Mojo struct
List
The List
type is a dynamically-allocated list.
It supports pushing and popping from the back resizing the underlying storage as needed. When it is deallocated, it frees its memory.
Parameters
- T (
CollectionElement
): The type of the elements. - hint_trivial_type (
Bool
): A hint to the compiler that the type T is trivial. It's not mandatory, but if set, it allows some optimizations.
Fields
- data (
UnsafePointer[T, 0, 0, alignof[::AnyType,__mlir_type.!kgen.target]() if triple_is_nvidia_cuda() else 1]
): The underlying storage for the list. - size (
Int
): The number of elements in the list. - capacity (
Int
): The amount of elements that can fit in the list without resizing it.
Implemented traits
AnyType
,
Boolable
,
CollectionElement
,
CollectionElementNew
,
Copyable
,
ExplicitlyCopyable
,
Movable
,
Sized
Methods
__init__
__init__(inout self: Self)
Constructs an empty list.
__init__(inout self: Self, *, other: Self)
Creates a deep copy of the given list.
Args:
- other (
Self
): The list to copy.
__init__(inout self: Self, *, capacity: Int)
Constructs a list with the given capacity.
Args:
- capacity (
Int
): The requested capacity of the list.
__init__(inout self: Self, owned *values: T)
Constructs a list from the given values.
Args:
- *values (
T
): The values to populate the list with.
__init__(inout self: Self, *, owned variadic_list: VariadicListMem[elt_is_mutable, T, lifetime])
Constructs a list from the given values.
Args:
- variadic_list (
VariadicListMem[elt_is_mutable, T, lifetime]
): The values to populate the list with.
__init__(inout self: Self, span: Span[is_mutable, T, lifetime])
Constructs a list from the a Span of values.
Args:
- span (
Span[is_mutable, T, lifetime]
): The span of values to populate the list with.
__init__(inout self: Self, *, unsafe_pointer: UnsafePointer[T, 0, 0, alignof[::AnyType,__mlir_type.!kgen.target]() if triple_is_nvidia_cuda() else 1], size: Int, capacity: Int)
Constructs a list from a pointer, its size, and its capacity.
Args:
- unsafe_pointer (
UnsafePointer[T, 0, 0, alignof[::AnyType,__mlir_type.!kgen.target]() if triple_is_nvidia_cuda() else 1]
): The pointer to the data. - size (
Int
): The number of elements in the list. - capacity (
Int
): The capacity of the list.
__copyinit__
__copyinit__(inout self: Self, existing: Self)
Creates a deepcopy of the given list.
Args:
- existing (
Self
): The list to copy.
__moveinit__
__moveinit__(inout self: Self, owned existing: Self)
Move data of an existing list into a new one.
Args:
- existing (
Self
): The existing list.
__del__
__del__(owned self: Self)
Destroy all elements in the list and free its memory.
__bool__
__bool__(self: Self) -> Bool
Checks whether the list has any elements or not.
Returns:
False
if the list is empty, True
if there is at least one element.
__getitem__
__getitem__(self: Self, span: Slice) -> Self
Gets the sequence of elements at the specified positions.
Args:
- span (
Slice
): A slice that specifies positions of the new list.
Returns:
A new list containing the list at the specified span.
__getitem__(ref [self_is_lifetime] self: Self, idx: Int) -> ref [_] T
Gets the list element at the given index.
Args:
- idx (
Int
): The index of the element.
Returns:
A reference to the element at the given index.
__eq__
__eq__[U: EqualityComparableCollectionElement, //](self: List[U, hint_trivial_type], other: List[U, hint_trivial_type]) -> Bool
Checks if two lists are equal.
Examples:
var x = List[Int](1, 2, 3)
var y = List[Int](1, 2, 3)
if x == y: print("x and y are equal")
var x = List[Int](1, 2, 3)
var y = List[Int](1, 2, 3)
if x == y: print("x and y are equal")
Parameters:
- U (
EqualityComparableCollectionElement
): The type of the elements in the list. Must implement the traitsEqualityComparable
andCollectionElement
.
Args:
- other (
List[U, hint_trivial_type]
): The list to compare with.
Returns:
True if the lists are equal, False otherwise.
__ne__
__ne__[U: EqualityComparableCollectionElement, //](self: List[U, hint_trivial_type], other: List[U, hint_trivial_type]) -> Bool
Checks if two lists are not equal.
Examples:
var x = List[Int](1, 2, 3)
var y = List[Int](1, 2, 4)
if x != y: print("x and y are not equal")
var x = List[Int](1, 2, 3)
var y = List[Int](1, 2, 4)
if x != y: print("x and y are not equal")
Parameters:
- U (
EqualityComparableCollectionElement
): The type of the elements in the list. Must implement the traitsEqualityComparable
andCollectionElement
.
Args:
- other (
List[U, hint_trivial_type]
): The list to compare with.
Returns:
True if the lists are not equal, False otherwise.
