Is there any generic iteration function that stops at first match?
something like filter[1] but that stops at first match? are there any native functions for this in D or I have to write one? just making sure to not reinvent the wheel [1]: https://devdocs.io/d/std_algorithm_iteration#filter
Re: Is there any generic iteration function that stops at first match?
On Fri, Mar 05, 2021 at 02:13:39AM +, Jack via Digitalmars-d-learn wrote: > something like filter[1] but that stops at first match? are there any > native functions for this in D or I have to write one? just making > sure to not reinvent the wheel [...] Why not just .front? E.g.: int[] data = [ 1,2,3,4,5 ]; auto r = data.filter!(v => v % 2 == 0); assert(r.front == 2); T -- There is no gravity. The earth sucks.
Re: Is there any generic iteration function that stops at first match?
On Friday, 5 March 2021 at 02:13:39 UTC, Jack wrote: something like filter[1] but that stops at first match? are there any native functions for this in D or I have to write one? just making sure to not reinvent the wheel [1]: https://devdocs.io/d/std_algorithm_iteration#filter std.algorithm.searching.until -Steve
Re: Is there any generic iteration function that stops at first match?
On Friday, 5 March 2021 at 02:43:36 UTC, H. S. Teoh wrote: On Fri, Mar 05, 2021 at 02:13:39AM +, Jack via Digitalmars-d-learn wrote: something like filter[1] but that stops at first match? are there any native functions for this in D or I have to write one? just making sure to not reinvent the wheel [...] Why not just .front? E.g.: int[] data = [ 1,2,3,4,5 ]; auto r = data.filter!(v => v % 2 == 0); assert(r.front == 2); T it loops over the entire array then returns, I'd like to stop as soon as the predicate return true
Re: Is there any generic iteration function that stops at first match?
On Friday, 5 March 2021 at 05:32:27 UTC, Jack wrote:
On Friday, 5 March 2021 at 02:43:36 UTC, H. S. Teoh wrote:
On Fri, Mar 05, 2021 at 02:13:39AM +, Jack via
Digitalmars-d-learn wrote:
something like filter[1] but that stops at first match? are
there any native functions for this in D or I have to write
one? just making sure to not reinvent the wheel
[...]
Why not just .front? E.g.:
int[] data = [ 1,2,3,4,5 ];
auto r = data.filter!(v => v % 2 == 0);
assert(r.front == 2);
T
it loops over the entire array then returns, I'd like to stop
as soon as the predicate return true
void main() {
import std.stdio, std.algorithm, std.range;
int[] data = iota(5).map!"a+1".array;
auto r = data.filter!(function (v) { writeln(v); return v %
2 == 0; });
assert(r.front == 2);
}
output:
1
2
'r' is an iterator. To force it to loop over the entire array that
would need a .array like I'm using for 'data'.
Re: Is there any generic iteration function that stops at first match?
On Friday, 5 March 2021 at 04:22:23 UTC, Steven Schveighoffer wrote: On Friday, 5 March 2021 at 02:13:39 UTC, Jack wrote: something like filter[1] but that stops at first match? are there any native functions for this in D or I have to write one? just making sure to not reinvent the wheel [1]: https://devdocs.io/d/std_algorithm_iteration#filter std.algorithm.searching.until -Steve thanks, totally overlooked this searching section
Re: Is there any generic iteration function that stops at first match?
On Friday, 5 March 2021 at 02:13:39 UTC, Jack wrote: something like filter[1] but that stops at first match? are there any native functions for this in D or I have to write one? just making sure to not reinvent the wheel [1]: https://devdocs.io/d/std_algorithm_iteration#filter std.algorithm.searching.find To summarize. * filter.front * find.front * until * find The first two provide you data at the first match, `until` produces a range exclusive of the first match. If you just use find it will produce a range that starts at the first match, unlike filter the range includes everything and not just the matching data.
