Re: Turning fixed sized array into tuple
On Saturday, 4 May 2024 at 19:11:14 UTC, Nick Treleaven wrote:
On Saturday, 4 May 2024 at 16:58:00 UTC, Dmitry Olshansky wrote:
So I have a function:
```d
size_t awaitAny(T...)(T args) { ... }
```
And I have:
``d
Event*[4] events;
``
How do I pass all 4 of events to awaitAny as tuple of
arguments?
Use `awaitAny(events.tupleof)`?
https://dlang.org/spec/arrays.html#array-properties
Thanks, totally missed it!
—
Dmitry Olshansky
CEO @ [Glow labs](https://glow-labs.pro)
https://olshansky.me
Turning fixed sized array into tuple
So I have a function:
```d
size_t awaitAny(T...)(T args) { ... }
```
And I have:
``d
Event*[4] events;
``
How do I pass all 4 of events to awaitAny as tuple of arguments?
--
Dmitry Olshansky
CEO @ [Glow labs](https://glow-labs.pro)
https://olshansky.me/about/
Re: Setting up CI for Dub project on Github
On Monday, 8 April 2024 at 13:23:12 UTC, Richard (Rikki) Andrew Cattermole wrote: On 09/04/2024 1:20 AM, Dmitry Olshansky wrote: I haven’t done any research on the subject, would be nice if somebody pointed me to good example of how it’s done. — Dmitry Olshansky CEO @ Glowlabs https://olshansky.me In case you haven't already found: https://github.com/dlang-community/setup-dlang Thanks, Rikki, that should do the trick. — Dmitry Olshansky CEO @ Glowlabs https://olshansky.me
Setting up CI for Dub project on Github
I haven’t done any research on the subject, would be nice if somebody pointed me to good example of how it’s done. — Dmitry Olshansky CEO @ Glowlabs https://olshansky.me
Re: Limits of implicit conversion of class arrays
On Saturday, 23 March 2024 at 09:08:45 UTC, Per Nordlöw wrote:
Is there a reason why
```d
class Base {}
class Derived : Base {}
@safe pure nothrow unittest {
Base b;
Derived d;
b = d; // pass
Base[] bs;
Derived[] ds;
bs ~= ds; // pass
bs = ds; // fail [1], should pass
bs = cast(Base[])ds; // fail [2], should pass
}
```
fails as
[1]: cannot implicitly convert expression `ds` of type
`Derived[]` to `Base[]`
[2]: cast from `Derived[]` to `Base[]` not allowed in safe code
?
The first and second is unsound (infamously allowed in Java).
Once you cast the slice you can populate it with Derived2 objects
that are not Derived, hence breaking type safety of the ds slice.
—
Dmitry Olshansky
CEO @ Glow labs
https://olshansky.me
Linker error, doing something wrong?
