/*
 * 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
 *
 *   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.
 */
package org.apache.tinkerpop.gremlin.process.traversal.step.filter;

import org.apache.tinkerpop.gremlin.process.traversal.P;
import org.apache.tinkerpop.gremlin.process.traversal.Step;
import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement;

import java.util.List;
import java.util.Set;

/**
 * Defines the contract for steps containing a single {@link P}.
 */
public interface IsStepContract<S> extends Step<S, S> {

    /**
     * Concrete implementations of this contract that can be referenced as TinkerPop implementations.
     */
    List<Class<? extends Step>> CONCRETE_STEPS = List.of(IsStep.class, IsStepPlaceholder.class);

    /**
     * Retrieves the step's predicate.
     *
     * @return the predicate associated with the step
     */
    public P<S> getPredicate();

    default P<S> getPredicateGValueSafe() {
        return getPredicate();
    }

    public Set<TraverserRequirement> getRequirements();
}
