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318 lines
13 KiB
318 lines
13 KiB
/*
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* Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*/
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/*
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*
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*
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*
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*
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*
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* Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* * Neither the name of JSR-310 nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package java.time.temporal;
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import java.time.DateTimeException;
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import java.util.Objects;
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/**
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* Framework-level interface defining read-only access to a temporal object,
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* such as a date, time, offset or some combination of these.
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* <p>
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* This is the base interface type for date, time and offset objects.
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* It is implemented by those classes that can provide information
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* as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}.
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* <p>
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* Most date and time information can be represented as a number.
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* These are modeled using {@code TemporalField} with the number held using
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* a {@code long} to handle large values. Year, month and day-of-month are
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* simple examples of fields, but they also include instant and offsets.
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* See {@link ChronoField} for the standard set of fields.
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* <p>
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* Two pieces of date/time information cannot be represented by numbers,
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* the {@linkplain java.time.chrono.Chronology chronology} and the
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* {@linkplain java.time.ZoneId time-zone}.
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* These can be accessed via {@linkplain #query(TemporalQuery) queries} using
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* the static methods defined on {@link TemporalQuery}.
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* <p>
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* A sub-interface, {@link Temporal}, extends this definition to one that also
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* supports adjustment and manipulation on more complete temporal objects.
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* <p>
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* This interface is a framework-level interface that should not be widely
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* used in application code. Instead, applications should create and pass
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* around instances of concrete types, such as {@code LocalDate}.
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* There are many reasons for this, part of which is that implementations
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* of this interface may be in calendar systems other than ISO.
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* See {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues.
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*
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* @implSpec
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* This interface places no restrictions on the mutability of implementations,
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* however immutability is strongly recommended.
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*
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* @since 1.8
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*/
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public interface TemporalAccessor {
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/**
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* Checks if the specified field is supported.
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* <p>
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* This checks if the date-time can be queried for the specified field.
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* If false, then calling the {@link #range(TemporalField) range} and {@link #get(TemporalField) get}
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* methods will throw an exception.
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*
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* @implSpec
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* Implementations must check and handle all fields defined in {@link ChronoField}.
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* If the field is supported, then true must be returned, otherwise false must be returned.
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* <p>
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* If the field is not a {@code ChronoField}, then the result of this method
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* is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
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* passing {@code this} as the argument.
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* <p>
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* Implementations must ensure that no observable state is altered when this
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* read-only method is invoked.
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*
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* @param field the field to check, null returns false
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* @return true if this date-time can be queried for the field, false if not
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*/
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boolean isSupported(TemporalField field);
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/**
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* Gets the range of valid values for the specified field.
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* <p>
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* All fields can be expressed as a {@code long} integer.
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* This method returns an object that describes the valid range for that value.
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* The value of this temporal object is used to enhance the accuracy of the returned range.
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* If the date-time cannot return the range, because the field is unsupported or for
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* some other reason, an exception will be thrown.
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* <p>
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* Note that the result only describes the minimum and maximum valid values
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* and it is important not to read too much into them. For example, there
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* could be values within the range that are invalid for the field.
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*
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* @implSpec
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* Implementations must check and handle all fields defined in {@link ChronoField}.
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* If the field is supported, then the range of the field must be returned.
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* If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
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* <p>
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* If the field is not a {@code ChronoField}, then the result of this method
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* is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessorl)}
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* passing {@code this} as the argument.
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* <p>
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* Implementations must ensure that no observable state is altered when this
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* read-only method is invoked.
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* <p>
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* The default implementation must behave equivalent to this code:
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* <pre>
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* if (field instanceof ChronoField) {
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* if (isSupported(field)) {
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* return field.range();
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* }
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* throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
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* }
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* return field.rangeRefinedBy(this);
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* </pre>
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*
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* @param field the field to query the range for, not null
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* @return the range of valid values for the field, not null
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* @throws DateTimeException if the range for the field cannot be obtained
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* @throws UnsupportedTemporalTypeException if the field is not supported
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*/
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default ValueRange range(TemporalField field) {
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if (field instanceof ChronoField) {
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if (isSupported(field)) {
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return field.range();
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}
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throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
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}
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Objects.requireNonNull(field, "field");
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return field.rangeRefinedBy(this);
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}
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/**
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* Gets the value of the specified field as an {@code int}.
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* <p>
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* This queries the date-time for the value of the specified field.
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* The returned value will always be within the valid range of values for the field.
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* If the date-time cannot return the value, because the field is unsupported or for
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* some other reason, an exception will be thrown.
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*
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* @implSpec
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* Implementations must check and handle all fields defined in {@link ChronoField}.
