Function std.algorithm.mutation.bringToFront
bringToFront takes two ranges front and back, which may
be of different types. Considering the concatenation of front and
back one unified range, bringToFront rotates that unified
range such that all elements in back are brought to the beginning
of the unified range. The relative ordering of elements in front
and back, respectively, remains unchanged.
size_t bringToFront(InputRange, ForwardRange)
(
InputRange front,
ForwardRange back
)
if (isInputRange!InputRange && isForwardRange!ForwardRange);
The bringToFront 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) evaluations of swap.
The bringToFront 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 and back are disjoint, or back is
reachable from front and front is not reachable from back.
Parameters
| Name | Description |
|---|---|
| front | an input range |
| back | a forward range |
Returns
The number of elements brought to the front, i.e., the length of back.
See Also
Example
The simplest use of bringToFront 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]
Example
The front range may actually "step over" the back
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 stdExample
Elements can be swapped across ranges of different types:
import stdExample
Unicode integrity is not preserved:
import std