__contains__
__contains__[U: EqualityComparableCollectionElement, //](self: List[U, hint_trivial_type], value: U) -> Bool
Verify if a given value is present in the list.
var x = List[Int](1,2,3)
if 3 in x: print("x contains 3")
var x = List[Int](1,2,3)
if 3 in x: print("x contains 3")
Parameters:
- U (
EqualityComparableCollectionElement
): The type of the elements in the list. Must implement the traitsEqualityComparable
andCollectionElement
.
Args:
- value (
U
): The value to find.
Returns:
True if the value is contained in the list, False otherwise.
__add__
__add__(self: Self, owned other: Self) -> Self
Concatenates self with other and returns the result as a new list.
Args:
- other (
Self
): List whose elements will be combined with the elements of self.
Returns:
The newly created list.
__mul__
__mul__(self: Self, x: Int) -> Self
Multiplies the list by x and returns a new list.
Args:
- x (
Int
): The multiplier number.
Returns:
The new list.
__iadd__
__iadd__(inout self: Self, owned other: Self)
Appends the elements of other into self.
Args:
- other (
Self
): List whose elements will be appended to self.
__imul__
__imul__(inout self: Self, x: Int)
Multiplies the list by x in place.
Args:
- x (
Int
): The multiplier number.
__iter__
__iter__(ref [self_is_lifetime] self: Self) -> _ListIter[$0, T, hint_trivial_type, $1, 1]
Iterate over elements of the list, returning immutable references.
Returns:
An iterator of immutable references to the list elements.
__reversed__
__reversed__(ref [self_is_lifetime] self: Self) -> _ListIter[$0, T, hint_trivial_type, $1, 0]
Iterate backwards over the list, returning immutable references.
Returns:
A reversed iterator of immutable references to the list elements.
__len__
__len__(self: Self) -> Int
Gets the number of elements in the list.
Returns:
The number of elements in the list.
__str__
__str__[U: RepresentableCollectionElement, //](self: List[U, hint_trivial_type]) -> String
Returns a string representation of a List
.
Note that since we can't condition methods on a trait yet, the way to call this method is a bit special. Here is an example below:
var my_list = List[Int](1, 2, 3)
print(my_list.__str__())
var my_list = List[Int](1, 2, 3)
print(my_list.__str__())
When the compiler supports conditional methods, then a simple str(my_list)
will
be enough.
The elements' type must implement the __repr__()
method for this to work.
Parameters:
- U (
RepresentableCollectionElement
): The type of the elements in the list. Must implement the traitsRepresentable
andCollectionElement
.
Returns:
A string representation of the list.
format_to
format_to[U: RepresentableCollectionElement, //](self: List[U, hint_trivial_type], inout writer: Formatter)
Write my_list.__str__()
to a Formatter
.
Parameters:
- U (
RepresentableCollectionElement
): The type of the List elements. Must have the traitRepresentableCollectionElement
.
Args:
- writer (
Formatter
): The formatter to write to.
__repr__
__repr__[U: RepresentableCollectionElement, //](self: List[U, hint_trivial_type]) -> String
Returns a string representation of a List
.
Note that since we can't condition methods on a trait yet, the way to call this method is a bit special. Here is an example below:
var my_list = List[Int](1, 2, 3)
print(my_list.__repr__())
var my_list = List[Int](1, 2, 3)
print(my_list.__repr__())
When the compiler supports conditional methods, then a simple repr(my_list)
will
be enough.
The elements' type must implement the __repr__()
for this to work.
Parameters:
- U (
RepresentableCollectionElement
): The type of the elements in the list. Must implement the traitsRepresentable
andCollectionElement
.
Returns:
A string representation of the list.
append
append(inout self: Self, owned value: T)
Appends a value to this list.
Args:
- value (
T
): The value to append.
insert
insert(inout self: Self, i: Int, owned value: T)
Inserts a value to the list at the given index. a.insert(len(a), value)
is equivalent to a.append(value)
.
Args:
- i (
Int
): The index for the value. - value (
T
): The value to insert.
__mul
__mul(inout self: Self, x: Int)
Appends the original elements of this list x-1 times.
var a = List[Int](1, 2)
a.__mul(2) # a = [1, 2, 1, 2]
var a = List[Int](1, 2)
a.__mul(2) # a = [1, 2, 1, 2]
Args:
- x (
Int
): The multiplier number.
extend
extend(inout self: Self, owned other: List[T, hint_trivial_type])
Extends this list by consuming the elements of other
.
Args:
- other (
List[T, hint_trivial_type]
): List whose elements will be added in order at the end of this list.
pop
pop(inout self: Self, i: Int = -1) -> T
Pops a value from the list at the given index.
Args:
- i (
Int
): The index of the value to pop.
Returns:
The popped value.
reserve
reserve(inout self: Self, new_capacity: Int)
Reserves the requested capacity.
If the current capacity is greater or equal, this is a no-op. Otherwise, the storage is reallocated and the date is moved.
