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    1   /*
    2    $Id: MetaClassRegistry.java,v 1.27 2006/05/30 18:14:45 blackdrag Exp $
    3
    4    Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
    5
    6    Redistribution and use of this software and associated documentation
    7    ("Software"), with or without modification, are permitted provided
    8    that the following conditions are met:
    9
    10   1. Redistributions of source code must retain copyright
    11      statements and notices.  Redistributions must also contain a
    12      copy of this document.
    13
    14   2. Redistributions in binary form must reproduce the
    15      above copyright notice, this list of conditions and the
    16      following disclaimer in the documentation and/or other
    17      materials provided with the distribution.
    18
    19   3. The name "groovy" must not be used to endorse or promote
    20      products derived from this Software without prior written
    21      permission of The Codehaus.  For written permission,
    22      please contact info@codehaus.org.
    23
    24   4. Products derived from this Software may not be called "groovy"
    25      nor may "groovy" appear in their names without prior written
    26      permission of The Codehaus. "groovy" is a registered
    27      trademark of The Codehaus.
    28
    29   5. Due credit should be given to The Codehaus -
    30      http://groovy.codehaus.org/
    31
    32   THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
    33   ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
    34   NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
    35   FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
    36   THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
    37   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    38   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    39   SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    40   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    41   STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    42   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
    43   OF THE POSSIBILITY OF SUCH DAMAGE.
    44
    45   */
    46  package groovy.lang;
    47
    48  import java.beans.IntrospectionException;
    49  import java.lang.reflect.Constructor;
    50  import java.lang.reflect.Method;
    51  import java.security.AccessController;
    52  import java.security.PrivilegedAction;
    53  import java.util.ArrayList;
    54  import java.util.Collections;
    55  import java.util.Iterator;
    56  import java.util.List;
    57  import java.util.Map;
    58  import java.util.WeakHashMap;
    59
    60  import org.codehaus.groovy.runtime.DefaultGroovyMethods;
    61  import org.codehaus.groovy.runtime.DefaultGroovyStaticMethods;
    62  import org.codehaus.groovy.runtime.MethodHelper;
    63  import org.codehaus.groovy.runtime.ReflectorLoader;
    64
    65  /***
    66   * A registery of MetaClass instances which caches introspection &
    67   * reflection information and allows methods to be dynamically added to
    68   * existing classes at runtime
    69   *
    70   * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
    71   * @version $Revision: 1.27 $
    72   */
    73  /***
    74   * @author John Wilson
    75   *
    76   */
    77  public class MetaClassRegistry {
    78      private Map metaClasses = Collections.synchronizedMap(new WeakHashMap());
    79      private boolean useAccessible;
    80      private Map loaderMap = Collections.synchronizedMap(new WeakHashMap());
    81
    82      public static final int LOAD_DEFAULT = 0;
    83      public static final int DONT_LOAD_DEFAULT = 1;
    84      private static MetaClassRegistry instanceInclude;
    85      private static MetaClassRegistry instanceExclude;
    86
    87
    88      public MetaClassRegistry() {
    89          this(LOAD_DEFAULT, true);
    90      }
    91
    92      public MetaClassRegistry(int loadDefault) {
    93          this(loadDefault, true);
    94      }
    95
    96      /***
    97       * @param useAccessible defines whether or not the {@link java.lang.reflect.AccessibleObject.setAccessible();}
    98       *                      method will be called to enable access to all methods when using reflection
    99       */
    100     public MetaClassRegistry(boolean useAccessible) {
    101         this(LOAD_DEFAULT, useAccessible);
    102     }
    103
    104     public MetaClassRegistry(final int loadDefault, final boolean useAccessible) {
    105         this.useAccessible = useAccessible;
    106
    107         if (loadDefault == LOAD_DEFAULT) {
    108             // lets register the default methods
    109             lookup(DefaultGroovyMethods.class);
    110             registerMethods(DefaultGroovyMethods.class, true);
    111             lookup(DefaultGroovyStaticMethods.class);
    112             registerMethods(DefaultGroovyStaticMethods.class, false);
    113             checkInitialised();
    114         }
    115     }
    116
    117     private void registerMethods(final Class theClass, final boolean instanceMethods) {
    118         Method[] methods = theClass.getMethods();
    119         for (int i = 0; i < methods.length; i++) {
    120             Method method = methods[i];
    121             if (MethodHelper.isStatic(method)) {
    122                 Class[] paramTypes = method.getParameterTypes();
    123                 if (paramTypes.length > 0) {
    124                     Class owner = paramTypes[0];
    125                     if (instanceMethods) {
    126                         lookup(owner).addNewInstanceMethod(method);
    127                     } else {
    128                         lookup(owner).addNewStaticMethod(method);
    129                     }
    130                 }
    131             }
    132         }
    133     }
    134
    135     public MetaClass getMetaClass(Class theClass) {
    136         synchronized (theClass) {
    137             MetaClass answer = (MetaClass) metaClasses.get(theClass);
    138             if (answer == null) {
    139                 answer = getMetaClassFor(theClass);
    140                 answer.checkInitialised();
