diff options
| -rw-r--r-- | lib/pure/collections/deques.nim | 97 |
1 files changed, 46 insertions, 51 deletions
diff --git a/lib/pure/collections/deques.nim b/lib/pure/collections/deques.nim index a26078887..d2b0099f2 100644 --- a/lib/pure/collections/deques.nim +++ b/lib/pure/collections/deques.nim @@ -50,7 +50,7 @@ runnableExamples: import std/private/since -import std/[hashes, math] +import std/[assertions, hashes, math] type Deque*[T] = object @@ -59,7 +59,14 @@ type ## To initialize an empty deque, ## use the `initDeque proc <#initDeque,int>`_. data: seq[T] - head, tail, count: int + + # `head` and `tail` are masked only when accessing an element of `data` + # so that `tail - head == data.len` when the deque is full. + # They are uint so that incrementing/decrementing them doesn't cause + # over/underflow. You can get a number of items with `tail - head` + # even if `tail` or `head` is wraps around and `tail < head`, because + # `tail - head == (uint.high + 1 + tail) - head` when `tail < head`. + head, tail: uint const defaultInitialSize* = 4 @@ -72,8 +79,8 @@ template checkIfInitialized(deq: typed) = if deq.data.len == 0: initImpl(deq, defaultInitialSize) -func mask[T](deq: Deque[T]): int {.inline.} = - deq.data.len - 1 +func mask[T](deq: Deque[T]): uint {.inline.} = + uint(deq.data.len) - 1 proc initDeque*[T](initialSize: int = defaultInitialSize): Deque[T] = ## Creates a new empty deque. @@ -87,22 +94,22 @@ proc initDeque*[T](initialSize: int = defaultInitialSize): Deque[T] = ## * `toDeque proc <#toDeque,openArray[T]>`_ result.initImpl(initialSize) -proc len*[T](deq: Deque[T]): int {.inline.} = +func len*[T](deq: Deque[T]): int {.inline.} = ## Returns the number of elements of `deq`. - result = deq.count + int(deq.tail - deq.head) template emptyCheck(deq) = # Bounds check for the regular deque access. when compileOption("boundChecks"): - if unlikely(deq.count < 1): + if unlikely(deq.len < 1): raise newException(IndexDefect, "Empty deque.") template xBoundsCheck(deq, i) = # Bounds check for the array like accesses. when compileOption("boundChecks"): # `-d:danger` or `--checks:off` should disable this. - if unlikely(i >= deq.count): # x < deq.low is taken care by the Natural parameter + if unlikely(i >= deq.len): # x < deq.low is taken care by the Natural parameter raise newException(IndexDefect, - "Out of bounds: " & $i & " > " & $(deq.count - 1)) + "Out of bounds: " & $i & " > " & $(deq.len - 1)) if unlikely(i < 0): # when used with BackwardsIndex raise newException(IndexDefect, "Out of bounds: " & $i & " < 0") @@ -116,7 +123,7 @@ proc `[]`*[T](deq: Deque[T], i: Natural): lent T {.inline.} = doAssertRaises(IndexDefect, echo a[8]) xBoundsCheck(deq, i) - return deq.data[(deq.head + i) and deq.mask] + return deq.data[(deq.head + i.uint) and deq.mask] proc `[]`*[T](deq: var Deque[T], i: Natural): var T {.inline.} = ## Accesses the `i`-th element of `deq` and returns a mutable @@ -127,7 +134,7 @@ proc `[]`*[T](deq: var Deque[T], i: Natural): var T {.inline.} = assert a[0] == 11 xBoundsCheck(deq, i) - return deq.data[(deq.head + i) and deq.mask] + return deq.data[(deq.head + i.uint) and deq.mask] proc `[]=`*[T](deq: var Deque[T], i: Natural, val: sink T) {.inline.} = ## Sets the `i`-th element of `deq` to `val`. @@ -139,7 +146,7 @@ proc `[]=`*[T](deq: var Deque[T], i: Natural, val: sink T) {.inline.} = checkIfInitialized(deq) xBoundsCheck(deq, i) - deq.data[(deq.head + i) and deq.mask] = val + deq.data[(deq.head + i.uint) and deq.mask] = val proc `[]`*[T](deq: Deque[T], i: BackwardsIndex): lent T {.inline.} = ## Accesses the backwards indexed `i`-th element. @@ -192,10 +199,8 @@ iterator items*[T](deq: Deque[T]): lent T = let a = [10, 20, 30, 40, 50].toDeque assert toSeq(a.items) == @[10, 20, 30, 40, 50] - var i = deq.head - for c in 0 ..< deq.count: - yield deq.data[i] - i = (i + 1) and deq.mask + for c in 0 ..< deq.len: + yield deq.data[(deq.head + c.uint) and deq.mask] iterator mitems*[T](deq: var Deque[T]): var T = ## Yields every element of `deq`, which can be modified. @@ -209,10 +214,8 @@ iterator mitems*[T](deq: var Deque[T]): var T = x = 5 * x - 1 assert $a == "[49, 99, 149, 199, 249]" - var i = deq.head - for c in 0 ..< deq.count: - yield deq.data[i] - i = (i + 1) and deq.mask + for c in 0 ..< deq.len: + yield deq.data[(deq.head + c.uint) and deq.mask] iterator pairs*[T](deq: Deque[T]): tuple[key: int, val: T] = ## Yields every `(position, value)`-pair of `deq`. @@ -222,10 +225,8 @@ iterator pairs*[T](deq: Deque[T]): tuple[key: int, val: T] = let a = [10, 20, 30].toDeque assert toSeq(a.pairs) == @[(0, 10), (1, 20), (2, 30)] - var i = deq.head - for c in 0 ..