/*
 * Copyright (c) 2009, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package java.util;

import jdk.internal.HotSpotIntrinsicCandidate;

import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;

/**
 * This class consists of {@code static} utility methods for operating
 * on objects, or checking certain conditions before operation.  These utilities
 * include {@code null}-safe or {@code null}-tolerant methods for computing the
 * hash code of an object, returning a string for an object, comparing two
 * objects, and checking if indexes or sub-range values are out-of-bounds.
 *
 * @apiNote
 * Static methods such as {@link Objects#checkIndex},
 * {@link Objects#checkFromToIndex}, and {@link Objects#checkFromIndexSize} are
 * provided for the convenience of checking if values corresponding to indexes
 * and sub-ranges are out-of-bounds.
 * Variations of these static methods support customization of the runtime
 * exception, and corresponding exception detail message, that is thrown when
 * values are out-of-bounds.  Such methods accept a functional interface
 * argument, instances of {@code BiFunction}, that maps out-of-bound values to a
 * runtime exception.  Care should be taken when using such methods in
 * combination with an argument that is a lambda expression, method reference or
 * class that capture values.  In such cases the cost of capture, related to
 * functional interface allocation, may exceed the cost of checking bounds.
 *
 * @since 1.7
 */
public final class Objects {
    private Objects() {
        throw new AssertionError("No java.util.Objects instances for you!");
    }

    /**
     * Returns {@code true} if the arguments are equal to each other
     * and {@code false} otherwise.
     * Consequently, if both arguments are {@code null}, {@code true}
     * is returned and if exactly one argument is {@code null}, {@code
     * false} is returned.  Otherwise, equality is determined by using
     * the {@link Object#equals equals} method of the first
     * argument.
     *
     * @param a an object
     * @param b an object to be compared with {@code a} for equality
     * @return {@code true} if the arguments are equal to each other
     * and {@code false} otherwise
     * @see Object#equals(Object)
     */
    public static boolean equals(Object a, Object b) {
        return (a == b) || (a != null && a.equals(b));
    }

   /**
    * Returns {@code true} if the arguments are deeply equal to each other
    * and {@code false} otherwise.
    *
    * Two {@code null} values are deeply equal.  If both arguments are
    * arrays, the algorithm in {@link Arrays#deepEquals(Object[],
    * Object[]) Arrays.deepEquals} is used to determine equality.
    * Otherwise, equality is determined by using the {@link
    * Object#equals equals} method of the first argument.
    *
    * @param a an object
    * @param b an object to be compared with {@code a} for deep equality
    * @return {@code true} if the arguments are deeply equal to each other
    * and {@code false} otherwise
    * @see Arrays#deepEquals(Object[], Object[])
    * @see Objects#equals(Object, Object)
    */
    public static boolean deepEquals(Object a, Object b) {
        if (a == b)
            return true;
        else if (a == null || b == null)
            return false;
        else
            return Arrays.deepEquals0(a, b);
    }

    /**
     * Returns the hash code of a non-{@code null} argument and 0 for
     * a {@code null} argument.
     *
     * @param o an object
     * @return the hash code of a non-{@code null} argument and 0 for
     * a {@code null} argument
     * @see Object#hashCode
     */
    public static int hashCode(Object o) {
        return o != null ? o.hashCode() : 0;
    }

   /**
    * Generates a hash code for a sequence of input values. The hash
    * code is generated as if all the input values were placed into an
    * array, and that array were hashed by calling {@link
    * Arrays#hashCode(Object[])}.
    *
    * <p>This method is useful for implementing {@link
    * Object#hashCode()} on objects containing multiple fields. For
    * example, if an object that has three fields, {@code x}, {@code
    * y}, and {@code z}, one could write:
    *
    * <blockquote><pre>
    * &#064;Override public int hashCode() {
    *     return Objects.hash(x, y, z);
    * }
    * </pre></blockquote>
    *
    * <b>Warning: When a single object reference is supplied, the returned
    * value does not equal the hash code of that object reference.</b> This
    * value can be computed by calling {@link #hashCode(Object)}.
    *
    * @param values the values to be hashed
    * @return a hash value of the sequence of input values
    * @see Arrays#hashCode(Object[])
    * @see List#hashCode
    */
    public static int hash(Object... values) {
        return Arrays.hashCode(values);
    }

