protostuff.runtime.preserve_null_elements replaces protostuff.runtime…

….allow_null_array_element, which now applies to both collections and arrays

CHANGELOG.md

@@ -1,3 +1,8 @@
+protostuff-1.8.x
+- `-Dprotostuff.runtime.preserve_null_elements=true` preserves null elements in collections/arrays.
+  This property replaces `-Dprotostuff.runtime.allow_null_array_element=true`, which only applied to arrays.
+  Note that this works only on the binary formats (protostuff/protobuf/graph)
+
 protostuff-1.7.2 2020-04-18
 ===========================
 - Issue 273 - fix bug on custom maps without a K (Key) parameter type. Only the V (value) parameter type is declared.

protostuff-collectionschema/src/main/java/io/protostuff/CollectionSchema.java

@@ -23,9 +23,8 @@
 /**
  * A schema for standard jdk {@link Collection collections}. Null values are not serialized/written.
  * <p>
- * If your application relies on {@link Object#equals(Object)}, it will fail when a serialized collection contains null
- * values (The deserialized collection will not contained the null value). {@link MapSchema} on the otherhand can
- * contain both null keys and null values and still succeeding on {@link Object#equals(Object)}.
+ * If {@link #preserveNull} is false and your application relies on {@link Object#equals(Object)}, 
+ * it will fail when a serialized collection contains null values.
  * 
  * @author David Yu
  * @created Jan 26, 2011
@@ -34,6 +33,7 @@ public abstract class CollectionSchema<V> implements Schema<Collection<V>>
 {
 
     public static final String FIELD_NAME_VALUE = "v";
+    public static final String FIELD_NAME_NULL = "n";
 
     /**
      * Creates new {@code Collection} messages.
@@ -340,15 +340,18 @@ public static boolean accept(String name)
      * Factory for creating {@link Collection} messages.
      */
     public final MessageFactory messageFactory;
+
+    public final boolean preserveNull;
 
-    public CollectionSchema()
+    public CollectionSchema(boolean preserveNull)
     {
-        this(MessageFactories.ArrayList);
+        this(MessageFactories.ArrayList, preserveNull);
     }
 
-    public CollectionSchema(MessageFactory messageFactory)
+    public CollectionSchema(MessageFactory messageFactory, boolean preserveNull)
     {
         this.messageFactory = messageFactory;
+        this.preserveNull = preserveNull;
     }
 
     /**
@@ -372,13 +375,26 @@ protected abstract void transferValue(Pipe pipe, Input input, Output output,
     @Override
     public final String getFieldName(int number)
     {
-        return number == 1 ? FIELD_NAME_VALUE : null;
+        switch (number)
+        {
+            case 1: return FIELD_NAME_VALUE;
+            case 2: return FIELD_NAME_NULL;
+            default: return null;
+        }
     }
 
     @Override
     public final int getFieldNumber(String name)
     {
-        return name.length() == 1 && name.charAt(0) == 'v' ? 1 : 0;
+        if (1 != name.length())
+            return 0;
+
+        switch (name.charAt(0))
+        {
+            case 'v': return 1;
+            case 'n': return 2;
+            default: return 0;
+        }
     }
 