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* If the field is supported and has an {@code int} range, then the value of
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* the field must be returned.
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* If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
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* <p>
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* If the field is not a {@code ChronoField}, then the result of this method
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* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
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* passing {@code this} as the argument.
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* <p>
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* Implementations must ensure that no observable state is altered when this
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* read-only method is invoked.
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* <p>
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* The default implementation must behave equivalent to this code:
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* <pre>
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* if (range(field).isIntValue()) {
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* return range(field).checkValidIntValue(getLong(field), field);
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* }
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* throw new UnsupportedTemporalTypeException("Invalid field " + field + " + for get() method, use getLong() instead");
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* </pre>
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*
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* @param field the field to get, not null
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* @return the value for the field, within the valid range of values
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* @throws DateTimeException if a value for the field cannot be obtained or
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* the value is outside the range of valid values for the field
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* @throws UnsupportedTemporalTypeException if the field is not supported or
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* the range of values exceeds an {@code int}
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* @throws ArithmeticException if numeric overflow occurs
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*/
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default int get(TemporalField field) {
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ValueRange range = range(field);
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if (range.isIntValue() == false) {
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throw new UnsupportedTemporalTypeException("Invalid field " + field + " for get() method, use getLong() instead");
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}
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long value = getLong(field);
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if (range.isValidValue(value) == false) {
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throw new DateTimeException("Invalid value for " + field + " (valid values " + range + "): " + value);
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}
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return (int) value;
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}
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/**
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* Gets the value of the specified field as a {@code long}.
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* <p>
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* This queries the date-time for the value of the specified field.
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* The returned value may be outside the valid range of values for the field.
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* If the date-time cannot return the value, because the field is unsupported or for
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* some other reason, an exception will be thrown.
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*
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* @implSpec
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* Implementations must check and handle all fields defined in {@link ChronoField}.
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* If the field is supported, then the value of the field must be returned.
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* If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
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* <p>
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* If the field is not a {@code ChronoField}, then the result of this method
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* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
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* passing {@code this} as the argument.
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* <p>
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* Implementations must ensure that no observable state is altered when this
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* read-only method is invoked.
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*
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* @param field the field to get, not null
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* @return the value for the field
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* @throws DateTimeException if a value for the field cannot be obtained
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* @throws UnsupportedTemporalTypeException if the field is not supported
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* @throws ArithmeticException if numeric overflow occurs
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*/
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long getLong(TemporalField field);
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/**
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* Queries this date-time.
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* <p>
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* This queries this date-time using the specified query strategy object.
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* <p>
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* Queries are a key tool for extracting information from date-times.
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* They exists to externalize the process of querying, permitting different
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* approaches, as per the strategy design pattern.
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* Examples might be a query that checks if the date is the day before February 29th
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* in a leap year, or calculates the number of days to your next birthday.
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* <p>
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* The most common query implementations are method references, such as
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* {@code LocalDate::from} and {@code ZoneId::from}.
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* Additional implementations are provided as static methods on {@link TemporalQuery}.
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*
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* @implSpec
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* The default implementation must behave equivalent to this code:
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* <pre>
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* if (query == TemporalQueries.zoneId() ||
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* query == TemporalQueries.chronology() || query == TemporalQueries.precision()) {
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* return null;
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* }
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* return query.queryFrom(this);
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* </pre>
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* Future versions are permitted to add further queries to the if statement.
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* <p>
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* All classes implementing this interface and overriding this method must call
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* {@code TemporalAccessor.super.query(query)}. JDK classes may avoid calling
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* super if they provide behavior equivalent to the default behaviour, however
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* non-JDK classes may not utilize this optimization and must call {@code super}.
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* <p>
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* If the implementation can supply a value for one of the queries listed in the
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* if statement of the default implementation, then it must do so.
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* For example, an application-defined {@code HourMin} class storing the hour
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* and minute must override this method as follows:
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* <pre>
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* if (query == TemporalQueries.precision()) {
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* return MINUTES;
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* }
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* return TemporalAccessor.super.query(query);
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* </pre>
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* <p>
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* Implementations must ensure that no observable state is altered when this
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* read-only method is invoked.
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*
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* @param <R> the type of the result
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* @param query the query to invoke, not null
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* @return the query result, null may be returned (defined by the query)
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* @throws DateTimeException if unable to query
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* @throws ArithmeticException if numeric overflow occurs
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*/
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default <R> R query(TemporalQuery<R> query) {
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if (query == TemporalQueries.zoneId()
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|| query == TemporalQueries.chronology()
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|| query == TemporalQueries.precision()) {
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return null;
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}
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return query.queryFrom(this);
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}
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}
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