applicationAttributes = new HashMap();

        this.resourceManager = resourceManager;
    }

    /**
     * This is the primary initialization method in the Velocity
     * Runtime. The systems that are setup/initialized here are
     * as follows:
     * <p/>
     * <ul>
     * <li>Logging System</li>
     * <li>ResourceManager</li>
     * <li>EventHandler</li>
     * <li>Parser Pool</li>
     * <li>Global Cache</li>
     * <li>Static Content Include System</li>
     * <li>Velocimacro System</li>
     * </ul>
     *
     * @throws Exception When an error occured during initialization.
     */
    public synchronized void init()
        throws Exception {
        if (!initialized && !initializing) {
            initializing = true;

            log.trace("*******************************************************************");
            log.debug("Starting Apache Velocity v@build.version@ (compiled: @build.time@)");
            log.trace("RuntimeInstance initializing.");

            initializeProperties();
            initializeLog();
            initializeResourceManager();
            initializeDirectives();
            initializeEventHandlers();
            initializeParserPool();

            initializeIntrospection();
            /*
             *  initialize the VM Factory.  It will use the properties
             * accessable from Runtime, so keep this here at the end.
             */
            vmFactory.initVelocimacro();

            log.trace("RuntimeInstance successfully initialized.");

            initialized = true;
            initializing = false;
        }
    }

    /**
     * Returns true if the RuntimeInstance has been successfully initialized.
     *
     * @return True if the RuntimeInstance has been successfully initialized.
     */
    public boolean isInitialized() {
        return initialized;
    }

    /**
     * Gets the classname for the Uberspect introspection package and
     * instantiates an instance.
     */
    private void initializeIntrospection()
        throws Exception {
        String rm = getString(RuntimeConstants.UBERSPECT_CLASSNAME);

        if (rm != null && rm.length() > 0) {
            Object o = null;

            try {
                o = ClassUtils.getNewInstance(rm);
            }
            catch (ClassNotFoundException cnfe) {
                String err = "The specified class for Uberspect (" + rm
                    + ") does not exist or is not accessible to the current classloader.";
                log.error(err);
                throw new Exception(err);
            }

            if (!(o instanceof Uberspect)) {
                String err = "The specified class for Uberspect ("
                    + rm + ") does not implement " + Uberspect.class.getName()
                    + "; Velocity is not initialized correctly.";

                log.error(err);
                throw new Exception(err);
            }

            uberSpect = (Uberspect) o;

            if (uberSpect instanceof UberspectLoggable) {
                ((UberspectLoggable) uberSpect).setLog(getLog());
            }

            if (uberSpect instanceof RuntimeServicesAware) {
                ((RuntimeServicesAware) uberSpect).setRuntimeServices(this);
            }

            uberSpect.init();
        } else {
            /*
             *  someone screwed up.  Lets not fool around...
             */

            String err = "It appears that no class was specified as the"
                + " Uberspect.  Please ensure that all configuration"
                + " information is correct.";

            log.error(err);
            throw new Exception(err);
        }
    }

    /**
     * Initializes the Velocity Runtime with properties file.
     * The properties file may be in the file system proper,
     * or the properties file may be in the classpath.
     */
    private void setDefaultProperties() {
        InputStream inputStream = null;
        try {
            inputStream = getClass()
                .getResourceAsStream('/' + DEFAULT_RUNTIME_PROPERTIES);

            configuration.load(inputStream);

            if (log.isDebugEnabled()) {
                log.debug("Default Properties File: " +
                    new File(DEFAULT_RUNTIME_PROPERTIES).getPath());
            }

        }
        catch (IOException ioe) {
            log.error("Cannot get Velocity Runtime default properties!", ioe);
        }
        finally {
            try {
                if (inputStream != null) {
                    inputStream.close();
                }
            }
            catch (IOException ioe) {
                log.error("Cannot close Velocity Runtime default properties!", ioe);
            }
        }
    }

