Continuing work to support "shape-shifting"

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/BeanDescription.java

@@ -193,7 +193,7 @@ public boolean isNonStaticInnerClass() {
      * defined by possible annotations and possible per-type config overrides.
      */
     public abstract JsonFormat.Value findExpectedFormat(Class<?> baseType);
-    
+
     /**
      * Method for finding {@link Converter} used for serializing instances
      * of this class.

src/main/java/com/fasterxml/jackson/databind/JsonSerializer.java

@@ -3,6 +3,7 @@
 import java.io.IOException;
 import java.util.Iterator;
 
+import com.fasterxml.jackson.annotation.JsonFormat;
 import com.fasterxml.jackson.core.*;
 
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitable;
@@ -151,6 +152,45 @@ public JsonSerializer<?> withFilterId(Object filterId) {
         return this;
     }
 
+    /**
+     * Mutant factory called if there is need to create a serializer with specified
+     * format overrides (typically from property on which this serializer would be used,
+     * based on type declaration). Method is called before {@link #createContextual}
+     * but right after serializer is either constructed or fetched from cache.
+     *<p>
+     * Method can do one of three things:
+     *<ul>
+     * <li>Return {@code this} instance as is: this means that none of overrides has any effect
+     *  </li>
+     * <li>Return an alternate {@link JsonSerializer}, suitable for use with specified format
+     *  </li>
+     * <li>Return {@code null} to indicate that this serializer instance is not suitable for
+     *    handling format variation, but does not know how to construct new serializer: caller
+     *    will typically then call {@link SerializerFactory} with overrides to construct new serializer
+     *  </li>
+     *</ul>
+     * One example of second approach is the case where {@link JsonFormat.Shape#STRING} indicates String
+     * representation and code can just construct simple "string-like serializer", or variant of itself
+     * (similar to how {@link #createContextual} is often implemented).
+     * And third case (returning {@code null}) is applicable for cases like format defines
+     * {@link JsonFormat.Shape#POJO}, requesting "introspect serializer for POJO regardless of type":
+     * {@link SerializerFactory} is needed for full re-introspection, typically.
+     *
+     * @param formatOverrides (not null) Override settings, NOT including original format settings (which
+     *    serializer needs to explicitly retain if needed)
+     *
+     * @since 3.0
+     */
+    public JsonSerializer<?> withFormatOverride(SerializationConfig config,
+            JsonFormat.Value formatOverrides)
+    {
+        // First: if no override, safe to use as is:
+        if (formatOverrides.getShape() == JsonFormat.Shape.ANY) {
+            return this;
+        }
+        return null;
+    }
+
     /*
     /**********************************************************************
     /* Serialization methods
@@ -211,7 +251,7 @@ public void serializeWithType(T value, JsonGenerator gen, SerializerProvider ser
 
     /*
     /**********************************************************************
-    /* Other accessors
+    /* Accessors for serializer metadata
     /**********************************************************************
      */
 
@@ -221,26 +261,10 @@ public void serializeWithType(T value, JsonGenerator gen, SerializerProvider ser
      * may be a more generic (super-type) -- but it should not be
      * incorrect (return a non-related type).
      *<p>
-     * Default implementation will return null, which essentially means
-     * same as returning <code>Object.class</code> would; that is, that
-     * nothing is known about handled type.
-     *<p>
+     * NOTE: starting with 3.0, left {@code abstract}.
      */
-    public Class<T> handledType() { return null; }
+    public Class<?> handledType() { return Object.class; }
 
-    /**
-     * Method called to check whether given serializable value is
-     * considered "empty" value (for purposes of suppressing serialization
-     * of empty values).
-     *<p>
-     * Default implementation will consider only null values to be empty.
-     */
-    public boolean isEmpty(SerializerProvider provider, T value)
-        throws IOException
-    {
-        return (value == null);
-    }
-    
     /**
      * Method that can be called to see whether this serializer instance
      * will use Object Id to handle cyclic references.
@@ -258,7 +282,7 @@ public boolean usesObjectId() {
     public boolean isUnwrappingSerializer() {
         return false;
     }
-    
+
     /**
      * Accessor that can be used to determine if this serializer uses
      * another serializer for actual serialization, by delegating
@@ -284,6 +308,25 @@ public Iterator<PropertyWriter> properties() {
         return ClassUtil.emptyIterator();
     }
 
+    /*
+    /**********************************************************************
+    /* Accessors for introspecting handling of values
+    /**********************************************************************
+     */
+    
+    /**
+     * Method called to check whether given serializable value is
+     * considered "empty" value (for purposes of suppressing serialization
+     * of empty values).
+     *<p>
+     * Default implementation will consider only null values to be empty.
+     */
+    public boolean isEmpty(SerializerProvider provider, T value)
+        throws IOException
+    {
+        return (value == null);
+    }
+
     /*
     /**********************************************************************
     /* Default JsonFormatVisitable implementation

src/main/java/com/fasterxml/jackson/databind/ser/ContainerSerializer.java

@@ -41,7 +41,7 @@ public abstract class ContainerSerializer<T>
     /**********************************************************************
      */
 
