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    1   /*
    2    $Id: BuilderSupport.java,v 1.7 2004/07/31 03:37:31 jstrachan 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.util;
    47
    48
    49  import groovy.lang.Closure;
    50  import groovy.lang.GroovyObjectSupport;
    51
    52  import java.util.List;
    53  import java.util.Map;
    54
    55  import org.codehaus.groovy.runtime.InvokerHelper;
    56
    57  /***
    58   * An abstract base class for creating arbitrary nested trees of objects
    59   * or events
    60   *
    61   * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
    62   * @version $Revision: 1.7 $
    63   */
    64  public abstract class BuilderSupport extends GroovyObjectSupport {
    65
    66      private Object current;
    67      private Closure nameMappingClosure;
    68      private BuilderSupport proxyBuilder;
    69
    70      public BuilderSupport() {
    71          this.proxyBuilder = this;
    72      }
    73
    74      public BuilderSupport(BuilderSupport proxyBuilder) {
    75          this(null, proxyBuilder);
    76      }
    77
    78      public BuilderSupport(Closure nameMappingClosure, BuilderSupport proxyBuilder) {
    79          this.nameMappingClosure = nameMappingClosure;
    80          this.proxyBuilder = proxyBuilder;
    81      }
    82
    83      public Object invokeMethod(String methodName, Object args) {
    84          Object name = getName(methodName);
    85          return doInvokeMethod(methodName, name, args);
    86      }
    87
    88      protected Object doInvokeMethod(String methodName, Object name, Object args) {
    89          Object node = null;
    90          Closure closure = null;
    91          List list = InvokerHelper.asList(args);
    92
    93          //System.out.println("Called invokeMethod with name: " + name + " arguments: " + list);
    94
    95          switch (list.size()) {
    96          		case 0:
    97          		    break;
    98          	    	case 1:
    99          	    	{
    100         	    	    	Object object = list.get(0);
    101         	    	    	if (object instanceof Map) {
    102         	    	    	    node = proxyBuilder.createNode(name, (Map) object);
    103         	    	    	} else if (object instanceof Closure) {
    104         	    	    	    closure = (Closure) object;
    105         	    	    	    node = proxyBuilder.createNode(name);
    106         	    	    	} else {
    107         	    	    	    node = proxyBuilder.createNode(name, object);
    108         	    	    	}
    109         	    	}
    110         	    	break;
    111         	    	case 2:
    112         	    	{
    113         	    	    Object object1 = list.get(0);
    114     	    	        Object object2 = list.get(1);
    115         	    	    if (object1 instanceof Map) {
    116         	    	        if (object2 instanceof Closure) {
    117         	    	            closure = (Closure) object2;
    118         	    	            node = proxyBuilder.createNode(name, (Map) object1);
    119         	    	        } else {
    120         	    	            node = proxyBuilder.createNode(name, (Map) object1, object2);
    121         	    	        }
    122         	    	    } else {
    123         	    	        if (object2 instanceof Closure) {
    124         	    	            closure = (Closure) object2;
    125         	    	            node = proxyBuilder.createNode(name, object1);
    126         	    	        }
    127         	    	    }
    128         	    	}
    129         	    	break;
    130         	    	case 3:
    131         	    	{
    132         	    	    Object attributes = list.get(0);
    133         	    	    Object value = list.get(1);
    134         	    	    closure = (Closure) list.get(2);
    135         	    	    node = proxyBuilder.createNode(name, (Map) attributes, value);
    136         	    	}
    137         	    	break;
    138         }
    139
    140         	if (node == null) {
    141 	    	    node = proxyBuilder.createNode(name);
    142         	}
    143
    144         if (current != null) {
    145             proxyBuilder.setParent(current, node);
    146         }
    147
    148         if (closure != null) {
    149             // push new node on stack
    150             Object oldCurrent = current;
    151             current = node;
    152
    153             // lets register the builder as the delegate
    154             setClosureDelegate(closure, node);
    155             closure.call();
    156
    157             current = oldCurrent;
    158         }
    159
    160         proxyBuilder.nodeCompleted(current, node);
    161         return node;
    162     }
    163
    164     /***
    165      * A strategy method to allow derived builders to use
    166      * builder-trees and switch in different kinds of builders.
    167      * This method should call the setDelegate() method on the closure
    168      * which by default passes in this but if node is-a builder
    169      * we could pass that in instead (or do something wacky too)
    170      *
    171      * @param closure the closure on which to call setDelegate()
    172      * @param node the node value that we've just created, which could be
    173      * a builder
    174      */
    175     protected void setClosureDelegate(Closure closure, Object node) {
    176         closure.setDelegate(this);
    177     }
    178
    179     protected abstract void setParent(Object parent, Object child);
    180     protected abstract Object createNode(Object name);
    181     protected abstract Object createNode(Object name, Object value);
    182     protected abstract Object createNode(Object name, Map attributes);
    183     protected abstract Object createNode(Object name, Map attributes, Object value);
    184
    185     /***
    186      * A hook to allow names to be converted into some other object
    187      * such as a QName in XML or ObjectName in JMX
    188      * @param methodName
    189      * @return
    190      */
    191     protected Object getName(String methodName) {
    192         if (nameMappingClosure != null) {
    193             return nameMappingClosure.call(methodName);
    194         }
    195         return methodName;
    196     }
    197
    198
    199     /***
    200      * A hook to allow nodes to be processed once they have had all of their
    201      * children applied
    202      */
    203     protected void nodeCompleted(Object parent, Object node) {
    204     }
    205
    206     protected Object getCurrent() {
    207         return current;
    208     }
    209
    210     protected void setCurrent(Object current) {
    211         this.current = current;
    212     }
    213 }