Added support for auto-generated initial value for the "id" property.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@655766 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 60 insertions, 1 deletions

diff --git a/src/java/org/apache/fop/fo/FOEventHandler.java b/src/java/org/apache/fop/fo/FOEventHandler.java
index 5a9a5bb9d..a2a67d594 100644
--- a/src/java/org/apache/fop/fo/FOEventHandler.java
+++ b/src/java/org/apache/fop/fo/FOEventHandler.java
@@ -96,6 +96,11 @@ public abstract class FOEventHandler {
     private boolean inMarker = false;
     
     /**
+     * Keeps track of automatically generated ids in the current document
+     */
+    private long lastGeneratedId = 1;
+    
+    /**
      * Main constructor
      * @param foUserAgent the apps.FOUserAgent instance for this process
      */
@@ -169,6 +174,13 @@ public abstract class FOEventHandler {
     }
     
     /**
+     * Return the next value for automatically generated ids
+     */
+    public long getNextId() {
+        return this.lastGeneratedId++;
+    }
+    
+    /**
      * This method is called to indicate the start of a new document run.
      * @throws SAXException In case of a problem
      */
diff --git a/src/java/org/apache/fop/fo/FOPropertyMapping.java b/src/java/org/apache/fop/fo/FOPropertyMapping.java
index 8fed90a35..96cbc5329 100644
--- a/src/java/org/apache/fop/fo/FOPropertyMapping.java
+++ b/src/java/org/apache/fop/fo/FOPropertyMapping.java
@@ -2503,7 +2503,7 @@ public final class FOPropertyMapping implements Constants {
         addPropertyMaker("content-type", m);
 
         // id
-        m  = new StringProperty.Maker(PR_ID);
+        m  = new StringProperty.IdMaker(PR_ID);
         m.setInherited(false);
         m.setDefault("");
         addPropertyMaker("id", m);
diff --git a/src/java/org/apache/fop/fo/properties/StringProperty.java b/src/java/org/apache/fop/fo/properties/StringProperty.java
index 194170fec..e7c477a27 100644
--- a/src/java/org/apache/fop/fo/properties/StringProperty.java
+++ b/src/java/org/apache/fop/fo/properties/StringProperty.java
@@ -21,6 +21,11 @@ package org.apache.fop.fo.properties;
 
 import org.apache.fop.fo.FObj;
 import org.apache.fop.fo.PropertyList;
+import org.apache.fop.fo.FOValidationEventProducer;
+import org.apache.fop.fo.ValidationException;
+import org.apache.fop.fo.expr.PropertyException;
+
+import java.util.Set;
 
 /**
  * Exists primarily as a container for its Maker inner class, which is
@@ -77,6 +82,48 @@ public final class StringProperty extends Property {
 
     }
 
+    /**
+     * Inner class dedicated to the "id" property, which should provide a random
+     * unique identifier as an initial value.
+     * The values for "id" are never cached, as they're typically valid for one
+     * document.
+     */
+    public static class IdMaker extends PropertyMaker {
+
+        /**
+         * @param propId    the id of the property for which the maker should be created
+         */
+        public IdMaker(int propId) {
+            super(propId);
+        }
+
+        /** {@inheritDoc} */
+        public Property make(PropertyList propertyList) throws PropertyException {
+            String newId = "FO#";
+            newId += propertyList.getFObj().getFOEventHandler().getNextId();
+            return new StringProperty(newId);
+        }
+        
+        /** {@inheritDoc} */
+        public Property make(PropertyList propertyList, 
+                             String value,
+                             FObj fo) throws PropertyException {
+            
+            Property idProp;
+            
+            //no parsing necessary; just return a new StringProperty
+            //TODO: Should we move validation here? (see FObj#checkId())
+            if ("".equals(value)) {
+                //if an empty string was specified, return the default
+                idProp = this.make(propertyList);
+            } else {
+                idProp = new StringProperty(value);
+            }
+            
+            return idProp;
+        }
+    }
+
     /** cache containing all canonical StringProperty instances */
     private static final PropertyCache cache = new PropertyCache(StringProperty.class);