Marius Gedminas wrote:
> For the special case of UTF-8, caching could be a solution: store the
> (char_index, byte_offset) pair of the last access in the string, and
> if the next access has a small char_index difference, start looping
> from the previous byte_offset.
>
> UTF-8 is self-synchronizing: the start byte of any character has its
> MSB set to 0, so you can iterate backwards and forwards from any
> position.
Yes, this is what is done for a list, the last accessed item and its
index is remembered.
For a string it requires an extra allocation for the structure that
stores the cached values. That causes overhead when it's not used.
I wonder if we can put the cached values in a list, so that we don't
need to add a new data type. Something like:
l = [0]
c = char_forward(text, l)
" now l is [3] for a 3-byte character
Adding the character index might be useful:
l = [0, 0]
c = char_forward(text, l)
" now l is [1, 3] for a 3-byte character
Might want a function to get the character as a number and a function to
get the character as a string (which can then also include composing
characters). Although just using a string would be sufficient, there
are other functions to get the character as a number.
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