Trying to compile the following: https://github.com/DmitryOlshansky/photon/blob/master/tests/curl_download.d with: ldc2 curl_download.d -L-lcurl get: "__D6photon12__ModuleInfoZ", referenced from: __D13curl_download12__ModuleInfoZ in curl_download.o "__D6photon5macos4core2goFDFZvZv", referenced from: __D13curl_download4mainFZ13spawnDownloadMFAyaQdZv in curl_download.o "__D6photon5macos4core9startloopFZv", referenced from: __Dmain in curl_download.o "__D6photon9runFibersFZv", referenced from: __Dmain in curl_download.o ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation) Error: /usr/bin/cc failed with status: 1 Am I missing something? -- Dmitry Olshansky https://olshansky.me
Re: Easiest CI to build on github.com
On Friday, 7 July 2023 at 10:29:14 UTC, Richard (Rikki) Andrew Cattermole wrote: I believe: https://github.com/dlang-community/setup-dlang Thx! — Dmitry Olshansky CEO @ Glow Labs https://olshansky.me https://t.me/glowlabs32
Easiest CI to build on github.com
Simply enough dub test should pass. How do I go about it? — Dmitry Olshansky CEO @ Glow Labs https://olshansky.me https://t.me/glowlabs32
Re: IntelliJ D language plugin
On Friday, 30 June 2023 at 16:26:26 UTC, Richard (Rikki) Andrew Cattermole wrote: I use it and contribute to it ;) Thanks to Rikki I was able to figure it out. — Dmitry Olshansky https://olshansky.me
IntelliJ D language plugin
Have anyone had any luck with it? So far I'm trying to install DMD as SDK but it fails with not a valid D compiler home. -- Dmitry Olshansky https://olshansky.me
Re: Running LDC on a recent MacOS
On Friday, 16 June 2023 at 16:14:19 UTC, Steven Schveighoffer wrote: On 6/16/23 11:56 AM, Dmitry Olshansky wrote: Any advice from MacOS users? Yep. Go into settings, then privacy and security. Make sure "App store and identified developers" is checked. On that page, you will see probably a thing saying "you tried to run ldc2 but I blocked it". Say "allow anyway". Then try it again. This time, it will still block it, but ask you if you want to run it. Yes, thanks that did the trick! -Steve
Re: Using DUB packages with Meson
On Wednesday, 12 April 2023 at 11:07:56 UTC, Richard (Rikki) Andrew Cattermole wrote: Did you compile the library with dub using ldc2? Yup, I do not have other compilers installed. -- Dmitry Olshansky
Re: Using DUB packages with Meson
On Wednesday, 12 April 2023 at 10:24:48 UTC, Richard (Rikki) Andrew Cattermole wrote: I'm going to guess that you need to use the version specifier in the package name. Because I'm not seeing anything there to handle it specifically. https://github.com/mesonbuild/meson/blob/master/mesonbuild/dependencies/dub.py i.e. ``dub build [[@]] []`` So use ``package:sub@1.0.2``. Also I just noticed meson doesn't support shared libraries from dub, so something to keep in mind. I'm getting closer. I'm stuck with this at the moment: Found DUB: /home/d.olshanskiy/bin/dub (DUB version 1.31.1, built on Mar 12 2023) ERROR: strand found but it wasn't compiled with ldc Run-time dependency strand found: NO src/meson.build:22:0: ERROR: Dependency "strand" not found -- Dmitry Olshansky
Re: Using DUB packages with Meson
On Wednesday, 12 April 2023 at 10:24:48 UTC, Richard (Rikki) Andrew Cattermole wrote: I'm going to guess that you need to use the version specifier in the package name. Because I'm not seeing anything there to handle it specifically. https://github.com/mesonbuild/meson/blob/master/mesonbuild/dependencies/dub.py i.e. ``dub build [[@]] []`` So use ``package:sub@1.0.2``. Also I just noticed meson doesn't support shared libraries from dub, so something to keep in mind. Oh, Rikki, you are so helpful. Thanks! -- Dmitry Olshansky
Using DUB packages with Meson
I'm trying to use my new DUB package from Photon, which is polyglot project and is built with Meson. Have anyone worked with DUB packages in Meson? I've found this bit of documentation: https://mesonbuild.com/Dependencies.html#dub And I did fetch & build but I do not understand how to introduce library dependency on a specific DUB package. -- Dmitry Olshansky
Re: Help with registering dub package
On Wednesday, 12 April 2023 at 08:25:54 UTC, Richard (Rikki) Andrew Cattermole wrote: Your branches + tag is all messed up. You have both ~master and ~main. ~main has dub.json (which is required), but the tag is based upon ~master which has your README. Between the two branches everything is there, its just that it needs to be all in one. Thanks, Rikki! — Dmitry Olshansky
Help with registering dub package
Could someone walk me through the steps of publish my dub package? I'm stuck with this: https://code.dlang.org/packages/strand For some reason code.dlang.org cannot find my semver tag I guess. -- Dmitry Olshansky
Re: How to build DMD/Phobos on Windows
On Wednesday, 24 August 2022 at 21:11:42 UTC, rikki cattermole
wrote:
For dmd you use build.d that is in the repository.
