/
date_range.ex
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/
date_range.ex
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defmodule Date.Range do
@moduledoc """
Returns an inclusive range between dates.
Ranges must be created with the `Date.range/2` or `Date.range/3` function.
The following fields are public:
* `:first` - the initial date on the range
* `:last` - the last date on the range
* `:step` - (since v1.12.0) the step
The remaining fields are private and should not be accessed.
"""
@type t :: %__MODULE__{
first: Date.t(),
last: Date.t(),
first_in_iso_days: iso_days(),
last_in_iso_days: iso_days(),
step: pos_integer | neg_integer
}
@typep iso_days() :: Calendar.iso_days()
defstruct [:first, :last, :first_in_iso_days, :last_in_iso_days, :step]
defimpl Enumerable do
def member?(
%Date.Range{
first: %{calendar: calendar},
first_in_iso_days: first_days,
last_in_iso_days: last_days,
step: step
} = range,
%Date{calendar: calendar} = date
) do
{days, _} = Date.to_iso_days(date)
cond do
empty?(range) ->
{:ok, false}
first_days <= last_days ->
{:ok, first_days <= days and days <= last_days and rem(days - first_days, step) == 0}
true ->
{:ok, last_days <= days and days <= first_days and rem(days - first_days, step) == 0}
end
end
def member?(%Date.Range{step: _}, _) do
{:ok, false}
end
# TODO: Remove me on v2.0
def member?(
%{__struct__: Date.Range, first_in_iso_days: first_days, last_in_iso_days: last_days} =
date_range,
date
) do
step = if first_days <= last_days, do: 1, else: -1
member?(Map.put(date_range, :step, step), date)
end
def count(range) do
{:ok, size(range)}
end
def slice(
%Date.Range{
first_in_iso_days: first,
first: %{calendar: calendar},
step: step
} = range
) do
{:ok, size(range), &slice(first + &1 * step, step, &2, calendar)}
end
# TODO: Remove me on v2.0
def slice(
%{__struct__: Date.Range, first_in_iso_days: first_days, last_in_iso_days: last_days} =
date_range
) do
step = if first_days <= last_days, do: 1, else: -1
slice(Map.put(date_range, :step, step))
end
defp slice(current, _step, 1, calendar) do
[date_from_iso_days(current, calendar)]
end
defp slice(current, step, remaining, calendar) do
[
date_from_iso_days(current, calendar)
| slice(current + step, step, remaining - 1, calendar)
]
end
def reduce(
%Date.Range{
first_in_iso_days: first_days,
last_in_iso_days: last_days,
first: %{calendar: calendar},
step: step
},
acc,
fun
) do
reduce(first_days, last_days, acc, fun, step, calendar)
end
# TODO: Remove me on v2.0
def reduce(
%{__struct__: Date.Range, first_in_iso_days: first_days, last_in_iso_days: last_days} =
date_range,
acc,
fun
) do
step = if first_days <= last_days, do: 1, else: -1
reduce(Map.put(date_range, :step, step), acc, fun)
end
defp reduce(_first_days, _last_days, {:halt, acc}, _fun, _step, _calendar) do
{:halted, acc}
end
defp reduce(first_days, last_days, {:suspend, acc}, fun, step, calendar) do
{:suspended, acc, &reduce(first_days, last_days, &1, fun, step, calendar)}
end
defp reduce(first_days, last_days, {:cont, acc}, fun, step, calendar)
when step > 0 and first_days <= last_days
when step < 0 and first_days >= last_days do
reduce(
first_days + step,
last_days,
fun.(date_from_iso_days(first_days, calendar), acc),
fun,
step,
calendar
)
end
defp reduce(_, _, {:cont, acc}, _fun, _step, _calendar) do
{:done, acc}
end
defp date_from_iso_days(days, Calendar.ISO) do
{year, month, day} = Calendar.ISO.date_from_iso_days(days)
%Date{year: year, month: month, day: day, calendar: Calendar.ISO}
end
defp date_from_iso_days(days, calendar) do
{year, month, day, _, _, _, _} =
calendar.naive_datetime_from_iso_days({days, {0, 86_400_000_000}})
%Date{year: year, month: month, day: day, calendar: calendar}
end
defp size(%Date.Range{first_in_iso_days: first_days, last_in_iso_days: last_days, step: step})
when step > 0 and first_days > last_days,
do: 0
defp size(%Date.Range{first_in_iso_days: first_days, last_in_iso_days: last_days, step: step})
when step < 0 and first_days < last_days,
do: 0
defp size(%Date.Range{first_in_iso_days: first_days, last_in_iso_days: last_days, step: step}),
do: abs(div(last_days - first_days, step)) + 1
# TODO: Remove me on v2.0
defp size(
%{__struct__: Date.Range, first_in_iso_days: first_days, last_in_iso_days: last_days} =
date_range
) do
step = if first_days <= last_days, do: 1, else: -1
size(Map.put(date_range, :step, step))
end
defp empty?(%Date.Range{
first_in_iso_days: first_days,
last_in_iso_days: last_days,
step: step
})
when step > 0 and first_days > last_days,
do: true
defp empty?(%Date.Range{
first_in_iso_days: first_days,
last_in_iso_days: last_days,
step: step
})
when step < 0 and first_days < last_days,
do: true
defp empty?(%Date.Range{step: _}), do: false
# TODO: Remove me on v2.0
defp empty?(
%{__struct__: Date.Range, first_in_iso_days: first_days, last_in_iso_days: last_days} =
date_range
) do
step = if first_days <= last_days, do: 1, else: -1
empty?(Map.put(date_range, :step, step))
end
end
defimpl Inspect do
import Kernel, except: [inspect: 2]
def inspect(%Date.Range{first: first, last: last, step: 1}, _) do
"#DateRange<" <> inspect(first) <> ", " <> inspect(last) <> ">"
end
def inspect(%Date.Range{first: first, last: last, step: step}, _) do
"#DateRange<" <> inspect(first) <> ", " <> inspect(last) <> ", #{step}>"
end
# TODO: Remove me on v2.0
def inspect(%{__struct__: Date.Range, first: first, last: last} = date_range, opts) do
step = if first <= last, do: 1, else: -1
inspect(Map.put(date_range, :step, step), opts)
end
end
end