< deq.count: - yield (c, deq.data[i]) - i = (i + 1) and deq.mask + for c in 0 ..< deq.len: + yield (c, deq.data[(deq.head + c.uint) and deq.mask]) proc contains*[T](deq: Deque[T], item: T): bool {.inline.} = ## Returns true if `item` is in `deq` or false if not found. @@ -244,8 +245,9 @@ proc contains*[T](deq: Deque[T], item: T): bool {.inline.} = proc expandIfNeeded[T](deq: var Deque[T]) = checkIfInitialized(deq) - var cap = deq.data.len - if unlikely(deq.count >= cap): + let cap = deq.data.len + assert deq.len <= cap + if unlikely(deq.len == cap): var n = newSeq[T](cap * 2) var i = 0 for x in mitems(deq): @@ -253,7 +255,7 @@ proc expandIfNeeded[T](deq: var Deque[T]) = else: n[i] = move(x) inc i deq.data = move(n) - deq.tail = deq.count + deq.tail = cap.uint deq.head = 0 proc addFirst*[T](deq: var Deque[T], item: sink T) = @@ -268,9 +270,8 @@ proc addFirst*[T](deq: var Deque[T], item: sink T) = assert $a == "[50, 40, 30, 20, 10]" expandIfNeeded(deq) - inc deq.count - deq.head = (deq.head - 1) and deq.mask - deq.data[deq.head] = item + dec deq.head + deq.data[deq.head and deq.mask] = item proc addLast*[T](deq: var Deque[T], item: sink T) = ## Adds an `item` to the end of `deq`. @@ -284,9 +285,8 @@ proc addLast*[T](deq: var Deque[T], item: sink T) = assert $a == "[10, 20, 30, 40, 50]" expandIfNeeded(deq) - inc deq.count - deq.data[deq.tail] = item - deq.tail = (deq.tail + 1) and deq.mask + deq.data[deq.tail and deq.mask] = item + inc deq.tail proc toDeque*[T](x: openArray[T]): Deque[T] {.since: (1, 3).} = ## Creates a new deque that contains the elements of `x` (in the same order). @@ -315,7 +315,7 @@ proc peekFirst*[T](deq: Deque[T]): lent T {.inline.} = assert len(a) == 5 emptyCheck(deq) - result = deq.data[deq.head] + result = deq.data[deq.head and deq.mask] proc peekLast*[T](deq: Deque[T]): lent T {.inline.} = ## Returns the last element of `deq`, but does not remove it from the deque. @@ -345,7 +345,7 @@ proc peekFirst*[T](deq: var Deque[T]): var T {.inline, since: (1, 3).} = assert $a == "[99, 20, 30, 40, 50]" emptyCheck(deq) - result = deq.data[deq.head] + result = deq.data[deq.head and deq.mask] proc peekLast*[T](deq: var Deque[T]): var T {.inline, since: (1, 3).} = ## Returns a mutable reference to the last element of `deq`, @@ -378,9 +378,8 @@ proc popFirst*[T](deq: var Deque[T]): T {.inline, discardable.} = assert $a == "[20, 30, 40, 50]" emptyCheck(deq) - dec deq.count - result = move deq.data[deq.head] - deq.head = (deq.head + 1) and deq.mask + result = move deq.data[deq.head and deq.mask] + inc deq.head proc popLast*[T](deq: var Deque[T]): T {.inline, discardable.} = ## Removes and returns the last element of the `deq`. @@ -395,9 +394,8 @@ proc popLast*[T](deq: var Deque[T]): T {.inline, discardable.} = assert $a == "[10, 20, 30, 40]" emptyCheck(deq) - dec deq.count - deq.tail = (deq.tail - 1) and deq.mask - result = move deq.data[deq.tail] + dec deq.tail + result = move deq.data[deq.tail and deq.mask] proc clear*[T](deq: var Deque[T]) {.inline.} = ## Resets the deque so that it is empty. @@ -411,7 +409,6 @@ proc clear*[T](deq: var Deque[T]) {.inline.} = assert len(a) == 0 for el in mitems(deq): destroy(el) - deq.count = 0 deq.tail = deq.head proc shrink*[T](deq: var Deque[T], fromFirst = 0, fromLast = 0) = @@ -431,19 +428,17 @@ proc shrink*[T](deq: var Deque[T], fromFirst = 0, fromLast = 0) = a.shrink(fromFirst = 2, fromLast = 1) assert $a == "[30, 40]" - if fromFirst + fromLast > deq.count: + if fromFirst + fromLast > deq.len: clear(deq) return for i in 0 ..< fromFirst: - destroy(deq.data[deq.head]) - deq.head = (deq.head + 1) and deq.mask + destroy(deq.data[deq.head and deq.mask]) + inc deq.head for i in 0 ..< fromLast: destroy(deq.data[(deq.tail - 1) and deq.mask]) - deq.tail = (deq.tail - 1) and deq.mask - - dec deq.count, fromFirst + fromLast + dec deq.tail proc `$`*[T](deq: Deque[T]): string = ## Turns a deque into its string representation. @@ -468,11 +463,11 @@ func `==`*[T](deq1, deq2: Deque[T]): bool = b.addLast(2) doAssert a == b - if deq1.count != deq2.count: + if deq1.len != deq2.len: return false - for i in 0 ..< deq1.count: - if deq1.data[(deq1.head + i) and deq1.mask] != deq2.data[(deq2.head + i) and deq2.mask]: + for i in 0 ..< deq1.len: + if deq1.data[(deq1.head + i.uint) and deq1.mask] != deq2.data[(deq2.head + i.uint) and deq2.mask]: return false true |