Re: regex issue
On 21 March 2012 04:26, Jay Norwood wrote: > yes, thanks. I read your other link and that was helpful. I think I > presumed that the escape handling was something belonging to stdio, while > regex would have its own valid escapes that would include \p. But I see now > that the string literals have their own set of escapes. Can you imagine the madness if escapes were specific to stdio, or some other library! "Ok, and I'll just send this newline over the network... Dammit, std.network doesn't escape \n". Also means that you have perfect consistency between usages of strings, no strange other usages of the same escape sequence... -- James Miller
Re: regex issue
On Tuesday, 20 March 2012 at 10:28:11 UTC, Dmitry Olshansky wrote:
Note that if your task is to split buffer by exactly '\n' byte
then loop with memchr is about as fast as it gets, no amount of
magic compiler optimizations would make other generic ways
better (even theoretically). What they *could* do is bring the
difference lower.
ok, I'll use memchr.
>> This works ok, but though concise it is not very fast
void wcp (string fn)
{
string input = cast(string)std.file.read(fn);
ulong l_cnt = std.algorithm.count(input,"\n");
}
BTW I suggest to separate I/O from actual work or better yet,
time both separately via std.datetime.StopWatch.
I'm timing with the stopwatch. I have separate functions where
I've measured empty func, just the file reads with empty loop, so
I can see the deltas. All these are being executed inside a
parallel foreach loop ... so 7 threads reading different files,
and since that is the end target, the overall measurement in the
context is more meaningful to me. The file io is on the order of
25ms for chunk reads or 30ms for full file reads in these
results, as it is all reads of about 20MB for the full test from
a 510 series ssd drive with sata3. The reads are being done in
parallel by the threads in the threadpool. Each file is 2MB.
So any total times you see in my comments are for 10 tasks being
executed in a parallel foreach loop, with the file read portion
previously timed at around 30ms.
This fails to build, so I'd guess is missing \p
void wcp (string fn)
{
enum ctr = ctRegex!("\p{WhiteSpace}","m");
}
-- Build started: Project: a7, Configuration: Release Win32
--
Building Release\a7.exe...
a7.d(210): undefined escape sequence \p
Not a bug, a compiler escape sequence.
How do you think \n works in your non-regex examples ? ;)
yes, thanks. I read your other link and that was helpful. I
think I presumed that the escape handling was something belonging
to stdio, while regex would have its own valid escapes that would
include \p. But I see now that the string literals have their
own set of escapes.
Re: regex issue
On 19.03.2012 23:24, Jay Norwood wrote:
On Monday, 19 March 2012 at 13:55:39 UTC, Dmitry Olshansky wrote:
That's right, however counting is completely separate from regex,
you'd want to use std.algorithm count:
count(match(,"\n"));
or more unicode-friendly:
count(match(, regex("$","m")); //note the multi-line flag
Ehm, forgot "g" flag myself, so it would be
count(match(, regex("$","gm"));
and
count(match(, regex("\n","g"));
Note that if your task is to split buffer by exactly '\n' byte then loop
with memchr is about as fast as it gets, no amount of magic compiler
optimizations would make other generic ways better (even theoretically).
What they *could* do is bring the difference lower.
This only sets l_cnt to 1
void wcp_cnt_match1 (string fn)
{
string input = cast(string)std.file.read(fn);
enum ctr = ctRegex!("$","m");
ulong l_cnt = std.algorithm.count(match(input,ctr));
}
This works ok, but though concise it is not very fast
void wcp (string fn)
{
string input = cast(string)std.file.read(fn);
ulong l_cnt = std.algorithm.count(input,"\n");
}
BTW I suggest to separate I/O from actual work or better yet, time both
separately via std.datetime.StopWatch.
This fails to build, so I'd guess is missing \p
void wcp (string fn)
{
enum ctr = ctRegex!("\p{WhiteSpace}","m");
}
-- Build started: Project: a7, Configuration: Release Win32
--
Building Release\a7.exe...
a7.d(210): undefined escape sequence \p
Not a bug, a compiler escape sequence.