    /**
     * Returns the result of calling {@code toString} for a non-{@code
     * null} argument and {@code "null"} for a {@code null} argument.
     *
     * @param o an object
     * @return the result of calling {@code toString} for a non-{@code
     * null} argument and {@code "null"} for a {@code null} argument
     * @see Object#toString
     * @see String#valueOf(Object)
     */
    public static String toString(Object o) {
        return String.valueOf(o);
    }

    /**
     * Returns the result of calling {@code toString} on the first
     * argument if the first argument is not {@code null} and returns
     * the second argument otherwise.
     *
     * @param o an object
     * @param nullDefault string to return if the first argument is
     *        {@code null}
     * @return the result of calling {@code toString} on the first
     * argument if it is not {@code null} and the second argument
     * otherwise.
     * @see Objects#toString(Object)
     */
    public static String toString(Object o, String nullDefault) {
        return (o != null) ? o.toString() : nullDefault;
    }

    /**
     * Returns 0 if the arguments are identical and {@code
     * c.compare(a, b)} otherwise.
     * Consequently, if both arguments are {@code null} 0
     * is returned.
     *
     * <p>Note that if one of the arguments is {@code null}, a {@code
     * NullPointerException} may or may not be thrown depending on
     * what ordering policy, if any, the {@link Comparator Comparator}
     * chooses to have for {@code null} values.
     *
     * @param <T> the type of the objects being compared
     * @param a an object
     * @param b an object to be compared with {@code a}
     * @param c the {@code Comparator} to compare the first two arguments
     * @return 0 if the arguments are identical and {@code
     * c.compare(a, b)} otherwise.
     * @see Comparable
     * @see Comparator
     */
    public static <T> int compare(T a, T b, Comparator<? super T> c) {
        return (a == b) ? 0 :  c.compare(a, b);
    }

    /**
     * Checks that the specified object reference is not {@code null}. This
     * method is designed primarily for doing parameter validation in methods
     * and constructors, as demonstrated below:
     * <blockquote><pre>
     * public Foo(Bar bar) {
     *     this.bar = Objects.requireNonNull(bar);
     * }
     * </pre></blockquote>
     *
     * @param obj the object reference to check for nullity
     * @param <T> the type of the reference
     * @return {@code obj} if not {@code null}
     * @throws NullPointerException if {@code obj} is {@code null}
     */
    public static <T> T requireNonNull(T obj) {
        if (obj == null)
            throw new NullPointerException();
        return obj;
    }

    /**
     * Checks that the specified object reference is not {@code null} and
     * throws a customized {@link NullPointerException} if it is. This method
     * is designed primarily for doing parameter validation in methods and
     * constructors with multiple parameters, as demonstrated below:
     * <blockquote><pre>
     * public Foo(Bar bar, Baz baz) {
     *     this.bar = Objects.requireNonNull(bar, "bar must not be null");
     *     this.baz = Objects.requireNonNull(baz, "baz must not be null");
     * }
     * </pre></blockquote>
     *
     * @param obj     the object reference to check for nullity
     * @param message detail message to be used in the event that a {@code
     *                NullPointerException} is thrown
     * @param <T> the type of the reference
     * @return {@code obj} if not {@code null}
     * @throws NullPointerException if {@code obj} is {@code null}
     */
    public static <T> T requireNonNull(T obj, String message) {
        if (obj == null)
            throw new NullPointerException(message);
        return obj;
    }

    /**
     * Returns {@code true} if the provided reference is {@code null} otherwise
     * returns {@code false}.
     *
     * @apiNote This method exists to be used as a
     * {@link java.util.function.Predicate}, {@code filter(Objects::isNull)}
     *
     * @param obj a reference to be checked against {@code null}
     * @return {@code true} if the provided reference is {@code null} otherwise
     * {@code false}
     *
     * @see java.util.function.Predicate
     * @since 1.8
     */
    public static boolean isNull(Object obj) {
        return obj == null;
    }

