Merged branch

https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_ProcessingFeedback
into Trunk.

Changes on branch:
........
  r615153 | jeremias | 2008-01-25 10:07:21 +0100 (Fr, 25 Jan 2008) | 1 line
  
  Created temporary branch for processing feedback.
........
  r615155 | jeremias | 2008-01-25 10:11:59 +0100 (Fr, 25 Jan 2008) | 1 line
  
  Initial commit of what I've built already for those who prefer code to minimalistic design docs.
........
  r615278 | jeremias | 2008-01-25 18:25:00 +0100 (Fr, 25 Jan 2008) | 1 line
  
  EventProducer interfaces now operational.
........
  r615773 | jeremias | 2008-01-28 10:06:16 +0100 (Mo, 28 Jan 2008) | 1 line
  
  No casting in client code when creating EventProducer instances.
........
  r616242 | vhennebert | 2008-01-29 11:34:45 +0100 (Di, 29 Jan 2008) | 3 lines
  
  Trick to avoid hard-coding the class name of EventProducer in the source file.
  Feel free to revert if it's not ok.
........
  r616900 | jeremias | 2008-01-30 21:59:31 +0100 (Mi, 30 Jan 2008) | 1 line
  
  Generate event model XMLs in to the build directory: build/gensrc and build/test-gensrc (the latter is new and needs to be setup as source folder in your IDE!)
........
  r616907 | jeremias | 2008-01-30 22:12:59 +0100 (Mi, 30 Jan 2008) | 1 line
  
  Added an XMLResourceBundle that uses an XML file instead of a properties file to load the translations. The XML format is the same as for Cocoon's XMLResourceBundle.
........
  r617097 | vhennebert | 2008-01-31 11:53:21 +0100 (Do, 31 Jan 2008) | 2 lines
  
  Minor typo + slight improvement of Javadoc
........
  r617176 | jeremias | 2008-01-31 19:14:19 +0100 (Do, 31 Jan 2008) | 5 lines
  
  Renamed FopEvent to Event as suggested by Simon.
  EventProducerCollectorTask.java now reads the EventSeverity from a doclet tag.
  Added generation of EventProducer translations (including simple merging, no validation, yet)
  EventFormatter introduced (only basic functionality, yet).
  Added a simple EventListener implementation that uses EventFormatter to convert the events to human-readable, localized messages that are sent to the log via Commons Logging.
........
  r617362 | jeremias | 2008-02-01 08:18:07 +0100 (Fr, 01 Feb 2008) | 1 line
  
  Some remaining rename operations based on an earlier discussion.
........
  r617413 | jeremias | 2008-02-01 10:46:26 +0100 (Fr, 01 Feb 2008) | 2 lines
  
  Extracted formatting functionality into utility class AdvancedMessageFormat.java.
  AdvancedMessageFormat.java now supports conditional sub-groups (delimited by []).
........
  r618682 | jeremias | 2008-02-05 17:07:08 +0100 (Di, 05 Feb 2008) | 1 line
  
  Add support for special object formatters (where toString() isn't good enough). ATM, it's hard-coded but could later be hooked into dynamic discovery if we have multiple such formatters. The SAX Locator is the only example for now.
........
  r618686 | jeremias | 2008-02-05 17:12:56 +0100 (Di, 05 Feb 2008) | 3 lines
  
  Hooked most of FONode into the new event mechanism. The FOUserAgent provides a DefaultEventBroadcaster instance.
  If a producer method declares throwing an exception, the event is automatically marked FATAL and the dynamic proxy throws an exception right after notifying the listeners.
  The exceptions are created through the EventExceptionManager. It currently contains only one exception factory for ValidationException. If we need more such factories it's better to register them dynamically. Right now, they're hard-coded.
........
  r619313 | jeremias | 2008-02-07 10:14:15 +0100 (Do, 07 Feb 2008) | 1 line
  
  Make sure no events are now just silently swallowed because after upgrading a user doesn't know about the event system.
........
  r619314 | jeremias | 2008-02-07 10:14:46 +0100 (Do, 07 Feb 2008) | 1 line
  
  Log what translation file is being written.
........
  r619320 | jeremias | 2008-02-07 10:31:00 +0100 (Do, 07 Feb 2008) | 2 lines
  