    /**
     * Allows an external system to set a property in
     * the Velocity Runtime.
     *
     * @param key   property key
     * @param value property value
     */
    public void setProperty(String key, Object value) {
        if (overridingProperties == null) {
            overridingProperties = new ExtendedProperties();
        }

        overridingProperties.setProperty(key, value);
    }

    /**
     * Allow an external system to set an ExtendedProperties
     * object to use. This is useful where the external
     * system also uses the ExtendedProperties class and
     * the velocity configuration is a subset of
     * parent application's configuration. This is
     * the case with Turbine.
     *
     * @param configuration
     */
    public void setConfiguration(ExtendedProperties configuration) {
        if (overridingProperties == null) {
            overridingProperties = configuration;
        } else {
            // Avoid possible ConcurrentModificationException
            if (overridingProperties != configuration) {
                overridingProperties.combine(configuration);
            }
        }
    }

    /**
     * Add a property to the configuration. If it already
     * exists then the value stated here will be added
     * to the configuration entry. For example, if
     * <p/>
     * resource.loader = file
     * <p/>
     * is already present in the configuration and you
     * <p/>
     * addProperty("resource.loader", "classpath")
     * <p/>
     * Then you will end up with a Vector like the
     * following:
     * <p/>
     * ["file", "classpath"]
     *
     * @param key
     * @param value
     */
    public void addProperty(String key, Object value) {
        if (overridingProperties == null) {
            overridingProperties = new ExtendedProperties();
        }

        overridingProperties.addProperty(key, value);
    }

    /**
     * Clear the values pertaining to a particular
     * property.
     *
     * @param key of property to clear
     */
    public void clearProperty(String key) {
        if (overridingProperties != null) {
            overridingProperties.clearProperty(key);
        }
    }

    /**
     * Allows an external caller to get a property.  The calling
     * routine is required to know the type, as this routine
     * will return an Object, as that is what properties can be.
     *
     * @param key property to return
     * @return Value of the property or null if it does not exist.
     */
    public Object getProperty(String key) {
        Object o = null;

        /**
         * Before initialization, check the user-entered properties first.
         */
        if (!initialized && !initializing && overridingProperties != null) {
            o = overridingProperties.get(key);
        }

        /**
         * After initialization, configuration will hold all properties.
         */
        if (o == null) {
            o = configuration.getProperty(key);
        }
        if (o instanceof String) {
            return StringUtils.nullTrim((String) o);
        } else {
            return o;
        }
    }

    /**
     * Initialize Velocity properties, if the default
     * properties have not been laid down first then
     * do so. Then proceed to process any overriding
     * properties. Laying down the default properties
     * gives a much greater chance of having a
     * working system.
     */
    private void initializeProperties() {
        /*
         * Always lay down the default properties first as
         * to provide a solid base.
         */
        if (configuration.isInitialized() == false) {
            setDefaultProperties();
        }

        if (overridingProperties != null) {
            configuration.combine(overridingProperties);
        }
    }

    /**
     * Initialize the Velocity Runtime with a Properties
     * object.
     *
     * @param p
     * @throws Exception When an error occurs during initialization.
     */
    public void init(Properties p) throws Exception {
        overridingProperties = ExtendedProperties.convertProperties(p);
        init();
    }

    /**
     * Initialize the Velocity Runtime with the name of
     * ExtendedProperties object.
     *
     * @param configurationFile
     * @throws Exception When an error occurs during initialization.
     */
    public void init(String configurationFile)
        throws Exception {
        overridingProperties = new ExtendedProperties(configurationFile);
        init();
    }

    private void initializeResourceManager() throws Exception {
        if (resourceManager == null) {
            throw new Exception("Required ResourceManager is missing");
        }
        resourceManager.initialize(this);
    }

    private void initializeEventHandlers()
        throws Exception {

        eventCartridge = new EventCartridge();

        /**
         * For each type of event handler, get the class name, instantiate it, and store it.
         */

        String[] referenceinsertion = configuration.getStringArray(RuntimeConstants.EVENTHANDLER_REFERENCEINSERTION);
        if (referenceinsertion != null) {
            for (int i = 0; i < referenceinsertion.length; i++) {
                EventHandler ev = initializeSpecificEventHandler(referenceinsertion[i], RuntimeConstants.EVENTHANDLER_REFERENCEINSERTION, ReferenceInsertionEventHandler.class);
                if (ev != null)
                    eventCartridge.addReferenceInsertionEventHandler((ReferenceInsertionEventHandler) ev);
            }
        }