     @Override
@@ -414,7 +430,7 @@ public final Collection<V> newMessage()
     @Override
     public void mergeFrom(Input input, Collection<V> message) throws IOException
     {
-        for (int number = input.readFieldNumber(this);; number = input.readFieldNumber(this))
+        for (int number = input.readFieldNumber(this), i, nullCount;; number = input.readFieldNumber(this))
         {
             switch (number)
             {
@@ -423,24 +439,57 @@ public void mergeFrom(Input input, Collection<V> message) throws IOException
                 case 1:
                     addValueFrom(input, message);
                     break;
+                case 2:
+                    for (nullCount = input.readUInt32(), i = 0; i < nullCount; i++)
+                        message.add(null);
+                    break;
                 default:
-                    throw new ProtostuffException("The collection was incorrectly " +
-                            "serialized.");
+                    throw new ProtostuffException("The collection was incorrectly serialized.");
             }
         }
     }
-
-    @Override
-    public void writeTo(Output output, Collection<V> message) throws IOException
+
+    private void writeWithNullTo(Output output, Collection<V> message) throws IOException
+    {
+        int nullCount = 0;
+        for (V value : message)
+        {
+            if (value != null)
+            {
+                if (nullCount != 0)
+                {
+                    output.writeUInt32(2, nullCount, false);
+                    nullCount = 0;
+                }
+                writeValueTo(output, 1, value, true);
+            }
+            else
+            {
+                nullCount++;
+            }
+        }
+        if (nullCount != 0)
+            output.writeUInt32(2, nullCount, false);
+    }
+
+    private void writeWithoutNullTo(Output output, Collection<V> message) throws IOException
     {
         for (V value : message)
         {
-            // null values not serialized.
             if (value != null)
                 writeValueTo(output, 1, value, true);
         }
     }
 
+    @Override
+    public void writeTo(Output output, Collection<V> message) throws IOException
+    {
+        if (preserveNull)
+            writeWithNullTo(output, message);
+        else
+            writeWithoutNullTo(output, message);
+    }
+
     public final Pipe.Schema<Collection<V>> pipeSchema =
             new Pipe.Schema<Collection<V>>(CollectionSchema.this)
             {
@@ -458,9 +507,11 @@ protected void transfer(Pipe pipe, Input input, Output output) throws IOExceptio
                             case 1:
                                 transferValue(pipe, input, output, 1, true);
                                 break;
+                            case 2:
+                                output.writeUInt32(2, input.readUInt32(), false);
+                                break;
                             default:
-                                throw new ProtostuffException("The collection was incorrectly " +
-                                        "serialized.");
+                                throw new ProtostuffException("The collection was incorrectly serialized.");
                         }
                     }
                 }

protostuff-collectionschema/src/main/java/io/protostuff/MessageCollectionSchema.java

@@ -36,13 +36,14 @@ public final class MessageCollectionSchema<V> extends CollectionSchema<V>
      */
     public final Pipe.Schema<V> pipeSchema;
 
-    public MessageCollectionSchema(Schema<V> schema)
+    public MessageCollectionSchema(Schema<V> schema, boolean preserveNull)
     {
-        this(schema, null);
+        this(schema, null, preserveNull);
     }
 
-    public MessageCollectionSchema(Schema<V> schema, Pipe.Schema<V> pipeSchema)
+    public MessageCollectionSchema(Schema<V> schema, Pipe.Schema<V> pipeSchema, boolean preserveNull)
     {
+        super(preserveNull);
         this.schema = schema;
         this.pipeSchema = pipeSchema;
     }

protostuff-runtime-md/src/main/java/io/protostuff/runtime/RuntimeEnv.java

@@ -44,7 +44,7 @@ public final class RuntimeEnv
      * Disabled by default. Writes a sentinel value (uint32) in place of null values. Works only on the binary formats
      * (protostuff/graph/protobuf).
      */
-    public static final boolean ALLOW_NULL_ARRAY_ELEMENT;
+    public static final boolean PRESERVE_NULL_ELEMENTS;
 
     /**
      * Disabled by default. For pojos that are not declared final, they could still be morphed to their respective
@@ -187,8 +187,8 @@ public final class RuntimeEnv
         AUTO_LOAD_POLYMORPHIC_CLASSES = Boolean.parseBoolean(props.getProperty(
                 "protostuff.runtime.auto_load_polymorphic_classes", "true"));
 
-        ALLOW_NULL_ARRAY_ELEMENT = Boolean.parseBoolean(props.getProperty(
-                "protostuff.runtime.allow_null_array_element", "false"));
+        PRESERVE_NULL_ELEMENTS = Boolean.parseBoolean(props.getProperty(
+                "protostuff.runtime.preserve_null_elements", "false"));
 
