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std.range.primitives.pop_back - multiple declarations

Function popBack

Implements the range interface primitive popBack for built-in arrays. Due to the fact that nonmember functions can be called with the first argument using the dot notation, array.popBack is equivalent to popBack(array). For narrow strings, popFront automatically eliminates the last code point.

Prototype

void popBack(T)(
  T[] a
) pure nothrow @nogc @safe
if (!isNarrowString!(T[]) && !is(T[] == void[]));

Example

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

Function popBackN

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

Prototype

size_t popBackN(Range)(
  Range r,
  size_t n
)
if (isBidirectionalRange!Range);

Returns

How much r was actually advanced, which may be less than n if r did not have at least n elements.

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

Example

int[] a = [ 1, 2, 3, 4, 5 ];
a.popFrontN(2);
assert(a == [ 3, 4, 5 ]);
a.popFrontN(7);
assert(a == [ ]);

Example

import std.algorithm : equal;
import std.range : iota;
auto LL = iota(1L, 7L);
auto r = popFrontN(LL, 2);
assert(equal(LL, [3L, 4L, 5L, 6L]));
assert(r == 2);

Example

int[] a = [ 1, 2, 3, 4, 5 ];
a.popBackN(2);
assert(a == [ 1, 2, 3 ]);
a.popBackN(7);
assert(a == [ ]);

Example

import std.algorithm : equal;
import std.range : iota;
auto LL = iota(1L, 7L);
auto r = popBackN(LL, 2);
assert(equal(LL, [1L, 2L, 3L, 4L]));
assert(r == 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