http://d.puremagic.com/issues/show_bug.cgi?id=10098

           Summary: byLine should return empty string instead of null when
                    line is empty
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: andrej.mitrovich@gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-05-16 17:15:26 PDT ---
The following code is well-intentioned, however it's currently broken:

-----
import std.stdio;
import std.range;

void main()
{
    auto file1 = File("text1.txt", "r");
    auto file2 = File("text2.txt", "r");

    foreach (char[] line1, char[] line2; zip(StoppingPolicy.longest,
file1.byLine, file2.byLine))
    {
        if (line1 is null)
        {
            // file 1 has less lines
            writefln("<!empty!> <%s>", line2);
        }

        if (line2 is null)
        {
            // file 2 has less lines
            writefln("<%s> <!empty!>", line1);
        }

        writefln("<%s> <%s>", line1, line2);
    }
}
-----

The problem is, line1 or line 2 will be null when an empty line is found. They should really be a zero-length non-null array, otherwise you can't tell that zip has actually ran out of lines for one of the files (note that we're using StoppingPolicy.longest here).

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull
         AssignedTo|nobody@puremagic.com        |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-09-17 16:31:51 PDT ---
https://github.com/D-Programming-Language/phobos/pull/1584

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|pull                        |
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


--- Comment #2 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-09-18 05:35:20 PDT ---
The test-case was invalid, the code worked as-is in 2.060+. Here's a better example:

-----
import std.stdio;
import std.range;

void main()
{
    auto fn1 = "foo1.txt";
    auto fn2 = "foo2.txt";
    scope(exit) std.file.remove(fn1);
    scope(exit) std.file.remove(fn2);
    std.file.write(fn1, "\n\n\n\n");
    std.file.write(fn2, "a\nb\nc\n");
    auto file1 = File(fn1, "r");
    auto file2 = File(fn2, "r");
    size_t lines1, lines2;

    foreach (char[] line1, char[] line2; zip(StoppingPolicy.longest,
file1.byLine, file2.byLine))
    {
        // line1 or line2 should be null only if the files are exhausted,
        // and not when the lines are empty (tested as true in 2.060+)
        writefln(`line1 is null: %s - "%s"`, line1 is null, line1);
        writefln(`line2 is null: %s - "%s"`, line2 is null, line2);
    }
}
-----

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