Local date range

[PeterAttardo]

This pull request enables Kotlin range and progression semantics with the LocalDate and DatePeriod classes. Its implementation borrows from the patterns used for IntRange.

Example:

val start = LocalDate.parse("2020-01-01")
val end = LocalDate.parse("2020-12-31")

// calls function for each day of the year in 2020
(start..end).forEach {
    processDayOf2020(it)
}

// calls function for each day of the year in 2020, ordered in reverse
(end downTo start).forEach {
   processDayOf2020(it)
}

// calls function for every other day of the year in 2020
(start..end step DatePeriod(days=2)).forEach {
   processDayOf2020(it)
}

[dkhalanskyjb]

We have a similar request, but for Instant: #34
Could you please describe why this is needed? Either in the issue I linked if your use cases are similar to the ones listed there, or in a new issue.

[boswelja]

@dkhalanskyjb I've had a use case for this, though it's more of a convenience having a dedicated LocalDateRange compared to a ClosedRange<LocalDate>. I'm building a calendar library that allows consumers to update a particular range of dates on the screen, the intended use case for this is to allow changing the rendered content in chunks.

A few other use cases off the top of my head:

• Representing a selected date range
• Using plus/minus + forEach in conjunction to iterate over a large range in chunks (granted this could be achieved by having a list of dates and chunking that, but if you've only got a start and end date this could be more efficient)