org.threeten.bp.temporal.TemporalAmount.scala Maven / Gradle / Ivy

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/*
 * Copyright (c) 2007-present, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
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 *
 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
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package org.threeten.bp.temporal

/**
 * Framework-level interface defining an amount of time, such as "6 hours", "8 days" or "2 years and
 * 3 months".
 *
 * This is the base interface type for amounts of time. An amount is distinct from a date or
 * time-of-day in that it is not tied to any specific point on the time-line.
 *
 * The amount can be thought of as a Map of {@code TemporalUnit} to long, exposed via {@link
 * #getUnits()} and {@link #get(TemporalUnit)}. A simple case might have a single unit-value pair,
 * such as "6 hours". A more complex case may have multiple unit-value pairs, such as "7 years, 3
 * months and 5 days".
 *
 * There are two common implementations. {@link Period} is a date-based implementation, storing
 * years, months and days. {@link Duration} is a time-based implementation, storing seconds and
 * nanoseconds, but providing some access using other duration based units such as minutes, hours
 * and fixed 24-hour days.
 *
 * 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
 * Period} and {@code Duration}.
 *
 * Specification for implementors This interface places no restrictions on the mutability
 * of implementations, however immutability is strongly recommended.
 */
trait TemporalAmount {

  /**
   * Gets the list of units, from largest to smallest, that fully define this amount.
   *
   * @return
   *   the list of units.
   */
  def getUnits: java.util.List[TemporalUnit]

  /**
   * Gets the amount associated with the specified unit.
   *
   * @param unit
   *   the unit to get, not null
   * @return
   *   the amount of the unit
   * @throws DateTimeException
   *   if the amount cannot be obtained
   */
  def get(unit: TemporalUnit): Long

  /**
   * Adds to the specified temporal object.
   *
   * This adds to the specified temporal object using the logic encapsulated in the implementing
   * class.
   *
   * 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(TemporalAmount)}:  // these two lines
   * are equivalent, but the second approach is recommended dateTime = amount.addTo(dateTime);
   * dateTime = dateTime.plus(amount);  It is recommended to use the second approach, {@code
   * plus(TemporalAmount)}, as it is a lot clearer to read in code.
   *
   * Specification for implementors The implementation must take the input object and add
   * to it. The implementation defines the logic of the addition and is responsible for documenting
   * that logic. It may use any method on {@code Temporal} to query the temporal object and perform
   * the addition. The returned object must have the same observable type as the input object
   *
   * The input object must not be altered. Instead, an adjusted copy of the original must be
   * returned. This provides equivalent, safe behavior for immutable and mutable temporal objects.
   *
   * The input temporal object may be in a calendar system other than ISO. Implementations may
   * choose to document compatibility with other calendar systems, or reject non-ISO temporal
   * objects by {@link TemporalQueries#chronology() querying the chronology}.
   *
   * This method may be called from multiple threads in parallel. It must be thread-safe when
   * invoked.
   *
   * @param temporal
   *   the temporal object to adjust, not null
   * @return
   *   an object of the same observable type with the addition made, not null
   * @throws DateTimeException
   *   if unable to add
   * @throws ArithmeticException
   *   if numeric overflow occurs
   */
  def addTo(temporal: Temporal): Temporal

  /**
   * Subtracts this object from the specified temporal object.
   *
   * This adds to the specified temporal object using the logic encapsulated in the implementing
   * class.
   *
   * There are two equivalent ways of using this method. The first is to invoke this method
   * directly. The second is to use {@link Temporal#minus(TemporalAmount)}:  // these two lines
   * are equivalent, but the second approach is recommended dateTime =
   * amount.subtractFrom(dateTime); dateTime = dateTime.minus(amount);  It is recommended to
   * use the second approach, {@code minus(TemporalAmount)}, as it is a lot clearer to read in code.
   *
   * Specification for implementors The implementation must take the input object and
   * subtract from it. The implementation defines the logic of the subtraction and is responsible
   * for documenting that logic. It may use any method on {@code Temporal} to query the temporal
   * object and perform the subtraction. The returned object must have the same observable type as
   * the input object
   *
   * The input object must not be altered. Instead, an adjusted copy of the original must be
   * returned. This provides equivalent, safe behavior for immutable and mutable temporal objects.
   *
   * The input temporal object may be in a calendar system other than ISO. Implementations may
   * choose to document compatibility with other calendar systems, or reject non-ISO temporal
   * objects by {@link TemporalQueries#chronology() querying the chronology}.
   *
   * This method may be called from multiple threads in parallel. It must be thread-safe when
   * invoked.
   *
   * @param temporal
   *   the temporal object to adjust, not null
   * @return
   *   an object of the same observable type with the subtraction made, not null
   * @throws DateTimeException
   *   if unable to subtract
   * @throws ArithmeticException
   *   if numeric overflow occurs
   */
  def subtractFrom(temporal: Temporal): Temporal
}