std.algorithm.mutation
Function Name | Description |
---|---|
bringToFront | If a = [1, 2, 3] and b = [4, 5, 6, 7], bringToFront(a, b) leaves a = [4, 5, 6] and b = [7, 1, 2, 3]. |
copy | Copies a range to another. If a = [1, 2, 3] and b = new int[5], then copy(a, b) leaves b = [1, 2, 3, 0, 0] and returns b[3 .. $]. |
fill | Fills a range with a pattern, e.g., if a = new int[3], then fill(a, 4) leaves a = [4, 4, 4] and fill(a, [3, 4]) leaves a = [3, 4, 3]. |
initializeAll | If a = [1.2, 3.4], then initializeAll(a) leaves a = [double.init, double.init]. |
move | move(a, b) moves a into b. move(a) reads a destructively when necessary. |
moveEmplace | Similar to move but assumes target is uninitialized. |
moveAll | Moves all elements from one range to another. |
moveEmplaceAll | Similar to moveAll but assumes all elements in target are uninitialized. |
moveSome | Moves as many elements as possible from one range to another. |
moveEmplaceSome | Similar to moveSome but assumes all elements in target are uninitialized. |
remove | Removes elements from a range in-place, and returns the shortened range. |
reverse | If a = [1, 2, 3], reverse(a) changes it to [3, 2, 1]. |
strip | Strips all leading and trailing elements equal to a value, or that satisfy a predicate. If a = [1, 1, 0, 1, 1], then strip(a, 1) and strip!(e => e == 1)(a) returns [0]. |
stripLeft | Strips all leading elements equal to a value, or that satisfy a predicate. If a = [1, 1, 0, 1, 1], then stripLeft(a, 1) and stripLeft!(e => e == 1)(a) returns [0, 1, 1]. |
stripRight | Strips all trailing elements equal to a value, or that satisfy a predicate. If a = [1, 1, 0, 1, 1], then stripRight(a, 1) and stripRight!(e => e == 1)(a) returns [1, 1, 0]. |
swap | Swaps two values. |
swapAt | Swaps two values by indices. |
swapRanges | Swaps all elements of two ranges. |
uninitializedFill | Fills a range (assumed uninitialized) with a value. |
Source std/algorithm/mutation.d
- size_t
bringToFront
(InputRange, ForwardRange)(InputRangefront
, ForwardRangeback
)
if (isInputRange!InputRange && isForwardRange!ForwardRange); bringToFront
takes two rangesfront
andback
, which may be of different types. Considering the concatenation offront
andback
one unified range,bringToFront
rotates that unified range such that all elements inback
are brought to the beginning of the unified range. The relative ordering of elements infront
andback
, respectively, remains unchanged.ThebringToFront
function treats strings at the code unit level and it is not concerned with Unicode character integrity.bringToFront
is designed as a function for moving elements in ranges, not as a string function. Performs Ο(max(front.length, back.length)) evaluations of swap. ThebringToFront
function can rotate elements in one buffer left or right, swap buffers of equal length, and even move elements across disjoint buffers of different types and different lengths.Preconditions Either
front
andback
are disjoint, orback
is reachable fromfront
andfront
is not reachable from back.Parameters:InputRange front
an input range ForwardRange back
a forward range Returns:The number of elements brought to the front, i.e., the length ofback
.See Also:Examples:The simplest use ofbringToFront
is for rotating elements in a buffer. For example:auto arr = [4, 5, 6, 7, 1, 2, 3]; auto p = bringToFront(arr[0 .. 4], arr[4 .. $]); writeln(p); // arr.length - 4 writeln(arr); // [1, 2, 3, 4, 5, 6, 7]
Examples:Thefront
range may actually "step over" theback
range. This is very useful with forward ranges that cannot compute comfortably right-bounded subranges like arr[0 .. 4] above. In the example below, r2 is a right subrange of r1.import std.algorithm.comparison : equal; import std.container : SList; import std.range.primitives : popFrontN; auto list = SList!(int)(4, 5, 6, 7, 1, 2, 3); auto r1 = list[]; auto r2 = list[]; popFrontN(r2, 4); assert(equal(r2, [ 1, 2, 3 ])); bringToFront(r1, r2); assert(equal(list[], [ 1, 2, 3, 4, 5, 6, 7 ]));
Examples:Elements can be swapped across ranges of different types:import std.algorithm.comparison : equal; import std.container : SList; auto list = SList!(int)(4, 5, 6, 7); auto vec = [ 1, 2, 3 ]; bringToFront(list[], vec); assert(equal(list[], [ 1, 2, 3, 4 ])); assert(equal(vec, [ 5, 6, 7 ]));
