dev.langchain4j.data.message.GsonChatMessageJsonCodec Maven / Gradle / Ivy

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package dev.langchain4j.data.message;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

import java.lang.reflect.Type;
import java.util.List;

import static java.util.Collections.emptyList;

/**
 * A codec for serializing and deserializing {@link ChatMessage} objects to and from JSON.
 */
public class GsonChatMessageJsonCodec implements ChatMessageJsonCodec {

    /**
     * The {@link Gson} instance used for serialization and deserialization.
     */
    static final Gson GSON = new GsonBuilder()
            .registerTypeAdapter(ChatMessage.class, new GsonChatMessageAdapter())
            .registerTypeAdapter(SystemMessage.class, new GsonChatMessageAdapter())
            .registerTypeAdapter(UserMessage.class, new GsonChatMessageAdapter())
            .registerTypeAdapter(AiMessage.class, new GsonChatMessageAdapter())
            .registerTypeAdapter(ToolExecutionResultMessage.class, new GsonChatMessageAdapter())
            .create();

    /**
     * A {@link Type} object representing a list of {@link ChatMessage} objects.
     */
    private static final Type MESSAGE_LIST_TYPE = (new TypeToken>() {}).getType();

    /**
     * Constructs a new {@link GsonChatMessageJsonCodec}.
     */
    public GsonChatMessageJsonCodec() {}

    @Override
    public ChatMessage messageFromJson(String json) {
        return GSON.fromJson(json, ChatMessage.class);
    }

    @Override
    public List messagesFromJson(String json) {
        List messages = GSON.fromJson(json, MESSAGE_LIST_TYPE);
        return messages == null ? emptyList() : messages;
    }

    @Override
    public String messageToJson(ChatMessage message) {
        return GSON.toJson(message);
    }

    @Override
    public String messagesToJson(List messages) {
        return GSON.toJson(messages);
    }
}