View source code Display the source code in std/range/primitives.d from which this page was generated on github. Improve this page Quickly fork, edit online, and submit a pull request for this page. Requires a signed-in GitHub account. This works well for small changes. If you'd like to make larger changes you may want to consider using local clone. Page wiki View or edit the community-maintained wiki page associated with this page.

Function std.range.primitives.popBackExactly

Eagerly advances r itself (not a copy) exactly n times (by calling r.popFront). popFrontExactly takes r by ref, so it mutates the original range. Completes in Ο(1) steps for ranges that support slicing, and have either length or are infinite. Completes in Ο(n) time for all other ranges.

Prototype

void popBackExactly(Range)(
  Range r,
  size_t n
)
if (isBidirectionalRange!Range);

Note

Unlike popFrontN, popFrontExactly will assume that the range holds at least n elements. This makes popFrontExactly faster than popFrontN, but it also means that if range does not contain at least n elements, it will attempt to call popFront on an empty range, which is undefined behavior. So, only use popFrontExactly when it is guaranteed that range holds at least n elements.

popBackExactly will behave the same but instead removes elements from the back of the (bidirectional) range instead of the front.

Example

import std.algorithm : filterBidirectional, equal;

auto a = [1, 2, 3];
a.popFrontExactly(1);
assert(a == [2, 3]);
a.popBackExactly(1);
assert(a == [2]);

string s = "日本語";
s.popFrontExactly(1);
assert(s == "本語");
s.popBackExactly(1);
assert(s == "本");

auto bd = filterBidirectional!"true"([1, 2, 3]);
bd.popFrontExactly(1);
assert(bd.equal([2, 3]));
bd.popBackExactly(1);
assert(bd.equal([2]));

Authors

Andrei Alexandrescu, David Simcha, and Jonathan M Davis. Credit for some of the ideas in building this module goes to Leonardo Maffi.

License

Boost License 1.0.

Comments