        String[] nullset = configuration.getStringArray(RuntimeConstants.EVENTHANDLER_NULLSET);
        if (nullset != null) {
            for (int i = 0; i < nullset.length; i++) {
                EventHandler ev = initializeSpecificEventHandler(nullset[i], RuntimeConstants.EVENTHANDLER_NULLSET, NullSetEventHandler.class);
                if (ev != null)
                    eventCartridge.addNullSetEventHandler((NullSetEventHandler) ev);
            }
        }

        String[] methodexception = configuration.getStringArray(RuntimeConstants.EVENTHANDLER_METHODEXCEPTION);
        if (methodexception != null) {
            for (int i = 0; i < methodexception.length; i++) {
                EventHandler ev = initializeSpecificEventHandler(methodexception[i], RuntimeConstants.EVENTHANDLER_METHODEXCEPTION, MethodExceptionEventHandler.class);
                if (ev != null)
                    eventCartridge.addMethodExceptionHandler((MethodExceptionEventHandler) ev);
            }
        }

        String[] includeHandler = configuration.getStringArray(RuntimeConstants.EVENTHANDLER_INCLUDE);
        if (includeHandler != null) {
            for (int i = 0; i < includeHandler.length; i++) {
                EventHandler ev = initializeSpecificEventHandler(includeHandler[i], RuntimeConstants.EVENTHANDLER_INCLUDE, IncludeEventHandler.class);
                if (ev != null)
                    eventCartridge.addIncludeEventHandler((IncludeEventHandler) ev);
            }
        }

        String[] invalidReferenceSet = configuration.getStringArray(RuntimeConstants.EVENTHANDLER_INVALIDREFERENCES);
        if (invalidReferenceSet != null) {
            for (int i = 0; i < invalidReferenceSet.length; i++) {
                EventHandler ev = initializeSpecificEventHandler(invalidReferenceSet[i], RuntimeConstants.EVENTHANDLER_INVALIDREFERENCES, InvalidReferenceEventHandler.class);
                if (ev != null) {
                    eventCartridge.addInvalidReferenceEventHandler((InvalidReferenceEventHandler) ev);
                }
            }
        }

    }

    private EventHandler initializeSpecificEventHandler(String classname, String paramName, Class EventHandlerInterface)
        throws Exception {
        if (classname != null && classname.length() > 0) {
            Object o = null;
            try {
                o = ClassUtils.getNewInstance(classname);
            }
            catch (ClassNotFoundException cnfe) {
                String err = "The specified class for "
                    + paramName + " (" + classname
                    + ") does not exist or is not accessible to the current classloader.";
                log.error(err);
                throw new Exception(err);
            }

            if (!EventHandlerInterface.isAssignableFrom(EventHandlerInterface)) {
                String err = "The specified class for " + paramName + " ("
                    + classname + ") does not implement "
                    + EventHandlerInterface.getName()
                    + "; Velocity is not initialized correctly.";

                log.error(err);
                throw new Exception(err);
            }

            EventHandler ev = (EventHandler) o;
            if (ev instanceof RuntimeServicesAware)
                ((RuntimeServicesAware) ev).setRuntimeServices(this);
            return ev;

        } else
            return null;
    }

    /**
     * Initialize the Velocity logging system.
     *
     * @throws Exception
     */
    private void initializeLog() throws Exception {
        // since the Log we started with was just placeholding,
        // let's update it with the real LogChute settings.
        LogManager.updateLog(this.log, this);
    }

    /**
     * This methods initializes all the directives
     * that are used by the Velocity Runtime. The
     * directives to be initialized are listed in
     * the RUNTIME_DEFAULT_DIRECTIVES properties
     * file.
     *
     * @throws Exception
     */
    private void initializeDirectives()
        throws Exception {
        /*
         * Initialize the runtime directive table.
         * This will be used for creating parsers.
         */
        runtimeDirectives = new Hashtable();

        Properties directiveProperties = new Properties();

