On Wednesday, 30 March 2016 at 05:16:04 UTC, H. S. Teoh wrote:
If we didn't have autodecoding, would be a simple matter of
searching for sentinel substrings. This also indicates that
most of the work done by autodecoding is unnecessary -- it's
wasted work since most of the string data is treated opaquely
anyway.
Just to drive this point home, I made a very simple benchmark.
Iterating over code points when you don't need to is 100x slower
than iterating over code units.
import std.datetime;
import std.stdio;
import std.array;
import std.utf;
import std.uni;
enum testCount = 1_000_000;
enum var = "Lorem ipsum dolor sit amet, consectetur adipiscing
elit. Praesent justo ante, vehicula in felis vitae, finibus
tincidunt dolor. Fusce sagittis.";
void test()
{
auto a = var.array;
}
void test2()
{
auto a = var.byCodeUnit.array;
}
void test3()
{
auto a = var.byGrapheme.array;
}
void main()
{
import std.conv : to;
auto r = benchmark!(test, test2, test3)(testCount);
auto result = to!Duration(r[0] / testCount);
auto result2 = to!Duration(r[1] / testCount);
auto result3 = to!Duration(r[2] / testCount);
writeln("auto-decoding", "\t\t", result);
writeln("byCodeUnit", "\t\t", result2);
writeln("byGrapheme", "\t\t", result3);
}
$ ldc2 -O3 -release -boundscheck=off test.d
$ ./test
auto-decoding 1 μs
byCodeUnit 0 hnsecs
byGrapheme 11 μs
