Re: Traverse a DList and insert / remove in place?

[Bastiaan Veelo via Digitalmars-d-learn]

On Sunday, 19 March 2023 at 13:15:58 UTC, Armando wrote:

I would like to do something like traversing a DList, operating on the current element, and potentially removing that element or inserting a new one before/after it - an easy operation if you code a DList yourself. Maybe I missed something?

This is one way to do that:
```d
import std;

struct MyType
{
    int id;
    // [...] other stuff
}

void main()
{
    auto list = DList!MyType();

    // Fill the list.
    foreach (i; 0 .. 10)
        list.insertBack(MyType(i));

    // Traverse the list, conditionally remove one element.
    for (auto range = list[]; !range.empty;)
        if (range.front.id == 3)
            list.popFirstOf(range);
        else
            range.popFront();

    // Traverse the list, conditionally insert one element.
    for (auto range = list[]; !range.empty;)
    {
        if (range.front.id == 6)
            list.insertBefore(range, MyType(66));
        range.popFront();
    }

    // Print modified list.
    foreach (e; list)
        writeln(e);

}
```

Output:
```
MyType(0)
MyType(1)
MyType(2)
MyType(4)
MyType(5)
MyType(66)
MyType(6)
MyType(7)
MyType(8)
MyType(9)
```

https://run.dlang.io/is/kk80FD

-- Bastiaan.