Hm, I guess the makefiles should be deleted?
For phobos win64.mak (used for 32bit by default as well):
"# Makefile to build D runtime library phobos{64,32mscoff}.lib
for Windows MSVC"
So MSVC make.
It’s a shame as I cannot install MSVC on this laptop
(permissions).
Beyond that idk, but its starting point (oh and druntime is now
in dmd repo, so ugh... yeah)
Yeah, I see that build become more involved.
How to build DMD/Phobos on Windows
It's been a long time but I've found some spare hours I want to devote to finally updating our std.uni to Unicode 14 (soon to migrate to 15 I guess). I downloaded source code of DMD/Phobos as usual and dropped them in the src folder of unpacked 7z distribution archive. Now time to build. Since DMD doesn't ship make anymore I guessed I needed a GNU make so I got that. Doing make -f win32.mak shows an endless stream of make entering the folder and then leaving it. make[45]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak make[46]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak make[47]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak make[48]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak make[49]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak make[50]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak make[51]: Entering directory 'C:/exp/dmd2/src/dmd' cd compiler\src make -f win32.mak Trying to run any makefiles in compiler/druntime folders do not produce anything useful either. So what is the canonical way to build D on Windows? Any pointers would be greately appreciated.
Re: Why The D Style constants are written in camelCase?
On Wednesday, 9 May 2018 at 09:38:14 UTC, BoQsc wrote: The D Style suggest to camelCase constants, while Java naming conventions always promoted uppercase letter. Is there an explanation why D Style chose to use camelCase instead of all UPPERCASE for constants, was there any technical problem that would appear while writing in all UPPERCASE? It is D style for standard library. It is mostly arbitrary but in general sensible. That’s it.
Re: dynamically allocating on the stack
On Saturday, 21 April 2018 at 14:25:58 UTC, Cym13 wrote: On Saturday, 21 April 2018 at 13:54:14 UTC, H. S. Teoh wrote: On Sat, Apr 21, 2018 at 01:30:55PM +, Cym13 via Digitalmars-d-learn wrote: On Saturday, 21 April 2018 at 12:08:09 UTC, Dmitry Olshansky wrote: [...] > Unbounded allocation on stack is kind of anti-pattern and a > potential DoS vector. I'm having trouble seeing how unbounded heap allocations aren't equally a potential DoS vector. [...] Generally speaking, the heap is much bigger than the stack (often many times so) and so is less prone to overflow. Though it's true, it still does happen if you just blindly allocate memory based on unsanitized external input. T Wait, why? Don't they share the same address space and grow in opposite directions? That was true more like 25 years ago. Same address space is obviously still true. These days heap is usually not using sbrk which is basically what you describe. Also imagine threads and tell me which stack grows towards which ;) Heap is allocated with mmap on Posix’es and VirtualAlloc on Windows. Stack is typically fixed limit imposed by ulimit and how it grows is beside the point really.
Re: dynamically allocating on the stack
On Saturday, 21 April 2018 at 13:30:55 UTC, Cym13 wrote:
On Saturday, 21 April 2018 at 12:08:09 UTC, Dmitry Olshansky
wrote:
On Saturday, 21 April 2018 at 07:37:50 UTC, Mike Franklin
wrote:
Does D have some way to dynamically allocate on the stack?
I'm looking for something roughly equivalent to the following
C code.
int doSomething(size_t len)
{
char stackBuffer[len + 1];
doSomethingElse(stackBuffer);
}
Unbounded allocation on stack is kind of anti-pattern and a
potential DoS vector.
I'm having trouble seeing how unbounded heap allocations aren't
equally a potential DoS vector.
I could see what you meant, but really stack is typically far
more limited then heap in size.
