[Octave-patch-tracker] [patch #8783] C++ implementation of textscan

[Philip Nienhuis]

Follow-up Comment #6, patch #8783 (project octave):

Thanks for the new patch.

I was able to build Octave-dev with the patch and also cross-build it with
mxe-octave, but it needed a bit of attention:

1. To make a dist archive ("make all dist") amenable for cross-building with
mxe-octave, the file textscan.h must be included in the dist archive; all I
know is that it doesn't happen automatically and it must be referenced
somewhere. I just added it in libinterp/module.mk under
LIBINTERP_BUILT_DISTFILES but that may well be the wrong place (although it
worked).

2. textscan.cc invokes pow10() (from glibc I guess) but several other target
hosts do not implement pow10, notably mingw. I tried to include it using
gnulib but AFAIU that only supplies pow and powf. (I'm unfamiliar with gnulib,
I just tried along the ways shown by other gnulib additions in the core Octave
repo log.)
For the moment I used a kludge: simple replace pow10 by "10^"

3. I'd rather not drop textscan.m yet from the dev version until textscan()
works sufficiently reliably. My suggestion is to provisionally either:
- rename textscan() to xtextscan, or
- rename textscan.m to otextscan.m (and replace all occurrences in that
file).

Right, with that out of the way some tests.

- textscan() passes all 62 tests on Linux. On Mingw it cannot find the tests,
I need to do some more work there :-)

The examples from the TMW site
(http://nl.mathworks.com/help/matlab/ref/textscan.html) do not go that well.
The first two work fine, but all examples starting with reading "scan1.dat"
give different results than Matlab. 
On Linux:

>> fid = fopen ("scan1.dat")
fid =  19
>> C = textscan(fid, '%s %s %f32 %d8 %u %f %f %s %f')
C =
{
  [1,1] =
  {
    [1,1] = 09/12/2005
    [2,1] = 10/12/2005
    [3,1] = No
    [4,1] = Level3
  }
  [1,2] =
  {
    [1,1] = Level1
    [2,1] = Level2
    [3,1] = 2.2-.5i
    [4,1] = 34.90
  }
  [1,3] =

     12.340
     23.540
     11.000
     12.000

  [1,4] =

     45
     60
      0
    127

  [1,5] =

     0
     0
     0
    10

  [1,6] =

     Inf +   0i
       0 -   1i
     NaN +   0i
     100 +   0i

  [1,7] =

     NaN
     NaN
     NaN
     NaN

  [1,8] =
  {
    [1,1] = Yes
    [2,1] = nf
    [3,1] = /12/2005
    [4,1] = No
  }
  [1,9] =

     5.10000 + 3.00000i
     0.00100 + 0.00000i
         NaN + 0.00000i
     3.10000 + 0.10000i

}
>>


...and on Mingw (Windows) I got different results, yet again different with
CRLF EOLs rather than with LF EOLs.

Supposedly textscan() gets out of sync somewhere. Based on my experience with
strread.m/textscan.m I expect this to be a simple issue, as usual ;-)

It would be nice if textscan() can pass all examples on that Mathworks site.

In spite of all the above comments, I am very positive about this C++ textscan
version!

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