  FObj hooked into the event system.
  Code reduction using a protected method on FONode to acquire a FOValidationEventProducer.
........
  r619359 | jeremias | 2008-02-07 11:59:19 +0100 (Do, 07 Feb 2008) | 2 lines
  
  Fop's QName now extends XGCommons' QName to initiate a transition.
  Hooked PropertyList into the event mechanism.
........
  r631252 | jeremias | 2008-02-26 16:24:33 +0100 (Di, 26 Feb 2008) | 1 line
  
  Removed superfluous warning.
........
  r631268 | jeremias | 2008-02-26 17:08:11 +0100 (Di, 26 Feb 2008) | 1 line
  
  Deprecated two methods which are a problem for localization. Also helps finding additional spots to switch over to the event mechanism.
........
  r633852 | jeremias | 2008-03-05 15:20:24 +0100 (Mi, 05 Mrz 2008) | 1 line
  
  Add severity to formatting parameters.
........
  r633855 | jeremias | 2008-03-05 15:21:57 +0100 (Mi, 05 Mrz 2008) | 4 lines
  
  Added support for additional field styles:
  {<fieldname>,if,<true-text>,<false-text>}
  {<fieldname>,equals,<test-string>,<true-text>,<false-text>}
........
  r633856 | jeremias | 2008-03-05 15:24:04 +0100 (Mi, 05 Mrz 2008) | 2 lines
  
  Javadocs and TODOs.
  EventListeners can change the event severity.
........
  r633857 | jeremias | 2008-03-05 15:27:08 +0100 (Mi, 05 Mrz 2008) | 4 lines
  
  Javadocs.
  Moved out event listener registration into a CompositeEventListener.
  Event broadcaster uses the events effective severity, not the initial value (for the case where listeners override the initial value).
  Set up a special EventBroadCaster in the FOUserAgent that filters events through a class (FOValidationEventListenerProxy) that adjusts the event severity for relaxed validation.
........
  r633858 | jeremias | 2008-03-05 15:32:07 +0100 (Mi, 05 Mrz 2008) | 2 lines
  
  Instead of always decentrally checking whether strict validation is enabled or not, this is now done in a special event listener. The event producer method caller simply indicates whether it can recover from the error condition and continue.
  Started switching to event production in table FOs.
........
  r634027 | jeremias | 2008-03-05 21:58:35 +0100 (Mi, 05 Mrz 2008) | 7 lines
  
  Moved AdvancedMessageFormat into its own package.
  AdvancedMessageFormat got the following added functionality:
  - Alternative conditional regions [ bla {field}] -> [ bla {field1}| even more bla {field2}]
  - Functions: functions get access to the parameters and they can produce an object that is then formatted ({#gatherContextInfo})
  - "if" and "equals" format moved to top-level classes and added by dynamic registration.
  EventFormatter now supports includes in the form {{includeName}} so you can include other entries from the resource bundle for better reuse.
  Some more events in table code.
........
  r634031 | jeremias | 2008-03-05 22:05:22 +0100 (Mi, 05 Mrz 2008) | 1 line
  
  SVN Props
........
  r634208 | jeremias | 2008-03-06 11:26:52 +0100 (Do, 06 Mrz 2008) | 2 lines
  
  Improved context gathering.
  Moved GatherContextInfoFunction to an inner class of FONode to reduce visibilities.
........
  r634209 | jeremias | 2008-03-06 11:28:14 +0100 (Do, 06 Mrz 2008) | 1 line
  
  Made FOPException localizable.
........
  r634280 | jeremias | 2008-03-06 15:38:30 +0100 (Do, 06 Mrz 2008) | 2 lines
  
  ExceptionFactory is now dynamically registered.
  More table warnings and errors switch to events.
........
  r634326 | jeremias | 2008-03-06 17:08:16 +0100 (Do, 06 Mrz 2008) | 1 line
  
  Remaining table FOs switched to events.
........
  r634328 | jeremias | 2008-03-06 17:09:21 +0100 (Do, 06 Mrz 2008) | 1 line
  
  Deprecated FOP's QName. Mixing with Commons' variant only produces problems.
........
  r634381 | jeremias | 2008-03-06 20:12:57 +0100 (Do, 06 Mrz 2008) | 2 lines
  
