software.amazon.smithy.model.validation.validators.UnionValidator Maven / Gradle / Ivy

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/*
 * Copyright 2022 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.validation.validators;

import java.util.ArrayList;
import java.util.List;
import software.amazon.smithy.model.Model;
import software.amazon.smithy.model.node.Node;
import software.amazon.smithy.model.shapes.MemberShape;
import software.amazon.smithy.model.shapes.Shape;
import software.amazon.smithy.model.shapes.UnionShape;
import software.amazon.smithy.model.traits.BoxTrait;
import software.amazon.smithy.model.traits.DefaultTrait;
import software.amazon.smithy.model.validation.AbstractValidator;
import software.amazon.smithy.model.validation.ValidationEvent;
import software.amazon.smithy.utils.SmithyInternalApi;

@SmithyInternalApi
public final class UnionValidator extends AbstractValidator {
    @Override
    public List validate(Model model) {
        List events = new ArrayList<>();
        for (UnionShape union : model.getUnionShapes()) {
            if (union.members().isEmpty()) {
                events.add(error(union, "Tagged unions must have one or more members"));
            } else {
                for (MemberShape member : union.getAllMembers().values()) {
                    Shape target = model.expectShape(member.getTarget());
                    validateUnionMemberTarget(member, target, events);
                    validateUnionMember(member, events);
                }
            }
        }
        return events;
    }

    private void validateUnionMemberTarget(MemberShape member, Shape target, List events) {
        if (target.hasTrait(DefaultTrait.class)) {
            events.add(note(member, String.format(
                    "This union member targets `%s`, a shape with a default value of `%s`. Note that "
                    + "default values are only applicable to structures and ignored in tagged unions. It "
                    + "is a best practice for union members to target shapes with no default value (for example, "
                    + "instead of targeting PrimitiveInteger, target Integer).",
                    target.getId(), Node.printJson(target.expectTrait(DefaultTrait.class).toNode()))));
        }
    }

    private void validateUnionMember(MemberShape member, List events) {
        if (member.hasTrait(BoxTrait.class)) {
            events.add(warning(member, member.expectTrait(BoxTrait.class),
                               "Invalid box trait found on a union member. The box trait on union members "
                               + "has no effect because union members are implicitly nullable."));
        }
    }
}