/*
 * Copyright 2008-2020 the original author or authors.
 *
 * 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
 *
 *      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.springframework.data.jpa.repository;

import java.util.List;
import java.util.Optional;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.lang.Nullable;

Interface to allow execution of Specifications based on the JPA criteria API. 
Author:
Oliver Gierke, Christoph Strobl/**
 * Interface to allow execution of {@link Specification}s based on the JPA criteria API.
 *
 * @author Oliver Gierke
 * @author Christoph Strobl
 */
public interface JpaSpecificationExecutor<T> {

	
Returns a single entity matching the given Specification or Optional.empty() if none found. 
Params:
spec – can be null.
Throws:
IncorrectResultSizeDataAccessException – if more than one entity found.
Returns:
never null./**
	 * Returns a single entity matching the given {@link Specification} or {@link Optional#empty()} if none found.
	 *
	 * @param spec can be {@literal null}.
	 * @return never {@literal null}.
	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one entity found.
	 */
	Optional<T> findOne(@Nullable Specification<T> spec);

	
Returns all entities matching the given Specification. 
Params:
spec – can be null.
Returns:
never null./**
	 * Returns all entities matching the given {@link Specification}.
	 *
	 * @param spec can be {@literal null}.
	 * @return never {@literal null}.
	 */
	List<T> findAll(@Nullable Specification<T> spec);

	
Returns a Page of entities matching the given Specification. 
Params:
spec – can be null.
pageable – must not be null.
Returns:
never null./**
	 * Returns a {@link Page} of entities matching the given {@link Specification}.
	 *
	 * @param spec can be {@literal null}.
	 * @param pageable must not be {@literal null}.
	 * @return never {@literal null}.
	 */
	Page<T> findAll(@Nullable Specification<T> spec, Pageable pageable);

	
Returns all entities matching the given Specification and Sort. 
Params:
spec – can be null.
sort – must not be null.
Returns:
never null./**
	 * Returns all entities matching the given {@link Specification} and {@link Sort}.
	 *
	 * @param spec can be {@literal null}.
	 * @param sort must not be {@literal null}.
	 * @return never {@literal null}.
	 */
	List<T> findAll(@Nullable Specification<T> spec, Sort sort);

	
Returns the number of instances that the given Specification will return. 
Params:
spec – the Specification to count instances for. Can be null.
Returns:
the number of instances./**
	 * Returns the number of instances that the given {@link Specification} will return.
	 *
	 * @param spec the {@link Specification} to count instances for. Can be {@literal null}.
	 * @return the number of instances.
	 */
	long count(@Nullable Specification<T> spec);
}