    /**
     * Returns {@code true} if the provided reference is non-{@code null}
     * otherwise returns {@code false}.
     *
     * @apiNote This method exists to be used as a
     * {@link java.util.function.Predicate}, {@code filter(Objects::nonNull)}
     *
     * @param obj a reference to be checked against {@code null}
     * @return {@code true} if the provided reference is non-{@code null}
     * otherwise {@code false}
     *
     * @see java.util.function.Predicate
     * @since 1.8
     */
    public static boolean nonNull(Object obj) {
        return obj != null;
    }

    /**
     * Returns the first argument if it is non-{@code null} and
     * otherwise returns the non-{@code null} second argument.
     *
     * @param obj an object
     * @param defaultObj a non-{@code null} object to return if the first argument
     *                   is {@code null}
     * @param <T> the type of the reference
     * @return the first argument if it is non-{@code null} and
     *        otherwise the second argument if it is non-{@code null}
     * @throws NullPointerException if both {@code obj} is null and
     *        {@code defaultObj} is {@code null}
     * @since 9
     */
    public static <T> T requireNonNullElse(T obj, T defaultObj) {
        return (obj != null) ? obj : requireNonNull(defaultObj, "defaultObj");
    }

    /**
     * Returns the first argument if it is non-{@code null} and otherwise
     * returns the non-{@code null} value of {@code supplier.get()}.
     *
     * @param obj an object
     * @param supplier of a non-{@code null} object to return if the first argument
     *                 is {@code null}
     * @param <T> the type of the first argument and return type
     * @return the first argument if it is non-{@code null} and otherwise
     *         the value from {@code supplier.get()} if it is non-{@code null}
     * @throws NullPointerException if both {@code obj} is null and
     *        either the {@code supplier} is {@code null} or
     *        the {@code supplier.get()} value is {@code null}
     * @since 9
     */
    public static <T> T requireNonNullElseGet(T obj, Supplier<? extends T> supplier) {
        return (obj != null) ? obj
                : requireNonNull(requireNonNull(supplier, "supplier").get(), "supplier.get()");
    }

    /**
     * Checks that the specified object reference is not {@code null} and
     * throws a customized {@link NullPointerException} if it is.
     *
     * <p>Unlike the method {@link #requireNonNull(Object, String)},
     * this method allows creation of the message to be deferred until
     * after the null check is made. While this may confer a
     * performance advantage in the non-null case, when deciding to
     * call this method care should be taken that the costs of
     * creating the message supplier are less than the cost of just
     * creating the string message directly.
     *
     * @param obj     the object reference to check for nullity
     * @param messageSupplier supplier of the detail message to be
     * used in the event that a {@code NullPointerException} is thrown
     * @param <T> the type of the reference
     * @return {@code obj} if not {@code null}
     * @throws NullPointerException if {@code obj} is {@code null}
     * @since 1.8
     */
    public static <T> T requireNonNull(T obj, Supplier<String> messageSupplier) {
        if (obj == null)
            throw new NullPointerException(messageSupplier.get());
        return obj;
    }

    /**
     * Maps out-of-bounds values to a runtime exception.
     *
     * @param checkKind the kind of bounds check, whose name may correspond
     *        to the name of one of the range check methods, checkIndex,
     *        checkFromToIndex, checkFromIndexSize
     * @param args the out-of-bounds arguments that failed the range check.
     *        If the checkKind corresponds a the name of a range check method
     *        then the bounds arguments are those that can be passed in order
     *        to the method.
     * @param oobef the exception formatter that when applied with a checkKind
     *        and a list out-of-bounds arguments returns a runtime exception.
     *        If {@code null} then, it is as if an exception formatter was
     *        supplied that returns {@link IndexOutOfBoundsException} for any
     *        given arguments.
     * @return the runtime exception
     */
    private static RuntimeException outOfBounds(
            BiFunction<String, List<Integer>, ? extends RuntimeException> oobef,
            String checkKind,
            Integer... args) {
        List<Integer> largs = List.of(args);
        RuntimeException e = oobef == null
                             ? null : oobef.apply(checkKind, largs);
        return e == null
               ? new IndexOutOfBoundsException(outOfBoundsMessage(checkKind, largs)) : e;
    }