  Made the "invalidChild" event fully localizable by adding a "lookup" field for the optional rule to be displayed.
  And a few switches to the event system.
........
  r634692 | jeremias | 2008-03-07 15:31:43 +0100 (Fr, 07 Mrz 2008) | 1 line
  
  More FO tree stuff switched to events.
........
  r634712 | jeremias | 2008-03-07 16:19:21 +0100 (Fr, 07 Mrz 2008) | 1 line
  
  Avoid an NPE that says nothing (ex. could happen if the message template is wrong).
........
  r634738 | jeremias | 2008-03-07 17:38:21 +0100 (Fr, 07 Mrz 2008) | 2 lines
  
  Non-FO children were not properly run through validation by FOTreeBuilder.
  Unified the way that non-FO elements are validated. Some FOs were already fixed. I now fixed the rest, so foreign elements can occur everywhere.
........
  r637833 | jeremias | 2008-03-17 12:01:41 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Exception while cloning for RetrieveMarker to be handled by user as suggested by Andreas.
........
  r637835 | jeremias | 2008-03-17 12:03:31 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Throw a RuntimeException of no other Exception class is specified for an event as a fallback if someone just sets the event severity to FATAL.
........
  r637838 | jeremias | 2008-03-17 12:06:10 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Throw a meaningful exception when the property name is wrong. Otherwise, there will be an ArrayIndexOutOfBoundsException.
........
  r637859 | jeremias | 2008-03-17 13:35:26 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Throw a meaningful exception when the property name is wrong. Otherwise, there will be an ArrayIndexOutOfBoundsException.
........
  r637938 | jeremias | 2008-03-17 16:19:51 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Switched pagination package to events.
........
  r637947 | jeremias | 2008-03-17 16:45:16 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Removed unlocalizable validation helper methods.
........
  r637952 | jeremias | 2008-03-17 16:59:02 +0100 (Mo, 17 Mrz 2008) | 1 line
  
  Events on FOTreeBuilder.
........
  r638299 | jeremias | 2008-03-18 11:09:30 +0100 (Di, 18 Mrz 2008) | 2 lines
  
  Added support for java.util.text's ChoiceFormat to AdvancedMessageFormat.
  Reuse the regexes as constants.
........
  r638302 | jeremias | 2008-03-18 11:17:06 +0100 (Di, 18 Mrz 2008) | 1 line
  
  Events for inline-level layout managers.
........
  r638774 | jeremias | 2008-03-19 11:17:36 +0100 (Mi, 19 Mrz 2008) | 1 line
  
  Added DEBUG level.
........
  r638777 | jeremias | 2008-03-19 11:23:40 +0100 (Mi, 19 Mrz 2008) | 3 lines
  
  Generalized FOValidationEventListenerProxy into FOPEventListenerProxy, the main proxy for FOP's own event manipulation proxy. Done because of support for overflow="hidden" vs. overflow="error-if-overflow".
  Switched block-level layout managers to events.
  Some cleanup along the way.
........
  r639222 | jeremias | 2008-03-20 10:27:34 +0100 (Do, 20 Mrz 2008) | 2 lines
  
  Some initial work for event forwarding from Batik.
  Missing errors/exceptions converted to events in PageSequenceMaster.
........
  r639270 | jeremias | 2008-03-20 13:50:35 +0100 (Do, 20 Mrz 2008) | 1 line
  
  Removed DEBUG event severity again. Promoted constrained geometry adjustment event to INFO level as per discussion.
........
  r640395 | jeremias | 2008-03-24 13:39:13 +0100 (Mo, 24 Mrz 2008) | 3 lines
  
  Moved the creation of the fallback LoggingEventListener to FOUserAgent so event before the startDocument() SAX event arrive in the log.
  Dynamic discovery of event models. Renderers and extensions can register renderer-specific event models.
  Switched the most important parts of the renderers to events (maybe not everything is converted).
........
  r640397 | jeremias | 2008-03-24 13:43:04 +0100 (Mo, 24 Mrz 2008) | 1 line
  
