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Merge pull request #3043 from takaomag/fix_algorithm_reversed

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Fix algorithm.reversed to accept non-zero 'first' arg
This commit is contained in:
Andreas Rumpf 2015-07-03 00:19:10 +02:00
commit dc65f9a5f7
1 changed files with 11 additions and 5 deletions
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16
lib/pure/algorithm.nim
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@ -50,12 +50,12 @@ proc reverse*[T](a: var openArray[T]) =
proc reversed*[T](a: openArray[T], first, last: Natural): seq[T] = proc reversed*[T](a: openArray[T], first, last: Natural): seq[T] =
## returns the reverse of the array `a[first..last]`. ## returns the reverse of the array `a[first..last]`.
result = newSeq[T](last - first + 1) var i = last - first
var x = first.int var x = first.int
var y = last.int result = newSeq[T](i + 1)
while x <= last: while i >= 0:
result[x] = a[y] result[i] = a[x]
dec(y) dec(i)
inc(x) inc(x)
proc reversed*[T](a: openArray[T]): seq[T] = proc reversed*[T](a: openArray[T]): seq[T] =
@ -361,4 +361,10 @@ when isMainModule:
assert srt3.isSorted(cmp) == true assert srt3.isSorted(cmp) == true
var srtseq = newSeq[int]() var srtseq = newSeq[int]()
assert srtseq.isSorted(cmp) == true assert srtseq.isSorted(cmp) == true
# Tests for reversed
var arr1 = @[0,1,2,3,4]
assert arr1.reversed() == @[4,3,2,1,0]
for i in 0 .. high(arr1):
assert arr1.reversed(0, i) == arr1.reversed()[high(arr1) - i .. high(arr1)]
assert arr1.reversed(i, high(arr1)) == arr1.reversed()[0 .. high(arr1) - i]