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/*
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* Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
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* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright notice,
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package java.time.temporal;
import java.time.DateTimeException;
import java.util.Objects;
/**
* Framework-level interface defining read-only access to a temporal object,
* such as a date, time, offset or some combination of these.
* <p>
* This is the base interface type for date, time and offset objects.
* It is implemented by those classes that can provide information
* as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}.
* <p>
* Most date and time information can be represented as a number.
* These are modeled using {@code TemporalField} with the number held using
* a {@code long} to handle large values. Year, month and day-of-month are
* simple examples of fields, but they also include instant and offsets.
* See {@link ChronoField} for the standard set of fields.
* <p>
* Two pieces of date/time information cannot be represented by numbers,
* the {@linkplain java.time.chrono.Chronology chronology} and the
* {@linkplain java.time.ZoneId time-zone}.
* These can be accessed via {@linkplain #query(TemporalQuery) queries} using
* the static methods defined on {@link TemporalQuery}.
* <p>
* A sub-interface, {@link Temporal}, extends this definition to one that also
* supports adjustment and manipulation on more complete temporal objects.
* <p>
* This interface is a framework-level interface that should not be widely
* used in application code. Instead, applications should create and pass
* around instances of concrete types, such as {@code LocalDate}.
* There are many reasons for this, part of which is that implementations
* of this interface may be in calendar systems other than ISO.
* See {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues.
*
* @implSpec
* This interface places no restrictions on the mutability of implementations,
* however immutability is strongly recommended.
*
* @since 1.8
*/
public interface TemporalAccessor {
/**
* Checks if the specified field is supported.
* <p>
* This checks if the date-time can be queried for the specified field.
* If false, then calling the {@link #range(TemporalField) range} and {@link #get(TemporalField) get}
* methods will throw an exception.
*
* @implSpec
* Implementations must check and handle all fields defined in {@link ChronoField}.
* If the field is supported, then true must be returned, otherwise false must be returned.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
* passing {@code this} as the argument.
* <p>
* Implementations must ensure that no observable state is altered when this
* read-only method is invoked.
*
* @param field the field to check, null returns false
* @return true if this date-time can be queried for the field, false if not
*/
boolean isSupported(TemporalField field);
/**
* Gets the range of valid values for the specified field.
* <p>
* All fields can be expressed as a {@code long} integer.
* This method returns an object that describes the valid range for that value.
* The value of this temporal object is used to enhance the accuracy of the returned range.
* If the date-time cannot return the range, because the field is unsupported or for
* some other reason, an exception will be thrown.
* <p>
* Note that the result only describes the minimum and maximum valid values
* and it is important not to read too much into them. For example, there
* could be values within the range that are invalid for the field.
*
* @implSpec
* Implementations must check and handle all fields defined in {@link ChronoField}.
* If the field is supported, then the range of the field must be returned.
* If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessorl)}
* passing {@code this} as the argument.
* <p>
* Implementations must ensure that no observable state is altered when this
* read-only method is invoked.
* <p>
* The default implementation must behave equivalent to this code:
* <pre>
* if (field instanceof ChronoField) {
* if (isSupported(field)) {
* return field.range();
* }
* throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
* }
* return field.rangeRefinedBy(this);
* </pre>
*
* @param field the field to query the range for, not null
* @return the range of valid values for the field, not null
* @throws DateTimeException if the range for the field cannot be obtained
* @throws UnsupportedTemporalTypeException if the field is not supported
*/
default ValueRange range(TemporalField field) {
if (field instanceof ChronoField) {
if (isSupported(field)) {
return field.range();
}
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
Objects.requireNonNull(field, "field");
return field.rangeRefinedBy(this);
}
/**
* Gets the value of the specified field as an {@code int}.
* <p>
* This queries the date-time for the value for the specified field.
* The returned value will always be within the valid range of values for the field.
* If the date-time cannot return the value, because the field is unsupported or for
* some other reason, an exception will be thrown.
*
* @implSpec
* Implementations must check and handle all fields defined in {@link ChronoField}.