Unless you tune the stack size yourself (i.e. you both build an
app and control the environment) there is no sensible way to know
the size you can use. It’s also heavily platform dependent.
With heap it’s usually far less limited resource.
Lastly Fibers usually have small stacks.
A separate region allocator is exactly as fast and can easily
survive across boundaries of function calls.
I guess if OP wants it on the stack it's because it doesn't
need to survive across boundaries of function calls so this
buys nothing in this case.
Yet nothing to lose and much safer bet in general.
In general, I’d expect performance to be the goal here. If so
then zone/region allocation is a well known pattern that is not
restricted to individual arrays and is widely used in games and
industry-grade stuff like browsers/VMs.
Also you probably want something like char[X] = void;
for efficiency if allocating on stack.
Thanks,
Mike
Re: dynamically allocating on the stack
On Saturday, 21 April 2018 at 07:37:50 UTC, Mike Franklin wrote:
Does D have some way to dynamically allocate on the stack? I'm
looking for something roughly equivalent to the following C
code.
int doSomething(size_t len)
{
char stackBuffer[len + 1];
doSomethingElse(stackBuffer);
}
Unbounded allocation on stack is kind of anti-pattern and a
potential DoS vector.
A separate region allocator is exactly as fast and can easily
survive across boundaries of function calls.
Also you probably want something like char[X] = void;
for efficiency if allocating on stack.
Thanks,
Mike
Re: Is socket.send thread safe?
On Monday, 26 March 2018 at 16:14:31 UTC, Jonathan wrote: Can I send data over an std.socket on multiple threads without manual mutexing? If not, can I send data on a separate thread than receive? The docs for std.socket say nothing of it (which I guess means I should assume it is not thread safe but...). It’s thin-wrapper over system interface. It’s thread-safe in that system will not topple over, you will likely get some interleaving of data. HOWEVER: there is such a thing as short-writes, which means that since OS buffer may fill up it could write less then you intended to and return that amount. It certainly happens with O_NONBLOCK. In normal blocking mode it might work, but in general it’s a bad idea to do writes to a single socket from multiple threads w/o some coordination s.t. only can do it at any given time. Lastly as far as guarantees go, POSIX doesn’t state that 2 writes will be interleaved “exactly”, it may for instance splice them zebra-style by some chunk size and I could imagine why (on long buffers). My suggestion is to have a queue of messages and a thread to send them. You might also want to check and see if there is a better protocol then TCP to take advantage of unordered messages. I think there is at least RDP (reliable datagram protocol) on Linux that might fit the bill. Thanks!
Re: core.stdc.stdlib._compare_fp_t and qsort
On Sunday, 18 March 2018 at 18:11:02 UTC, Dmitry Olshansky wrote:
On Sunday, 18 March 2018 at 16:45:16 UTC, Joe wrote:
[...]
No it just creates a pair of pointer to recs[0] + length of
recs, like this:
struct Array
{
size_t length;
Record* ptr;
}
In D it’s typed as Record[] and has a number of nice
properties, like not losing its length;)
[...]
Well since recs is array of pointers this looks like a null
pointer in your data.
Or rather if 10 is capacity and num_recs is actual length, then:
recs[0..num_recs] is the slice with data that you want to sort.
Re: core.stdc.stdlib._compare_fp_t and qsort
On Sunday, 18 March 2018 at 16:45:16 UTC, Joe wrote:
On Sunday, 18 March 2018 at 13:10:08 UTC, Dmitry Olshansky
wrote:
Do this to get the usual ptr + length:
sort!((a, b) => to!string((*a).name) <
to!string((*b).name))(recs[]);
Also to!string would be computed on each compare anew. May
want to use schwartzSort to avoid that, on 10 elements there
is no real difference though.
The 10 elements are just because it's a small test program.
What does changing "recs" to "recs[]" as the argument actually
do? Does it duplicate the fixed array on the fly? [I guess I
have to study more!]
