Mojo trait
Iterator
The Iterator trait describes a type that can be used as an iterator, e.g. in a for loop.
Implemented traits
AnyType,
Copyable,
Movable,
UnknownDestructibility
Aliases
__copyinit__is_trivial
alias __copyinit__is_trivial
A flag (often compiler generated) to indicate whether the implementation of __copyinit__ is trivial.
The implementation of __copyinit__ is considered to be trivial if:
- The struct has a compiler-generated trivial
__copyinit__and all its fields have a trivial__copyinit__method.
In practice, it means the value can be copied by copying the bits from one location to another without side effects.
__del__is_trivial
alias __del__is_trivial
A flag (often compiler generated) to indicate whether the implementation of __del__ is trivial.
The implementation of __del__ is considered to be trivial if:
- The struct has a compiler-generated trivial destructor and all its fields
have a trivial
__del__method.
In practice, it means that the __del__ can be considered as no-op.
__moveinit__is_trivial
alias __moveinit__is_trivial
A flag (often compiler generated) to indicate whether the implementation of __moveinit__ is trivial.
The implementation of __moveinit__ is considered to be trivial if:
- The struct has a compiler-generated
__moveinit__and all its fields have a trivial__moveinit__method.
In practice, it means the value can be moved by moving the bits from one location to another without side effects.
Element
alias Element
Required methods
__copyinit__
__copyinit__(out self: _Self, existing: _Self, /)
Create a new instance of the value by copying an existing one.
Args:
- existing (
_Self): The value to copy.
Returns:
_Self
__moveinit__
__moveinit__(out self: _Self, var existing: _Self, /)
Create a new instance of the value by moving the value of another.
Args:
- existing (
_Self): The value to move.
Returns:
_Self
__has_next__
__next__
__next__(mut self: _Self) -> _Self.Element
Returns:
_Self.Element
Provided methods
bounds
bounds(self: _Self) -> Tuple[Int, Optional[Int]]
Returns bounds [lower, upper] for the remaining iterator length.
Returns a tuple where the first element is the lower bound and the second
is an optional upper bound (None means unknown or upper > Int.MAX).
This helps collections pre-allocate memory when constructed from iterators.
The default implementation returns (0, None).
Safety
If the upper bound is not None, implementations must ensure that lower <= upper.
The bounds are hints only - iterators may not comply with them. Never omit safety
checks when using bounds to build collections.
Example:
fn build_list[I: Iterator & Iterable](iter: I) -> List[I.Element]:
var lower, _upper = iter.bounds()
var list = List[I.Element](capacity=lower)
for element in iter:
list.append(element^)
return listReturns:
copy
copy(self: _Self) -> _Self
Explicitly construct a copy of self.
Returns:
_Self: A copy of this value.
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