helpers for empty collections

core/src/main/java/org/jclouds/collect/IterableWithMarkers.java

@@ -26,6 +26,7 @@ import org.jclouds.javax.annotation.Nullable;
 
 import com.google.common.annotations.Beta;
 import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableSet;
 
 /**
  * Utilities for using {@link IterableWithMarker}s.
@@ -35,6 +36,9 @@ import com.google.common.base.Optional;
 @Beta
 public class IterableWithMarkers {
    
+   @SuppressWarnings("rawtypes")
+   public static final IterableWithMarker EMPTY = from(ImmutableSet.of());
+
    /**
     * Returns a paginated iterable containing the given elements and null marker.
     * 

core/src/main/java/org/jclouds/collect/PagedIterables.java

@@ -35,6 +35,17 @@ import com.google.common.collect.ImmutableSet;
  */
 @Beta
 public class PagedIterables {
+   
+   @SuppressWarnings("rawtypes")
+   public static final PagedIterable EMPTY = new PagedIterable() {
+
+      @Override
+      public Iterator<IterableWithMarker> iterator() {
+         return ImmutableSet.of(IterableWithMarkers.EMPTY).iterator();
+      }
+
+   };
+   
    /**
     * @param only
     *           the only page of data

core/src/main/java/org/jclouds/json/config/GsonModule.java

@@ -39,6 +39,8 @@ import org.jclouds.json.Json;
 import org.jclouds.json.internal.DeserializationConstructorAndReflectiveTypeAdapterFactory;
 import org.jclouds.json.internal.EnumTypeAdapterThatReturnsFromValue;
 import org.jclouds.json.internal.GsonWrapper;
+import org.jclouds.json.internal.IgnoreNullFluentIterableTypeAdapterFactory;
+import org.jclouds.json.internal.IgnoreNullIterableTypeAdapterFactory;
 import org.jclouds.json.internal.IgnoreNullMapTypeAdapterFactory;
 import org.jclouds.json.internal.IgnoreNullMultimapTypeAdapterFactory;
 import org.jclouds.json.internal.IgnoreNullSetTypeAdapterFactory;
@@ -81,7 +83,10 @@ public class GsonModule extends AbstractModule {
    @Provides
    @Singleton
    Gson provideGson(TypeAdapter<JsonBall> jsonAdapter, DateAdapter adapter, ByteListAdapter byteListAdapter,
-            ByteArrayAdapter byteArrayAdapter, PropertiesAdapter propertiesAdapter, JsonAdapterBindings bindings)
+            ByteArrayAdapter byteArrayAdapter, PropertiesAdapter propertiesAdapter, JsonAdapterBindings bindings,
+            OptionalTypeAdapterFactory optional, IgnoreNullSetTypeAdapterFactory set,
+            IgnoreNullMapTypeAdapterFactory map, IgnoreNullMultimapTypeAdapterFactory multimap,
+            IgnoreNullIterableTypeAdapterFactory iterable, IgnoreNullFluentIterableTypeAdapterFactory fluentIterable)
             throws Exception {
 
       FieldNamingStrategy serializationPolicy = new AnnotationOrNameFieldNamingStrategy(new ExtractSerializedName(),
@@ -96,10 +101,12 @@ public class GsonModule extends AbstractModule {
       }.getType(), byteListAdapter.nullSafe());
       builder.registerTypeAdapter(byte[].class, byteArrayAdapter.nullSafe());
       builder.registerTypeAdapter(JsonBall.class, jsonAdapter.nullSafe());
-      builder.registerTypeAdapterFactory(new OptionalTypeAdapterFactory());
+      builder.registerTypeAdapterFactory(optional);
-      builder.registerTypeAdapterFactory(new IgnoreNullSetTypeAdapterFactory());
+      builder.registerTypeAdapterFactory(set);
-      builder.registerTypeAdapterFactory(new IgnoreNullMapTypeAdapterFactory());
+      builder.registerTypeAdapterFactory(map);
-      builder.registerTypeAdapterFactory(new IgnoreNullMultimapTypeAdapterFactory());
+      builder.registerTypeAdapterFactory(multimap);
+      builder.registerTypeAdapterFactory(iterable);
+      builder.registerTypeAdapterFactory(fluentIterable);
 
       AnnotationConstructorNamingStrategy deserializationPolicy =
             new AnnotationConstructorNamingStrategy(

core/src/main/java/org/jclouds/json/internal/IgnoreNullFluentIterableTypeAdapterFactory.java

