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DSL Platform compatible Java JSON library (https://dsl-platform.com)

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package com.dslplatform.json.runtime;

import com.dslplatform.json.*;

import java.util.ArrayList;
import java.util.Collection;

public final class CollectionEncoder> implements JsonWriter.WriteObject, ExplicitDescription {

	private final DslJson json;
	private final JsonWriter.WriteObject encoder;

	public CollectionEncoder(
			final DslJson json,
			@Nullable final JsonWriter.WriteObject encoder) {
		if (json == null) throw new IllegalArgumentException("json can't be null");
		this.json = json;
		this.encoder = encoder;
	}

	private static final byte[] EMPTY = {'[', ']'};

	@Override
	public void write(final JsonWriter writer, @Nullable final T value) {
		if (value == null) writer.writeNull();
		else if (value.isEmpty()) writer.writeAscii(EMPTY);
		else if (encoder != null) {
			writer.writeByte(JsonWriter.ARRAY_START);
			if (value instanceof ArrayList) {
				final ArrayList list = (ArrayList)value;
				encoder.write(writer, list.get(0));
				for(int i = 1; i < list.size(); i++) {
					writer.writeByte(JsonWriter.COMMA);
					encoder.write(writer, list.get(i));
				}
			} else {
				boolean pastFirst = false;
				for (final E e : value) {
					if (pastFirst) {
						writer.writeByte(JsonWriter.COMMA);
					} else {
						pastFirst = true;
					}
					encoder.write(writer, e);
				}
			}
			writer.writeByte(JsonWriter.ARRAY_END);
		} else {
			boolean pastFirst = false;
			writer.writeByte(JsonWriter.ARRAY_START);
			Class lastClass = null;
			JsonWriter.WriteObject lastEncoder = null;
			for (final E e : value) {
				if (pastFirst) {
					writer.writeByte(JsonWriter.COMMA);
				} else {
					pastFirst = true;
				}
				if (e == null) writer.writeNull();
				else {
					final Class currentClass = e.getClass();
					if (currentClass != lastClass) {
						lastClass = currentClass;
						lastEncoder = json.tryFindWriter(lastClass);
						if (lastEncoder == null) {
							throw new ConfigurationException("Unable to find writer for " + lastClass);
						}
					}
					lastEncoder.write(writer, e);
				}
			}
			writer.writeByte(JsonWriter.ARRAY_END);
		}
	}
}