Examples:Unicode integrity is not preserved:import std.string : representation; auto ar = representation("a".dup); auto br = representation("ç".dup); bringToFront(ar, br); auto a = cast(char[]) ar; auto b = cast(char[]) br; // Illegal UTF-8 writeln(a); // "\303" // Illegal UTF-8 writeln(b); // "\247a"
- TargetRange
copy
(SourceRange, TargetRange)(SourceRangesource
, TargetRangetarget
)
if (isInputRange!SourceRange && isOutputRange!(TargetRange, ElementType!SourceRange)); - Copies the content of
source
intotarget
and returns the remaining (unfilled) part oftarget
.Preconditions
target
shall have enough room to accommodate the entirety ofsource
.Parameters:SourceRange source
an input range TargetRange target
an output range Returns:The unfilled part of targetExamples:int[] a = [ 1, 5 ]; int[] b = [ 9, 8 ]; int[] buf = new int[](a.length + b.length + 10); auto rem = a.copy(buf); // copy a into buf rem = b.copy(rem); // copy b into remainder of buf writeln(buf[0 .. a.length + b.length]); // [1, 5, 9, 8] assert(rem.length == 10); // unused slots in buf
Examples:As long as the target range elements support assignment from source range elements, different types of ranges are accepted:float[] src = [ 1.0f, 5 ]; double[] dest = new double[src.length]; src.copy(dest);
Examples:To copy at most n elements from a range, you may want to use std.range.take:import std.range; int[] src = [ 1, 5, 8, 9, 10 ]; auto dest = new int[](3); src.take(dest.length).copy(dest); writeln(dest); // [1, 5, 8]
Examples:To copy just those elements from a range that satisfy a predicate, use filter:import std.algorithm.iteration : filter; int[] src = [ 1, 5, 8, 9, 10, 1, 2, 0 ]; auto dest = new int[src.length]; auto rem = src .filter!(a => (a & 1) == 1) .copy(dest); writeln(dest[0 .. $ - rem.length]); // [1, 5, 9, 1]
Examples:std.range.retro can be used to achieve behavior similar to STL's copy_backward':import std.algorithm, std.range; int[] src = [1, 2, 4]; int[] dest = [0, 0, 0, 0, 0]; src.retro.copy(dest.retro); writeln(dest); // [0, 0, 1, 2, 4]
- void
fill
(Range, Value)(auto ref Rangerange
, auto ref Valuevalue
)
if (isInputRange!Range && is(typeof(range
.front =value
)) || isSomeChar!Value && is(typeof(range
[] =value
)));
voidfill
(InputRange, ForwardRange)(InputRangerange
, ForwardRangefiller
)
if (isInputRange!InputRange && (isForwardRange!ForwardRange || isInputRange!ForwardRange && isInfinite!ForwardRange) && is(typeof(InputRange.init.front = ForwardRange.init.front))); - Assigns
value
to each element of input rangerange
.Alternatively, instead of using a singlevalue
to fill therange
, a filter forward range can be provided. The length offiller
andrange
do not need to match, butfiller
must not be empty.Parameters:Range range
An input range that exposes references to its elements and has assignable elements Value value
Assigned to each element of range ForwardRange filler
A forward range representing the fill pattern. Throws:Iffiller
is empty.See Also:Examples:int[] a = [ 1, 2, 3, 4 ]; fill(a, 5); writeln(a); // [5, 5, 5, 5]
Examples:int[] a = [ 1, 2, 3, 4, 5 ]; int[] b = [ 8, 9 ]; fill(a, b); writeln(a); // [8, 9, 8, 9, 8]
- void
initializeAll
(Range)(Rangerange
)
if (isInputRange!Range && hasLvalueElements!Range && hasAssignableElements!Range);
voidinitializeAll
(Range)(Rangerange
)
if (is(Range == char[]) || is(Range == wchar[])); - Initializes all elements of
range
with their .init value. Assumes that the elements of the range are uninitialized.Parameters:Range range
An input range that exposes references to its elements and has assignable elements See Also:Examples:import core.stdc.stdlib : malloc, free; struct S { int a = 10; } auto s = (cast(S*) malloc(5 * S.sizeof))[0 .. 5]; initializeAll(s); writeln(s); // [S(10), S(10), S(10), S(10), S(10)] scope(exit) free(s.ptr);
- void
move
(T)(ref Tsource
, ref Ttarget
);
Tmove
(T)(return ref scope Tsource
); - Moves
source
intotarget
, via a destructive copy when necessary.If T is a struct with a destructor or postblit defined, source is reset to its .init value after it is moved into target, otherwise it is left unchanged.Preconditions If source has internal pointers that point to itself and doesn't define opPostMove, it cannot be moved, and will trigger an assertion failure.
