Re: Need help: Return reference slice

[Steven Schveighoffer via Digitalmars-d-learn]

On 10/29/14 3:50 PM, advibm wrote:
Hello,
I would like to create a D function that returns a slice of a string.
This slice shall be a reference to a part of the string argument.
Is this generally possible in D?

This is the function:
auto ref betweenTwoStrings(T)(inout T src, string start, string end) {
   long a = src.countUntil(start);
   if (a < 0)
     return src; // null
   a += start.length;
   long b = src[a..$].countUntil(end);
   if (b < 0)
     return src; // null
   b += a;
   return src[a..b];
}


I would like to have something like that:

char[] buf; // already filled array
char[] partOfBuf = betweenTwoStrings(buf, "START", "END");
partOfBuf[0] = 'a'; // THIS should also change the 'buf' variable
assert(buf[0] == 'a');

Thanks for your help


How I would do it:

inout(T)[] betweenTwoStrings(T, U, V)(inout(T)[] src, const(U)[] start, 
const(V)[] end) if(allSatisfy!(isSomeChar, T, U, V)) {
  long a = src.countUntil(start);
  if (a < 0)
    return src; // null
  a += start.length;
  long b = src[a..$].countUntil(end);
  if (b < 0)
    return src; // null
  b += a;
  return src[a..b];
}

This should accept any kind of strings, in any constancy for all the 
parameters, yet guarantee it does not change any data in any of them.

-Steve.