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A Speedment bundle that shades all dependencies into one jar. This is useful when deploying an application on a server.
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/*
 *
 * Copyright (c) 2006-2019, Speedment, Inc. 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.
 */
package com.speedment.runtime.compute.expression;

import com.speedment.runtime.compute.expression.orelse.OrElseGetExpression;
import com.speedment.runtime.compute.expression.orelse.OrElseThrowExpression;

/**
 * Specialized {@link Expression} that is not nullable, but that wraps an
 * expression that is and that has some routine for dealing with {@code null}
 * values determined by {@link #nullStrategy()}.
 * 
 * Equality is determined by looking at {@link #innerNullable()} and
 * {@link #nullStrategy()}, and additionally by the
 * {@link OrElseGetExpression#defaultValueGetter()} or the
 * {@code getDefaultValue()} if the strategy is
 * {@link NullStrategy#APPLY_DEFAULT_METHOD} or
 * {@link NullStrategy#USE_DEFAULT_VALUE} respectively.
 *
 * @param       the input entity type
 * @param   the type of the inner expression
 *
 * @author Emil Forslund
 * @since  3.1.0
 */
public interface NonNullableExpression>
extends Expression {

    /**
     * Returns the inner nullable expression.
     *
     * @return  the inner nullable expression
     */
    INNER innerNullable();

    /**
     * Returns the strategy used by this expression to deal with the case when
     * {@link #innerNullable()} would have returned {@code null}.
     *
     * @return  the null-strategy used
     */
    NullStrategy nullStrategy();

    /**
     * The strategies possible when dealing with {@code null}-values.
     */
    enum NullStrategy {

        /**
         * Whenever the {@link #innerNullable() inner} expression returns a
         * {@code null} value, a specific constant value will be returned by
         * this expression. If this strategy is used, then the class should also
         * implement the corresponding {@code To__OrElseExpression} depending on
         * the {@link Expression#expressionType() type}.
         */
        USE_DEFAULT_VALUE,

        /**
         * Whenever the {@link #innerNullable() inner} expression returns a
         * {@code null} value, the
         * {@link OrElseGetExpression#defaultValueGetter() other} expression
         * will be invoked to determine the value instead. If this strategy is
         * used, then the class should also implement
         * {@link OrElseGetExpression}.
         */
        APPLY_DEFAULT_METHOD,

        /**
         * Whenever the {@link #innerNullable() inner} expression returns a
         * {@code null} value, a {@code NullPointerException} is thrown. If this
         * strategy is used, then the class should also implement
         * {@link OrElseThrowExpression}.
         */
        THROW_EXCEPTION
    }
}