Parameters:T source
Data to copy. T target
Where to copy into. The destructor, if any, is invoked before the copy is performed. Examples:For non-struct types,move
just performstarget
=source
:Object obj1 = new Object; Object obj2 = obj1; Object obj3; move(obj2, obj3); assert(obj3 is obj1); // obj2 unchanged assert(obj2 is obj1);
Examples:// Structs without destructors are simply copied struct S1 { int a = 1; int b = 2; } S1 s11 = { 10, 11 }; S1 s12; move(s11, s12); writeln(s12); // S1(10, 11) writeln(s11); // s12 // But structs with destructors or postblits are reset to their .init value // after copying to the target. struct S2 { int a = 1; int b = 2; ~this() pure nothrow @safe @nogc { } } S2 s21 = { 3, 4 }; S2 s22; move(s21, s22); writeln(s21); // S2(1, 2) writeln(s22); // S2(3, 4)
Examples:Non-copyable structs can still be moved:struct S { int a = 1; @disable this(this); ~this() pure nothrow @safe @nogc {} } S s1; s1.a = 2; S s2 = move(s1); writeln(s1.a); // 1 writeln(s2.a); // 2
Examples:opPostMove will be called if defined:struct S { int a; void opPostMove(const ref S old) { writeln(a); // old.a a++; } } S s1; s1.a = 41; S s2 = move(s1); writeln(s2.a); // 42
- pure @system void
moveEmplace
(T)(ref Tsource
, ref Ttarget
); - Similar to move but assumes
target
is uninitialized. This is more efficient becausesource
can be blitted overtarget
without destroying or initializing it first.Parameters:T source
value to be moved into target T target
uninitialized value to be filled by source Examples:static struct Foo { pure nothrow @nogc: this(int* ptr) { _ptr = ptr; } ~this() { if (_ptr) ++*_ptr; } int* _ptr; } int val; Foo foo1 = void; // uninitialized auto foo2 = Foo(&val); // initialized assert(foo2._ptr is &val); // Using `move(foo2, foo1)` would have an undefined effect because it would destroy // the uninitialized foo1. // moveEmplace directly overwrites foo1 without destroying or initializing it first. moveEmplace(foo2, foo1); assert(foo1._ptr is &val); assert(foo2._ptr is null); writeln(val); // 0
- InputRange2
moveAll
(InputRange1, InputRange2)(InputRange1src
, InputRange2tgt
)
if (isInputRange!InputRange1 && isInputRange!InputRange2 && is(typeof(move(src
.front,tgt
.front)))); - Calls move(a, b) for each element a in
src
and the corresponding element b intgt
, in increasing order.Preconditions walkLength(
src
) <= walkLength(tgt
). This precondition will be asserted. If you cannot ensure there is enough room intgt
to accommodate all ofsrc
use moveSome instead.Parameters:InputRange1 src
An input range with movable elements. InputRange2 tgt
An input range with elements that elements from src
can be moved into.Returns:The leftover portion oftgt
after all elements fromsrc
have been moved.Examples:int[3] a = [ 1, 2, 3 ]; int[5] b; assert(moveAll(a[], b[]) is b[3 .. $]); writeln(a[]); // b[0 .. 3] int[3] cmp = [ 1, 2, 3 ]; writeln(a[]); // cmp[]
- @system InputRange2
moveEmplaceAll
(InputRange1, InputRange2)(InputRange1src
, InputRange2tgt
)
if (isInputRange!InputRange1 && isInputRange!InputRange2 && is(typeof(moveEmplace(src
.front,tgt
.front)))); - Similar to moveAll but assumes all elements in
tgt
are uninitialized. Uses moveEmplace to move elements fromsrc
over elements fromtgt
.Examples:static struct Foo { ~this() pure nothrow @nogc { if (_ptr) ++*_ptr; } int* _ptr; } int[3] refs = [0, 1, 2]; Foo[3] src = [Foo(&refs[0]), Foo(&refs[1]), Foo(&refs[2])]; Foo[5] dst = void; auto tail = moveEmplaceAll(src[], dst[]); // move 3 value from src over dst assert(tail.length == 2); // returns remaining uninitialized values initializeAll(tail); import std.algorithm.searching : all; assert(src[].all!(e => e._ptr is null)); assert(dst[0 .. 3].all!(e => e._ptr !is null));
- Tuple!(InputRange1, InputRange2)
moveSome
(InputRange1, InputRange2)(InputRange1src
