--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/time/temporal/TemporalUnit.java Tue Jan 22 20:59:21 2013 -0800
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2012, 2013, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * * Neither the name of JSR-310 nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package java.time.temporal;
+
+import java.time.DateTimeException;
+import java.time.Duration;
+import java.time.Period;
+
+/**
+ * A unit of date-time, such as Days or Hours.
+ * <p>
+ * Measurement of time is built on units, such as years, months, days, hours, minutes and seconds.
+ * Implementations of this interface represent those units.
+ * <p>
+ * An instance of this interface represents the unit itself, rather than an amount of the unit.
+ * See {@link Period} for a class that represents an amount in terms of the common units.
+ * <p>
+ * The most commonly used units are defined in {@link ChronoUnit}.
+ * Further units are supplied in {@link ISOFields}.
+ * Units can also be written by application code by implementing this interface.
+ * <p>
+ * The unit works using double dispatch. Client code calls methods on a date-time like
+ * {@code LocalDateTime} which check if the unit is a {@code ChronoUnit}.
+ * If it is, then the date-time must handle it.
+ * Otherwise, the method call is re-dispatched to the matching method in this interface.
+ *
+ * <h3>Specification for implementors</h3>
+ * This interface must be implemented with care to ensure other classes operate correctly.
+ * All implementations that can be instantiated must be final, immutable and thread-safe.
+ * It is recommended to use an enum where possible.
+ *
+ * @since 1.8
+ */
+public interface TemporalUnit {
+
+ /**
+ * Gets a descriptive name for the unit.
+ * <p>
+ * This should be in the plural and upper-first camel case, such as 'Days' or 'Minutes'.
+ *
+ * @return the name, not null
+ */
+ String getName();
+
+ /**
+ * Gets the duration of this unit, which may be an estimate.
+ * <p>
+ * All units return a duration measured in standard nanoseconds from this method.
+ * For example, an hour has a duration of {@code 60 * 60 * 1,000,000,000ns}.
+ * <p>
+ * Some units may return an accurate duration while others return an estimate.
+ * For example, days have an estimated duration due to the possibility of
+ * daylight saving time changes.
+ * To determine if the duration is an estimate, use {@link #isDurationEstimated()}.
+ *
+ * @return the duration of this unit, which may be an estimate, not null
+ */
+ Duration getDuration();
+
+ /**
+ * Checks if the duration of the unit is an estimate.
+ * <p>
+ * All units have a duration, however the duration is not always accurate.
+ * For example, days have an estimated duration due to the possibility of
+ * daylight saving time changes.
+ * This method returns true if the duration is an estimate and false if it is
+ * accurate. Note that accurate/estimated ignores leap seconds.
+ *
+ * @return true if the duration is estimated, false if accurate
+ */
+ boolean isDurationEstimated();
+
+ //-----------------------------------------------------------------------
+ /**
+ * Checks if this unit is supported by the specified temporal object.
+ * <p>
+ * This checks that the implementing date-time can add/subtract this unit.
+ * This can be used to avoid throwing an exception.
+ * <p>
+ * This default implementation derives the value using
+ * {@link Temporal#plus(long, TemporalUnit)}.
+ *
+ * @param temporal the temporal object to check, not null
+ * @return true if the unit is supported
+ */
+ public default boolean isSupported(Temporal temporal) {
+ try {
+ temporal.plus(1, this);
+ return true;
+ } catch (RuntimeException ex) {
+ try {
+ temporal.plus(-1, this);
+ return true;
+ } catch (RuntimeException ex2) {
+ return false;
+ }
+ }
+ }
+
+ /**
+ * Returns a copy of the specified temporal object with the specified period added.
+ * <p>
+ * The period added is a multiple of this unit. For example, this method
+ * could be used to add "3 days" to a date by calling this method on the
+ * instance representing "days", passing the date and the period "3".
+ * The period to be added may be negative, which is equivalent to subtraction.
+ * <p>
+ * There are two equivalent ways of using this method.
+ * The first is to invoke this method directly.
+ * The second is to use {@link Temporal#plus(long, TemporalUnit)}:
+ * <pre>
+ * // these two lines are equivalent, but the second approach is recommended
+ * temporal = thisUnit.doPlus(temporal);
+ * temporal = temporal.plus(thisUnit);
+ * </pre>
+ * It is recommended to use the second approach, {@code plus(TemporalUnit)},
+ * as it is a lot clearer to read in code.
+ * <p>
+ * Implementations should perform any queries or calculations using the units
+ * available in {@link ChronoUnit} or the fields available in {@link ChronoField}.
+ * If the field is not supported a {@code DateTimeException} must be thrown.
+ * <p>
+ * Implementations must not alter the specified temporal object.
+ * Instead, an adjusted copy of the original must be returned.
+ * This provides equivalent, safe behavior for immutable and mutable implementations.
+ *
+ * @param <R> the type of the Temporal object
+ * @param dateTime the temporal object to adjust, not null
+ * @param periodToAdd the period of this unit to add, positive or negative
+ * @return the adjusted temporal object, not null
+ * @throws DateTimeException if the period cannot be added
+ */
+ <R extends Temporal> R doPlus(R dateTime, long periodToAdd);
+
+ //-----------------------------------------------------------------------
+ /**
+ * Calculates the period in terms of this unit between two temporal objects of the same type.
+ * <p>
+ * The period will be positive if the second date-time is after the first, and
+ * negative if the second date-time is before the first.
+ * Call {@link SimplePeriod#abs() abs()} on the result to ensure that the result
+ * is always positive.
+ * <p>
+ * The result can be queried for the {@link SimplePeriod#getAmount() amount}, the
+ * {@link SimplePeriod#getUnit() unit} and used directly in addition/subtraction:
+ * <pre>
+ * date = date.minus(MONTHS.between(start, end));
+ * </pre>
+ *
+ * @param <R> the type of the Temporal object; the two date-times must be of the same type
+ * @param dateTime1 the base temporal object, not null
+ * @param dateTime2 the other temporal object, not null
+ * @return the period between datetime1 and datetime2 in terms of this unit;
+ * positive if datetime2 is later than datetime1, not null
+ */
+ <R extends Temporal> SimplePeriod between(R dateTime1, R dateTime2);
+
+ //-----------------------------------------------------------------------
+ /**
+ * Outputs this unit as a {@code String} using the name.
+ *
+ * @return the name of this unit, not null
+ */
+ @Override
+ String toString();
+
+}