  Remaining fixcrlfs. Xalan likes to mix CRLF and LF on Windows.
........
  r640398 | jeremias | 2008-03-24 13:43:54 +0100 (Mo, 24 Mrz 2008) | 1 line
  
  Ignore namespace declarations for property handling.
........
  r640463 | jeremias | 2008-03-24 17:59:52 +0100 (Mo, 24 Mrz 2008) | 2 lines
  
  Event in area package.
  Exposed getUserAgent() in Renderer interface (was already public in AbstractRenderer).
........
  r642972 | jeremias | 2008-03-31 14:18:39 +0200 (Mo, 31 Mrz 2008) | 1 line
  
  Code restructured a bit.
........
  r642975 | jeremias | 2008-03-31 14:24:07 +0200 (Mo, 31 Mrz 2008) | 2 lines
  
  Plugged fonts package into the event subsystem. Note: I did not follow the same pattern as for the rest as the font package is to be considered FOP-external, so I just added a manual adapter for the FontEventListener. This demonstrates how an external library can be integrated with the event system.
  Missing warning for unknown formatting objects added. Warning is not issued by the ElementMappingRegistry anymore but by FOTreeBuilder which has access to more context information.
........
  r642997 | jeremias | 2008-03-31 16:10:08 +0200 (Mo, 31 Mrz 2008) | 1 line
  
  Added an example to demonstrate how to write your own event listener and how to deal with the exceptions thrown in the process.
........
  r642998 | jeremias | 2008-03-31 16:13:40 +0200 (Mo, 31 Mrz 2008) | 1 line
  
  Removed unused method. Event formatting should not be part of the Event class. Use EventFormatter.format(Event) instead.
........
  r643066 | jeremias | 2008-03-31 19:18:54 +0200 (Mo, 31 Mrz 2008) | 1 line
  
  First part of the event subsystem documentation (DRAFT).
........
  r643784 | jeremias | 2008-04-02 10:05:33 +0200 (Mi, 02 Apr 2008) | 1 line
  
  More documentation.
........
  r643785 | jeremias | 2008-04-02 10:06:38 +0200 (Mi, 02 Apr 2008) | 1 line
  
  Some nits.
........
  r643787 | jeremias | 2008-04-02 10:24:41 +0200 (Mi, 02 Apr 2008) | 1 line
  
  Completed javadocs
........
  r643824 | jeremias | 2008-04-02 12:00:30 +0200 (Mi, 02 Apr 2008) | 1 line
  
  Javadocs.
........
  r645847 | vhennebert | 2008-04-08 12:54:16 +0200 (Di, 08 Apr 2008) | 2 lines
  
  Minor typo fixes
........
  r645848 | vhennebert | 2008-04-08 12:58:30 +0200 (Di, 08 Apr 2008) | 2 lines
  
  Another small typo fix
........
  r647678 | jeremias | 2008-04-14 09:20:26 +0200 (Mo, 14 Apr 2008) | 1 line
  
  Renamed *EventProducer.Factory.create() to *EventProducer.Provider.get() to better reflect what the method does (instances may be cached and reused).
........


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@647742 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 487 insertions, 0 deletions