, InputRange2tgt
)
if (isInputRange!InputRange1 && isInputRange!InputRange2 && is(typeof(move(src
.front,tgt
.front)))); - Calls move(a, b) for each element a in
src
and the corresponding element b intgt
, in increasing order, stopping when either range has been exhausted.Parameters:InputRange1 src
An input range with movable elements. InputRange2 tgt
An input range with elements that elements from src
can be moved into.Returns:The leftover portions of the two ranges after one or the other of the ranges have been exhausted.Examples:int[5] a = [ 1, 2, 3, 4, 5 ]; int[3] b; assert(moveSome(a[], b[])[0] is a[3 .. $]); writeln(a[0 .. 3]); // b writeln(a); // [1, 2, 3, 4, 5]
- @system Tuple!(InputRange1, InputRange2)
moveEmplaceSome
(InputRange1, InputRange2)(InputRange1src
, InputRange2tgt
)
if (isInputRange!InputRange1 && isInputRange!InputRange2 && is(typeof(move(src
.front,tgt
.front)))); - Same as moveSome but assumes all elements in
tgt
are uninitialized. Uses moveEmplace to move elements fromsrc
over elements fromtgt
.Examples:static struct Foo { ~this() pure nothrow @nogc { if (_ptr) ++*_ptr; } int* _ptr; } int[4] refs = [0, 1, 2, 3]; Foo[4] src = [Foo(&refs[0]), Foo(&refs[1]), Foo(&refs[2]), Foo(&refs[3])]; Foo[3] dst = void; auto res = moveEmplaceSome(src[], dst[]); writeln(res.length); // 2 import std.algorithm.searching : all; assert(src[0 .. 3].all!(e => e._ptr is null)); assert(src[3]._ptr !is null); assert(dst[].all!(e => e._ptr !is null));
- enum
SwapStrategy
: int; - Defines the swapping strategy for algorithms that need to swap elements in a range (such as partition and sort). The strategy concerns the swapping of elements that are not the core concern of the algorithm. For example, consider an algorithm that sorts [ "abc", "b", "aBc" ] according to toUpper(a) < toUpper(b). That algorithm might choose to swap the two equivalent strings "abc" and "aBc". That does not affect the sorting since both ["abc", "aBc", "b" ] and [ "aBc", "abc", "b" ] are valid outcomes.Some situations require that the algorithm must NOT ever change the relative ordering of equivalent elements (in the example above, only [ "abc", "aBc", "b" ] would be the correct result). Such algorithms are called stable. If the ordering algorithm may swap equivalent elements discretionarily, the ordering is called unstable. Yet another class of algorithms may choose an intermediate tradeoff by being stable only on a well-defined subrange of the range. There is no established terminology for such behavior; this library calls it semistable. Generally, the stable ordering strategy may be more costly in time and/or space than the other two because it imposes additional constraints. Similarly, semistable may be costlier than unstable. As (semi-)stability is not needed very often, the ordering algorithms in this module parameterized by
SwapStrategy
all chooseSwapStrategy
.unstable as the default.Examples:int[] a = [0, 1, 2, 3]; writeln(remove!(SwapStrategy.stable)(a, 1)); // [0, 2, 3] a = [0, 1, 2, 3]; writeln(remove!(SwapStrategy.unstable)(a, 1)); // [0, 3, 2]
Examples:import std.algorithm.sorting : partition; // Put stuff greater than 3 on the left auto arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; writeln(partition!(a => a > 3, SwapStrategy.stable)(arr)); // [1, 2, 3] writeln(arr); // [4, 5, 6, 7, 8, 9, 10, 1, 2, 3] arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; writeln(partition!(a => a > 3, SwapStrategy.semistable)(arr)); // [2, 3, 1] writeln(arr); // [4, 5, 6, 7, 8, 9, 10, 2, 3, 1] arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; writeln(partition!(a => a > 3, SwapStrategy.unstable)(arr)); // [3, 2, 1] writeln(arr); // [10, 9, 8, 4, 5, 6, 7, 3, 2, 1]
unstable
- Allows freely swapping of elements as long as the output satisfies the algorithm's requirements.