No it just creates a pair of pointer to recs[0] + length of recs,
like this:
struct Array
{
size_t length;
Record* ptr;
}
In D it’s typed as Record[] and has a number of nice properties,
like not losing its length;)
The change does pass the compiler, but at runtime it causes a
segfault. The next to last frame in the backtrace shows
(having changed from to!string to fromStringz and using a
string template instead of a lambda):
Well since recs is array of pointers this looks like a null
pointer in your data.
The usual ways to fix that is either print stuff or poke around
in debugger to see if a Record* is null or .name is null.
#6 0x55565760 in
std.algorithm.sorting.sort!("fromStringz((*a).name.ptr) <
fromStringz((*b).name.ptr)", 0,
testd.Record*[]).sort(testd.Record*[]) (r=...)
Also you don’t need (*a).name, D understands that . can access
data through pointer (what would be an error in C and require ->).
Then it goes through quickSortImpl, shortSort and sort5, moving
on to either std.functional.binaryFun or processing of the
lambda, with a and b equal to 0, ending with a segfault in a ??
call from fromStringz or in memcpy called from object._dup (in
the to!string case).
Re: core.stdc.stdlib._compare_fp_t and qsort
On Sunday, 18 March 2018 at 11:29:47 UTC, Joe wrote: On Monday, 12 March 2018 at 03:50:42 UTC, Joe wrote: On Monday, 12 March 2018 at 03:13:08 UTC, Seb wrote: Out of interest: I wonder what's your usecase for using qsort. Or in other words: why you can't use the high-level std.algorithm.sorting.sort? This is only temporary. I will be using std.algorithm.sorting.sort. I was converting a C program and it annoyed me that I couldn't get the qsort invocation past the D compiler. Now that I'm trying to use std.algorithm.sorting, I'm again puzzled by what I need to use for the "less" predicate. My first try was: sort!((a, b) => to!string((*a).name) < to!string((*b).name))(recs); This results in the error: Error: template std.algorithm.sorting.sort cannot deduce function from argument types !((a, b) => to!string((*a).name) < to!string((*b).name))(Record*[10]), This basically says you have fixed size array, in D they don’t decay to slices/pointers for safety reasons (it’s stack memory that is easy to leak out of scope with disasterous consequences). Do this to get the usual ptr + length: sort!((a, b) => to!string((*a).name) < to!string((*b).name))(recs[]); Also to!string would be computed on each compare anew. May want to use schwartzSort to avoid that, on 10 elements there is no real difference though.
Re: Networking library
On Thursday, 15 March 2018 at 00:06:49 UTC, Cecil Ward wrote: Can anyone point me in the direction of a library that provides very very lightweight (minimum overhead) asynchronous i/o routines for - shopping list 1. sending and receiving IPv4 / IPv6 packets, 2. sending receiving ICMP and 3, handling incoming outgoing TCP connections and 4. handling SCTP connections. Given the low-level nature of some of your requests, I’d suggest seriously look at DPDK. I don’t know if there is a ready-made D wrapper, but it should be stright-forward to bind to it. That covers all of your direct packet manipulation at extreme speeds.
Re: Garbage collected pointers?
On Thursday, 1 March 2018 at 10:10:27 UTC, John Burton wrote: In the language spec here :- https://dlang.org/spec/garbage.html#pointers_and_gc It refers to a distinction between pointers to garbage collected memory and pointers that are not. In particular it says that with a non garbage collected pointer you can do anything that is legal in C but with a garbage collected pointer there are a lot of undefined behaviors if you don't follow some restrictions. Basically you can do whatever you want with pointers, you may twart ability of GC to free an object b/c you constructed some value that points to GC heap. That’s pretty much it. Second side is loosing pointers to GC owned object, this happens when you put pointers into eg malloced chunk of memory. Calling GC.addRange/removeRange you can let GC know that you stored pointers to GC heap in some place other then stack or GC heap.