How do you think \n works in your non-regex examples ? ;)
--
Dmitry Olshansky
Re: regex issue
On Monday, 19 March 2012 at 19:24:30 UTC, Jay Norwood wrote:
This fails to build, so I'd guess is missing \p
void wcp (string fn)
{
enum ctr = ctRegex!("\p{WhiteSpace}","m");
}
-- Build started: Project: a7, Configuration: Release Win32
--
Building Release\a7.exe...
a7.d(210): undefined escape sequence \p
Building Release\a7.exe failed!
Details saved as "file://G:\d\a7\a7\Release\a7.buildlog.html"
== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped
==
So I tried something a little different, and this apparently gets
further along to another error message. But it looks like at
this point it decides that the unicode properties are not
available at compile time...
void wcp_bug_no_p(string fn)
{
enum ctr = ctRegex!(r"\p{WhiteSpace}","m");
}
-- Build started: Project: a7, Configuration: Debug Win32
--
Building Debug\a7.exe...
G:\d\dmd2\windows\bin\..\..\src\phobos\std\regex.d(786): Error:
static variable unicodeProperties cannot be read at compile time
G:\d\dmd2\windows\bin\..\..\src\phobos\std\regex.d(786):
called from here: assumeSorted(unicodeProperties)
G:\d\dmd2\windows\bin\..\..\src\phobos\std\regex.d(1937):
called from here:
getUnicodeSet(result[0u..k],negated,cast(bool)(this.re_flags &
cast(RegexOption)2u))
Re: regex issue
On Monday, 19 March 2012 at 13:55:39 UTC, Dmitry Olshansky wrote:
That's right, however counting is completely separate from
regex, you'd want to use std.algorithm count:
count(match(,"\n"));
or more unicode-friendly:
count(match(, regex("$","m")); //note the multi-line flag
This only sets l_cnt to 1
void wcp_cnt_match1 (string fn)
{
string input = cast(string)std.file.read(fn);
enum ctr = ctRegex!("$","m");
ulong l_cnt = std.algorithm.count(match(input,ctr));
}
This works ok, but though concise it is not very fast
void wcp (string fn)
{
string input = cast(string)std.file.read(fn);
ulong l_cnt = std.algorithm.count(input,"\n");
}
Also observe that there is simply no way to get more then
constant number of submatches.
(regex) Matches subexpression regex, saving matched portion of
text for
later retrival.
An example of unicode properties:
\p{WhiteSpace} matches any unicode whitespace char
This fails to build, so I'd guess is missing \p
void wcp (string fn)
{
enum ctr = ctRegex!("\p{WhiteSpace}","m");
}
-- Build started: Project: a7, Configuration: Release Win32
--
Building Release\a7.exe...
a7.d(210): undefined escape sequence \p
Building Release\a7.exe failed!
Details saved as "file://G:\d\a7\a7\Release\a7.buildlog.html"
== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped
==
Re: regex issue
On 19.03.2012 17:39, Jay Norwood wrote:
On Monday, 19 March 2012 at 13:27:03 UTC, Jay Norwood wrote:
ok, global. So the document implies that I should be able to get a
single match object with a count of the submatches. So I think maybe
I've jumped to the wrong conclusion about how to use it, thinking I
could just use "\n" and "g" flag got get all the matches for the range
of "\n". So it looks like instead that the term "submatches" needs
more explanation. What exactly constitutes a submatch? I infered it
just meant any single match among many.
//create static regex at compile-time, contains fast native code
enum ctr = ctRegex!(`^.*/([^/]+)/?$`);
//works just like normal regex:
auto m2 = match("foo/bar", ctr); //first match found here if any
assert(m2); // be sure to check if there is a match, before examining
contents!
assert(m2.captures[1] == "bar");//captures is a range of submatches, 0
- full match
btw, I couldn't get this \p option to work for the uni properties. Can
you provide some example of that which works?
\p{PropertyName} Matches character that belongs to unicode
PropertyName set. Single letter abreviations could be used without
surrounding {,}.
so, to answer my own question, it appears that the (regex) is the
portion that is considered a submatch that gets counted.
so counting lines would be something that has a (\n) in it, although
I'll have to figure out what that will be exactly.
That's right, however counting is completely separate from regex, you'd
want to use std.algorithm count:
count(match(,"\n"));
or more unicode-friendly:
count(match(, regex("$","m")); //note the multi-line flag
Also observe that there is simply no way to get more then constant
number of submatches.
(regex) Matches subexpression regex, saving matched portion of text for
later retrival.
