Hi,
I just spend a day with the D programming language and I am very
excited about being able to write such performant programs in
such an clear and concise way!
I tried to write a little search tool.
The BoyerMooreFinder docs say that the comparison operator can be
specified. Unfortunately, this doesn't work in practice:
import std.algorithm;
import std.stdio;
void main(string[] args) {
writeln("> ", find("Hello World", boyerMooreFinder("World")));
writeln("> ", find("Hello World", boyerMooreFinder!("toLower(a)
== toLower(b)")("world")));
writeln("> ", find("EE Hello World",
boyerMooreFinder!("toLower(a) == toLower(b)")("worl")));
}
Result:
World
World
The problem is here:
https://github.com/D-Programming-Language/phobos/blob/v2.069.1/std/algorithm/searching.d#L280
When it looks letters up in its private lookup tables, it uses
the original letters, not the lower case ones. To work around
this, I copied the algorithm class, customized this to use the
.toLower letter here as well and it works like a charm.
I wondered: Do I miss something here? Calling .toLower() on the
whole string makes this a lot slower; is there a way to customize
the algorithm with some mapping for the characters? Is there a
use case for customizing the predicate only?
Greetings,
Ralf
