On Monday, 30 December 2013 at 22:30:02 UTC, John Colvin wrote:
On Monday, 30 December 2013 at 22:17:21 UTC, John Colvin wrote:
On Monday, 30 December 2013 at 21:40:58 UTC, Thomas Gann wrote:
I've written a Markov bot in D, and I have function whose job
it is to take an input string, convert all newline characters
to spaces and all uppercase letters to lowercase, and then
return an array of words that are generated by splitting the
string up by whitespace. Here is the function is question:
string[] split_sentence(string input)
{
string line;
foreach(c; input)
{
if(c == '\n' || c == '\r')
line ~= ' ';
else
line ~= c.toLower();
}
return line.splitter(' ').filter!(a => a.length).array;
}
Obviously, one issue is that because the string is immutable,
I can't modify it directly, and so I actually build an
entirely new string in place. I would have just made a
mutable duplicate of the input and modify that, but then I
would get errors returning, because it expects string[] and
not char[][]. Is there a more elegant way to do what I'm
doing?
A few points:
by declaring a new string and appending to it you are risking
a lot of allocations. Either use std.array.appender or
allocate the array with the correct size at the beginning.
using .array on the end of the ufcs chain is yet another
allocation. It can be avoided using std.algorithm.copy to copy
the result back in to 'line'
In my opinion the whole API would be better as range-based:
auto splitSentence(R)(R input)
if(isInputRange!R)
{
return input
.map!(c => (c == "\n"[0] || c == "\r"[0]) ? ' ' :
c.toLower)
.splitter!(' ')
.filter!(a => !(a.empty));
}
sorry, ignore that attempt, it's woefully broken...
Re: weird literal syntax, you didn't happen to be using dpaste to
test and have trouble with character literals, did you? Because
I did and thought I was going insane until realized DPaste was
broken.