diff --git a/src/java/org/apache/fop/util/text/AdvancedMessageFormat.java b/src/java/org/apache/fop/util/text/AdvancedMessageFormat.java
new file mode 100644
index 000000000..a2169156a
--- /dev/null
+++ b/src/java/org/apache/fop/util/text/AdvancedMessageFormat.java
@@ -0,0 +1,487 @@
+/*
+ * 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.
+ */
+
+/* $Id$ */
+
+package org.apache.fop.util.text;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import org.apache.xmlgraphics.util.Service;
+
+
+/**
+ * Formats messages based on a template and with a set of named parameters. This is similar to
+ * {@link java.util.MessageFormat} but uses named parameters and supports conditional sub-groups.
+ * <p>
+ * Example:
+ * </p>
+ * <p><code>Missing field "{fieldName}"[ at location: {location}]!</code></p>
+ * <ul>
+ *   <li>Curly brackets ("{}") are used for fields.</li>
+ *   <li>Square brackets ("[]") are used to delimit conditional sub-groups. A sub-group is
+ *     conditional when all fields inside the sub-group have a null value. In the case, everything
+ *     between the brackets is skipped.</li>
+ * </ul>
+ */
+public class AdvancedMessageFormat {
+
+    /** Regex that matches "," but not "\," (escaped comma) */
+    static final Pattern COMMA_SEPARATOR_REGEX = Pattern.compile("(?<!\\\\),");
+    
+    private static final Map PART_FACTORIES = new java.util.HashMap();
+    private static final List OBJECT_FORMATTERS = new java.util.ArrayList();
+    private static final Map FUNCTIONS = new java.util.HashMap();
+    
+    private CompositePart rootPart;
+    
+    static {
+        Iterator iter;
+        iter = Service.providers(PartFactory.class, true);
+        while (iter.hasNext()) {
+            PartFactory factory = (PartFactory)iter.next();
+            PART_FACTORIES.put(factory.getFormat(), factory);
+        }
+        iter = Service.providers(ObjectFormatter.class, true);
+        while (iter.hasNext()) {
+            OBJECT_FORMATTERS.add((ObjectFormatter)iter.next());
+        }
+        iter = Service.providers(Function.class, true);
+        while (iter.hasNext()) {
+            Function function = (Function)iter.next();
+            FUNCTIONS.put(function.getName(), function);
+        }
+    }
+    
+    /**
+     * Construct a new message format.
+     * @param pattern the message format pattern.
+     */
+    public AdvancedMessageFormat(CharSequence pattern) {
+        parsePattern(pattern);
+    }
+    
+    private void parsePattern(CharSequence pattern) {
+        rootPart = new CompositePart(false);
+        StringBuffer sb = new StringBuffer();
+        parseInnerPattern(pattern, rootPart, sb, 0);
+    }
+    
+    private int parseInnerPattern(CharSequence pattern, CompositePart parent,
+            StringBuffer sb, int start) {
+        assert sb.length() == 0;
+        int i = start;
+        int len = pattern.length();
+        loop:
+        while (i < len) {
+            char ch = pattern.charAt(i);
+            switch (ch) {
+            case '{':
+                if (sb.length() > 0) {
+                    parent.addChild(new TextPart(sb.toString()));
+                    sb.setLength(0);
+                }
+                i++;
+                int nesting = 1;
+                while (i < len) {
+                    ch = pattern.charAt(i);
+                    if (ch == '{') {
+                        nesting++;
+                    } else if (ch == '}') {
+                        nesting--;
+                        if (nesting == 0) {
+                            i++;
+                            break;
+                        }
+                    }
+                    sb.append(ch);
+                    i++;
+                }
+                parent.addChild(parseField(sb.toString()));
+                sb.setLength(0);
+                break;
+            case ']':
+                i++;
+                break loop; //Current composite is finished
+            case '[':
+                if (sb.length() > 0) {
+                    parent.addChild(new TextPart(sb.toString()));
+                    sb.setLength(0);
+                }
+                i++;
+                CompositePart composite = new CompositePart(true);
+                parent.addChild(composite);
+                i += parseInnerPattern(pattern, composite, sb, i);
+                break;
+            case '|':
+                if (sb.length() > 0) {
+                    parent.addChild(new TextPart(sb.toString()));
+                    sb.setLength(0);
+                }
+                parent.newSection();
+                i++;
+                break;
+            case '\\':
+                if (i < len - 1) {
+                    i++;
+                    ch = pattern.charAt(i);
+                }
+                //no break here! Must be right before "default" section
+            default:
+                sb.append(ch);
+                i++;
+            }
+        }
+        if (sb.length() > 0) {
+            parent.addChild(new TextPart(sb.toString()));
+            sb.setLength(0);
+        }
+        return i - start;
+    }
+    
+    private Part parseField(String field) {
+        String[] parts = COMMA_SEPARATOR_REGEX.split(field, 3);
+        String fieldName = parts[0];
+        if (parts.length == 1) {
+            if (fieldName.startsWith("#")) {
