[Guava] Suppport simple deserialization of Cache (#116)

guava/src/main/java/com/fasterxml/jackson/datatype/guava/GuavaDeserializers.java

@@ -1,6 +1,9 @@
 package com.fasterxml.jackson.datatype.guava;
 
 import com.google.common.base.Optional;
+import com.google.common.cache.Cache;
+import com.google.common.cache.ForwardingCache;
+import com.google.common.cache.LoadingCache;
 import com.google.common.collect.*;
 import com.google.common.hash.HashCode;
 import com.google.common.net.HostAndPort;
@@ -260,10 +263,42 @@ public JsonDeserializer<?> findMapLikeDeserializer(MapLikeType type,
         if (Table.class.isAssignableFrom(raw)) {
             // !!! TODO
         }
+        // @since 2.16 : support Cache deserialization
+        java.util.Optional<JsonDeserializer<?>> cacheDeserializer = findCacheDeserializer(raw, type, config, 
+                                        beanDesc, keyDeserializer, elementTypeDeserializer, elementDeserializer);
+        if (cacheDeserializer.isPresent()) {
+            return cacheDeserializer.get();
+        }
 
         return null;
     }
 
+    /**
+     * Find matching implementation of {@link Cache} deserializers by checking
+     * if the parameter {@code raw} type is assignable.
+     *
+     * NOTE: Make sure the cache implementations are checked in such a way that more concrete classes are
+     * compared first before more abstract ones.
+     *
+     * @return An optional {@link JsonDeserializer} for the cache type, if found.
+     * @since 2.16
+     */
+    private java.util.Optional<JsonDeserializer<?>> findCacheDeserializer(Class<?> raw, MapLikeType type, 
+        DeserializationConfig config, BeanDescription beanDesc, KeyDeserializer keyDeserializer, 
+        TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer) 
+    {
+        /* // Example implementations
+        if (LoadingCache.class.isAssignableFrom(raw)) {
+            return ....your implementation....;
+        }
+        */
+        if (Cache.class.isAssignableFrom(raw)) {
+            return java.util.Optional.of(
+                new SimpleCacheDeserializer(type, keyDeserializer, elementTypeDeserializer, elementDeserializer));
+        }
+        return java.util.Optional.empty();
+    }
+
     @Override // since 2.7
     public JsonDeserializer<?> findReferenceDeserializer(ReferenceType refType,
             DeserializationConfig config, BeanDescription beanDesc,

guava/src/main/java/com/fasterxml/jackson/datatype/guava/SimpleCacheDeserializer.java

@@ -0,0 +1,57 @@
+package com.fasterxml.jackson.datatype.guava;
+
+import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.KeyDeserializer;
+import com.fasterxml.jackson.databind.deser.NullValueProvider;
+import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
+import com.fasterxml.jackson.databind.type.MapLikeType;
+import com.fasterxml.jackson.datatype.guava.deser.cache.GuavaCacheDeserializer;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+
+/**
+ * {@link GuavaCacheDeserializer} class implementation for deserializing Guava {@link Cache} instances.
+ *
+ * @since 2.16
+ */
+public class SimpleCacheDeserializer 
+    extends GuavaCacheDeserializer<Cache<Object,Object>> 
+{
+
+    /*
+    /**********************************************************
+    /* Life-cycle
+    /**********************************************************
+     */
+
+    public SimpleCacheDeserializer(MapLikeType type, KeyDeserializer keyDeserializer,
+        TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer) 
+    {
+        super(type, keyDeserializer, elementTypeDeserializer, elementDeserializer);
+    }
+
+    public SimpleCacheDeserializer(MapLikeType type, KeyDeserializer keyDeserializer,
+        TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer,
+        NullValueProvider nvp) 
+    {
+        super(type, keyDeserializer, elementTypeDeserializer, elementDeserializer, nvp);
+    }
+
+    /*
+    /**********************************************************************
+    /* Abstract method overrides
+    /**********************************************************************
+     */
+
+    @Override
+    protected Cache<Object, Object> createCache() {
+        return CacheBuilder.newBuilder().build();
+    }
+
+    @Override
+    protected JsonDeserializer<?> _createContextual(MapLikeType t, 
+        KeyDeserializer kd, TypeDeserializer vtd, JsonDeserializer<?> vd, NullValueProvider np) 
+    {
+        return new SimpleCacheDeserializer(t, kd, vtd, vd, np);
+    }
+}

guava/src/main/java/com/fasterxml/jackson/datatype/guava/deser/cache/GuavaCacheDeserializer.java