        /*
         * Grab the properties file with the list of directives
         * that we should initialize.
         */

        InputStream inputStream = null;

        try {
            inputStream = getClass().getResourceAsStream('/' + DEFAULT_RUNTIME_DIRECTIVES);

            if (inputStream == null) {
                throw new Exception("Error loading directive.properties! " +
                    "Something is very wrong if these properties " +
                    "aren't being located. Either your Velocity " +
                    "distribution is incomplete or your Velocity " +
                    "jar file is corrupted!");
            }

            directiveProperties.load(inputStream);

        }
        catch (IOException ioe) {
            log.error("Error while loading directive properties!", ioe);
        }
        finally {
            try {
                if (inputStream != null) {
                    inputStream.close();
                }
            }
            catch (IOException ioe) {
                log.error("Cannot close directive properties!", ioe);
            }
        }

        /*
        * Grab all the values of the properties. These
        * are all class names for example:
        *
        * org.apache.velocity.runtime.directive.Foreach
        */
        Enumeration directiveClasses = directiveProperties.elements();

        while (directiveClasses.hasMoreElements()) {
            String directiveClass = (String) directiveClasses.nextElement();
            loadDirective(directiveClass);
            log.debug("Loaded System Directive: " + directiveClass);
        }

        /*
         *  now the user's directives
         */

        String[] userdirective = configuration.getStringArray("userdirective");

        for (int i = 0; i < userdirective.length; i++) {
            loadDirective(userdirective[i]);
            if (log.isInfoEnabled()) {
                log.info("Loaded User Directive: " + userdirective[i]);
            }
        }

    }

    /**
     * instantiates and loads the directive with some basic checks
     *
     * @param directiveClass classname of directive to load
     */
    private void loadDirective(String directiveClass) {
        try {
            Object o = ClassUtils.getNewInstance(directiveClass);

            if (o instanceof Directive) {
                Directive directive = (Directive) o;
                runtimeDirectives.put(directive.getName(), directive);
            } else {
                log.error(directiveClass + " does not implement "
                    + Directive.class.getName() + "; it cannot be loaded.");
            }
        }
        // The ugly threesome:  ClassNotFoundException,
        // IllegalAccessException, InstantiationException.
        // Ignore Findbugs complaint for now.
        catch (Exception e) {
            log.error("Failed to load Directive: " + directiveClass, e);
        }
    }

    /**
     * Initializes the Velocity parser pool.
     */
    private void initializeParserPool() throws Exception {
        /*
         * Which parser pool?
         */
        String pp = getString(RuntimeConstants.PARSER_POOL_CLASS);

        if (pp != null && pp.length() > 0) {
            /*
             *  if something was specified, then make one.
             *  if that isn't a ParserPool, consider
             *  this a huge error and throw
             */

            Object o = null;

            try {
                o = ClassUtils.getNewInstance(pp);
            }
            catch (ClassNotFoundException cnfe) {
                String err = "The specified class for ParserPool ("
                    + pp
                    + ") does not exist (or is not accessible to the current classloader.";
                log.error(err);
                throw new Exception(err);
            }

            if (!(o instanceof ParserPool)) {
                String err = "The specified class for ParserPool ("
                    + pp + ") does not implement " + ParserPool.class
                    + " Velocity not initialized correctly.";

                log.error(err);
                throw new Exception(err);
            }

            parserPool = (ParserPool) o;

            parserPool.initialize(this);
        } else {
            /*
             *  someone screwed up.  Lets not fool around...
             */

            String err = "It appears that no class was specified as the"
                + " ParserPool.  Please ensure that all configuration"
                + " information is correct.";

            log.error(err);
            throw new Exception(err);
        }

    }

    /**
     * Returns a JavaCC generated Parser.
     *
     * @return Parser javacc generated parser
     */
    public Parser createNewParser() {
        /* must be initialized before we use runtimeDirectives */
        if (!initialized && !initializing) {
            log.debug("Velocity was not initialized! Calling init()...");
            try {
                init();
            }
            catch (Exception e) {
                getLog().error("Could not auto-initialize Velocity", e);
                throw new IllegalStateException("Velocity could not be initialized!");
            }
        }