    141                 metaClasses.put(theClass, answer);
    142             }
    143             return answer;
    144         }
    145     }
    146
    147     public void removeMetaClass(Class theClass) {
    148         metaClasses.remove(theClass);
    149     }
    150
    151
    152     /***
    153      * Registers a new MetaClass in the registry to customize the type
    154      *
    155      * @param theClass
    156      * @param theMetaClass
    157      */
    158     public void setMetaClass(Class theClass, MetaClass theMetaClass) {
    159         metaClasses.put(theClass, theMetaClass);
    160     }
    161
    162     public boolean useAccessible() {
    163         return useAccessible;
    164     }
    165
    166     /***
    167      * A helper class to load meta class bytecode into the class loader
    168      */
    169     public Class createReflectorClass(final ClassLoader parent, final String name, final byte[] bytecode) throws ClassNotFoundException {
    170         return (Class) AccessController.doPrivileged(new PrivilegedAction() {
    171             public Object run() {
    172                 return getReflectorLoader(parent).defineClass(name, bytecode, getClass().getProtectionDomain());
    173             }
    174         });
    175     }
    176
    177     private ReflectorLoader getReflectorLoader(final ClassLoader loader) {
    178         synchronized (loaderMap) {
    179             ReflectorLoader reflectorLoader = (ReflectorLoader) loaderMap.get(loader);
    180             if (reflectorLoader == null) {
    181                 reflectorLoader = (ReflectorLoader) AccessController.doPrivileged(new PrivilegedAction() {
    182                     public Object run() {
    183                         return new ReflectorLoader(loader);
    184                     }
    185                 });
    186                 loaderMap.put(loader, reflectorLoader);
    187             }
    188             return reflectorLoader;
    189         }
    190     }
    191
    192     /***
    193      * Ensures that all the registered MetaClass instances are initalized
    194      */
    195     void checkInitialised() {
    196         // lets copy all the classes in the repository right now
    197         // to avoid concurrent modification exception
    198         List list = new ArrayList(metaClasses.values());
    199         for (Iterator iter = list.iterator(); iter.hasNext();) {
    200             MetaClass metaClass = (MetaClass) iter.next();
    201             metaClass.checkInitialised();
    202         }
    203     }
    204
    205     /***
    206      * Used by MetaClass when registering new methods which avoids initializing the MetaClass instances on lookup
    207      */
    208     MetaClass lookup(Class theClass) {
    209         MetaClass answer = (MetaClass) metaClasses.get(theClass);
    210         if (answer == null) {
    211             answer = getMetaClassFor(theClass);
    212             metaClasses.put(theClass, answer);
    213         }
    214         return answer;
    215     }
    216
    217     /***
    218      * Find a MetaClass for the class
    219      * If there is a custom MetaClass then return an instance of that. Otherwise return an instance of the standard MetaClass
    220      *
    221      * @param theClass
    222      * @return An instace of the MetaClass which will handle this class
    223      */
    224     private MetaClass getMetaClassFor(final Class theClass) {
    225         try {
    226         final Class customMetaClass = Class.forName("groovy.runtime.metaclass." + theClass.getName() + "MetaClass");
    227         final Constructor customMetaClassConstructor = customMetaClass.getConstructor(new Class[]{MetaClassRegistry.class, Class.class});
    228
    229             return (MetaClass)customMetaClassConstructor.newInstance(new Object[]{this, theClass});
    230         } catch (final ClassNotFoundException e) {
    231             try {
    232                 return new MetaClassImpl(this, theClass);
    233             } catch (final IntrospectionException e1) {
    234                 throw new GroovyRuntimeException("Could not introspect class: " + theClass.getName() + ". Reason: " + e1, e1);
    235             }
    236         } catch (final Exception e) {
    237             throw new GroovyRuntimeException("Could not instantiate custom Metaclass for class: " + theClass.getName() + ". Reason: " + e, e);
    238         }
    239     }
    240
    241     public MetaMethod getDefinedMethod(Class theClass, String methodName, Class[] args, boolean isStatic) {
    242         MetaClass metaclass = this.getMetaClass(theClass);
    243         if (metaclass == null) {
    244             return null;
    245         }
    246         else {
    247             if (isStatic) {
    248                 return metaclass.retrieveStaticMethod(methodName, args);
    249             }
    250             else {
    251                 return metaclass.retrieveMethod(methodName, args);
    252             }
    253         }
    254     }
    255
    256     public Constructor getDefinedConstructor(Class theClass, Class[] args) {
    257         MetaClass metaclass = this.getMetaClass(theClass);
    258         if (metaclass == null) {
    259             return null;
    260         }
    261         else {
    262             return metaclass.retrieveConstructor(args);
    263         }
    264     }
    265
    266     /***
    267      * Singleton of MetaClassRegistry. Shall we use threadlocal to store the instance?
    268      *
    269      * @param includeExtension
    270      * @return
    271      */
    272     public static MetaClassRegistry getIntance(int includeExtension) {
    273         if (includeExtension != DONT_LOAD_DEFAULT) {
    274             if (instanceInclude == null) {
    275                 instanceInclude = new MetaClassRegistry();
    276             }
    277             return instanceInclude;
    278         }
    279         else {
    280             if (instanceExclude == null) {
    281                 instanceExclude = new MetaClassRegistry(DONT_LOAD_DEFAULT);
    282             }
    283             return instanceExclude;
    284         }
    285     }
    286 }