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Function std.range.dropBackExactly

Similar to drop and dropBack but they call range.popFrontExactly(n) and range.popBackExactly(n) instead.

Prototype

R dropBackExactly(R)(
  R range,
  size_t n
)
if (isBidirectionalRange!R);

Note

Unlike drop, dropExactly will assume that the range holds at least n elements. This makes dropExactly faster than drop, 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.

Example

import std.algorithm : equal, filterBidirectional;

auto a = [1, 2, 3];
assert(a.dropExactly(2) == [3]);
assert(a.dropBackExactly(2) == [1]);

string s = "日本語";
assert(s.dropExactly(2) == "語");
assert(s.dropBackExactly(2) == "日");

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

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