    // Specific out-of-bounds exception producing methods that avoid
    // the varargs-based code in the critical methods there by reducing their
    // the byte code size, and therefore less likely to peturb inlining

    private static RuntimeException outOfBoundsCheckIndex(
            BiFunction<String, List<Integer>, ? extends RuntimeException> oobe,
            int index, int length) {
        return outOfBounds(oobe, "checkIndex", index, length);
    }

    private static RuntimeException outOfBoundsCheckFromToIndex(
            BiFunction<String, List<Integer>, ? extends RuntimeException> oobe,
            int fromIndex, int toIndex, int length) {
        return outOfBounds(oobe, "checkFromToIndex", fromIndex, toIndex, length);
    }

    private static RuntimeException outOfBoundsCheckFromIndexSize(
            BiFunction<String, List<Integer>, ? extends RuntimeException> oobe,
            int fromIndex, int size, int length) {
        return outOfBounds(oobe, "checkFromIndexSize", fromIndex, size, length);
    }

    /**
     * Returns an out-of-bounds exception formatter from an given exception
     * factory.  The exception formatter is a function that formats an
     * out-of-bounds message from its arguments and applies that message to the
     * given exception factory to produce and relay an exception.
     *
     * <p>The exception formatter accepts two arguments: a {@code String}
     * describing the out-of-bounds range check that failed, referred to as the
     * <em>check kind</em>; and a {@code List<Integer>} containing the
     * out-of-bound integer values that failed the check.  The list of
     * out-of-bound values is not modified.
     *
     * <p>Three check kinds are supported {@code checkIndex},
     * {@code checkFromToIndex} and {@code checkFromIndexSize} corresponding
     * respectively to the specified application of an exception formatter as an
     * argument to the out-of-bounds range check methods
     * {@link #checkIndex(int, int, BiFunction) checkIndex},
     * {@link #checkFromToIndex(int, int, int, BiFunction) checkFromToIndex}, and
     * {@link #checkFromIndexSize(int, int, int, BiFunction) checkFromIndexSize}.
     * Thus a supported check kind corresponds to a method name and the
     * out-of-bound integer values correspond to method argument values, in
     * order, preceding the exception formatter argument (similar in many
     * respects to the form of arguments required for a reflective invocation of
     * such a range check method).
     *
     * <p>Formatter arguments conforming to such supported check kinds will
     * produce specific exception messages describing failed out-of-bounds
     * checks.  Otherwise, more generic exception messages will be produced in
     * any of the following cases: the check kind is supported but fewer
     * or more out-of-bounds values are supplied, the check kind is not
     * supported, the check kind is {@code null}, or the list of out-of-bound
     * values is {@code null}.
     *
     * @apiNote
     * This method produces an out-of-bounds exception formatter that can be
     * passed as an argument to any of the supported out-of-bounds range check
     * methods declared by {@code Objects}.  For example, a formatter producing
     * an {@code ArrayIndexOutOfBoundsException} may be produced and stored on a
     * {@code static final} field as follows:
     * <pre>{@code
     * static final
     * BiFunction<String, List<Integer>, ArrayIndexOutOfBoundsException> AIOOBEF =
     *     outOfBoundsExceptionFormatter(ArrayIndexOutOfBoundsException::new);
     * }</pre>
     * The formatter instance {@code AIOOBEF} may be passed as an argument to an
     * out-of-bounds range check method, such as checking if an {@code index}
     * is within the bounds of a {@code limit}:
     * <pre>{@code
     * checkIndex(index, limit, AIOOBEF);
     * }</pre>
     * If the bounds check fails then the range check method will throw an
     * {@code ArrayIndexOutOfBoundsException} with an appropriate exception
     * message that is a produced from {@code AIOOBEF} as follows:
     * <pre>{@code
     * AIOOBEF.apply("checkIndex", List.of(index, limit));
     * }</pre>
     *
     * @param f the exception factory, that produces an exception from a message
     *        where the message is produced and formatted by the returned
     *        exception formatter.  If this factory is stateless and side-effect
     *        free then so is the returned formatter.
     *        Exceptions thrown by the factory are relayed to the caller
     *        of the returned formatter.
     * @param <X> the type of runtime exception to be returned by the given
     *        exception factory and relayed by the exception formatter
     * @return the out-of-bounds exception formatter
     */
    public static <X extends RuntimeException>
    BiFunction<String, List<Integer>, X> outOfBoundsExceptionFormatter(Function<String, X> f) {
        // Use anonymous class to avoid bootstrap issues if this method is
        // used early in startup
        return new BiFunction<String, List<Integer>, X>() {
            @Override
            public X apply(String checkKind, List<Integer> args) {
                return f.apply(outOfBoundsMessage(checkKind, args));
            }
        };
    }

