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digitalmars.D.bugs - [Issue 10543] New: std.algorithm.map incorrectly uses source range length for narrow strings

reply d-bugmail puremagic.com writes:
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           Summary: std.algorithm.map incorrectly uses source range length
                    for narrow strings
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: peter.alexander.au gmail.com



09:30:32 PDT ---
void main()
{
    import std.algorithm;
    import std.stdio;
    string s = "こんにちは世界";
    auto m = s.map!(a => 1);
    writeln(m, ", ", m.length);
}

Gives:

[1, 1, 1, 1, 1, 1, 1], 21

Clearly the reported length (21) is wrong, it should be 7.

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Jul 04 2013
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09:31:54 PDT ---


 Clearly the reported length (21) is wrong, it should be 7.


Scratch that. length shouldn't be available at all for narrow strings as it is
unobtainable in constant time.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs eml.cc



Where's the bug here?

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10:43:22 PDT ---


 Where's the bug here?


It says the length of [1, 1, 1, 1, 1, 1, 1] is 21. It isn't. It's 7.

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9999 <mailnew4ster gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mailnew4ster gmail.com



21 is the number of UTF-8 code units.
Using dstring produces 7.

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10:54:42 PDT ---


 21 is the number of UTF-8 code units.
 Using dstring produces 7.


I am not requesting the length of the string, I am requesting the length of the
map over the string. As ranges, strings are ranges of code points, not code
units, so the number of elements in the *map* (confirmed by the output) is
seven, i.e. that is the number of times you can safely call popFront on the
map.

I'm struggling to understand the confusion.

m is a range of seven integers
m.length is 21
walkLength(m) is also 21

This is completely broken.

I fully understand that narrow strings use length to report code units, not
code points, but m is not a string, so that distinction does not apply.

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monarchdodra gmail.com changed:

           What    |Removed                     |Added
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                 CC|                            |monarchdodra gmail.com





 I'm struggling to understand the confusion.


The problem is perfectly clear.

Are you already correcting this? If not, I'll take care of it.

I remember having seen this in one of my first pulls correcting map, but got
confused about the fact there is an *explicit* test to do things wrong... Time
to correct it for good I guess.

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13:15:10 PDT ---




 I'm struggling to understand the confusion.


 
 The problem is perfectly clear.
 
 Are you already correcting this? If not, I'll take care of it.
 
 I remember having seen this in one of my first pulls correcting map, but got
 confused about the fact there is an *explicit* test to do things wrong... Time
 to correct it for good I guess.


I'm not fixing it right now, go ahead.

I only noticed it when I looked at the source. No idea why it's explicitly
coded to be wrong...

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monarchdodra gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
             Status|NEW                         |ASSIGNED
         AssignedTo|nobody puremagic.com        |monarchdodra gmail.com



https://github.com/D-Programming-Language/phobos/pull/1389

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Jul 05 2013
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Commits pushed to master at https://github.com/D-Programming-Language/phobos

https://github.com/D-Programming-Language/phobos/commit/0a710876007bf8509d4f62453311e0bb6adbc7ca
Fix Issue 10543 - std.algorithm.map incorrectly uses source range length for
narrow strings  

Strange, because there was an explicit override for strings to forward length.

In any case, this is now fixed.

https://github.com/D-Programming-Language/phobos/commit/201edf4c8055ca0ac0079b9a8b711b68668c7974


Fix Issue 10543 - std.algorithm.map incorrectly uses source range length...

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Jul 06 2013
prev sibling parent d-bugmail puremagic.com writes:
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Kenji Hara <k.hara.pg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


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