Args:
- new_capacity (
Int
): The new capacity.
resize
resize(inout self: Self, new_size: Int, value: T)
Resizes the list to the given new size.
If the new size is smaller than the current one, elements at the end are discarded. If the new size is larger than the current one, the list is appended with new values elements up to the requested size.
Args:
- new_size (
Int
): The new size. - value (
T
): The value to use to populate new elements.
resize(inout self: Self, new_size: Int)
Resizes the list to the given new size.
With no new value provided, the new size must be smaller than or equal to the current one. Elements at the end are discarded.
Args:
- new_size (
Int
): The new size.
reverse
reverse(inout self: Self)
Reverses the elements of the list.
index
index[C: EqualityComparableCollectionElement, //](ref [self_is_lifetime] self: List[C, hint_trivial_type], value: C, start: Int = 0, stop: Optional[Int] = #kgen.none) -> Int
Returns the index of the first occurrence of a value in a list restricted by the range given the start and stop bounds.
var my_list = List[Int](1, 2, 3)
print(my_list.index(2)) # prints `1`
var my_list = List[Int](1, 2, 3)
print(my_list.index(2)) # prints `1`
Parameters:
- C (
EqualityComparableCollectionElement
): The type of the elements in the list. Must implement theEqualityComparableCollectionElement
trait.
Args:
- value (
C
): The value to search for. - start (
Int
): The starting index of the search, treated as a slice index (defaults to 0). - stop (
Optional[Int]
): The ending index of the search, treated as a slice index (defaults to None, which means the end of the list).
Returns:
The index of the first occurrence of the value in the list.
Raises:
ValueError: If the value is not found in the list.
clear
clear(inout self: Self)
Clears the elements in the list.
steal_data
steal_data(inout self: Self) -> UnsafePointer[T, 0, 0, alignof[::AnyType,__mlir_type.!kgen.target]() if triple_is_nvidia_cuda() else 1]
Take ownership of the underlying pointer from the list.
Returns:
The underlying data.
unsafe_get
unsafe_get(ref [self_is_lifetime] self: Self, idx: Int) -> ref [_] T
Get a reference to an element of self without checking index bounds.
Users should consider using __getitem__
instead of this method as it
is unsafe. If an index is out of bounds, this method will not abort, it
will be considered undefined behavior.
Note that there is no wraparound for negative indices, caution is
advised. Using negative indices is considered undefined behavior. Never
use my_list.unsafe_get(-1)
to get the last element of the list.
Instead, do my_list.unsafe_get(len(my_list) - 1)
.
Args:
- idx (
Int
): The index of the element to get.
Returns:
A reference to the element at the given index.
unsafe_set
unsafe_set(inout self: Self, idx: Int, owned value: T)
Write a value to a given location without checking index bounds.
Users should consider using my_list[idx] = value
instead of this method as it
is unsafe. If an index is out of bounds, this method will not abort, it
will be considered undefined behavior.
Note that there is no wraparound for negative indices, caution is
advised. Using negative indices is considered undefined behavior. Never
use my_list.unsafe_set(-1, value)
to set the last element of the list.
Instead, do my_list.unsafe_set(len(my_list) - 1, value)
.
Args:
- idx (
Int
): The index of the element to set. - value (
T
): The value to set.
count
count[T: EqualityComparableCollectionElement, //](self: List[T, hint_trivial_type], value: T) -> Int
Counts the number of occurrences of a value in the list. Note that since we can't condition methods on a trait yet, the way to call this method is a bit special. Here is an example below.
var my_list = List[Int](1, 2, 3)
print(my_list.count(1))
var my_list = List[Int](1, 2, 3)
print(my_list.count(1))
When the compiler supports conditional methods, then a simple my_list.count(1)
will
be enough.
Parameters:
- T (
EqualityComparableCollectionElement
): The type of the elements in the list. Must implement the traitsEqualityComparable
andCollectionElement
.
Args:
- value (
T
): The value to count.
Returns:
The number of occurrences of the value in the list.
swap_elements
swap_elements(inout self: Self, elt_idx_1: Int, elt_idx_2: Int)
Swaps elements at the specified indexes if they are different.
var my_list = List[Int](1, 2, 3)
my_list.swap_elements(0, 2)
print(my_list) # 3, 2, 1
var my_list = List[Int](1, 2, 3)
my_list.swap_elements(0, 2)
print(my_list) # 3, 2, 1
This is useful because swap(my_list[i], my_list[j])
cannot be
supported by Mojo, because a mutable alias may be formed.
Args:
- elt_idx_1 (
Int
): The index of one element. - elt_idx_2 (
Int
): The index of the other element.
unsafe_ptr
unsafe_ptr(self: Self) -> UnsafePointer[T, 0, 0, alignof[::AnyType,__mlir_type.!kgen.target]() if triple_is_nvidia_cuda() else 1]
Retrieves a pointer to the underlying memory.
Returns:
The UnsafePointer to the underlying memory.
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