    private static String outOfBoundsMessage(String checkKind, List<Integer> args) {
        if (checkKind == null && args == null) {
            return String.format("Range check failed");
        } else if (checkKind == null) {
            return String.format("Range check failed: %s", args);
        } else if (args == null) {
            return String.format("Range check failed: %s", checkKind);
        }

        int argSize = 0;
        switch (checkKind) {
            case "checkIndex":
                argSize = 2;
                break;
            case "checkFromToIndex":
            case "checkFromIndexSize":
                argSize = 3;
                break;
            default:
        }

        // Switch to default if fewer or more arguments than required are supplied
        switch ((args.size() != argSize) ? "" : checkKind) {
            case "checkIndex":
                return String.format("Index %d out-of-bounds for length %d",
                                     args.get(0), args.get(1));
            case "checkFromToIndex":
                return String.format("Range [%d, %d) out-of-bounds for length %d",
                                     args.get(0), args.get(1), args.get(2));
            case "checkFromIndexSize":
                return String.format("Range [%d, %<d + %d) out-of-bounds for length %d",
                                     args.get(0), args.get(1), args.get(2));
            default:
                return String.format("Range check failed: %s %s", checkKind, args);
        }
    }

    /**
     * Checks if the {@code index} is within the bounds of the range from
     * {@code 0} (inclusive) to {@code length} (exclusive).
     *
     * <p>The {@code index} is defined to be out-of-bounds if any of the
     * following inequalities is true:
     * <ul>
     *  <li>{@code index < 0}</li>
     *  <li>{@code index >= length}</li>
     *  <li>{@code length < 0}, which is implied from the former inequalities</li>
     * </ul>
     *
     * <p>This method behaves as if {@link #checkIndex(int, int, BiFunction)}
     * was called with same out-of-bounds arguments and an exception formatter
     * argument produced from an invocation of
     * {@code outOfBoundsExceptionFormatter(IndexOutOfBounds::new)} (though it may
     * be more efficient).
     *
     * @param index the index
     * @param length the upper-bound (exclusive) of the range
     * @return {@code index} if it is within bounds of the range
     * @throws IndexOutOfBoundsException if the {@code index} is out-of-bounds
     * @since 9
     */
    public static
    int checkIndex(int index, int length) {
        return checkIndex(index, length, null);
    }

    /**
     * Checks if the {@code index} is within the bounds of the range from
     * {@code 0} (inclusive) to {@code length} (exclusive).
     *
     * <p>The {@code index} is defined to be out-of-bounds if any of the
     * following inequalities is true:
     * <ul>
     *  <li>{@code index < 0}</li>
     *  <li>{@code index >= length}</li>
     *  <li>{@code length < 0}, which is implied from the former inequalities</li>
     * </ul>
     *
     * <p>If the {@code index} is out-of-bounds, then a runtime exception is
     * thrown that is the result of applying the following arguments to the
     * exception formatter: the name of this method, {@code checkIndex};
     * and an unmodifiable list integers whose values are, in order, the
     * out-of-bounds arguments {@code index} and {@code length}.
     *
     * @param <X> the type of runtime exception to throw if the arguments are
     *        out-of-bounds
     * @param index the index
     * @param length the upper-bound (exclusive) of the range
     * @param oobef the exception formatter that when applied with this
     *        method name and out-of-bounds arguments returns a runtime
     *        exception.  If {@code null} or returns {@code null} then, it is as
     *        if an exception formatter produced from an invocation of
     *        {@code outOfBoundsExceptionFormatter(IndexOutOfBounds::new)} is used
     *        instead (though it may be more efficient).
     *        Exceptions thrown by the formatter are relayed to the caller.
     * @return {@code index} if it is within bounds of the range
     * @throws X if the {@code index} is out-of-bounds and the exception
     *         formatter is non-{@code null}
     * @throws IndexOutOfBoundsException if the {@code index} is out-of-bounds
     *         and the exception formatter is {@code null}
     * @since 9
     *
     * @implNote
     * This method is made intrinsic in optimizing compilers to guide them to
     * perform unsigned comparisons of the index and length when it is known the
     * length is a non-negative value (such as that of an array length or from
     * the upper bound of a loop)
    */
    @HotSpotIntrinsicCandidate
    public static <X extends RuntimeException>
    int checkIndex(int index, int length,
                   BiFunction<String, List<Integer>, X> oobef) {
        if (index < 0 || index >= length)
            throw outOfBoundsCheckIndex(oobef, index, length);
        return index;
    }

