Iterator methods
An Iterator is a stateful traversal handle. Its source collection is not mutated when the cursor moves.
Method reference
| Full syntax | Result | Meaning |
|---|---|---|
iterator.Next(step? = 1) |
any \| null |
Move first, then return the destination value. Steps may be positive, zero, or negative. |
iterator.Peek(offset? = 0) |
any \| null |
Read relative to the cursor without moving. |
iterator.Done() |
1 \| null |
Test whether an advancing read crossed an end. |
iterator.Index() |
Integer \| null |
Return 0 before traversal, the current index, or null when done. |
iterator.Reset(index?) |
Iterator |
Reset to 0, or position an indexable source directly at index. |
iterator.CheckTraits() |
1 \| null |
Validate attached semantic traits. |
Checked examples
it := [10, 20, 30].Iterator();
it.Index() ##@ == 0;
it.Next() ##@ == 10;
it.Peek(1) ##@ == 20;
it.Index() ##@ == 1;
it.Next(2) ##@ == 30;
it.Done() ##@ == _;
it.Next() ##@ == _;
it.Done() ##@ == 1;
it.Index() ##@ == _;
it.Reset(2); it.Peek() ##@ == 20;
it.Reset(); it.Next() ##@ == 10;
it.CheckTraits() ##@ == 1;The initial cursor is 0, before the first one-based item. Next(0) at that initial position returns null; after traversal begins it rereads the current item.