+                return new FunctionPart(fieldName.substring(1));
+            } else {
+                return new SimpleFieldPart(fieldName);
+            }
+        } else {
+            String format = parts[1];
+            PartFactory factory = (PartFactory)PART_FACTORIES.get(format);
+            if (factory == null) {
+                throw new IllegalArgumentException(
+                        "No PartFactory available under the name: " + format);
+            }
+            if (parts.length == 2) {
+                return factory.newPart(fieldName, null);
+            } else {
+                return factory.newPart(fieldName, parts[2]);
+            }
+        }
+    }
+
+    private static Function getFunction(String functionName) {
+        return (Function)FUNCTIONS.get(functionName);
+    }
+
+    /**
+     * Formats a message with the given parameters.
+     * @param params a Map of named parameters (Contents: <String, Object>)
+     * @return the formatted message
+     */
+    public String format(Map params) {
+        StringBuffer sb = new StringBuffer();
+        format(params, sb);
+        return sb.toString();
+    }
+
+    /**
+     * Formats a message with the given parameters.
+     * @param params a Map of named parameters (Contents: <String, Object>)
+     * @param target the target StringBuffer to write the formatted message to
+     */
+    public void format(Map params, StringBuffer target) {
+        rootPart.write(target, params);
+    }
+    
+    /**
+     * Represents a message template part. This interface is implemented by various variants of
+     * the single curly braces pattern ({field}, {field,if,yes,no} etc.).
+     */
+    public interface Part {
+        
+        /**
+         * Writes the formatted part to a string buffer.
+         * @param sb the target string buffer
+         * @param params the parameters to work with
+         */
+        void write(StringBuffer sb, Map params);
+        
+        /**
+         * Indicates whether there is any content that is generated by this message part.
+         * @param params the parameters to work with
+         * @return true if the part has content
+         */
+        boolean isGenerated(Map params);
+    }
+    
+    /**
+     * Implementations of this interface parse a field part and return message parts.
+     */
+    public interface PartFactory {
+        
+        /**
+         * Creates a new part by parsing the values parameter to configure the part.
+         * @param fieldName the field name
+         * @param values the unparsed parameter values
+         * @return the new message part
+         */
+        Part newPart(String fieldName, String values);
+        
+        /**
+         * Returns the name of the message part format.
+         * @return the name of the message part format
+         */
+        String getFormat();
+    }
+    
+    /**
+     * Implementations of this interface format certain objects to strings.
+     */
+    public interface ObjectFormatter {
+        
+        /**
+         * Formats an object to a string and writes the result to a string buffer.
+         * @param sb the target string buffer
+         * @param obj the object to be formatted
+         */
+        void format(StringBuffer sb, Object obj);
+        
+        /**
+         * Indicates whether a given object is supported.
+         * @param obj the object
+         * @return true if the object is supported by the formatter
+         */
+        boolean supportsObject(Object obj);
+    }
+    
+    /**
+     * Implementations of this interface do some computation based on the message parameters
+     * given to it. Note: at the moment, this has to be done in a local-independent way since
+     * there is no locale information.
+     */
+    public interface Function {
+        
+        /**
+         * Executes the function.
+         * @param params the message parameters
+         * @return the function result
+         */
+        Object evaluate(Map params);
+        
+        /**
+         * Returns the name of the function.
+         * @return the name of the function
+         */
+        Object getName();
+    }
+    
+    private static class TextPart implements Part {
+        
+        private String text;
+        
+        public TextPart(String text) {
+            this.text = text;
+        }
+        
+        public void write(StringBuffer sb, Map params) {
+            sb.append(text);
+        }
+        
+        public boolean isGenerated(Map params) {
+            return true;
+        }
+
+        /** {@inheritDoc} */
+        public String toString() {
+            return this.text;
+        }
+    }
+    
+    private static class SimpleFieldPart implements Part {
+        
+        private String fieldName;
+        
+        public SimpleFieldPart(String fieldName) {
+            this.fieldName = fieldName;
+        }
+        
+        public void write(StringBuffer sb, Map params) {
+            if (!params.containsKey(fieldName)) {
+                throw new IllegalArgumentException(
+                        "Message pattern contains unsupported field name: " + fieldName);
+            }
+            Object obj = params.get(fieldName);
+            formatObject(obj, sb);
+        }
+
+        public boolean isGenerated(Map params) {
+            Object obj = params.get(fieldName);
