Improving strread / textread / textscan

[PhilipNienhuis]

Motivated by this thread
https://mailman.cae.wisc.edu/pipermail/help-octave/2011-October/048038.html
I had another look at strread.m. I have 2 questions about it:

Q1:
After searching around on the web, I now have inferred the following
behavior of strread (& textscan) in ML:
a. "Words" or fields (to be interpreted later) are separated by white-space.
b. The white-space char set can be adapted by the user with the "whitespace"
keyword. It can even be set to empty.
c. White-space is understood to possibly be a vector of white-space chars
that during reading is folded into one char that separates two fields.
d. Delimiters are characters that are augmented to white-space (they don't
replace the white-space char set), but other than white-space, vectors of
delimiters, or of several delimiters and white-space, are not folded into
one char that separates fields.
e. Yet, vectors of white-space and one delimiter are folded into one
white-space that separates fields.
f. However, if so desired, multiple consecutive delimiters can be folded
into one delimiter if "MultipleDelimsAsOne" parameter is set to 1.
g. EOL char sequences (\n, \r\n, or \r) are also delimiters, but are not
affected by the MultipleDelimsAsOne parameter.
(...what a mess...)

Is there agreement with my interpretation of ML's behaviour?

Q2: 
There's ample room for improvement in various parts I wrote. But I need to
know:
which one is faster,  strrep  or  regexprep ?
Both of these are needed in several places, but AFAICS regexprep is more
versatile.
Roughly speaking, as strread.m stands now, for each of the points above a
separate regexprep or strrep run (or series of runs) is needed on the entire
"file". So it is important to know what functions are the fastest.

Thanks,

Philip


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