@@ -0,0 +1,78 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.
+ */
+package org.jclouds.json.internal;
+
+import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+import com.google.common.collect.FluentIterable;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+/**
+ * Eliminates null values when deserializing FluentIterables
+ * <p/>
+ * Treats [null] as the empty set; [A, null] as [A]; etc.
+ * 
+ * @author Adam Lowe
+ */
+public class IgnoreNullFluentIterableTypeAdapterFactory implements TypeAdapterFactory {
+   
+   @SuppressWarnings("unchecked")
+   public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
+      Type type = typeToken.getType();
+      if (typeToken.getRawType() != FluentIterable.class || !(type instanceof ParameterizedType)) {
+         return null;
+      }
+
+      Type elementType = ((ParameterizedType) type).getActualTypeArguments()[0];
+      TypeAdapter<?> elementAdapter = gson.getAdapter(TypeToken.get(elementType));
+      return (TypeAdapter<T>) newFluentIterableAdapter(elementAdapter);
+   }
+
+   private <E> TypeAdapter<FluentIterable<E>> newFluentIterableAdapter(final TypeAdapter<E> elementAdapter) {
+      return new TypeAdapter<FluentIterable<E>>() {
+         public void write(JsonWriter out, FluentIterable<E> value) throws IOException {
+            out.beginArray();
+            for (E element : value) {
+               elementAdapter.write(out, element);
+            }
+            out.endArray();
+         }
+
+         public FluentIterable<E> read(JsonReader in) throws IOException {
+                                                                 in.beginArray();
+            Builder<E> builder = ImmutableList.<E>builder();
+            while (in.hasNext()) {
+               E element = elementAdapter.read(in);
+               if (element != null) builder.add(element);
+            }
+            in.endArray();
+            return FluentIterable.from(builder.build());
+         }
+      }.nullSafe();
+   }
+}

core/src/main/java/org/jclouds/json/internal/IgnoreNullIterableTypeAdapterFactory.java

@@ -0,0 +1,77 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.
+ */
+package org.jclouds.json.internal;
+
+import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+/**
+ * Eliminates null values when deserializing Iterables
+ * <p/>
+ * Treats [null] as the empty set; [A, null] as [A]; etc.
+ * 
+ * @author Adam Lowe
+ */
+public class IgnoreNullIterableTypeAdapterFactory implements TypeAdapterFactory {
+   
+   @SuppressWarnings("unchecked")
+   public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
+      Type type = typeToken.getType();
+      if (typeToken.getRawType() != Iterable.class || !(type instanceof ParameterizedType)) {
+         return null;
+      }
+
+      Type elementType = ((ParameterizedType) type).getActualTypeArguments()[0];
+      TypeAdapter<?> elementAdapter = gson.getAdapter(TypeToken.get(elementType));
+      return (TypeAdapter<T>) newIterableAdapter(elementAdapter);
+   }
+
+   private <E> TypeAdapter<Iterable<E>> newIterableAdapter(final TypeAdapter<E> elementAdapter) {
+      return new TypeAdapter<Iterable<E>>() {
+         public void write(JsonWriter out, Iterable<E> value) throws IOException {
+            out.beginArray();
+            for (E element : value) {
+               elementAdapter.write(out, element);
+            }
+            out.endArray();
+         }
+
+         public Iterable<E> read(JsonReader in) throws IOException {
+                                                                 in.beginArray();
+            Builder<E> builder = ImmutableList.<E>builder();
+            while (in.hasNext()) {
+               E element = elementAdapter.read(in);
+               if (element != null) builder.add(element);
+            }
+            in.endArray();
+            return builder.build();
+         }
+      }.nullSafe();
+   }
+}

core/src/main/java/org/jclouds/rest/functions/ReturnEmptyFluentIterableOnNotFoundOr404.java

@@ -0,0 +1,59 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.
+ */
+package org.jclouds.rest.functions;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import org.jclouds.http.functions.ReturnTrueOn404;
+import org.jclouds.rest.ResourceNotFoundException;
+
+import com.google.common.base.Function;
+import com.google.common.base.Throwables;
+import com.google.common.collect.FluentIterable;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+
+/**
+ * 
+ * @author Adrian Cole
+ */
+@Singleton
+public class ReturnEmptyFluentIterableOnNotFoundOr404 implements Function<Exception, Object> {
+   private final ReturnTrueOn404 rto404;
+
+   @Inject
+   private ReturnEmptyFluentIterableOnNotFoundOr404(ReturnTrueOn404 rto404) {
+      this.rto404 = checkNotNull(rto404, "rto404");
+   }
+
+   public Object apply(Exception from) {
+      Iterable<ResourceNotFoundException> throwables = Iterables.filter(Throwables.getCausalChain(from),
+               ResourceNotFoundException.class);
+      if (Iterables.size(throwables) >= 1) {
+         return FluentIterable.from(ImmutableSet.of());
+      } else if (rto404.apply(from)) {
+         return FluentIterable.from(ImmutableSet.of());
+      }
+      throw Throwables.propagate(from);
+   }
+
+}

core/src/main/java/org/jclouds/rest/functions/ReturnEmptyIterableWithMarkerOnNotFoundOr404.java

