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/*
 * Copyright 2002-2013 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
 *
 *      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 spark.utils;

/**
 * Assertion utility class that assists in validating arguments.
 * Useful for identifying programmer errors early and clearly at runtime.
 * For example, if the contract of a public method states it does not
 * allow {@code null} arguments, Assert can be used to validate that
 * contract. Doing this clearly indicates a contract violation when it
 * occurs and protects the class's invariants.
 * 
Typically used to validate method arguments rather than configuration
 * properties, to check for cases that are usually programmer errors rather than
 * configuration errors. In contrast to config initialization code, there is
 * usually no point in falling back to defaults in such methods.
 * 
This class is similar to JUnit's assertion library. If an argument value is
 * deemed invalid, an {@link IllegalArgumentException} is thrown (typically).
 *
 * @author Keith Donald
 * @author Juergen Hoeller
 * @author Colin Sampaleanu
 * @author Rob Harrop
 *
 * Code copied from Spring source. Modifications made (mostly removal of methods) by Per Wendel.
 */
public abstract class Assert {

    /**
     * Assert a boolean expression, throwing {@code IllegalArgumentException}
     * if the test result is {@code false}.
     * 
Assert.isTrue(i > 0, "The value must be greater than zero");
     *
     * @param expression a boolean expression
     * @param message    the exception message to use if the assertion fails
     * @throws IllegalArgumentException if expression is {@code false}
     */
    public static void isTrue(boolean expression, String message) {
        if (!expression) {
            throw new IllegalArgumentException(message);
        }
    }

    /**
     * Assert that an object is not {@code null} .
     * Assert.notNull(clazz, "The class must not be null");
     *
     * @param object  the object to check
     * @param message the exception message to use if the assertion fails
     * @throws IllegalArgumentException if the object is {@code null}
     */
    public static void notNull(Object object, String message) {
        if (object == null) {
            throw new IllegalArgumentException(message);
        }
    }

    /**
     * Assert that an object is not {@code null} .
     * Assert.notNull(clazz);
     *
     * @param object the object to check
     * @throws IllegalArgumentException if the object is {@code null}
     */
    public static void notNull(Object object) {
        notNull(object, "[Assertion failed] - this argument is required; it must not be null");
    }

    /**
     * Assert that the given String is not empty; that is,
     * it must not be {@code null} and not the empty String.
     * Assert.hasLength(name, "Name must not be empty");
     *
     * @param text    the String to check
     * @param message the exception message to use if the assertion fails
     * @see StringUtils#hasLength
     */
    public static void hasLength(String text, String message) {
        if (!StringUtils.hasLength(text)) {
            throw new IllegalArgumentException(message);
        }
    }

    /**
     * Assert that an array has elements; that is, it must not be
     * {@code null} and must have at least one element.
     * Assert.notEmpty(array, "The array must have elements");
     *
     * @param array   the array to check
     * @param message the exception message to use if the assertion fails
     * @throws IllegalArgumentException if the object array is {@code null} or has no elements
     */
    public static void notEmpty(Object[] array, String message) {
        if (ObjectUtils.isEmpty(array)) {
            throw new IllegalArgumentException(message);
        }
    }

    /**
     * Assert a boolean expression, throwing {@code IllegalStateException}
     * if the test result is {@code false}. Call isTrue if you wish to
     * throw IllegalArgumentException on an assertion failure.
     * Assert.state(id == null, "The id property must not already be initialized");
     *
     * @param expression a boolean expression
     * @param message    the exception message to use if the assertion fails
     * @throws IllegalStateException if expression is {@code false}
     */
    public static void state(boolean expression, String message) {
        if (!expression) {
            throw new IllegalStateException(message);
        }
    }

}