    /**
     * Checks if the sub-range from {@code fromIndex} (inclusive) to
     * {@code toIndex} (exclusive) is within the bounds of range from {@code 0}
     * (inclusive) to {@code length} (exclusive).
     *
     * <p>The sub-range is defined to be out-of-bounds if any of the following
     * inequalities is true:
     * <ul>
     *  <li>{@code fromIndex < 0}</li>
     *  <li>{@code fromIndex > toIndex}</li>
     *  <li>{@code toIndex > length}</li>
     *  <li>{@code length < 0}, which is implied from the former inequalities</li>
     * </ul>
     *
     * <p>This method behaves as if {@link #checkFromToIndex(int, int, int, BiFunction)}
     * was called with same out-of-bounds arguments and an exception formatter
     * argument produced from an invocation of
     * {@code outOfBoundsExceptionFormatter(IndexOutOfBounds::new)} (though it may
     * be more efficient).
     *
     * @param fromIndex the lower-bound (inclusive) of the sub-range
     * @param toIndex the upper-bound (exclusive) of the sub-range
     * @param length the upper-bound (exclusive) the range
     * @return {@code fromIndex} if the sub-range within bounds of the range
     * @throws IndexOutOfBoundsException if the sub-range is out-of-bounds
     * @since 9
     */
    public static
    int checkFromToIndex(int fromIndex, int toIndex, int length) {
        return checkFromToIndex(fromIndex, toIndex, length, null);
    }

    /**
     * Checks if the sub-range from {@code fromIndex} (inclusive) to
     * {@code toIndex} (exclusive) is within the bounds of range from {@code 0}
     * (inclusive) to {@code length} (exclusive).
     *
     * <p>The sub-range is defined to be out-of-bounds if any of the following
     * inequalities is true:
     * <ul>
     *  <li>{@code fromIndex < 0}</li>
     *  <li>{@code fromIndex > toIndex}</li>
     *  <li>{@code toIndex > length}</li>
     *  <li>{@code length < 0}, which is implied from the former inequalities</li>
     * </ul>
     *
     * <p>If the sub-range  is out-of-bounds, then a runtime exception is
     * thrown that is the result of applying the following arguments to the
     * exception formatter: the name of this method, {@code checkFromToIndex};
     * and an unmodifiable list integers whose values are, in order, the
     * out-of-bounds arguments {@code fromIndex}, {@code toIndex}, and {@code length}.
     *
     * @param <X> the type of runtime exception to throw if the arguments are
     *        out-of-bounds
     * @param fromIndex the lower-bound (inclusive) of the sub-range
     * @param toIndex the upper-bound (exclusive) of the sub-range
     * @param length the upper-bound (exclusive) the range
     * @param oobef the exception formatter that when applied with this
     *        method name and out-of-bounds arguments returns a runtime
     *        exception.  If {@code null} or returns {@code null} then, it is as
     *        if an exception formatter produced from an invocation of
     *        {@code outOfBoundsExceptionFormatter(IndexOutOfBounds::new)} is used
     *        instead (though it may be more efficient).
     *        Exceptions thrown by the formatter are relayed to the caller.
     * @return {@code fromIndex} if the sub-range within bounds of the range
     * @throws X if the sub-range is out-of-bounds and the exception factory
     *         function is non-{@code null}
     * @throws IndexOutOfBoundsException if the sub-range is out-of-bounds and
     *         the exception factory function is {@code null}
     * @since 9
     */
    public static <X extends RuntimeException>
    int checkFromToIndex(int fromIndex, int toIndex, int length,
                         BiFunction<String, List<Integer>, X> oobef) {
        if (fromIndex < 0 || fromIndex > toIndex || toIndex > length)
            throw outOfBoundsCheckFromToIndex(oobef, fromIndex, toIndex, length);
        return fromIndex;
    }