semistable
- In algorithms partitioning ranges in two, preserve relative ordering of elements only to the left of the partition point.
stable
- Preserve the relative ordering of elements to the largest extent allowed by the algorithm's requirements.
- Range
remove
(SwapStrategy s = SwapStrategy.stable, Range, Offset...)(Rangerange
, Offsetoffset
)
if (Offset.length >= 1 && allSatisfy!(isValidIntegralTuple, Offset)); - Eliminates elements at given offsets from
range
and returns the shortened range.For example, here is how to remove a single element from an array:string[] a = [ "a", "b", "c", "d" ]; a = a.remove(1); // remove element at offset 1 assert(a == [ "a", "c", "d"]);
Note thatremove
does not change the length of the original range directly; instead, it returns the shortened range. If its return value is not assigned to the original range, the original range will retain its original length, though its contents will have changed:int[] a = [ 3, 5, 7, 8 ]; assert(remove(a, 1) == [ 3, 7, 8 ]); assert(a == [ 3, 7, 8, 8 ]);
The element at offset 1 has been removed and the rest of the elements have shifted up to fill its place, however, the original array remains of the same length. This is because all functions in std.algorithm only change content, not topology. The value 8 is repeated because move was invoked to rearrange elements, and on integers move simply copies the source to the destination. To replace a with the effect of the removal, simply assign the slice returned byremove
to it, as shown in the first example. Multiple indices can be passed intoremove
. In that case, elements at the respective indices are all removed. The indices must be passed in increasing order, otherwise an exception occurs.int[] a = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]; assert(remove(a, 1, 3, 5) == [ 0, 2, 4, 6, 7, 8, 9, 10 ]);
(Note that all indices refer to slots in the original array, not in the array as it is being progressively shortened.) Tuples of two integral offsets can be used to remove an indices range:int[] a = [ 3, 4, 5, 6, 7]; assert(remove(a, 1, tuple(1, 3), 9) == [ 3, 6, 7 ]);
The tuple passes in a range closed to the left and open to the right (consistent with built-in slices), e.g. tuple(1, 3) means indices 1 and 2 but not 3. Finally, any combination of integral offsets and tuples composed of two integral offsets can be passed in:int[] a = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]; assert(remove(a, 1, tuple(3, 5), 9) == [ 0, 2, 5, 6, 7, 8, 10 ]);
In this case, the slots at positions 1, 3, 4, and 9 are removed from the array. If the need is to remove some elements in the range but the order of the remaining elements does not have to be preserved, you may want to pass SwapStrategy.unstable toremove
.int[] a = [ 0, 1, 2, 3 ]; assert(remove!(SwapStrategy.unstable)(a, 1) == [ 0, 3, 2 ]);
In the case above, the element at slot 1 is removed, but replaced with the last element of the range. Taking advantage of the relaxation of the stability requirement,remove
moved elements from the end of the array over the slots to be removed. This way there is less data movement to be done which improves the execution time of the function. The functionremove
works on bidirectional ranges that have assignable lvalue elements. The moving strategy is (listed from fastest to slowest):- If s == SwapStrategy.unstable && isRandomAccessRange!Range && hasLength!Range && hasLvalueElements!Range, then elements are moved from the end of the range into the slots to be filled. In this case, the absolute minimum of moves is performed.
