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Mojo struct

CodepointSliceIter

struct CodepointSliceIter[mut: Bool, //, origin: Origin[mut], forward: Bool = True]

Iterator for StringSlice over substring slices containing a single Unicode codepoint.

The forward parameter only controls the behavior of the __next__() method used for normal iteration. Calls to next() will always take an element from the front of the iterator, and calls to next_back() will always take an element from the end.

Parameters​

  • ​mut (Bool): Whether the slice is mutable.
  • ​origin (Origin[mut]): The origin of the underlying string data.
  • ​forward (Bool): The iteration direction. False is backwards.

Implemented traits​

AnyType, Copyable, ExplicitlyCopyable, Movable, UnknownDestructibility

Methods​

__next__​

__next__(mut self) -> StringSlice[origin]

Get the next codepoint in the underlying string slice.

This returns the next single-codepoint substring slice encoded in the underlying string, and advances the iterator state.

If forward is set to False, this will return the next codepoint from the end of the string.

This function will abort if this iterator has been exhausted.

Returns:

The next character in the string.

__has_next__​

__has_next__(self) -> Bool

Returns True if there are still elements in this iterator.

Returns:

A boolean indicating if there are still elements in this iterator.

__len__​

__len__(self) -> Int

Returns the remaining length of this iterator in Codepoints.

The value returned from this method indicates the number of subsequent calls to next() that will return a value.

Returns:

Number of codepoints remaining in this iterator.

peek_next​

peek_next(self) -> Optional[StringSlice[origin]]

Check what the next single-codepoint slice in this iterator is, without advancing the iterator state.

Repeated calls to this method will return the same value.

Examples

peek_next() does not advance the iterator, so repeated calls will return the same value:

from collections.string import StringSlice, Codepoint
from testing import assert_equal

var input = StringSlice("123")
var iter = input.codepoint_slices()

assert_equal(iter.peek_next().value(), "1")
assert_equal(iter.peek_next().value(), "1")
assert_equal(iter.peek_next().value(), "1")

# A call to `next()` return the same value as `peek_next()` had,
# but also advance the iterator.
assert_equal(iter.next().value(), "1")

# Later `peek_next()` calls will return the _new_ next character:
assert_equal(iter.peek_next().value(), "2")
from collections.string import StringSlice, Codepoint
from testing import assert_equal

var input = StringSlice("123")
var iter = input.codepoint_slices()

assert_equal(iter.peek_next().value(), "1")
assert_equal(iter.peek_next().value(), "1")
assert_equal(iter.peek_next().value(), "1")

# A call to `next()` return the same value as `peek_next()` had,
# but also advance the iterator.
assert_equal(iter.next().value(), "1")

# Later `peek_next()` calls will return the _new_ next character:
assert_equal(iter.peek_next().value(), "2")

.

Returns:

The next codepoint slice in the underlying string, or None if the string is empty.

peek_back​

peek_back(mut self) -> Optional[StringSlice[origin]]

Check what the last single-codepoint slice in this iterator is, without advancing the iterator state.

Repeated calls to this method will return the same value.

Examples

peek_back() does not advance the iterator, so repeated calls will return the same value:

from collections.string import StringSlice, Codepoint
from testing import assert_equal

var input = StringSlice("123")
var iter = input.codepoint_slices()

# Repeated calls to `peek_back()` return the same value.
assert_equal(iter.peek_back().value(), "3")
assert_equal(iter.peek_back().value(), "3")
assert_equal(iter.peek_back().value(), "3")

# A call to `next_back()` return the same value as `peek_back()` had,
# but also advance the iterator.
assert_equal(iter.next_back().value(), "3")

# Later `peek_back()` calls will return the _new_ next character:
assert_equal(iter.peek_back().value(), "2")
from collections.string import StringSlice, Codepoint
from testing import assert_equal

var input = StringSlice("123")
var iter = input.codepoint_slices()

# Repeated calls to `peek_back()` return the same value.
assert_equal(iter.peek_back().value(), "3")
assert_equal(iter.peek_back().value(), "3")
assert_equal(iter.peek_back().value(), "3")

# A call to `next_back()` return the same value as `peek_back()` had,
# but also advance the iterator.
assert_equal(iter.next_back().value(), "3")

# Later `peek_back()` calls will return the _new_ next character:
assert_equal(iter.peek_back().value(), "2")

.

Returns:

The last codepoint slice in the underlying string, or None if the string is empty.

next​

next(mut self) -> Optional[StringSlice[origin]]

Get the next codepoint slice in the underlying string slice, or None if the iterator is empty.

This returns the next single-codepoint substring encoded in the underlying string, and advances the iterator state.

Returns:

A character if the string is not empty, otherwise None.

next_back​

next_back(mut self) -> Optional[StringSlice[origin]]

Get the last single-codepoint slice in this iterator is, or None if the iterator is empty.

This returns the last codepoint slice in this iterator, and advances the iterator state.

Returns:

The last codepoint slice in the underlying string, or None if the string is empty.