net.time4j.engine

Interface ChronoMerger<T>

Type Parameters:

T - generic type of time context (compatible to ChronoEntity)

All Known Implementing Classes:

Chronology, TimeAxis

public interface ChronoMerger<T>

Merges any set of chronological informations to a new chronological entity.

This interface abstracts the knowledge of the chronology how to construct a new entity based on any set of chronological informations. It is mainly used by a parser in order to interprete textual representations of chronological entities.

Using this low-level-interface is usually reserved for Time4J and serves for internal format support. However, for constructing new calendar systems implementing this interface is an essential part for parsing support. Implementation note: All classes of this type must be immutable.

Author:

Meno Hochschild

Method Summary

Methods

Modifier and Type	Method and Description
T	createFrom(ChronoEntity<?> entity, AttributeQuery attributes, boolean preparsing) Creates a new entity of type T based on given chronological data.
T	createFrom(TimeSource<?> clock, AttributeQuery attributes) Creates a new entity which reflects current time.
ChronoDisplay	preformat(T context, AttributeQuery attributes) Transforms the current context/entity into another set of chronological values which finally shall be formatted using given attributes.
Chronology<?>	preparser() This method defines a child chronology which can preparse a chronological text.

Method Detail

createFrom

T createFrom(TimeSource<?> clock,
           AttributeQuery attributes)

Creates a new entity which reflects current time.

In a date-only chronology this method will create the current date using the necessary timezone contained in given attributes.

Parameters:

clock - source for current time

attributes - configuration attributes which might contain the timezone to translate current time to local time

Returns:

new time context or null if given data are insufficient

createFrom

T createFrom(ChronoEntity<?> entity,
           AttributeQuery attributes,
           boolean preparsing)

Creates a new entity of type T based on given chronological data.

Typically the method will query the given entity with different priorities for elements which can compose a new chronological entity (per group). For example a calendar date can be composed either by epoch days or the group (year)-(month)-(day-of-month) or the group (year)-(day-of-year) etc.

A text parser will call this method after having resolved a text into single chronological elements and values. Implementations should always validate the parsed values. In case of error, they are free to either throw an IllegalArgumentException or to generate and to save an error message by mean of the expression entity.with(ValidationElement.ERROR_MESSAGE, message.

Parameters:

entity - any chronological entity like parsed elements with their values

attributes - configuration attributes given by parser

preparsing - preparsing phase active?

Returns:

new time context or null if given data are insufficient

Throws:

IllegalArgumentException - in any case of inconsistent data

See Also:

ValidationElement.ERROR_MESSAGE

preformat

ChronoDisplay preformat(T context,
                      AttributeQuery attributes)

Transforms the current context/entity into another set of chronological values which finally shall be formatted using given attributes.

Parameters:

attributes - controls attributes during formatting

Returns:

replacement entity which will finally be used for formatting

Throws:

IllegalArgumentException - in any case of inconsistent data

preparser

Chronology<?> preparser()

This method defines a child chronology which can preparse a chronological text.

Returns:

preparsing chronology or null