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Function `std.algorithm.iteration.uniq`

Lazily iterates unique consecutive elements of the given range (functionality akin to the uniq system utility). Equivalence of elements is assessed by using the predicate pred, by default "a == b". The predicate is passed to binaryFun, and can either accept a string, or any callable that can be executed via pred(element, element). If the given range is bidirectional, uniq also yields a bidirectional range.


						
				auto uniq(alias pred, Range)
				(
				

				  Range r
				

				)
				

				if (isInputRange!Range && is(typeof(binaryFun!pred(r.front, r.front)) == bool));

Parameters

Name	Description
pred	Predicate for determining equivalence between range elements.
r	An input range of elements to filter.

Returns

An input range of consecutively unique elements in the original range. If r is also a forward range or bidirectional range, the returned range will be likewise.

Example

import std.algorithm.comparison : equal;
import std.algorithm.mutation : copy;

int[] arr = [ 1, 2, 2, 2, 2, 3, 4, 4, 4, 5 ];
assert(equal(uniq(arr), [ 1, 2, 3, 4, 5 ][]));

// Filter duplicates in-place using copy
arr.length -= arr.uniq().copy(arr).length;
writeln(arr); // [1, 2, 3, 4, 5]

// Note that uniqueness is only determined consecutively; duplicated
// elements separated by an intervening different element will not be
// eliminated:
assert(equal(uniq([ 1, 1, 2, 1, 1, 3, 1]), [1, 2, 1, 3, 1]));

Authors

Andrei Alexandrescu

License

Boost License 1.0.