@@ -0,0 +1,161 @@
+package com.fasterxml.jackson.datatype.guava.deser.cache;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
+import com.fasterxml.jackson.databind.deser.NullValueProvider;
+import com.fasterxml.jackson.databind.deser.impl.NullsConstantProvider;
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
+import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
+import com.fasterxml.jackson.databind.type.LogicalType;
+import com.fasterxml.jackson.databind.type.MapLikeType;
+import com.google.common.cache.Cache;
+
+import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+
+public abstract class GuavaCacheDeserializer<T extends Cache<Object, Object>> 
+    extends StdDeserializer<T> implements ContextualDeserializer 
+{
+    private static final long serialVersionUID = 1L;
+
+    private final MapLikeType type;
+    private final KeyDeserializer keyDeserializer;
+    private final TypeDeserializer elementTypeDeserializer;
+    private final JsonDeserializer<?> elementDeserializer;
+
+    /*
+     * @since 2.16 : in 3.x demote to `ContainerDeserializerBase`
+     */
+    private final NullValueProvider nullProvider;
+    private final boolean skipNullValues;
+
+    /*
+    /**********************************************************
+    /* Life-cycle
+    /**********************************************************
+     */
+
+    public GuavaCacheDeserializer(MapLikeType type, KeyDeserializer keyDeserializer,
+            TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer) {
+        this(type, keyDeserializer, elementTypeDeserializer, elementDeserializer, null);
+    }
+
+    public GuavaCacheDeserializer(MapLikeType type, KeyDeserializer keyDeserializer,
+            TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer,
+            NullValueProvider nvp)
+    {
+        super(type);
+        this.type = type;
+        this.keyDeserializer = keyDeserializer;
+        this.elementTypeDeserializer = elementTypeDeserializer;
+        this.elementDeserializer = elementDeserializer;
+        this.nullProvider = nvp;
+        skipNullValues = (nvp == null) ? false : NullsConstantProvider.isSkipper(nvp);
+    }
+
+    /*
+    /**********************************************************
+    /* Post-processing (contextualization)
+    /**********************************************************
+     */
+
+    @Override
+    public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
+            BeanProperty property) throws JsonMappingException 
+    {
+        KeyDeserializer kd = keyDeserializer;
+        if (kd == null) {
+            kd = ctxt.findKeyDeserializer(type.getKeyType(), property);
+        }
+        JsonDeserializer<?> valueDeser = elementDeserializer;
+        final JavaType vt = type.getContentType();
+        if (valueDeser == null) {
+            valueDeser = ctxt.findContextualValueDeserializer(vt, property);
+        } else { // if directly assigned, probably not yet contextual, so:
+            valueDeser = ctxt.handleSecondaryContextualization(valueDeser, property, vt);
+        }
+        // Type deserializer is slightly different; must be passed, but needs to become contextual:
+        TypeDeserializer vtd = elementTypeDeserializer;
+        if (vtd != null) {
+            vtd = vtd.forProperty(property);
+        }
+        return _createContextual(type, kd, vtd, valueDeser, 
+                findContentNullProvider(ctxt, property, valueDeser));
+    }
+
+    /*
+    /**********************************************************************
+    /* Abstract methods for subclasses
+    /**********************************************************************
+     */
+
+    protected abstract T createCache();
+
+    protected abstract JsonDeserializer<?> _createContextual(MapLikeType t, KeyDeserializer kd,
+            TypeDeserializer vtd, JsonDeserializer<?> vd, NullValueProvider np);
+
+    /*
+    /**********************************************************************
+    /* Implementations
+    /**********************************************************************
+     */
+
+    @Override
+    public LogicalType logicalType() {
+        return LogicalType.Map;
+    }
+
+    @Override
+    public T deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
+        return deserializeContents(p, ctxt);
+    }
+
+    private T deserializeContents(JsonParser p, DeserializationContext ctxt)
+        throws IOException
+    {
+        T cache = createCache();
+
+        JsonToken currToken = p.currentToken();
+        if (currToken != JsonToken.FIELD_NAME) {
+            // 01-Mar-2023, tatu: [datatypes-collections#104] Handle empty Maps too
+            if (currToken != JsonToken.END_OBJECT) {
+                expect(p, JsonToken.START_OBJECT);
+                currToken = p.nextToken();
+            }
+        }
+
+        for (; currToken == JsonToken.FIELD_NAME; currToken = p.nextToken()) {
+            final Object key;
+            if (keyDeserializer != null) {
+                key = keyDeserializer.deserializeKey(p.currentName(), ctxt);
+            } else {
+                key = p.currentName();
+            }
+
+            p.nextToken();
+
+            final Object value;
+            if (p.currentToken() == JsonToken.VALUE_NULL) {
+                if (skipNullValues) {
+                    continue;
+                }
+                value = nullProvider.getNullValue(ctxt);
+            } else if (elementTypeDeserializer != null) {
+                value = elementDeserializer.deserializeWithType(p, ctxt, elementTypeDeserializer);
+            } else {
+                value = elementDeserializer.deserialize(p, ctxt);
+            }
+            cache.put(key, value);
+        }
+        return cache;
+    }
+
+    private void expect(JsonParser p, JsonToken token) throws IOException {
+        if (p.getCurrentToken() != token) {
+            throw new JsonMappingException(p, "Expecting " + token + " to start `Cache` value, found " + p.currentToken(),
+                p.getCurrentLocation());
+        }
+    }
+}