Re: forcing tabs in regex
On Wednesday, 28 February 2018 at 05:09:03 UTC, psychoticRabbit
wrote:
On Wednesday, 28 February 2018 at 01:06:30 UTC, dark777 wrote:
Regex validates years bisexto and not bisextos in format:
const std::regex
pattern(R"(^(?:(?:(0?[1-9]|1\d|2[0-8])([-/.])(0?[1-9]|1[0-2]|[Jj](?:an|u[nl])|[Mm]a[ry]|[Aa](?:pr|ug)|[Ss]ep|[Oo]ct|[Nn]ov|[Dd]ec|[Ff]eb)|(29|30)([-/.])(0?[13-9]|1[0-2]|[Jj](?:an|u[nl])|[Mm]a[ry]|[Aa](?:pr|ug)|[Ss]ep|[Oo]ct|[Nn]ov|[Dd]ec)|(31)([-/.])(0?[13578]|1[02]|[Jj]an|[Mm]a[ry]|[Jj]ul|[Aa]ug|[Oo]ct|[Dd]ec))(?:\2|\5|\8)(0{2,3}[1-9]|0{1,2}[1-9]\d|0?[1-9]\d{2}|[1-9]\d{3})|(29)([-/.])(0?2|[Ff]eb)\12(\d{1,2}(?:0[48]|[2468][048]|[13579][26])|(?:0?[48]|[13579][26]|[2468][048])00))$)");
this regex above validates the formats through backreferences.
what is this evil dark magic?
Something that is horribly slow and might be incorrect, there are
very few reasons to write large regexes like that and they
usually boil down to “it only accepts regex” otherwise parser
combinators are much better fit.
Re: multithread/concurrency/parallel methods and performance
On Monday, 19 February 2018 at 14:57:22 UTC, SrMordred wrote: On Monday, 19 February 2018 at 05:54:53 UTC, Dmitry Olshansky wrote: The operation is trivial and dataset is rather small. In such cases SIMD with eg array ops is the way to go: result[] = values[] * values2[]; Yes, absolutely right :) I make a simple example to understand why the threads are not scaling in the way i thought they would. Yeah, the world is ugly place where trivial math sometimes doesn’t work. I suggest to: - run with different number of threads from 1 to n - vary sizes from 100k to 10m For your numbers - 400ms / 64 is ~ 6ms, if we divide by # cores it’s 6/7 ~ 0.86ms which is a deal smaller then a CPU timeslice. In essence a single core runs fast b/c it doesn’t wait for all others to complete via join easily burning its quota in one go. In MT I bet some of overhead comes from not all threads finishing (and starting) at once, so the join block in the kernel. You could run your MT code with strace to see if it hits the futex call or some such, if it does that’s where you are getting delays. (that’s assuming you are on Linux) std.parallel version is a bit faster b/c I think it caches created threadpool so you don’t start threads anew on each run. I imagine that, if one core work is done in 200ms a 4 core work will be done in 50ms, plus some overhead, since they are working on separate block of memory, without need of sync, and without false sharing, etc (at least I think i don´t have this problem here). If you had a long queue of small tasks like that and you don’t wait to join all threads untill absolutely required you get near perfect scalability. (Unless hitting other bottlenecks like RAM).
Re: multithread/concurrency/parallel methods and performance
On Sunday, 18 February 2018 at 17:54:58 UTC, SrMordred wrote:
I´m experimenting with threads and related recently.
(i´m just started so may be some terrrible mistakes here)
With this base work:
foreach(i ; 0 .. SIZE)
{
results[i] = values1[i] * values2[i];
}
and then with this 3 others methods: parallel, spawn and
Threads.
this was my results:
_base : 456 ms and 479 us
_parallel : 331 ms, 324 us, and 4 hnsecs
_concurrency : 367 ms, 348 us, and 2 hnsecs
_thread : 369 ms, 565 us, and 3 hnsecs
(code here : https://run.dlang.io/is/2pdmmk )
All methods have minor speedup gains. I was expecting a lot
more.
