I have a string that contains a sequence of elements, then a
terminator character, followed by a different sequence of
elements (of a different type).
I want to create an input range that traverses the initial
sequence. This is easy enough. But after the initial sequence has
been traversed, the caller will need to know where the next
sequence starts. That is, the caller needs to know the index in
the input string where the initial sequence ends and the next
sequence begins.
The values returned by the range are a transformation of the
input, so the values by themselves are insufficient for the
caller to determined how much of the string has been consumed.
And, the caller cannot simply search for the terminator character.
Tracking the number of bytes consumed is easy enough. I like to
do in a way that is consistent with D's normal range paradigm.
Two candidate approaches:
a) Instead of having the range return the individual values, it
could return a tuple containing the value and the number of bytes
consumed.
b) Give the input range an extra member function which returns
the number of bytes consumed. The caller could call this after
'empty()' returns true to find the amount of data consumed.
Both will work, but I'm not especially satisfied with either.
Approach (a) seems more consistent with the typical range
paradigms, but also more of a hassle for callers.
Is there a better way to write this?
--Jon
