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Central API Module.
There is a newer version: 0.12.0
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
 *
 *   https://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.apache.plc4x.java.api.model;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonTypeInfo;

/**
 * Base type for all field types.
 * Typically every driver provides an implementation of this interface in order
 * to be able to describe the fields of a resource. As this is completely tied to
 * the implemented protocol, this base interface makes absolutely no assumption to
 * any information it should provide.
 *
 * In order to stay platform and protocol independent every driver connection implementation
 * provides a prepareField(String) method that is able to parse a string representation of
 * a resource into it's individual field type. Manually constructing PlcField objects
 * manually makes the solution less independent from the protocol, but might be faster.
 */
@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, property = "className")
public interface PlcField {

    /**
     * Returns the "default" type of the response one can expect from this field as java type.
     * I.e., a call to getXXX for the ResponseItem should succeed.
     *
     * The contract is not to return the exact type which is internally hold by PLC4X but to
     * return a "casteable" type, i.e., a type for which the getXXX method succeeds.
     * So for example if a type is internally a short, but the getInt() method is implemented, it
     * is allowed to return Integer.class by this method.
     *
     * This method should always return the BOXED type for primitives. E.g. not bool.class but Boolean.class
     * @return Either specific type or Object.class if no specific type is known.
     */
    @JsonIgnore
    default Class getDefaultJavaType() {
        return Object.class;
    }

    /**
     * Returns the "datatype" of the response one can expect from this field.
     * I.e. The mapping between this string and the PlcValue datatype is handled in the Valuehandler class.
     *
     * The contract is to return a String description of the datatype. This doesn't necessarily
     * define the PlcValue type but should be related.
     * i.e. returns "BOOL" -> PlcBOOL, returns "INT16" -> PlcINT
     * returning an empty string results in the default handler for that dattype to be evaluated.
     *
     * @return The data type is generally parsed to the PlcField class, if not a default datatype is returned.
     */
    @JsonIgnore
    default String getPlcDataType() {
        return "";
    }

    /**
     * Returns the number of elements to expect of the response one can expect from this field.
     *
     *
     * @return The number of elements to expect.
     */
    @JsonIgnore
    default int getNumberOfElements() {
        return 1;
    }



}