An example of unicode properties:
\p{WhiteSpace} matches any unicode whitespace char
--
Dmitry Olshansky
Re: regex issue
On 19.03.2012 17:27, Jay Norwood wrote:
On Monday, 19 March 2012 at 08:05:18 UTC, Dmitry Olshansky wrote:
Like I told in main D group it's wrong - regex doesn't only count
matches. It finds slices that do match.
Thus to make it more efficient, it returns lazy range that does
searches on request. "g" - means global :)
Then code like this is cool and fast:
foreach(m; match(input, ctr))
{
if(m.hit == "magic we are looking for")
break; // <<< no greedy find it all syndrome
}
ok, global. So the document implies that I should be able to get a
single match object with a count of the submatches. So I think maybe
I've jumped to the wrong conclusion about how to use it, thinking I
could just use "\n" and "g" flag got get all the matches for the range
of "\n". So it looks like instead that the term "submatches" needs more
explanation. What exactly constitutes a submatch? I infered it just
meant any single match among many.
Maybe a replacement of submatch ---> capture helps. But I thought it was
easy to get that any subexpression in regex e.g. "(\w+)" is captured
into submatch. Are you aware sub-expressions in regex are also extracted
from the text?
//create static regex at compile-time, contains fast native code
enum ctr = ctRegex!(`^.*/([^/]+)/?$`);
//works just like normal regex:
auto m2 = match("foo/bar", ctr); //first match found here if any
assert(m2); // be sure to check if there is a match, before examining
contents!
assert(m2.captures[1] == "bar");//captures is a range of submatches, 0 -
full match
BTW, In the above example what captures are should be clearly visible.
btw, I couldn't get this \p option to work for the uni properties. Can
you provide some example of that which works?
\p{PropertyName} Matches character that belongs to unicode PropertyName
set. Single letter abreviations could be used without surrounding {,}.
Ouch, I see that docs are no good :)
But well, they are reference-like anyway, you might want to take a look
for more healthy and lengthy overview:
http://blackwhale.github.com/regular-expression.html
--
Dmitry Olshansky
Re: regex issue
On Monday, 19 March 2012 at 13:27:03 UTC, Jay Norwood wrote:
ok, global. So the document implies that I should be able to
get a single match object with a count of the submatches. So I
think maybe I've jumped to the wrong conclusion about how to
use it, thinking I could just use "\n" and "g" flag got get all
the matches for the range of "\n". So it looks like instead
that the term "submatches" needs more explanation. What
exactly constitutes a submatch? I infered it just meant any
single match among many.
//create static regex at compile-time, contains fast native
code
enum ctr = ctRegex!(`^.*/([^/]+)/?$`);
//works just like normal regex:
auto m2 = match("foo/bar", ctr); //first match found here
if any
assert(m2); // be sure to check if there is a match, before
examining contents!
assert(m2.captures[1] == "bar");//captures is a range of
submatches, 0 - full match
btw, I couldn't get this \p option to work for the uni
properties. Can you provide some example of that which works?
\p{PropertyName} Matches character that belongs to unicode
PropertyName set. Single letter abreviations could be used
without surrounding {,}.
so, to answer my own question, it appears that the (regex) is
the portion that is considered a submatch that gets counted.
so counting lines would be something that has a (\n) in it,
although I'll have to figure out what that will be exactly.
(regex) Matches subexpression regex, saving matched portion of
text for later retrival.
Re: regex issue
On Monday, 19 March 2012 at 08:05:18 UTC, Dmitry Olshansky wrote:
Like I told in main D group it's wrong - regex doesn't only
count matches. It finds slices that do match.
Thus to make it more efficient, it returns lazy range that does
searches on request. "g" - means global :)
Then code like this is cool and fast:
foreach(m; match(input, ctr))
{
if(m.hit == "magic we are looking for")
break; // <<< no greedy find it all syndrome
}
ok, global. So the document implies that I should be able to get
a single match object with a count of the submatches. So I think
maybe I've jumped to the wrong conclusion about how to use it,
thinking I could just use "\n" and "g" flag got get all the
matches for the range of "\n". So it looks like instead that the
term "submatches" needs more explanation. What exactly
constitutes a submatch? I infered it just meant any single match
among many.