- Otherwise, if s ==
SwapStrategy.unstable && isBidirectionalRange!Range && hasLength!Range
&& hasLvalueElements!Range, then elements are still moved from the
end of the range, but time is spent on advancing between slots by repeated
calls to
range
.popFront. - Otherwise, elements are moved
incrementally towards the front of
range
; a given element is never moved several times, but more elements are moved than in the previous cases.
Parameters:s a SwapStrategy to determine if the original order needs to be preserved Range range
a bidirectional range with a length member Offset offset
which element(s) to remove Returns:A range containing all of the elements of range with offset removed. - Range
remove
(alias pred, SwapStrategy s = SwapStrategy.stable, Range)(Rangerange
); - Reduces the length of the bidirectional range
range
by removing elements that satisfy pred. If s = SwapStrategy.unstable, elements are moved from the right end of the range over the elements to eliminate. If s = SwapStrategy.stable (the default), elements are moved progressively to front such that their relative order is preserved. Returns the filtered range.Parameters:Range range
a bidirectional ranges with lvalue elements or mutable character arrays Returns:the range with all of the elements where pred is true removedExamples:static immutable base = [1, 2, 3, 2, 4, 2, 5, 2]; int[] arr = base[].dup; // using a string-based predicate writeln(remove!("a == 2")(arr)); // [1, 3, 4, 5] // The original array contents have been modified, // so we need to reset it to its original state. // The length is unmodified however. arr[] = base[]; // using a lambda predicate writeln(remove!(a => a == 2)(arr)); // [1, 3, 4, 5]
- Range
reverse
(Range)(Ranger
)
if (isBidirectionalRange!Range && (hasSwappableElements!Range || hasAssignableElements!Range && hasLength!Range && isRandomAccessRange!Range || isNarrowString!Range && isAssignable!(ElementType!Range))); - Reverses
r
in-place. Performsr
.length / 2 evaluations of swap. UTF sequences consisting of multiple code units are preserved properly.Parameters:Range r
a bidirectional range with either swappable elements, a random access range with a length member, or a narrow string Returns:r
Note When passing a string with unicode modifiers on characters, such as \u0301, this function will not properly keep the position of the modifier. For example, reversing ba\u0301d ("bád") will result in d\u0301ab ("d́ab") instead of da\u0301b ("dáb").
See Also:std.range.retro for a lazy reverse without changingr
Examples:int[] arr = [ 1, 2, 3 ]; writeln(arr.reverse); // [3, 2, 1]
Examples:char[] arr = "hello\U00010143\u0100\U00010143".dup; writeln(arr.reverse); // "\U00010143\u0100\U00010143olleh"
- Range
strip
(Range, E)(Rangerange
, Eelement
)
if (isBidirectionalRange!Range && is(typeof(range
.front ==element
) : bool));
Rangestrip
(alias pred, Range)(Rangerange
)
if (isBidirectionalRange!Range && is(typeof(pred(range
.back)) : bool));
RangestripLeft
(Range, E)(Rangerange
, Eelement
)
if (isInputRange!Range && is(typeof(range
.front ==element
) : bool));
RangestripLeft
(alias pred, Range)(Rangerange
)
if (isInputRange!Range && is(typeof(pred(range
.front)) : bool));
RangestripRight
(Range, E)(Rangerange
, Eelement
)
if (isBidirectionalRange!Range && is(typeof(range
.back ==element
) : bool));
RangestripRight
(alias pred, Range)(Rangerange
)
if (isBidirectionalRange!Range && is(typeof(pred(range
.back)) : bool)); - The strip group of functions allow stripping of either leading, trailing, or both leading and trailing elements.The
