software.amazon.smithy.model.selector.AttributeValue Maven / Gradle / Ivy
/*
* Copyright 2020 Amazon.com, Inc. or its affiliates. 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.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 software.amazon.smithy.model.selector;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import software.amazon.smithy.model.node.Node;
import software.amazon.smithy.model.shapes.ServiceShape;
import software.amazon.smithy.model.shapes.Shape;
import software.amazon.smithy.model.shapes.ShapeId;
import software.amazon.smithy.model.validation.linters.EmitEachSelectorValidator;
import software.amazon.smithy.utils.SimpleParser;
/**
* Selector attribute values are the data model of selectors.
*/
public interface AttributeValue {
/**
* Returns the string version of an attribute value.
*
* @return Returns the string representation or an empty string.
*/
@Override
String toString();
/**
* Returns a string representation of the value that can be used
* for creating formatted messages.
*
* This implementation gets the value of {@link #toString()}
* by default.
*
* @return Returns the message string.
*/
default String toMessageString() {
return toString();
}
/**
* Gets a property from the attribute value.
*
*
This method never returns null. It should instead return
* a null value object when the property does not exist.
*
* @param key Property to get.
* @return Returns the nested property.
*/
AttributeValue getProperty(String key);
/**
* Gets a property using a path to the property.
*
* @param path The path to select from the value.
* @return Returns the created attribute value.
*/
default AttributeValue getPath(List path) {
if (!isPresent() || path.isEmpty()) {
return this;
}
AttributeValue current = this;
for (String segment : path) {
current = current.getProperty(segment);
if (!current.isPresent()) {
break;
}
}
return current;
}
/**
* Checks if the attribute value is considered present.
*
* Attribute value are considered present if they are not null. If the
* attribute value is a projection, then it is considered present if it is
* not empty.
*
* @return Returns true if present.
*/
default boolean isPresent() {
return true;
}
/**
* Gets all of the attribute values contained in the attribute value.
*
*
This will yield a single result for normal attributes, or a list
* of multiple values for projections.
*
* @return Returns the flattened attribute values contained in the attribute value.
*/
default Collection getFlattenedValues() {
return Collections.singleton(this);
}
/**
* Creates a 'shape' {@code AttributeValue} for the given shape.
*
* @param shape Shape to path into.
* @param vars Variables accessible to the shape.
* @return Returns the created selector value.
*/
static AttributeValue shape(Shape shape, Map> vars) {
return new AttributeValueImpl.ShapeValue(shape, vars);
}
/**
* Creates an 'id' {@code AttributeValue} from a shape ID.
*
* @param id Shape ID to create.
* @return Returns the created selector value.
*/
static AttributeValue id(ShapeId id) {
return new AttributeValueImpl.Id(id);
}
/**
* Creates a 'service' {@code AttributeValue} from a service shape.
*
* @param service Shape to create.
* @return Returns the created selector value.
*/
static AttributeValue service(ServiceShape service) {
return new AttributeValueImpl.Service(service);
}
/**
* Creates an empty {@code AttributeValue} object.
*
* @return Returns the created selector value.
*/
static AttributeValue emptyValue() {
return AttributeValueImpl.EMPTY;
}
/**
* Creates an {@code AttributeValue} that contains a literal value.
*
* @param literal Literal value to wrap.
* @return Returns the created selector value.
*/
static AttributeValue literal(Object literal) {
return new AttributeValueImpl.Literal(literal);
}
/**
* Creates a 'node' {@code AttributeValue} for a {@link Node}.
*
* @param node Node to create the value from.
* @return Returns the created attribute value.
*/
static AttributeValue node(Node node) {
return new AttributeValueImpl.NodeValue(node);
}
/**
* Creates a 'projection' {@code AttributeValue}.
*
* @param values Values stored in the projection.
* @return Returns the created projection.
*/
static AttributeValue projection(Collection values) {
return new AttributeValueImpl.Projection(values);
}
/**
* Uses the given parser to parse a scoped attribute production.
*
* @param parser Parser to consume.
* @return Returns the list of validated scoped attribute path segments.
* @throws RuntimeException if the parser does not contain a valid scoped attribute production.
* @see EmitEachSelectorValidator for an example of how this is used.
*/
static List parseScopedAttribute(SimpleParser parser) {
return SelectorParser.parseScopedValuePath(parser);
}
}