Schedule

A protocol defining functionalities for a schedule.

Schedule protocol

A schedule timetable might be represented as ordered instances of DateInterval, where each instance's start date represents an occurence of the schedule event in fixed in time, and each instance's duration represents the effective duration of the scheduled event.

The Schedule protocol defines its Element as DateInterval. The functionalities defined in the protocol can be used to obtain the schedule timetable elements.

isEmpty property

Signals wheter a Schedule concrete instance is either empty or not.

contains(_:) method

Used to check wheter a Schedule concrete instance contains or not a given date. That is if the given date falls in the represented schedule timetable or not.

schedule(matching:direction) method

This method optionally returns an Element of the Schedule by checking the given date against the Schedule contained elements using the given CalendarCalculationMatchingDateDirection criteria for the calculation.

CalendarCalculationMatchingDateDirection enum

This enum is used to establish a criteria in calendar calculations for a schedule element. It consists in three cases:

• .on: the calendar calculation should be done by matching a given date. That is the returned Schedule.Element contains a given date.
• .firstAfter: the calendar calculation should be done by matching the first schedule element starting after a given date. That is the Schedule.Element start date has to be after a given date.
• .firstBefore: the calendar calculation should be done by matching the first schedule element starting before a given date. That is the Schedule.Element end date has to be before a given date

Schedule(in:queue:then:) method

Used to calculate asynchronoulsy the schedule elements in a given date interval. The result will be delivered in the given closure, which will be optionally excetuted on the given queue when provided. The delivered result is of type Result<[Element], Error>, hence it could be either an array of date interval instances representing the elements of the schedule in the given date interval, or an error in case something went wrong during the calculation.

generate(start:end:) method

This method returns a Sequence of the schedule's elements starting from the given start date and optionally ending on the given end date. That is, when end date is not provided the sequence might be infinite in case the schedule timetable doesn't define an end date internally. For this very reason is strongly recommended to use Schedule(in:queue:then:) method rather then iterating on the sequence returned from this method. Moreover, it's best to use lazy higher order functions (map, filter, etc.) on this sequence knowning it could be infinite. This method is provided as default implementation.

Schedule.Generator type and generator property

Schedule protocol defines a functional type (Date, CalendarCalculationMatchingDateDirection) -> DateInterval? and maps its instance property generator of this type to its instance method schedule(matching:direction). That is a "generator" of Schedule.Element is referred to a fucntion of type (Date, CalendarCalculationMatchingDateDirection) -> DateInterval?.

Schedule.ResultCompletion type

A convenient typealias for the closure type used for the result delivery from an asynchronous calculation: (Result<[Schedule.Element], Error>) -> Void.

Schedule.AsyncGenerator type and asyncGenerator property

Schedule protocol defines a functional type (DateInterval, DispatchQueue?, Schedule.ResultCompletion) -> Void and maps its instance property asyncGenerator of this type to its instance method Schedule(in:queue:then:). That is a "generator" of Schedule.Element working asynchronously is referred to a function of type (DateInterval, DispatchQueue?, Schedule.ResultCompletion) -> Void.

isEmptyGenerator(_:) global function

Check if given Schedule.Generator produces or not any Schedule.Element.

emptyGenerator global constant

Readonly property which returns a Schedule.Generator that never produce any Schedule.Element.

AnySchedule concrete Schedule type

A concrete Schedule type which can be used to hide details of an underlaying other concrete type. Can be initialized either by boxing another concrete Schedule instance, or by providing a closure of type Schedule.Generator. In the latter case, the resulting AnySchedule will use a default implementation for the Schedule(in:queue:then:) method which sequentially iterates over the elements calculated via the provided Schedule.Generator for providing its result. This sequential work is executed on a background queue.