Since I have 7 cores I expected like below 100ms.
The operation is trivial and dataset is rather small. In such
cases SIMD with eg array ops is the way to go:
result[] = values[] * values2[];
Parallelism is gets more interesting with more expensive
operations. You may also try bigger sizes or both.
I´m not seeing false sharing in this case. or i'm wrong?
If someone can expand on this, i'll be grateful.
Thanks!
Re: Get largest heap object at runtime? ...tracking the leak
On Sunday, 21 January 2018 at 17:28:13 UTC, Andres Clari wrote: Hi, is there any way to get from the GC all allocated objects, so I can see their size and find where I'm leaking memory? Or perhaps a good tool to help with this issue... I tried building my program with "profile-gc" but I got an invalid MemoryOperationError with no stack trace... so no luck using that. And the leak is only obvious when running in production, where after 6 hours I've seen 1.5Gb of memory usage. Are you by chance using vibe.d? In versions 0.8.x I observe a huge memory leak. Might be your problem. Right now, I'm able to extend the life of my program by injecting calls to: GC.collect GCminimize Within an event that happens every 5 seconds, which I estimate will give me about a week before the program's memory is again at +1.5Gb.
D on Power8 (PPC64)
What is the status of the platform? I might be doing some number crunching on one of the power8 beasts, would be nice to have D working there. --- Dmitry Olshansky
Re: Is it ok to inherit multiple times same templated interface?
On Sunday, 15 January 2017 at 20:33:30 UTC, Alexandru Ermicioi
wrote:
Good day,
Given following code example, where a templated interface Wr,
and an implementation Im is present:
From the standpoint of the compiler they are 3 distinct
interfaces, so all is good.
interface Wr(T) {
T get();
}
[...]
Re: Build your own Trie entry table
On Monday, 26 December 2016 at 10:12:20 UTC, Remi Thebault wrote: Hello I want to map a dchar to its Bidi_Class. I've built an utility that reads UnicodeData.txt into an AA and builds a trie with std.uni.codepointTrie from it. I use Trie.store() to export the trie entry table into a D module. (I believe in a similar manner than phobos' unicode_tables.d) Now I want to use this table to efficiently create a Trie in my code, the same way std.uni does, but found out that Trie constructor is private. I've copy-pasted the asTrie function (and also TrieEntry struct) in my code and it works well (which I don't understand because my code still ends up calling the private ctor). This must be an oversight on my part. Indeed it should be possible to store/load your own trie. Can you give indication on the workflow one should follow for this use case? Please file a bug report for Phobos basically stating your use case and the visibility problem. Thanks Rémi Dmitry Olshansky
Re: Degenerate Regex Case
On Friday, 24 April 2015 at 18:28:16 UTC, Guillaume wrote:
Hello, I'm trying to make a regex comparison with D, based off
of this article: https://swtch.com/~rsc/regexp/regexp1.html
I've written my code like so:
import std.stdio, std.regex;
void main(string argv[]) {
string m = argv[1];
auto p =
ctRegex!(a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaa);
if (match(m, p)) {
writeln(match);
} else {
writeln(no match);
}
}
And the compiler goes into swap. Doing it at runtime is no
better. I was under the impression that this particular regex
was used for showcasing the Thompson NFA which D claims to be
using.
A quick investigation shows that it gets stuck at the end of
pattern compilation stage.
The problem is that as a last pass D's regex goes to optimize the
pattern to construct simple bit-scanning engine as approximation
for prefix of original pattern. And that process is a lot like
Thompson NFA ... _BUT_ the trick of merging equivalent threads
wasn't applied there.
So in short: file a bug, optimizer absolutely should do
de-duplication of threads.
The golang code version of this runs fine, which makes me think
that maybe D isn't using the correct regex engine for this
particular regex. Or perhaps I'm using this wrong?
It uses 2 kinds of engines, run-time one is Thompson NFA.
Compile-time is (for now) still backtracking.
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Dmitry Olshansky