         MORPH_NON_FINAL_POJOS = Boolean.parseBoolean(props.getProperty(
                 "protostuff.runtime.morph_non_final_pojos", "false"));

protostuff-runtime/src/main/java/io/protostuff/runtime/ArraySchemas.java

@@ -303,7 +303,7 @@ public Base(IdStrategy strategy, final Handler handler)
 
             this.handler = handler;
 
-            allowNullArrayElement = 0 != (IdStrategy.ALLOW_NULL_ARRAY_ELEMENT & strategy.flags);
+            allowNullArrayElement = 0 != (IdStrategy.PRESERVE_NULL_ELEMENTS & strategy.flags);
         }
 
         @Override

protostuff-runtime/src/main/java/io/protostuff/runtime/IdStrategy.java

@@ -37,7 +37,7 @@ public abstract class IdStrategy
     public static final int 
             ENUMS_BY_NAME = 1,
             AUTO_LOAD_POLYMORPHIC_CLASSES = 1 << 1,
-            ALLOW_NULL_ARRAY_ELEMENT = 1 << 2,
+            PRESERVE_NULL_ELEMENTS = 1 << 2,
             MORPH_NON_FINAL_POJOS = 1 << 3,
             MORPH_COLLECTION_INTERFACES = 1 << 4,
             MORPH_MAP_INTERFACES = 1 << 5,
@@ -56,8 +56,8 @@ public abstract class IdStrategy
         if (RuntimeEnv.AUTO_LOAD_POLYMORPHIC_CLASSES)
             flags |= AUTO_LOAD_POLYMORPHIC_CLASSES;
 
-        if (RuntimeEnv.ALLOW_NULL_ARRAY_ELEMENT)
-            flags |= ALLOW_NULL_ARRAY_ELEMENT;
+        if (RuntimeEnv.PRESERVE_NULL_ELEMENTS)
+            flags |= PRESERVE_NULL_ELEMENTS;
 
         if (RuntimeEnv.MORPH_NON_FINAL_POJOS)
             flags |= MORPH_NON_FINAL_POJOS;
@@ -197,6 +197,9 @@ else if (groupId != 0)
             throw new RuntimeException("An IdStrategy without a primaryGroup "
                     + "(standalone) must have a groupId of zero.");
         }
+        // implicit
+        if (0 != (flags & PRESERVE_NULL_ELEMENTS))
+            flags |= COLLECTION_SCHEMA_ON_REPEATED_FIELDS;
 
         this.flags = flags;
         this.primaryGroup = primaryGroup;

protostuff-runtime/src/main/java/io/protostuff/runtime/PolymorphicPojoSchema.java

@@ -30,7 +30,7 @@
  * Will be used if either {@link RuntimeEnv#POJO_SCHEMA_ON_COLLECTION_FIELDS} or 
  * {@link RuntimeEnv#POJO_SCHEMA_ON_MAP_FIELDS} is set.
  * 
- * Applies to a field which is an interface and the type is assignable from List or Map.
+ * Applies to a field which is an interface and the type is assignable from Collection or Map.
  * 
  * @author David Yu
  * @created May 19, 2016

protostuff-runtime/src/main/java/io/protostuff/runtime/RuntimeCollectionField.java

@@ -41,10 +41,10 @@ abstract class RuntimeCollectionField<T, V> extends Field<T>
     protected final CollectionSchema<V> schema;
 
     public RuntimeCollectionField(FieldType type, int number, String name,
-            Tag tag, MessageFactory messageFactory)
+            Tag tag, MessageFactory messageFactory, boolean allowNullElement)
     {
         super(type, number, name, false, tag);
-        schema = new CollectionSchema<V>(messageFactory)
+        schema = new CollectionSchema<V>(messageFactory, allowNullElement)
         {
             @Override
             protected void addValueFrom(Input input, Collection<V> collection)