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enum.ex
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358 lines (298 loc) · 6.97 KB
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defmodule ElixirScript.Enum do
def all?(enumerable, fun \\ fn(x) -> x end) do
{_, acc} = Enumerable.reduce(enumerable, {:cont, true}, fn(item, _) ->
if fun.(item) do
{:cont, true}
else
{:halt, false}
end
end)
acc
end
def any?(enumerable, fun \\ fn(x) -> x end) do
{_, acc} = Enumerable.reduce(enumerable, {:cont, true}, fn(item, _) ->
if fun.(item) do
{:halt, true}
else
{:cont, false}
end
end)
acc
end
def at(enumerable, n, default \\ nil) do
index = if n < 0 do
{_, count} = Enumerable.count(enumerable)
count + n
else
n
end
result = Enumerable.reduce(enumerable, {:cont, 0}, fn(item, acc) ->
if index == acc do
{:halt, item}
else
{:cont, acc + 1}
end
end)
case result do
{:done, _} ->
default
{:halted, item} ->
item
end
end
def concat([]) do
[]
end
def concat([enumerable]) do
enumerable
end
def concat([h, t]) do
h.concat(t)
end
def concat([h | t]) do
h.concat(concat(t))
end
def concat(h, t) do
h.concat(t)
end
def count(enumerable) do
{:ok, num} = Enumerable.count(enumerable)
num
end
def count(enumerable, fun) do
{_, acc} = Enumerable.reduce(enumerable, {:cont, 0}, fn(item, acc) ->
if fun.(item) do
{:cont, acc + 1}
else
{:cont, acc}
end
end)
acc
end
def reduce(enumerable, fun) do
{_, result} = Enumerable.reduce(enumerable, {:cont, nil}, fn
item, nil ->
{:cont, {:acc, item}}
item, {:acc, acc} ->
{:cont, {:acc, fun.(item, acc)}}
end)
result
end
def reduce(enumerable, acc, fun) do
{_, result} = Enumerable.reduce(enumerable, {:cont, acc}, fn
item, acc ->
{:cont, fun.(item, acc)}
end)
result
end
def map(enumerable, fun) do
reduce(enumerable, [], fn(x, acc) ->
acc ++ fun.(x)
end)
end
def map_reduce(enumerable, acc, fun) do
reduce(enumerable, {[], acc}, fn(x, {m, acc}) ->
{v, new_acc} = fun.(x, acc)
{m ++ [v], new_acc}
end)
end
def each(enumerable, fun) do
map(enumerable, fun)
:ok
end
def empty?(enumerable) do
{:ok, count} = Enumerable.count(enumerable)
count == 0
end
def fetch(enumerable, index) do
index = if index < 0 do
{_, count} = Enumerable.count(enumerable)
count + index
else
index
end
result = Enumerable.reduce(enumerable, {:cont, 0}, fn(item, acc) ->
if index == acc do
{:halt, {:ok, item}}
else
{:cont, acc + 1}
end
end)
case result do
{:done, _} ->
:error
{:halted, item} ->
item
end
end
def fetch!(enumerable, index) do
case fetch(enumerable, index) do
{:ok, item} ->
item
:error ->
raise Enum.OutOfBoundsError
end
end
def filter(enumerable, fun) do
reduce(enumerable, [], fn(x, acc) ->
if fun.(x) do
acc ++ [x]
else
acc
end
end)
end
def filter_map(enumerable, filter, mapper) do
reduce(enumerable, [], fn(x, acc) ->
if filter.(x) do
acc ++ [mapper.(x)]
else
acc
end
end)
end
def find(enumerable, default \\ nil, fun) do
{_, result} = Enumerable.reduce(enumerable, {:cont, default}, fn(item, acc) ->
if fun.(item) do
{:halt, item}
else
{:cont, default}
end
end)
result
end
def into(enumerable, collectable) do
{init, fun} = Collectable.into(collectable)
reduce(enumerable, init, fn x, acc ->
fun.(acc, {:cont, x})
end)
end
def into(enumerable, collectable, transform) do
{init, fun} = Collectable.into(collectable)
reduce(enumerable, init, fn x, acc ->
fun.(acc, {:cont, transform.(x)})
end)
end
def member?(enumerable, value) do
{_, result} = Enumerable.reduce(enumerable, {:cont, false}, fn(item, acc) ->
if item == value do
{:halt, true}
else
{:cont, false}
end
end)
result
end
def drop(enumerable, count) when count < 0 do
enumerable
|> reverse
|> drop(abs(count))
|> reverse
end
def drop(enumerable, count) do
{_, {result, _}} = Enumerable.reduce(enumerable, {:cont, {[], 0}}, fn
(item, {taken, drop_count}) ->
if drop_count < count do
{:cont, {[], drop_count + 1 }}
else
{:cont, {taken ++ [item], drop_count}}
end
end)
result
end
def drop_every(enumerable, nth) do
{_, {result, _count}} = Enumerable.reduce(enumerable, {:cont, {[], 0}}, fn
(item, {taken, count}) ->
if rem(count, nth) == 0 do
{:cont, {taken, count + 1}}
else
{:cont, {taken ++ [item], count + 1}}
end
end)
result
end
def drop_while(enumerable, fun) do
{_, result} = Enumerable.reduce(enumerable, {:cont, :dropping}, fn
(item, :dropping) ->
if fun.(item) do
{:cont, :dropping}
else
{:cont, [item]}
end
(item, taken) ->
{:cont, taken ++ [item]}
end)
case result do
:dropping ->
[]
:done ->
[]
_ ->
result
end
end
def empty?(enumerable) do
{:ok, count} = Enumerable.count(enumerable)
count == 0
end
def take(enumerable, count) do
if Enumerable.count(enumerable) < count do
enumerable
else
{_, result} = Enumerable.reduce(enumerable, {:cont, {[], 0}}, fn
(item, {taken, taken_count}) ->
if taken_count == count do
{:halt, taken}
else
{:cont, {taken ++ [item], taken_count + 1}}
end
end)
result
end
end
def take_every(enumerable, nth) do
{_, {result, _count}} = Enumerable.reduce(enumerable, {:cont, {[], 0}}, fn
(item, {taken, count}) ->
if rem(count, nth) == 0 do
{:cont, {taken ++ [item], count + 1}}
else
{:cont, {taken, count + 1}}
end
end)
result
end
def take_while(enumerable, fun) do
{_, result} = Enumerable.reduce(enumerable, {:cont, []}, fn
(item, taken) ->
if fun.(item) do
{:cont, {taken ++ [item]}}
else
{:halt, taken}
end
end)
result
end
def to_list(enumerable) when is_list(enumerable) do
enumerable
end
def to_list(enumerable) do
map(enumerable, fn x -> x end)
end
def reverse(enumerable) when is_list(enumerable) do
enumerable.concat([]).reverse()
end
def reverse(enumerable) do
reduce(enumerable, [], fn(item, acc) ->
[item] ++ acc
end)
end
def reverse(enumerable, tail) when is_list(enumerable) do
enumerable.concat([]).reverse() ++ tail
end
def reverse(enumerable, tail) do
result = reduce(enumerable, [], fn(item, acc) ->
[item] ++ acc
end)
result ++ tail
end
end