        Parser parser = new Parser(this);
        parser.setDirectives(runtimeDirectives);
        return parser;
    }

    /**
     * Parse the input and return the root of
     * AST node structure.
     * <br><br>
     * In the event that it runs out of parsers in the
     * pool, it will create and let them be GC'd
     * dynamically, logging that it has to do that.  This
     * is considered an exceptional condition.  It is
     * expected that the user will set the
     * PARSER_POOL_SIZE property appropriately for their
     * application.  We will revisit this.
     *
     * @param reader       Reader retrieved by a resource loader
     * @param templateName name of the template being parsed
     * @return A root node representing the template as an AST tree.
     * @throws ParseException When the template could not be parsed.
     */
    public SimpleNode parse(Reader reader, String templateName)
        throws ParseException {
        /*
         *  do it and dump the VM namespace for this template
         */
        return parse(reader, templateName, true);
    }

    /**
     * Parse the input and return the root of the AST node structure.
     *
     * @param reader        Reader retrieved by a resource loader
     * @param templateName  name of the template being parsed
     * @param dumpNamespace flag to dump the Velocimacro namespace for this template
     * @return A root node representing the template as an AST tree.
     * @throws ParseException When the template could not be parsed.
     */
    public SimpleNode parse(Reader reader, String templateName, boolean dumpNamespace)
        throws ParseException {
        /* must be initialized before using parserPool */
        if (!initialized && !initializing) {
            log.debug("Velocity was not initialized! Calling init()...");
            try {
                init();
            }
            catch (Exception e) {
                getLog().error("Could not auto-initialize Velocity", e);
                throw new IllegalStateException("Velocity could not be initialized!");
            }
        }

        SimpleNode ast = null;
        Parser parser = (Parser) parserPool.get();

        if (parser == null) {
            /*
             *  if we couldn't get a parser from the pool
             *  make one and log it.
             */

            if (log.isInfoEnabled()) {
                log.info("Runtime : ran out of parsers. Creating a new one. "
                    + " Please increment the parser.pool.size property."
                    + " The current value is too small.");
            }

            parser = createNewParser();

        }

        /*
         *  now, if we have a parser
         */

        if (parser != null) {
            try {
                /*
                 *  dump namespace if we are told to.  Generally, you want to
                 *  do this - you don't in special circumstances, such as
                 *  when a VM is getting init()-ed & parsed
                 */

                if (dumpNamespace) {
                    dumpVMNamespace(templateName);
                }

                ast = parser.parse(reader, templateName);
            }
            finally {
                /*
                 *  put it back
                 */
                parserPool.put(parser);

            }
        } else {
            log.error("Runtime : ran out of parsers and unable to create more.");
        }
        return ast;
    }

    /**
     * Returns a <code>Template</code> from the resource manager.
     * This method assumes that the character encoding of the
     * template is set by the <code>input.encoding</code>
     * property.  The default is "ISO-8859-1"
     *
     * @param name The file name of the desired template.
     * @return The template.
     * @throws ResourceNotFoundException if template not found
     *                                   from any available source.
     * @throws ParseErrorException       if template cannot be parsed due
     *                                   to syntax (or other) error.
     * @throws Exception                 if an error occurs in template initialization
     */
    public Template getTemplate(String name)
        throws ResourceNotFoundException, ParseErrorException, Exception {
        return getTemplate(name, getString(INPUT_ENCODING, ENCODING_DEFAULT));
    }

    /**
     * Returns a <code>Template</code> from the resource manager
     *
     * @param name     The  name of the desired template.
     * @param encoding Character encoding of the template
     * @return The template.
     * @throws ResourceNotFoundException if template not found
     *                                   from any available source.
     * @throws ParseErrorException       if template cannot be parsed due
     *                                   to syntax (or other) error.
     * @throws Exception                 if an error occurs in template initialization
     */
    public Template getTemplate(String name, String encoding)
        throws ResourceNotFoundException, ParseErrorException, Exception {
        /* must be initialized before using resourceManager */
        if (!initialized && !initializing) {
            log.info("Velocity not initialized yet. Calling init()...");
            init();
        }

        return (Template)
            resourceManager.getResource(name,
                ResourceManager.RESOURCE_TEMPLATE, encoding);
    }

