147 lines
3.3 KiB
Nim
147 lines
3.3 KiB
Nim
import std/sugar
|
|
|
|
import pkg/questionable
|
|
import pkg/chronos
|
|
|
|
type
|
|
Function*[T, U] = proc(fut: T): U {.raises: [CatchableError], gcsafe, closure.}
|
|
IsFinished* = proc(): bool {.raises: [], gcsafe, closure.}
|
|
GenNext*[T] = proc(): T {.raises: [CatchableError], gcsafe, closure.}
|
|
Iter*[T] = ref object
|
|
finished: bool
|
|
next*: GenNext[T]
|
|
AsyncIter*[T] = Iter[Future[T]]
|
|
|
|
proc finish*[T](self: Iter[T]): void =
|
|
self.finished = true
|
|
|
|
proc finished*[T](self: Iter[T]): bool =
|
|
self.finished
|
|
|
|
iterator items*[T](self: Iter[T]): T =
|
|
while not self.finished:
|
|
yield self.next()
|
|
|
|
iterator pairs*[T](self: Iter[T]): tuple[key: int, val: T] {.inline.} =
|
|
var i = 0
|
|
while not self.finished:
|
|
yield (i, self.next())
|
|
inc(i)
|
|
|
|
proc map*[T, U](fut: Future[T], fn: Function[T, U]): Future[U] {.async.} =
|
|
let t = await fut
|
|
fn(t)
|
|
|
|
proc new*[T](_: type Iter, genNext: GenNext[T], isFinished: IsFinished, finishOnErr: bool = true): Iter[T] =
|
|
var iter = Iter[T]()
|
|
|
|
proc next(): T {.raises: [CatchableError].} =
|
|
if not iter.finished:
|
|
var item: T
|
|
try:
|
|
item = genNext()
|
|
except CatchableError as err:
|
|
if finishOnErr or isFinished():
|
|
iter.finish
|
|
raise err
|
|
|
|
if isFinished():
|
|
iter.finish
|
|
return item
|
|
else:
|
|
raise newException(CatchableError, "Iterator is finished but next item was requested")
|
|
|
|
if isFinished():
|
|
iter.finish
|
|
|
|
iter.next = next
|
|
return iter
|
|
|
|
proc fromItems*[T](_: type Iter, items: seq[T]): Iter[T] =
|
|
## Create new iterator from items
|
|
##
|
|
|
|
Iter.fromSlice(0..<items.len)
|
|
.map((i: int) => items[i])
|
|
|
|
proc fromSlice*[U, V: Ordinal](_: type Iter, slice: HSlice[U, V]): Iter[U] =
|
|
## Creates new iterator from slice
|
|
##
|
|
|
|
Iter.fromRange(slice.a.int, slice.b.int, 1)
|
|
|
|
proc fromRange*[U, V, S: Ordinal](_: type Iter, a: U, b: V, step: S = 1): Iter[U] =
|
|
## Creates new iterator in range a..b with specified step (default 1)
|
|
##
|
|
|
|
var i = a
|
|
|
|
proc genNext(): U =
|
|
let u = i
|
|
inc(i, step)
|
|
u
|
|
|
|
proc isFinished(): bool =
|
|
(step > 0 and i > b) or
|
|
(step < 0 and i < b)
|
|
|
|
Iter.new(genNext, isFinished)
|
|
|
|
proc map*[T, U](iter: Iter[T], fn: Function[T, U]): Iter[U] =
|
|
Iter.new(
|
|
genNext = () => fn(iter.next()),
|
|
isFinished = () => iter.finished
|
|
)
|
|
|
|
proc filter*[T](iter: Iter[T], predicate: Function[T, bool]): Iter[T] =
|
|
var nextT: Option[T]
|
|
|
|
proc tryFetch(): void =
|
|
nextT = T.none
|
|
while not iter.finished:
|
|
let t = iter.next()
|
|
if predicate(t):
|
|
nextT = some(t)
|
|
break
|
|
|
|
proc genNext(): T =
|
|
let t = nextT.unsafeGet
|
|
tryFetch()
|
|
return t
|
|
|
|
proc isFinished(): bool =
|
|
nextT.isNone
|
|
|
|
tryFetch()
|
|
Iter.new(genNext, isFinished)
|
|
|
|
proc prefetch*[T](iter: Iter[T], n: Positive): Iter[T] =
|
|
var ringBuf = newSeq[T](n)
|
|
var iterLen = int.high
|
|
var i = 0
|
|
|
|
proc tryFetch(j: int): void =
|
|
if not iter.finished:
|
|
let item = iter.next()
|
|
ringBuf[j mod n] = item
|
|
if iter.finished:
|
|
iterLen = min(j + 1, iterLen)
|
|
else:
|
|
if j == 0:
|
|
iterLen = 0
|
|
|
|
proc genNext(): T =
|
|
let item = ringBuf[i mod n]
|
|
tryFetch(i + n)
|
|
inc i
|
|
return item
|
|
|
|
proc isFinished(): bool =
|
|
i >= iterLen
|
|
|
|
# initialize ringBuf with n prefetched values
|
|
for j in 0..<n:
|
|
tryFetch(j)
|
|
|
|
Iter.new(genNext, isFinished)
|