-    protected ContainerSerializer(Class<T> t) {
+    protected ContainerSerializer(Class<?> t) {
         super(t);
         _property = null;
         _dynamicValueSerializers = PropertySerializerMap.emptyForProperties();
@@ -51,8 +51,9 @@ protected ContainerSerializer(Class<T> t) {
      * Alternate constructor that is (alas!) needed to work
      * around kinks of generic type handling
      */
+    @Deprecated
     protected ContainerSerializer(Class<?> t, boolean dummy) {
-        super(t, dummy);
+        super(t);
         _property = null;
         _dynamicValueSerializers = PropertySerializerMap.emptyForProperties();
     }
@@ -73,7 +74,7 @@ protected ContainerSerializer(ContainerSerializer<?> src) {
     }
 
     protected ContainerSerializer(ContainerSerializer<?> src, BeanProperty prop) {
-        super(src._handledType, false);
+        super(src._handledType);
         _property = prop;
         // 16-Apr-2018, tatu: Could retain, possibly, in some cases... but may be
         //    dangerous as general practice so reset

src/main/java/com/fasterxml/jackson/databind/ser/impl/UnknownSerializer.java

@@ -17,11 +17,8 @@ public UnknownSerializer() {
         super(Object.class);
     }
 
-    /**
-     * @since 2.6
-     */
     public UnknownSerializer(Class<?> cls) {
-        super(cls, false);
+        super(cls);
     }
 
     @Override

src/main/java/com/fasterxml/jackson/databind/ser/std/AsArraySerializerBase.java

@@ -56,7 +56,7 @@ public abstract class AsArraySerializerBase<T>
     protected AsArraySerializerBase(Class<?> cls, JavaType et, boolean staticTyping,
             TypeSerializer vts, JsonSerializer<?> elementSerializer)
     {
-        super(cls, false);
+        super(cls);
         _elementType = et;
         // static if explicitly requested, or if element type is final
         _staticTyping = staticTyping || (et != null && et.isFinal());

src/main/java/com/fasterxml/jackson/databind/ser/std/MapSerializer.java

@@ -138,7 +138,7 @@ protected MapSerializer(Set<String> ignoredEntries,
             TypeSerializer vts,
             JsonSerializer<?> keySerializer, JsonSerializer<?> valueSerializer)
     {
-        super(Map.class, false);
+        super(Map.class);
         _ignoredEntries = ((ignoredEntries == null) || ignoredEntries.isEmpty())
                 ? null : ignoredEntries;
         _keyType = keyType;

src/main/java/com/fasterxml/jackson/databind/ser/std/RawSerializer.java

@@ -22,7 +22,7 @@ public class RawSerializer<T>
      * just take wild card and coerce type.
      */
     public RawSerializer(Class<?> cls) {
-        super(cls, false);
+        super(cls);
     }
 
     @Override

src/main/java/com/fasterxml/jackson/databind/ser/std/StaticListSerializerBase.java

@@ -27,7 +27,7 @@ public abstract class StaticListSerializerBase<T extends Collection<?>>
     protected final Boolean _unwrapSingle;
 
     protected StaticListSerializerBase(Class<?> cls) {
-        super(cls, false);
+        super(cls);
         _unwrapSingle = null;
     }
 

src/main/java/com/fasterxml/jackson/databind/ser/std/StdDelegatingSerializer.java

@@ -66,7 +66,7 @@ public StdDelegatingSerializer(Converter<?,?> converter)
     @SuppressWarnings("unchecked")
     public <T> StdDelegatingSerializer(Class<T> cls, Converter<T,?> converter)
     {
-        super(cls, false);
+        super(cls);
         _converter = (Converter<Object,?>)converter;
         _delegateType = null;
         _delegateSerializer = null;

src/main/java/com/fasterxml/jackson/databind/ser/std/StdKeySerializers.java

@@ -129,7 +129,7 @@ public static class Default extends StdSerializer<Object> {
         protected final int _typeId;
 
         public Default(int typeId, Class<?> type) {
-            super(type, false);
+            super(type);
             _typeId = typeId;
         }
 
@@ -189,7 +189,7 @@ public static class Dynamic extends StdSerializer<Object>
         protected transient PropertySerializerMap _dynamicSerializers;
 
         public Dynamic() {
-            super(String.class, false);
+            super(String.class);
             _dynamicSerializers = PropertySerializerMap.emptyForProperties();
         }
 
@@ -243,7 +243,7 @@ protected JsonSerializer<Object> _findAndAddDynamic(PropertySerializerMap map,
      */
     public static class StringKeySerializer extends StdSerializer<Object>
     {
-        public StringKeySerializer() { super(String.class, false); }
+        public StringKeySerializer() { super(String.class); }
 
         @Override
         public void serialize(Object value, JsonGenerator g, SerializerProvider provider) throws IOException {
@@ -253,15 +253,13 @@ public void serialize(Object value, JsonGenerator g, SerializerProvider provider
 
     /**
      * Specialized instance to use for Enum keys, as per [databind#1322]
-     *
-     * @since 2.8
      */
     public static class EnumKeySerializer extends StdSerializer<Object>
     {
         protected final EnumValues _values;
 
         protected EnumKeySerializer(Class<?> enumType, EnumValues values) {
-            super(enumType, false);
+            super(enumType);
             _values = values;
         }