+            return obj != null;
+        }
+        
+        /** {@inheritDoc} */
+        public String toString() {
+            return "{" + this.fieldName + "}";
+        }
+    }
+    
+    /**
+     * Formats an object to a string and writes the result to a string buffer. This method
+     * usually uses the object's <code>toString()</code> method unless there is an
+     * {@link ObjectFormatter} that supports the object. {@link ObjectFormatter}s are registered
+     * through the service provider mechanism defined by the JAR specification.
+     * @param obj the object to be formatted
+     * @param target the target string buffer
+     */
+    public static void formatObject(Object obj, StringBuffer target) {
+        if (obj instanceof String) {
+            target.append(obj);
+        } else {
+            boolean handled = false;
+            Iterator iter = OBJECT_FORMATTERS.iterator();
+            while (iter.hasNext()) {
+                ObjectFormatter formatter = (ObjectFormatter)iter.next();
+                if (formatter.supportsObject(obj)) {
+                    formatter.format(target, obj);
+                    handled = true;
+                    break;
+                }
+            }
+            if (!handled) {
+                target.append(String.valueOf(obj));
+            }
+        }
+    }
+    
+    private static class FunctionPart implements Part {
+        
+        private Function function;
+        
+        public FunctionPart(String functionName) {
+            this.function = getFunction(functionName);
+            if (this.function == null) {
+                throw new IllegalArgumentException("Unknown function: " + functionName);
+            }
+        }
+        
+        public void write(StringBuffer sb, Map params) {
+            Object obj = this.function.evaluate(params);
+            formatObject(obj, sb);
+        }
+
+        public boolean isGenerated(Map params) {
+            Object obj = this.function.evaluate(params);
+            return obj != null;
+        }
+        
+        /** {@inheritDoc} */
+        public String toString() {
+            return "{#" + this.function.getName() + "}";
+        }
+    }
+    
+    private static class CompositePart implements Part {
+        
+        protected List parts = new java.util.ArrayList();
+        private boolean conditional;
+        private boolean hasSections = false;
+        
+        public CompositePart(boolean conditional) {
+            this.conditional = conditional;
+        }
+        
+        private CompositePart(List parts) {
+            this.parts.addAll(parts);
+            this.conditional = true;
+        }
+        
+        public void addChild(Part part) {
+            if (part == null) {
+                throw new NullPointerException("part must not be null");
+            }
+            if (hasSections) {
+                CompositePart composite = (CompositePart)this.parts.get(this.parts.size() - 1);
+                composite.addChild(part);
+            } else {
+                this.parts.add(part);
+            }
+        }
+        
+        public void newSection() {
+            if (!hasSections) {
+                List p = this.parts;
+                //Dropping into a different mode...
+                this.parts = new java.util.ArrayList();
+                this.parts.add(new CompositePart(p));
+                hasSections = true;
+            }
+            this.parts.add(new CompositePart(true));
+        }
+        
+        public void write(StringBuffer sb, Map params) {
+            if (hasSections) {
+                Iterator iter = this.parts.iterator();
+                while (iter.hasNext()) {
+                    CompositePart part = (CompositePart)iter.next();
+                    if (part.isGenerated(params)) {
+                        part.write(sb, params);
+                        break;
+                    }
+                }
+            } else {
+                if (isGenerated(params)) {
+                    Iterator iter = this.parts.iterator();
+                    while (iter.hasNext()) {
+                        Part part = (Part)iter.next();
+                        part.write(sb, params);
+                    }
+                }
+            }
+        }
+
+        public boolean isGenerated(Map params) {
+            if (hasSections) {
+                Iterator iter = this.parts.iterator();
+                while (iter.hasNext()) {
+                    Part part = (Part)iter.next();
+                    if (part.isGenerated(params)) {
+                        return true;
+                    }
+                }
+                return false;
+            } else {
+                if (conditional) {
+                    Iterator iter = this.parts.iterator();
+                    while (iter.hasNext()) {
+                        Part part = (Part)iter.next();
+                        if (!part.isGenerated(params)) {
+                            return false;
+                        }
+                    }
+                }
+                return true;
+            }
+        }
+        
+        /** {@inheritDoc} */
+        public String toString() {
+            return this.parts.toString();
+        }
+    }
+    
+    
+    static String unescapeComma(String string) {
+        return string.replaceAll("\\\\,", ",");
+    }
+}