//create static regex at compile-time, contains fast native code
enum ctr = ctRegex!(`^.*/([^/]+)/?$`);
//works just like normal regex:
auto m2 = match("foo/bar", ctr); //first match found here if
any
assert(m2); // be sure to check if there is a match, before
examining contents!
assert(m2.captures[1] == "bar");//captures is a range of
submatches, 0 - full match
btw, I couldn't get this \p option to work for the uni
properties. Can you provide some example of that which works?
\p{PropertyName} Matches character that belongs to unicode
PropertyName set. Single letter abreviations could be used
without surrounding {,}.
Re: regex issue
On 19.03.2012 16:59, Jay Norwood wrote: On Monday, 19 March 2012 at 08:14:18 UTC, Dmitry Olshansky wrote: On 19.03.2012 12:05, Dmitry Olshansky wrote: In that case, I should have been able to do something like: matches=match(input,ctr); l_cnt = matches.length(); I'm curious what this length() does as I have no length for RegexMatch in the API :) But I only get length=1, and so I'm a bit concerned that greedy is not really working. In fact, it is about 3x faster to just run the second piece of code, so I think something must be wrong... http://dlang.org/phobos/std_regex.html#length Yes, I should have typed matches.captures.length. It is always returning 1, even though the desciption indicates the "g" flag should create a match object that contains all the submatches. Captures is a range of submatches as in "(a)(b)(c)" has 3 sub matches + 1 whole match == 4. -- Dmitry Olshansky
Re: regex issue
On Monday, 19 March 2012 at 08:14:18 UTC, Dmitry Olshansky wrote: On 19.03.2012 12:05, Dmitry Olshansky wrote: In that case, I should have been able to do something like: matches=match(input,ctr); l_cnt = matches.length(); I'm curious what this length() does as I have no length for RegexMatch in the API :) But I only get length=1, and so I'm a bit concerned that greedy is not really working. In fact, it is about 3x faster to just run the second piece of code, so I think something must be wrong... http://dlang.org/phobos/std_regex.html#length Yes, I should have typed matches.captures.length. It is always returning 1, even though the desciption indicates the "g" flag should create a match object that contains all the submatches.
Re: regex issue
On 19.03.2012 12:05, Dmitry Olshansky wrote:
On 19.03.2012 6:50, Jay Norwood wrote:
On Friday, 16 March 2012 at 03:36:12 UTC, Joshua Niehus wrote:
Hello,
Does anyone know why I would get different results between
ctRegex and regex in the following snippet?
Thanks,
Josh
I'm also having questions about the matchers. From what I understand in
the docs, if I use this greedy matcher to count lines, it should have
counted all the lines in the first match (when I hade it outside the
foreach.
Like I told in main D group it's wrong - regex doesn't only count
matches. It finds slices that do match.
Thus to make it more efficient, it returns lazy range that does searches
on request. "g" - means global :)
Then code like this is cool and fast:
foreach(m; match(input, ctr))
{
if(m.hit == "magic we are looking for")
break; // <<< no greedy find it all syndrome
}
In that case, I should have been able to do something like:
matches=match(input,ctr);
l_cnt = matches.length();
I'm curious what this length() does as I have no length for RegexMatch
in the API :)
But I only get length=1, and so I'm a bit concerned that greedy is not
really working. In fact, it is about 3x faster to just run the second
piece of code, so I think something must be wrong...
--
Dmitry Olshansky
Re: regex issue
On 19.03.2012 6:50, Jay Norwood wrote:
On Friday, 16 March 2012 at 03:36:12 UTC, Joshua Niehus wrote:
Hello,
Does anyone know why I would get different results between
ctRegex and regex in the following snippet?
Thanks,
Josh
I'm also having questions about the matchers. From what I understand in
the docs, if I use this greedy matcher to count lines, it should have
counted all the lines in the first match (when I hade it outside the
foreach.
Like I told in main D group it's wrong - regex doesn't only count
matches. It finds slices that do match.
