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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019-2021 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* Licensed 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
*
* http://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.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.common.utils.coder;
import com.google.gson.JsonElement;
import java.io.Serializable;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Getter;
/**
* Object type used by the {@link StandardCoder}. Different serialization tools have
* different "standard objects". For instance, GSON uses {@link JsonElement}. This class
* wraps that object so that it can be used without exposing the object, itself.
*/
@AllArgsConstructor(access = AccessLevel.PROTECTED)
public class StandardCoderObject implements Serializable {
private static final long serialVersionUID = 1L;
/**
* Data wrapped by this.
*/
/*
* this should not be transient, but since it isn't serializable, we're stuck with it
* until there's time to address the issue
*/
@Getter(AccessLevel.PROTECTED)
private final transient JsonElement data;
/**
* Constructs the object.
*/
public StandardCoderObject() {
data = null;
}
/**
* Gets a field's value from this object, traversing the object hierarchy.
*
* @param fields field hierarchy. These may be strings, identifying fields within the
* object, or Integers, identifying an index within an array
* @return the field value or {@code null} if the field does not exist or is not a
* primitive
*/
public String getString(Object... fields) {
JsonElement jel = data;
for (Object field : fields) {
if (jel == null) {
return null;
}
if (field instanceof String) {
jel = getFieldFromObject(jel, field.toString());
} else if (field instanceof Integer) {
jel = getItemFromArray(jel, (int) field);
} else {
throw new IllegalArgumentException("subscript is not a string or integer: " + field);
}
}
return (jel != null && jel.isJsonPrimitive() ? jel.getAsString() : null);
}
/**
* Gets an item from an object.
*
* @param element object from which to extract the item
* @param field name of the field from which to extract the item
* @return the item, or {@code null} if the element is not an object or if the field
* does not exist
*/
protected JsonElement getFieldFromObject(JsonElement element, String field) {
if (!element.isJsonObject()) {
return null;
}
return element.getAsJsonObject().get(field);
}
/**
* Gets an item from an array.
*
* @param element array from which to extract the item
* @param index index of the item to extract
* @return the item, or {@code null} if the element is not an array or if the index is
* out of bounds
*/
protected JsonElement getItemFromArray(JsonElement element, int index) {
if (index < 0) {
throw new IllegalArgumentException("subscript is invalid: " + index);
}
if (!element.isJsonArray()) {
return null;
}
var array = element.getAsJsonArray();
if (index >= array.size()) {
return null;
}
return array.get(index);
}
}
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