On Friday, 1 February 2013 at 09:09:10 UTC, bioinfornatics wrote:
As i use a memory mapped file i won't copy my struct for able to
loop as i do not want map the file twice that is rather a big
problem for a big file this a perf issue. memory mapped file is
used to read fastly a file so is a nonsense
In a word, the problem is that your "FastqReader" is both
container and range. Those are complettly different notions that
should not be confused.
The fastqreader should be a container, that holds your binary
payload. You should be able to extract a range from the
container, and iterate on the container, without modifying the
container.
Currently, iterating on your fastqreader will mutate it. This is
very bad. The only cases I know of where this happens are with
pure input ranges, but in those cases, you virtually never have
access to the underlying container (which usually doesn't exist
anyways).
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The easy workaround is to start by renaming your "popFront" into
"removeFront": popFront is an iteration primitive. removeFront is
a container primitive. By changing this name, you fastqreader
will cease to adhere to any range interface, protecting you from
wrong usage.
Once there, you need to define a Range, or just have "opSlice()"
and "opSlice(size_t, size_t)" return said range.
Ideally, I'd avoid defining an actual "Range" type, and simply
return the string (as you are doing).
However, given you seem to be doing something with dna, and
require random access, I'm not sure "string" is the best (string
is unicode aware, so doesn't actually adhere to RA). I'd stick to
just returning a "const(ubyte)[]".
