com.dslplatform.json.runtime.CollectionAnalyzer Maven / Gradle / Ivy

Go to download
package com.dslplatform.json.runtime;

import com.dslplatform.json.DslJson;
import com.dslplatform.json.JsonReader;
import com.dslplatform.json.JsonWriter;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.*;
import java.util.concurrent.Callable;

public abstract class CollectionAnalyzer {

	private static final JsonWriter.WriteObject tmpWriter = (writer, value) -> {
		throw new IllegalStateException("Invalid configuration for writer. Temporary writer called");
	};
	private static final JsonReader.ReadObject tmpReader = reader -> {
		throw new IllegalStateException("Invalid configuration for reader. Temporary reader called");
	};

	public static final DslJson.ConverterFactory READER = (manifest, dslJson) -> {
		if (manifest instanceof Class) {
			return analyzeDecoding(manifest, Object.class, (Class)manifest, dslJson);
		}
		if (manifest instanceof ParameterizedType) {
			final ParameterizedType pt = (ParameterizedType) manifest;
			if (pt.getActualTypeArguments().length == 1 && pt.getRawType() instanceof Class) {
				return analyzeDecoding(manifest, pt.getActualTypeArguments()[0], (Class) pt.getRawType(), dslJson);
			}
		}
		return null;
	};

	public static final DslJson.ConverterFactory WRITER = (manifest, dslJson) -> {
		if (manifest instanceof Class) {
			return analyzeEncoding(manifest, Object.class, (Class)manifest, dslJson);
		}
		if (manifest instanceof ParameterizedType) {
			final ParameterizedType pt = (ParameterizedType) manifest;
			if (pt.getActualTypeArguments().length == 1 && pt.getRawType() instanceof Class) {
				return analyzeEncoding(manifest, pt.getActualTypeArguments()[0], (Class) pt.getRawType(), dslJson);
			}
		}
		return null;
	};

	private static CollectionDecoder analyzeDecoding(final Type manifest, final Type element, final Class collection, final DslJson json) {
		if (!Collection.class.isAssignableFrom(collection)) return null;
		final Callable newInstance;
		if (!collection.isInterface()) {
			try {
				collection.newInstance();
			} catch (Exception ex) {
				return null;
			}
			newInstance = collection::newInstance;
		} else if (Set.class.isAssignableFrom(collection)) {
			newInstance = () -> new LinkedHashSet<>(4);
		} else if (List.class.isAssignableFrom(collection) || Collection.class == collection) {
			newInstance = () -> new ArrayList<>(4);
		} else if (Queue.class.isAssignableFrom(collection)) {
			newInstance = LinkedList::new;
		} else {
			return null;
		}
		final JsonReader.ReadObject oldReader = json.registerReader(manifest, tmpReader);
		final JsonReader.ReadObject reader = json.tryFindReader(element);
		if (reader == null) {
			json.registerReader(manifest, oldReader);
			return null;
		}
		final CollectionDecoder converter = new CollectionDecoder(manifest, newInstance, reader);
		json.registerReader(manifest, converter);
		return converter;
	}

	private static CollectionEncoder analyzeEncoding(final Type manifest, final Type element, final Class collection, final DslJson json) {
		if (!Collection.class.isAssignableFrom(collection)) return null;
		final JsonWriter.WriteObject oldWriter = json.registerWriter(manifest, tmpWriter);
		final JsonWriter.WriteObject writer = json.tryFindWriter(element);
		if (Object.class != element && writer == null) {
			json.registerWriter(manifest, oldWriter);
			return null;
		}
		final CollectionEncoder encoder =
				new CollectionEncoder(json, Object.class == element ? null : writer);
		json.registerWriter(manifest, encoder);
		return encoder;
	}
}