@@ -0,0 +1,58 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.
+ */
+package org.jclouds.rest.functions;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import org.jclouds.collect.IterableWithMarkers;
+import org.jclouds.http.functions.ReturnTrueOn404;
+import org.jclouds.rest.ResourceNotFoundException;
+
+import com.google.common.base.Function;
+import com.google.common.base.Throwables;
+import com.google.common.collect.Iterables;
+
+/**
+ * 
+ * @author Adrian Cole
+ */
+@Singleton
+public class ReturnEmptyIterableWithMarkerOnNotFoundOr404 implements Function<Exception, Object> {
+   private final ReturnTrueOn404 rto404;
+
+   @Inject
+   private ReturnEmptyIterableWithMarkerOnNotFoundOr404(ReturnTrueOn404 rto404) {
+      this.rto404 = checkNotNull(rto404, "rto404");
+   }
+
+   public Object apply(Exception from) {
+      Iterable<ResourceNotFoundException> throwables = Iterables.filter(Throwables.getCausalChain(from),
+               ResourceNotFoundException.class);
+      if (Iterables.size(throwables) >= 1) {
+         return IterableWithMarkers.EMPTY;
+      } else if (rto404.apply(from)) {
+         return IterableWithMarkers.EMPTY;
+      }
+      throw Throwables.propagate(from);
+   }
+
+}

core/src/main/java/org/jclouds/rest/functions/ReturnEmptyListOnNotFoundOr404.java

@@ -20,8 +20,6 @@ package org.jclouds.rest.functions;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import java.util.List;
-
 import javax.inject.Inject;
 import javax.inject.Singleton;
 

core/src/main/java/org/jclouds/rest/functions/ReturnEmptyMapOnNotFoundOr404.java

@@ -20,8 +20,6 @@ package org.jclouds.rest.functions;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import java.util.Map;
-
 import javax.inject.Inject;
 import javax.inject.Singleton;
 

core/src/main/java/org/jclouds/rest/functions/ReturnEmptyMultimapOnNotFoundOr404.java

@@ -30,7 +30,6 @@ import com.google.common.base.Function;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
 
 /**
  * 

core/src/main/java/org/jclouds/rest/functions/ReturnEmptyPagedIterableOnNotFoundOr404.java

@@ -0,0 +1,58 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds 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.
+ */
+package org.jclouds.rest.functions;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import org.jclouds.collect.PagedIterables;
+import org.jclouds.http.functions.ReturnTrueOn404;
+import org.jclouds.rest.ResourceNotFoundException;
+
+import com.google.common.base.Function;
+import com.google.common.base.Throwables;
+import com.google.common.collect.Iterables;
+
+/**
+ * 
+ * @author Adrian Cole
+ */
+@Singleton
+public class ReturnEmptyPagedIterableOnNotFoundOr404 implements Function<Exception, Object> {
+   private final ReturnTrueOn404 rto404;
+
+   @Inject
+   private ReturnEmptyPagedIterableOnNotFoundOr404(ReturnTrueOn404 rto404) {
+      this.rto404 = checkNotNull(rto404, "rto404");
+   }
+
+   public Object apply(Exception from) {
+      Iterable<ResourceNotFoundException> throwables = Iterables.filter(Throwables.getCausalChain(from),
+               ResourceNotFoundException.class);
+      if (Iterables.size(throwables) >= 1) {
+         return PagedIterables.EMPTY;
+      } else if (rto404.apply(from)) {
+         return PagedIterables.EMPTY;
+      }
+      throw Throwables.propagate(from);
+   }
+
+}

core/src/main/java/org/jclouds/rest/functions/ReturnEmptySetOnNotFoundOr404.java

@@ -20,8 +20,6 @@ package org.jclouds.rest.functions;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import java.util.Set;
-
 import javax.inject.Inject;
 import javax.inject.Singleton;