stripLeft
function will strip the front of the range, thestripRight
function will strip the back of the range, while thestrip
function will strip both the front and back of the range. Note that thestrip
andstripRight
functions require the range to be a BidirectionalRange range. All of these functions come in two varieties: one takes a target element, where the range will be stripped as long as this element can be found. The other takes a lambda predicate, where the range will be stripped as long as the predicate returns true.Parameters:Range range
a bidirectional range or input range E element
the elements to remove Returns:a Range with all of range except element at the start and endExamples:Strip leading and trailing elements equal to the target element.writeln(" foobar ".strip(' ')); // "foobar" writeln("00223.444500".strip('0')); // "223.4445" writeln("ëëêéüŗōpéêëë".strip('ë')); // "êéüŗōpéê" writeln([1, 1, 0, 1, 1].strip(1)); // [0] writeln([0.0, 0.01, 0.01, 0.0].strip(0).length); // 2
Examples:Strip leading and trailing elements while the predicate returns true.writeln(" foobar ".strip!(a => a == ' ')()); // "foobar" writeln("00223.444500".strip!(a => a == '0')()); // "223.4445" writeln("ëëêéüŗōpéêëë".strip!(a => a == 'ë')()); // "êéüŗōpéê" writeln([1, 1, 0, 1, 1].strip!(a => a == 1)()); // [0] writeln([0.0, 0.01, 0.5, 0.6, 0.01, 0.0].strip!(a => a < 0.4)().length); // 2
Examples:Strip leading elements equal to the target element.writeln(" foobar ".stripLeft(' ')); // "foobar " writeln("00223.444500".stripLeft('0')); // "223.444500" writeln("ůůűniçodêéé".stripLeft('ů')); // "űniçodêéé" writeln([1, 1, 0, 1, 1].stripLeft(1)); // [0, 1, 1] writeln([0.0, 0.01, 0.01, 0.0].stripLeft(0).length); // 3
Examples:Strip leading elements while the predicate returns true.writeln(" foobar ".stripLeft!(a => a == ' ')()); // "foobar " writeln("00223.444500".stripLeft!(a => a == '0')()); // "223.444500" writeln("ůůűniçodêéé".stripLeft!(a => a == 'ů')()); // "űniçodêéé" writeln([1, 1, 0, 1, 1].stripLeft!(a => a == 1)()); // [0, 1, 1] writeln([0.0, 0.01, 0.10, 0.5, 0.6].stripLeft!(a => a < 0.4)().length); // 2
Examples:Strip trailing elements equal to the target element.writeln(" foobar ".stripRight(' ')); // " foobar" writeln("00223.444500".stripRight('0')); // "00223.4445" writeln("ùniçodêéé".stripRight('é')); // "ùniçodê" writeln([1, 1, 0, 1, 1].stripRight(1)); // [1, 1, 0] writeln([0.0, 0.01, 0.01, 0.0].stripRight(0).length); // 3
Examples:Strip trailing elements while the predicate returns true.writeln(" foobar ".stripRight!(a => a == ' ')()); // " foobar" writeln("00223.444500".stripRight!(a => a == '0')()); // "00223.4445" writeln("ùniçodêéé".stripRight!(a => a == 'é')()); // "ùniçodê" writeln([1, 1, 0, 1, 1].stripRight!(a => a == 1)()); // [1, 1, 0] writeln([0.0, 0.01, 0.10, 0.5, 0.6].stripRight!(a => a > 0.4)().length); // 3
- pure nothrow @nogc @trusted void
swap
(T)(ref Tlhs
, ref Trhs
)
if (isBlitAssignable!T && !is(typeof(lhs
.proxySwap(rhs
))));
voidswap
(T)(ref Tlhs
, ref Trhs
)
if (is(typeof(lhs
.proxySwap(rhs
)))); - Swaps
lhs
andrhs
. The instanceslhs
andrhs
are moved in memory, without ever calling opAssign, nor any other function. T need not be assignable at all to be swapped.Iflhs
andrhs
reference the same instance, then nothing is done.lhs
andrhs
must be mutable. If T is a struct or union, then its fields must also all be (recursively) mutable.Parameters:T lhs
Data to be swapped with rhs
.T rhs
Data to be swapped with lhs