    /**
     * Returns a static content resource from the
     * resource manager.  Uses the current value
     * if INPUT_ENCODING as the character encoding.
     *
     * @param name Name of content resource to get
     * @return parsed ContentResource object ready for use
     * @throws ResourceNotFoundException if template not found
     *                                   from any available source.
     * @throws ParseErrorException       When the template could not be parsed.
     * @throws Exception                 Any other error.
     */
    public ContentResource getContent(String name)
        throws ResourceNotFoundException, ParseErrorException, Exception {
        /*
         *  the encoding is irrelvant as we don't do any converstion
         *  the bytestream should be dumped to the output stream
         */

        return getContent(name, getString(INPUT_ENCODING, ENCODING_DEFAULT));
    }

    /**
     * Returns a static content resource from the
     * resource manager.
     *
     * @param name     Name of content resource to get
     * @param encoding Character encoding to use
     * @return parsed ContentResource object ready for use
     * @throws ResourceNotFoundException if template not found
     *                                   from any available source.
     * @throws ParseErrorException       When the template could not be parsed.
     * @throws Exception                 Any other error.
     */
    public ContentResource getContent(String name, String encoding)
        throws ResourceNotFoundException, ParseErrorException, Exception {
        /* must be initialized before using resourceManager */
        if (!initialized && !initializing) {
            log.info("Velocity not initialized yet. Calling init()...");
            init();
        }

        return (ContentResource)
            resourceManager.getResource(name,
                ResourceManager.RESOURCE_CONTENT, encoding);
    }

    /**
     * Determines if a template exists and returns name of the loader that
     * provides it.  This is a slightly less hokey way to support
     * the Velocity.resourceExists() utility method, which was broken
     * when per-template encoding was introduced.  We can revisit this.
     *
     * @param resourceName Name of template or content resource
     * @return class name of loader than can provide it
     */
    public String getLoaderNameForResource(String resourceName) {
        /* must be initialized before using resourceManager */
        if (!initialized && !initializing) {
            log.debug("Velocity was not initialized! Calling init()...");
            try {
                init();
            }
            catch (Exception e) {
                getLog().error("Could not initialize Velocity", e);
                throw new IllegalStateException("Velocity could not be initialized!");
            }
        }

        return resourceManager.getLoaderNameForResource(resourceName);
    }

    /**
     * Returns a convenient Log instance that wraps the current LogChute.
     * Use this to log error messages. It has the usual methods.
     *
     * @return A convenience Log instance that wraps the current LogChute.
     */
    public Log getLog() {
        return log;
    }

    /**
     * @param message The message to log.
     * @see Log#warn(Object)
     * @deprecated Use getLog() and call warn() on it.
     */
    public void warn(Object message) {
        getLog().warn(message);
    }

    /**
     * @param message The message to log.
     * @see Log#info(Object)
     * @deprecated Use getLog() and call info() on it.
     */
    public void info(Object message) {
        getLog().info(message);
    }

    /**
     * @param message The message to log.
     * @see Log#error(Object)
     * @deprecated Use getLog() and call error() on it.
     */
    public void error(Object message) {
        getLog().error(message);
    }

    /**
     * @param message The message to log.
     * @see Log#debug(Object)
     * @deprecated Use getLog() and call debug() on it.
     */
    public void debug(Object message) {
        getLog().debug(message);
    }

    /**
     * String property accessor method with default to hide the
     * configuration implementation.
     *
     * @param key          property key
     * @param defaultValue default value to return if key not
     *                     found in resource manager.
     * @return value of key or default
     */
    public String getString(String key, String defaultValue) {
        return configuration.getString(key, defaultValue);
    }

    /**
     * Returns the appropriate VelocimacroProxy object if strVMname
     * is a valid current Velocimacro.
     *
     * @param vmName       Name of velocimacro requested
     * @param templateName Name of the template that contains the velocimacro.
     * @return The requested VelocimacroProxy.
     */
    public Directive getVelocimacro(String vmName, String templateName) {
        return vmFactory.getVelocimacro(vmName, templateName);
    }

