Reading and wiping notes also adding more notes

[Joel]

On Tuesday, 18 October 2022 at 05:48:27 UTC, Ali Çehreli wrote:
> On 10/17/22 22:40, Joel wrote:
>
> > I have two text fields. The one on the left has the whole
> text, new
> > stuff being added to the bottom. The one on the right has
> text I've been
> > wiping as I'm reading.
>
> I think this can be modelled as a string array and an index 
> showing where the active part starts:
>
> import std;
>
> struct Notes {
>     string[] whole;
>     size_t activeIndex;
>
>     void add(string line) {
>         whole ~= line;
>     }
>
>     string[] activeText() {
>         return whole[activeIndex..$];
>     }
>
>     void wipeText() {
>         ++activeIndex;
>     }
> }
>
> void main() {
>     auto input = [ "I went for a walk and fell down a hole.",
>                    "There was a D guy on the roof.",
>                    "That was a tricky problem!", ];
>
>     Notes notes;
>
>     // add() to add()
>     input.each!(line => notes.add(line));
>
>     // activeText() will show the active part
>     // wipeText() will move forward
> }
>
> Ali

I want to have two text files, for each notes I'm reading and 
wiping. Keep adding to one and reading wiping and updating the 
other one. I want my program to process them by updating the 
temporary notes.