diff options
Diffstat (limited to 'lib/pure')
| -rw-r--r-- | lib/pure/collections/sequtils.nim | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/lib/pure/collections/sequtils.nim b/lib/pure/collections/sequtils.nim index 15bb2a154..e760c5e02 100644 --- a/lib/pure/collections/sequtils.nim +++ b/lib/pure/collections/sequtils.nim @@ -178,6 +178,24 @@ proc filter*[T](seq1: seq[T], pred: proc(item: T): bool {.closure.}): seq[T] = ## assert f2 == @["yellow"] accumulateResult(filter(seq1, pred)) +proc keepIf*[T](seq1: var seq[T], pred: proc(item: T): bool {.closure.}) = + ## Keeps the items in the passed sequence if they fulfilled the predicate. + ## Same as the ``filter`` proc, but modifies the sequence directly. + ## + ## Example: + ## + ## .. code-block:: nimrod + ## var floats = @[13.0, 12.5, 5.8, 2.0, 6.1, 9.9, 10.1] + ## filter(floats, proc(x: float): bool = x > 10) + ## assert floats == @[13.0, 12.5, 10.1] + var pos = 0 + for i in 0 .. <len(seq1): + if pred(seq1[i]): + if pos != i: + seq1[pos] = seq1[i] + inc(pos) + setLen(seq1, pos) + proc delete*[T](s: var seq[T], first=0, last=0) = ## Deletes in `s` the items at position `first` .. `last`. This modifies ## `s` itself, it does not return a copy. @@ -248,6 +266,27 @@ template filterIt*(seq1, pred: expr): expr {.immediate.} = if pred: result.add(it) result +template keepItIf*(varSeq, pred: expr) = + ## Convenience template around the ``keepIf`` proc to reduce typing. + ## + ## Unlike the `proc` version, the predicate needs to be an expression using + ## the ``it`` variable for testing, like: ``keepItIf("abcxyz", it == 'x')``. + ## Example: + ## + ## .. code-block:: nimrod + ## var candidates = @["foo", "bar", "baz", "foobar"] + ## keepItIf(candidates, it.len == 3 and it[0] == 'b') + ## assert candidates == @["bar", "baz"] + var pos = 0 + for i in 0 .. <len(varSeq): + let it {.inject.} = varSeq[i] + if pred: + if pos != i: + varSeq[pos] = varSeq[i] + inc(pos) + setLen(varSeq, pos) + + template toSeq*(iter: expr): expr {.immediate.} = ## Transforms any iterator into a sequence. ## @@ -414,6 +453,11 @@ when isMainModule: echo($n) # echoes 4, 8, 4 in separate lines + block: # keepIf test + var floats = @[13.0, 12.5, 5.8, 2.0, 6.1, 9.9, 10.1] + keepIf(floats, proc(x: float): bool = x > 10) + assert floats == @[13.0, 12.5, 10.1] + block: # filterIt test let temperatures = @[-272.15, -2.0, 24.5, 44.31, 99.9, -113.44] @@ -422,6 +466,11 @@ when isMainModule: assert acceptable == @[-2.0, 24.5, 44.31] assert notAcceptable == @[-272.15, 99.9, -113.44] + block: # keepItIf test + var candidates = @["foo", "bar", "baz", "foobar"] + keepItIf(candidates, it.len == 3 and it[0] == 'b') + assert candidates == @["bar", "baz"] + block: # toSeq test let numeric = @[1, 2, 3, 4, 5, 6, 7, 8, 9] |