    /**
     * Checks if the sub-range from {@code fromIndex} (inclusive) to
     * {@code fromIndex + size} (exclusive) is within the bounds of range from
     * {@code 0} (inclusive) to {@code length} (exclusive).
     *
     * <p>The sub-range is defined to be out-of-bounds if any of the following
     * inequalities is true:
     * <ul>
     *  <li>{@code fromIndex < 0}</li>
     *  <li>{@code size < 0}</li>
     *  <li>{@code fromIndex + size > length}, taking into account integer overflow</li>
     *  <li>{@code length < 0}, which is implied from the former inequalities</li>
     * </ul>
     *
     * <p>This method behaves as if {@link #checkFromIndexSize(int, int, int, BiFunction)}
     * was called with same out-of-bounds arguments and an exception formatter
     * argument produced from an invocation of
     * {@code outOfBoundsExceptionFormatter(IndexOutOfBounds::new)} (though it may
     * be more efficient).
     *
     * @param fromIndex the lower-bound (inclusive) of the sub-interval
     * @param size the size of the sub-range
     * @param length the upper-bound (exclusive) of the range
     * @return {@code fromIndex} if the sub-range within bounds of the range
     * @throws IndexOutOfBoundsException if the sub-range is out-of-bounds
     * @since 9
     */
    public static
    int checkFromIndexSize(int fromIndex, int size, int length) {
        return checkFromIndexSize(fromIndex, size, length, null);
    }

    /**
     * Checks if the sub-range from {@code fromIndex} (inclusive) to
     * {@code fromIndex + size} (exclusive) is within the bounds of range from
     * {@code 0} (inclusive) to {@code length} (exclusive).
     *
     * <p>The sub-range is defined to be out-of-bounds if any of the following
     * inequalities is true:
     * <ul>
     *  <li>{@code fromIndex < 0}</li>
     *  <li>{@code size < 0}</li>
     *  <li>{@code fromIndex + size > length}, taking into account integer overflow</li>
     *  <li>{@code length < 0}, which is implied from the former inequalities</li>
     * </ul>
     *
     * <p>If the sub-range  is out-of-bounds, then a runtime exception is
     * thrown that is the result of applying the following arguments to the
     * exception formatter: the name of this method, {@code checkFromIndexSize};
     * and an unmodifiable list integers whose values are, in order, the
     * out-of-bounds arguments {@code fromIndex}, {@code size}, and
     * {@code length}.
     *
     * @param <X> the type of runtime exception to throw if the arguments are
     *        out-of-bounds
     * @param fromIndex the lower-bound (inclusive) of the sub-interval
     * @param size the size of the sub-range
     * @param length the upper-bound (exclusive) of the range
     * @param oobef the exception formatter that when applied with this
     *        method name and out-of-bounds arguments returns a runtime
     *        exception.  If {@code null} or returns {@code null} then, it is as
     *        if an exception formatter produced from an invocation of
     *        {@code outOfBoundsExceptionFormatter(IndexOutOfBounds::new)} is used
     *        instead (though it may be more efficient).
     *        Exceptions thrown by the formatter are relayed to the caller.
     * @return {@code fromIndex} if the sub-range within bounds of the range
     * @throws X if the sub-range is out-of-bounds and the exception factory
     *         function is non-{@code null}
     * @throws IndexOutOfBoundsException if the sub-range is out-of-bounds and
     *         the exception factory function is {@code null}
     * @since 9
     */
    public static <X extends RuntimeException>
    int checkFromIndexSize(int fromIndex, int size, int length,
                           BiFunction<String, List<Integer>, X> oobef) {
        if ((length | fromIndex | size) < 0 || size > length - fromIndex)
            throw outOfBoundsCheckFromIndexSize(oobef, fromIndex, size, length);
        return fromIndex;
    }
}