.Examples:// Swapping POD (plain old data) types: int a = 42, b = 34; swap(a, b); assert(a == 34 && b == 42); // Swapping structs with indirection: static struct S { int x; char c; int[] y; } S s1 = { 0, 'z', [ 1, 2 ] }; S s2 = { 42, 'a', [ 4, 6 ] }; swap(s1, s2); writeln(s1.x); // 42 writeln(s1.c); // 'a' writeln(s1.y); // [4, 6] writeln(s2.x); // 0 writeln(s2.c); // 'z' writeln(s2.y); // [1, 2] // Immutables cannot be swapped: immutable int imm1 = 1, imm2 = 2; static assert(!__traits(compiles, swap(imm1, imm2))); int c = imm1 + 0; int d = imm2 + 0; swap(c, d); writeln(c); // 2 writeln(d); // 1
Examples:// Non-copyable types can still be swapped. static struct NoCopy { this(this) { assert(0); } int n; string s; } NoCopy nc1, nc2; nc1.n = 127; nc1.s = "abc"; nc2.n = 513; nc2.s = "uvwxyz"; swap(nc1, nc2); assert(nc1.n == 513 && nc1.s == "uvwxyz"); assert(nc2.n == 127 && nc2.s == "abc"); swap(nc1, nc1); swap(nc2, nc2); assert(nc1.n == 513 && nc1.s == "uvwxyz"); assert(nc2.n == 127 && nc2.s == "abc"); // Types containing non-copyable fields can also be swapped. static struct NoCopyHolder { NoCopy noCopy; } NoCopyHolder h1, h2; h1.noCopy.n = 31; h1.noCopy.s = "abc"; h2.noCopy.n = 65; h2.noCopy.s = null; swap(h1, h2); assert(h1.noCopy.n == 65 && h1.noCopy.s == null); assert(h2.noCopy.n == 31 && h2.noCopy.s == "abc"); swap(h1, h1); swap(h2, h2); assert(h1.noCopy.n == 65 && h1.noCopy.s == null); assert(h2.noCopy.n == 31 && h2.noCopy.s == "abc"); // Const types cannot be swapped. const NoCopy const1, const2; assert(const1.n == 0 && const2.n == 0); static assert(!__traits(compiles, swap(const1, const2)));
- void
swapAt
(R)(auto ref Rr
, size_ti1
, size_ti2
); - Swaps two elements in-place of a range
r
, specified by their indicesi1
andi2
.Parameters:R r
a range with swappable elements size_t i1
first index size_t i2
second index Examples:import std.algorithm.comparison : equal; auto a = [1, 2, 3]; a.swapAt(1, 2); assert(a.equal([1, 3, 2]));
- Tuple!(InputRange1, InputRange2)
swapRanges
(InputRange1, InputRange2)(InputRange1r1
, InputRange2r2
)
if (hasSwappableElements!InputRange1 && hasSwappableElements!InputRange2 && is(ElementType!InputRange1 == ElementType!InputRange2)); - Swaps all elements of
r1
with successive elements inr2
. Returns a tuple containing the remainder portions ofr1
and r2 that were not swapped (one of them will be empty). The ranges may be of different types but must have the same element type and support swapping.Parameters:InputRange1 r1
an input range with swappable elements InputRange2 r2
an input range with swappable elements Returns:Tuple containing the remainder portions of r1 and r2 that were not swappedExamples:import std.range : empty; int[] a = [ 100, 101, 102, 103 ]; int[] b = [ 0, 1, 2, 3 ]; auto c = swapRanges(a[1 .. 3], b[2 .. 4]); assert(c[0].empty && c[1].empty); writeln(a); // [100, 2, 3, 103] writeln(b); // [0, 1, 101, 102]
- void
uninitializedFill
(Range, Value)(Rangerange
, Valuevalue
)
if (isInputRange!Range && hasLvalueElements!Range && is(typeof(range
.front =value
))); - Initializes each element of
range
withvalue
. Assumes that the elements of the range are uninitialized. This is of interest for structs that define copy constructors (for all other types, fill and uninitializedFill are equivalent).Parameters:Range range
An input range that exposes references to its elements and has assignable elements Value value
Assigned to each element of range See Also:Examples:import core.stdc.stdlib : malloc, free; auto s = (cast(int*) malloc(5 * int.sizeof))[0 .. 5]; uninitializedFill(s, 42); writeln(s); // [42, 42, 42, 42, 42] scope(exit) free(s.ptr);