Respond to code review

Author: jyemin

bson/src/main/org/bson/codecs/Parameterizable.java

@@ -34,7 +34,8 @@ public interface Parameterizable {
      * @param codecRegistry the code registry to use to resolve codecs for the generic type arguments
      * @param types         the types that are parameterizing the containing type.  The size of the list should be equal to the number of type
      *                      parameters of the class whose codec is being parameterized, e.g. for a {@link Collection} the size of the list
-     *                      would be one since {@code Collection} has a single type parameter.
+     *                      would be one since {@code Collection} has a single type parameter. Additionally, the size will never be 0
+     *                      since there is no purpose in parameterizing a codec for a type that has no type parameters.
      * @return the Codec parameterized with the given types
      */
     Codec<?> parameterize(CodecRegistry codecRegistry, List<Type> types);

bson/src/main/org/bson/internal/ChildCodecRegistry.java

@@ -21,8 +21,12 @@
 import org.bson.codecs.configuration.CodecRegistry;
 
 import java.lang.reflect.Type;
-import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
+
+import static java.lang.String.format;
+import static org.bson.assertions.Assertions.isTrueArgument;
+import static org.bson.assertions.Assertions.notNull;
 
 // An implementation of CodecRegistry that is used to detect cyclic dependencies between Codecs
 class ChildCodecRegistry<T> implements CodecRegistry {
@@ -32,10 +36,6 @@ class ChildCodecRegistry<T> implements CodecRegistry {
     private final Class<T> codecClass;
     private final List<Type> types;
 
-    ChildCodecRegistry(final CycleDetectingCodecRegistry registry, final Class<T> codecClass) {
-        this(registry, codecClass, Collections.emptyList());
-    }
-
     ChildCodecRegistry(final CycleDetectingCodecRegistry registry, final Class<T> codecClass, final List<Type> types) {
         this.codecClass = codecClass;
         this.parent = null;
@@ -54,21 +54,26 @@ public Class<T> getCodecClass() {
         return codecClass;
     }
 
-    public List<Type> getTypes() {
-        return types;
+    public Optional<List<Type>> getTypes() {
+        return Optional.ofNullable(types);
     }
 
     // Gets a Codec, but if it detects a cyclic dependency, return a LazyCodec which breaks the chain.
     public <U> Codec<U> get(final Class<U> clazz) {
         if (hasCycles(clazz)) {
-            return new LazyCodec<U>(registry, clazz, types);
+            return new LazyCodec<>(registry, clazz, null);
         } else {
-            return registry.get(new ChildCodecRegistry<>(this, clazz, Collections.emptyList()));
+            return registry.get(new ChildCodecRegistry<>(this, clazz, null));
         }
     }
 
     @Override
     public <U> Codec<U> get(final Class<U> clazz, final List<Type> typeArguments) {
+        notNull("typeArguments", typeArguments);
+        isTrueArgument("typeArguments is not empty", typeArguments.size() >= 1);
+        isTrueArgument(format("typeArguments size should equal the number of type parameters in class %s, but is %d",
+                        clazz, typeArguments.size()),
+                clazz.getTypeParameters().length == typeArguments.size());
         if (hasCycles(clazz)) {
             return new LazyCodec<U>(registry, clazz, typeArguments);
         } else {

bson/src/main/org/bson/internal/LazyCodec.java

@@ -55,7 +55,7 @@ public T decode(final BsonReader reader, final DecoderContext decoderContext) {
 
     private Codec<T> getWrapped() {
         if (wrapped == null) {
-            if (types.isEmpty()) {
+            if (types == null) {
                 wrapped = registry.get(clazz);
             } else {
                 wrapped = registry.get(clazz, types);

bson/src/main/org/bson/internal/ProvidersCodecRegistry.java

@@ -26,7 +26,9 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import static java.lang.String.format;
 import static org.bson.assertions.Assertions.isTrueArgument;
+import static org.bson.assertions.Assertions.notNull;
 
 public final class ProvidersCodecRegistry implements CodecRegistry, CycleDetectingCodecRegistry {
     private final List<CodecProvider> codecProviders;
@@ -39,11 +41,16 @@ public ProvidersCodecRegistry(final List<? extends CodecProvider> codecProviders
 
     @Override
     public <T> Codec<T> get(final Class<T> clazz) {
-        return get(new ChildCodecRegistry<T>(this, clazz));
+        return get(new ChildCodecRegistry<T>(this, clazz, null));
     }
 
     @Override
     public <T> Codec<T> get(final Class<T> clazz, final List<Type> typeArguments) {
+        notNull("typeArguments", typeArguments);
+        isTrueArgument("typeArguments is not empty", typeArguments.size() >= 1);
+        isTrueArgument(format("typeArguments size should equal the number of type parameters in class %s, but is %d",
+                        clazz, typeArguments.size()),
+                clazz.getTypeParameters().length == typeArguments.size());
         return get(new ChildCodecRegistry<T>(this, clazz, typeArguments));
     }
 
@@ -60,13 +67,13 @@ public <T> Codec<T> get(final Class<T> clazz, final CodecRegistry registry) {
 
     @SuppressWarnings({"unchecked"})
     public <T> Codec<T> get(final ChildCodecRegistry<T> context) {
-        CodecCacheKey codecCacheKey = new CodecCacheKey(context.getCodecClass(), context.getTypes());
+        CodecCacheKey codecCacheKey = new CodecCacheKey(context.getCodecClass(), context.getTypes().orElse(null));
         if (!codecCache.containsKey(codecCacheKey)) {
             for (CodecProvider provider : codecProviders) {
                 Codec<T> codec = provider.get(context.getCodecClass(), context);
                 if (codec != null) {
-                    if (codec instanceof Parameterizable && !context.getTypes().isEmpty()) {
-                        codec = (Codec<T>) ((Parameterizable) codec).parameterize(context, context.getTypes());
+                    if (codec instanceof Parameterizable && context.getTypes().isPresent()) {
+                        codec = (Codec<T>) ((Parameterizable) codec).parameterize(context, context.getTypes().get());
                     }
                     return codecCache.putIfMissing(codecCacheKey, codec);
                 }