* If the field is supported and has an {@code int} range, then the value of
* the field must be returned.
* If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument.
* <p>
* Implementations must ensure that no observable state is altered when this
* read-only method is invoked.
* <p>
* The default implementation must behave equivalent to this code:
* <pre>
* if (range(field).isIntValue()) {
* return range(field).checkValidIntValue(getLong(field), field);
* }
* throw new UnsupportedTemporalTypeException("Invalid field " + field + " + for get() method, use getLong() instead");
* </pre>
*
* @param field the field to get, not null
* @return the value for the field, within the valid range of values
* @throws DateTimeException if a value for the field cannot be obtained or
* the value is outside the range of valid values for the field
* @throws UnsupportedTemporalTypeException if the field is not supported or
* the range of values exceeds an {@code int}
* @throws ArithmeticException if numeric overflow occurs
*/
default int get(TemporalField field) {
ValueRange range = range(field);
if (range.isIntValue() == false) {
throw new UnsupportedTemporalTypeException("Invalid field " + field + " for get() method, use getLong() instead");
}
long value = getLong(field);
if (range.isValidValue(value) == false) {
throw new DateTimeException("Invalid value for " + field + " (valid values " + range + "): " + value);
}
return (int) value;
}
/**
* Gets the value of the specified field as a {@code long}.
* <p>
* This queries the date-time for the value for the specified field.
* The returned value may be outside the valid range of values for the field.
* If the date-time cannot return the value, because the field is unsupported or for
* some other reason, an exception will be thrown.
*
* @implSpec
* Implementations must check and handle all fields defined in {@link ChronoField}.
* If the field is supported, then the value of the field must be returned.
* If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument.
* <p>
* Implementations must ensure that no observable state is altered when this
* read-only method is invoked.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained
* @throws UnsupportedTemporalTypeException if the field is not supported
* @throws ArithmeticException if numeric overflow occurs
*/
long getLong(TemporalField field);
/**
* Queries this date-time.
* <p>
* This queries this date-time using the specified query strategy object.
* <p>
* Queries are a key tool for extracting information from date-times.
* They exists to externalize the process of querying, permitting different
* approaches, as per the strategy design pattern.
* Examples might be a query that checks if the date is the day before February 29th
* in a leap year, or calculates the number of days to your next birthday.
* <p>
* The most common query implementations are method references, such as
* {@code LocalDate::from} and {@code ZoneId::from}.
* Additional implementations are provided as static methods on {@link TemporalQuery}.
*
* @implSpec
* The default implementation must behave equivalent to this code:
* <pre>
* if (query == TemporalQueries.zoneId() ||
* query == TemporalQueries.chronology() || query == TemporalQueries.precision()) {
* return null;
* }
* return query.queryFrom(this);
* </pre>
* Future versions are permitted to add further queries to the if statement.
* <p>
* All classes implementing this interface and overriding this method must call
* {@code TemporalAccessor.super.query(query)}. JDK classes may avoid calling
* super if they provide behavior equivalent to the default behaviour, however
* non-JDK classes may not utilize this optimization and must call {@code super}.
* <p>
* If the implementation can supply a value for one of the queries listed in the
* if statement of the default implementation, then it must do so.
* For example, an application-defined {@code HourMin} class storing the hour
* and minute must override this method as follows:
* <pre>
* if (query == TemporalQueries.precision()) {
* return MINUTES;
* }
* return TemporalAccessor.super.query(query);
* </pre>
* <p>
* Implementations must ensure that no observable state is altered when this
* read-only method is invoked.
*
* @param <R> the type of the result
* @param query the query to invoke, not null
* @return the query result, null may be returned (defined by the query)
* @throws DateTimeException if unable to query
* @throws ArithmeticException if numeric overflow occurs
*/
default <R> R query(TemporalQuery<R> query) {
if (query == TemporalQueries.zoneId()
|| query == TemporalQueries.chronology()
|| query == TemporalQueries.precision()) {
return null;
}
return query.queryFrom(this);
}
}