Thus to make it more efficient, it returns lazy range that does searches
on request. "g" - means global :)
Then code like this is cool and fast:
foreach(m; match(input, ctr))
{
if(m.hit == "magic we are looking for")
break; // <<< no greedy find it all syndrome
}
In that case, I should have been able to do something like:
matches=match(input,ctr);
l_cnt = matches.length();
But I only get length=1, and so I'm a bit concerned that greedy is not
really working. In fact, it is about 3x faster to just run the second
piece of code, so I think something must be wrong...
void wcp_ctRegex(string fn)
{
string input = cast(string)std.file.read(fn);
enum ctr = ctRegex!("\n","g");
ulong l_cnt;
foreach(m; match(input,ctr))
{
l_cnt ++;
}
}
void wcp_char(string fn)
{
string input = cast(string)std.file.read(fn);
ulong l_cnt;
foreach(c; input)
{
if (c == '\n')
l_cnt ++;
}
}
--
Dmitry Olshansky
Re: regex issue
On Friday, 16 March 2012 at 03:36:12 UTC, Joshua Niehus wrote:
Hello,
Does anyone know why I would get different results between
ctRegex and regex in the following snippet?
Thanks,
Josh
I'm also having questions about the matchers. From what I
understand in the docs, if I use this greedy matcher to count
lines, it should have counted all the lines in the first match
(when I hade it outside the foreach. In that case, I should have
been able to do something like:
matches=match(input,ctr);
l_cnt = matches.length();
But I only get length=1, and so I'm a bit concerned that greedy
is not really working. In fact, it is about 3x faster to just run
the second piece of code, so I think something must be wrong...
void wcp_ctRegex(string fn)
{
string input = cast(string)std.file.read(fn);
enum ctr = ctRegex!("\n","g");
ulong l_cnt;
foreach(m; match(input,ctr))
{
l_cnt ++;
}
}
void wcp_char(string fn)
{
string input = cast(string)std.file.read(fn);
ulong l_cnt;
foreach(c; input)
{
if (c == '\n')
l_cnt ++;
}
}
Re: regex issue
On 16.03.2012 20:05, Joshua Niehus wrote: On Friday, 16 March 2012 at 08:34:18 UTC, Dmitry Olshansky wrote: Ehm, because they have different engines that _should_ give identical results. And the default one apparently has a bug, that I'm looking into. Fill the bug report plz. Ok, submitted: id 7718 Thanks, Josh And the fix is coming https://github.com/D-Programming-Language/phobos/pull/462 I take this time to also thank you, as this was interestingly big oversight in that engine code that revealed to me some fundamental things. -- Dmitry Olshansky
Re: regex issue
On Friday, 16 March 2012 at 08:34:18 UTC, Dmitry Olshansky wrote: Ehm, because they have different engines that _should_ give identical results. And the default one apparently has a bug, that I'm looking into. Fill the bug report plz. Ok, submitted: id 7718 Thanks, Josh
Re: regex issue
On 16.03.2012 7:36, Joshua Niehus wrote:
Hello,
Does anyone know why I would get different results between
ctRegex and regex in the following snippet?
Ehm, because they have different engines that _should_ give identical
results. And the default one apparently has a bug, that I'm looking into.
Fill the bug report plz.
Thanks,
Josh
---
#!/usr/local/bin/rdmd
import std.stdio, std.regex;
void main() {
string strcmd = "./myApp.rb -os OSX -path \"/GIT/Ruby
Apps/sec\" -conf 'no timer'";
auto ctre = ctRegex!(`(".*")|('.*')`, "g");
auto re = regex (`(".*")|('.*')`, "g");
auto ctm = match(strcmd, ctre);
foreach(ct; ctm)
writeln(ct.hit());
auto m = match(strcmd, re);
foreach(h; m)
writeln(h.hit());
}
/* output */
"/GIT/Ruby Apps/sec"
'no timer'
"/GIT/Ruby Apps/sec"
--
Dmitry Olshansky
regex issue
Hello,
Does anyone know why I would get different results between
ctRegex and regex in the following snippet?
Thanks,
Josh
---
#!/usr/local/bin/rdmd
import std.stdio, std.regex;
void main() {
string strcmd = "./myApp.rb -os OSX -path \"/GIT/Ruby
Apps/sec\" -conf 'no timer'";
auto ctre = ctRegex!(`(".*")|('.*')`, "g");
auto re = regex (`(".*")|('.*')`, "g");
auto ctm = match(strcmd, ctre);
foreach(ct; ctm)
writeln(ct.hit());
auto m = match(strcmd, re);
foreach(h; m)
writeln(h.hit());
}
/* output */
"/GIT/Ruby Apps/sec"
'no timer'
"/GIT/Ruby Apps/sec"
