jyapayne/Nim
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

allow a negative distance argument. Improved documentation.

Browse source
This commit is contained in:
Arne Döring 2017-07-27 18:22:59 +02:00
commit 316886542b
1 changed files with 22 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

30
lib/pure/algorithm.nim
View file

@ -425,7 +425,7 @@ proc rotated_internal[T](arg: openarray[T]; first, middle, last: int): seq[T] =
result[i] = arg[i] result[i] = arg[i]
proc rotateLeft*[T](arg: var openarray[T]; slice: Slice[int]; dist: int): int = proc rotateLeft*[T](arg: var openarray[T]; slice: Slice[int]; dist: int): int =
## Performs a left rotation on a range of elements. ## Performs a left rotation on a range of elements. If you want to rotate right, use a negative ``dist``.
## Specifically, ``rotate`` rotates the elements at ``slice`` by ``dist`` positions.. ## Specifically, ``rotate`` rotates the elements at ``slice`` by ``dist`` positions..
## The element at index ``slice.a + dist`` will be at index ``slice.a``. ## The element at index ``slice.a + dist`` will be at index ``slice.a``.
## The element at index ``slice.b`` will be at ``slice.a + dist -1``. ## The element at index ``slice.b`` will be at ``slice.a + dist -1``.
@ -438,28 +438,36 @@ proc rotateLeft*[T](arg: var openarray[T]; slice: Slice[int]; dist: int): int =
## the indices of the element range that should be rotated. ## the indices of the element range that should be rotated.
## ##
## ``dist`` ## ``dist``
## the distance in amount of elements that the data should be rotated. ## the distance in amount of elements that the data should be rotated. Can be negative, can be any number.
## ##
## .. code-block:: nim ## .. code-block:: nim
## var list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] ## var list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
## list.rotateLeft(1 .. 8, 3) ## list.rotateLeft(1 .. 8, 3)
## echo @list # @[0, 4, 5, 6, 7, 8, 1, 2, 3, 9, 10] ## echo @list # @[0, 4, 5, 6, 7, 8, 1, 2, 3, 9, 10]
arg.rotate_internal(slice.a, slice.a+dist, slice.b + 1) let sliceLen = slice.b + 1 - slice.a
let distLeft = ((dist mod sliceLen) + sliceLen) mod sliceLen
arg.rotate_internal(slice.a, slice.a+distLeft, slice.b + 1)
proc rotateLeft*[T](arg: var openarray[T]; dist: int): int = proc rotateLeft*[T](arg: var openarray[T]; dist: int): int =
## default arguments for slice, so that this procedure operates on the entire ## default arguments for slice, so that this procedure operates on the entire
## ``arg``, and not just on a part of it. ## ``arg``, and not just on a part of it.
arg.rotate_internal(0, dist, arg.len) let arglen = arg.len
let distLeft = ((dist mod arglen) + arglen) mod arglen
arg.rotate_internal(0, distLeft, arglen)
proc rotatedLeft*[T](arg: openarray[T]; slice: Slice[int], dist: int): seq[T] = proc rotatedLeft*[T](arg: openarray[T]; slice: Slice[int], dist: int): seq[T] =
## same as ``rotateLeft``, just with the difference that it does ## same as ``rotateLeft``, just with the difference that it does
## not modify the argument. It creates a new ``seq`` instead ## not modify the argument. It creates a new ``seq`` instead
arg.rotated_internal(slice.a, slice.a+dist, slice.b+1) let sliceLen = slice.b + 1 - slice.a
let distLeft = ((dist mod sliceLen) + sliceLen) mod sliceLen
arg.rotated_internal(slice.a, slice.a+distLeft, slice.b+1)
proc rotatedLeft*[T](arg: openarray[T]; dist: int): seq[T] = proc rotatedLeft*[T](arg: openarray[T]; dist: int): seq[T] =
## same as ``rotateLeft``, just with the difference that it does ## same as ``rotateLeft``, just with the difference that it does
## not modify the argument. It creates a new ``seq`` instead ## not modify the argument. It creates a new ``seq`` instead
arg.rotated_internal(0, dist, arg.len) let arglen = arg.len
let distLeft = ((dist mod arglen) + arglen) mod arglen
arg.rotated_internal(0, distLeft, arg.len)
when isMainModule: when isMainModule:
var list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] var list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
@ -470,11 +478,17 @@ when isMainModule:
doAssert list == expected doAssert list == expected
doAssert list2 == @expected doAssert list2 == @expected
var s0,s1,s2 = "xxxabcdefgxxx" var s0,s1,s2,s3,s4,s5 = "xxxabcdefgxxx"
doAssert s0.rotateLeft(3 ..< 10, 3) == 7 doAssert s0.rotateLeft(3 ..< 10, 3) == 7
doAssert s0 == "xxxdefgabcxxx" doAssert s0 == "xxxdefgabcxxx"
doAssert s1.rotateLeft(3 ..< 10, 2) == 8 doAssert s1.rotateLeft(3 ..< 10, 2) == 8
doAssert s1 == "xxxcdefgabxxx" doAssert s1 == "xxxcdefgabxxx"
doAssert s2.rotateLeft(3 ..< 10, 4) == 6 doAssert s2.rotateLeft(3 ..< 10, 4) == 6
doassert s2 == "xxxefgabcdxxx" doAssert s2 == "xxxefgabcdxxx"
doAssert s3.rotateLeft(3 ..< 10, -3) == 6
doAssert s3 == "xxxefgabcdxxx"
doAssert s4.rotateLeft(3 ..< 10, -10) == 6
doAssert s4 == "xxxefgabcdxxx"
doAssert s5.rotateLeft(3 ..< 10, 11) == 6
doAssert s5 == "xxxefgabcdxxx"