    /**
     * Adds a new Velocimacro. Usually called by Macro only while parsing.
     *
     * @param name           Name of velocimacro
     * @param macro          String form of macro body
     * @param argArray       Array of strings, containing the
     *                       #macro() arguments.  the 0th is the name.
     * @param sourceTemplate Name of the template that contains the velocimacro.
     * @return True if added, false if rejected for some
     *         reason (either parameters or permission settings)
     */
    public boolean addVelocimacro(String name,
                                  String macro,
                                  String argArray[],
                                  String sourceTemplate) {
        return vmFactory.addVelocimacro(name, macro, argArray, sourceTemplate);
    }

    /**
     * Checks to see if a VM exists
     *
     * @param vmName       Name of the Velocimacro.
     * @param templateName Template on which to look for the Macro.
     * @return True if VM by that name exists, false if not
     */
    public boolean isVelocimacro(String vmName, String templateName) {
        return vmFactory.isVelocimacro(vmName, templateName);
    }

    /**
     * tells the vmFactory to dump the specified namespace.  This is to support
     * clearing the VM list when in inline-VM-local-scope mode
     *
     * @param namespace Namespace to dump.
     * @return True if namespace was dumped successfully.
     */
    public boolean dumpVMNamespace(String namespace) {
        return vmFactory.dumpVMNamespace(namespace);
    }

    /* --------------------------------------------------------------------
     * R U N T I M E  A C C E S S O R  M E T H O D S
     * --------------------------------------------------------------------
     * These are the getXXX() methods that are a simple wrapper
     * around the configuration object. This is an attempt
     * to make a the Velocity Runtime the single access point
     * for all things Velocity, and allow the Runtime to
     * adhere as closely as possible the the Mediator pattern
     * which is the ultimate goal.
     * --------------------------------------------------------------------
     */

    /**
     * String property accessor method to hide the configuration implementation
     *
     * @param key property key
     * @return value of key or null
     */
    public String getString(String key) {
        return StringUtils.nullTrim(configuration.getString(key));
    }

    /**
     * Int property accessor method to hide the configuration implementation.
     *
     * @param key Property key
     * @return value
     */
    public int getInt(String key) {
        return configuration.getInt(key);
    }

    /**
     * Int property accessor method to hide the configuration implementation.
     *
     * @param key          property key
     * @param defaultValue The default value.
     * @return value
     */
    public int getInt(String key, int defaultValue) {
        return configuration.getInt(key, defaultValue);
    }

    /**
     * Boolean property accessor method to hide the configuration implementation.
     *
     * @param key property key
     * @param def The default value if property not found.
     * @return value of key or default value
     */
    public boolean getBoolean(String key, boolean def) {
        return configuration.getBoolean(key, def);
    }

    /**
     * Return the velocity runtime configuration object.
     *
     * @return Configuration object which houses the Velocity runtime
     *         properties.
     */
    public ExtendedProperties getConfiguration() {
        return configuration;
    }

    /**
     * Return the Introspector for this instance
     *
     * @return The Introspector for this instance
     */
    public Introspector getIntrospector() {
        return introspector;
    }

    /**
     * Returns the event handlers for the application.
     *
     * @return The event handlers for the application.
     */
    public EventCartridge getApplicationEventCartridge() {
        return eventCartridge;
    }

    /**
     * Gets the application attribute for the given key
     *
     * @param key
     * @return The application attribute for the given key.
     */
    public Object getApplicationAttribute(Object key) {
        return applicationAttributes.get(key);
    }

    /**
     * Sets the application attribute for the given key
     *
     * @param key
     * @param o   The new application attribute.
     * @return The old value of this attribute or null if it hasn't been set before.
     */
    public Object setApplicationAttribute(Object key, Object o) {
        return applicationAttributes.put(key, o);
    }

    /**
     * Returns the Uberspect object for this Instance.
     *
     * @return The Uberspect object for this Instance.
     */
    public Uberspect getUberspect() {
        return uberSpect;
    }

}
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