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Template `std.algorithm.iteration.filterBidirectional`

Similar to filter, except it defines a bidirectional range. There is a speed disadvantage - the constructor spends time finding the last element in the range that satisfies the filtering condition (in addition to finding the first one). The advantage is that the filtered range can be spanned from both directions. Also, std.range.retro can be applied against the filtered range.


						
				template filterBidirectional(alias pred)
				;

The predicate is passed to unaryFun, and can either accept a string, or any callable that can be executed via pred(element).

Contained Functions

Name	Description
filterBidirectional

Parameters

Name	Description
pred	Function to apply to each element of range

Example

import std.algorithm.comparison : equal;
import std.range;

int[] arr = [ 1, 2, 3, 4, 5 ];
auto small = filterBidirectional!("a < 3")(arr);
static assert(isBidirectionalRange!(typeof(small)));
writeln(small.back); // 2
assert(equal(small, [ 1, 2 ]));
assert(equal(retro(small), [ 2, 1 ]));
// In combination with chain() to span multiple ranges
int[] a = [ 3, -2, 400 ];
int[] b = [ 100, -101, 102 ];
auto r = filterBidirectional!("a > 0")(chain(a, b));
writeln(r.back); // 102

Authors

Andrei Alexandrescu

License

Boost License 1.0.