CharsView

public struct CharsView { /* private fields */ }

A view over the Unicode code points in a String.

Returned by String.chars. Iteration is O(1) per code point but count() is O(n) because UTF-8 is variable-width. Range subscripts are O(n) (the segment-walk dominates) but yield a zero-copy CharsView sub-view — call .toString() to materialize an owned String. To index in O(1), use BytesView and convert byte offsets back yourself.

Examples

let s = "héllo";
s.chars.count;                       // 5 (code points)
s.bytes.count;                       // 6 (bytes — 'é' is 2 bytes)
s.chars(0..<4).toString();           // "héll"
s.chars.substring(0..<4);            // "héll"

Representation

A (ptr, length) pair, plus the on-demand UTF-8 decoder.

Memory Model

Borrows the source string's buffer. Invalidated by any mutation that reallocates the storage.

Properties

public var count: Int64 { get }

public var endIndex: CharIndex { get }

Char index at the end (one past the last byte).

public var first: Char? { get }

The first code point, or None if the view is empty.

public var isEmpty: Bool { get }

true when the view spans zero bytes (no code points).

O(1) — checks byteCount, not count.

public var last: Char? { get }

The last code point, or None if the view is empty.

public var reversed: ReversedCharsView { get }

A reversed view that iterates code points back-to-front.

public var startIndex: CharIndex { get }

Char index at byte 0 (the first code point).

Initializers

public init(slice: StringSlice)

Constructs a chars view backed by the given string slice. The view retains shared ownership of the underlying bytes.

Methods

public func firstIndex(of: Char) -> CharIndex?

Returns the index of the first occurrence of c, or .None.

public func firstIndex(where: (Char) -> Bool) -> CharIndex?

Returns the index of the first code point matching predicate, or .None.

public func index(at: Int64) -> CharIndex?

Resolves the n-th code point to its byte offset. O(n).

public func indexedIter() -> IndexedCharsIterator

Returns an iterator yielding (CharIndex, Char) pairs.

public func lastIndex(of: Char) -> CharIndex?

Returns the index of the last occurrence of c, or .None.

public func lastIndex(where: (Char) -> Bool) -> CharIndex?

Returns the index of the last code point matching predicate, or .None.

public func slice(from: CharIndex, to: CharIndex) -> StringSlice

Returns a StringSlice covering [start, end) by byte offset.

public func substring[__opaque_0](__opaque_0) -> String where __opaque_0: CharsSubstringIndex

Convenience: dispatches to a CharsSubstringIndex to produce an owned String covering the requested code-point range. Equivalent to self(range).toString() for both Range[Int64] and ClosedRange[Int64].

public func toString() -> String

Materializes the view as an owned String. O(n) — copies bytes.

Subscripts

public subscript[I](checked: I) -> I.CharsYield? { get }

Reads at index, returning .None on out-of-bounds.

public subscript[I](clamped: I) -> I.CharsClampedYield { get }

Reads at index with bounds saturated to [0, count). Single- char indexes yield Char? (None on empty view); range indexes yield CharsView (always valid, possibly empty).

public subscript[I](I) -> I.CharsYield { get }

Reads a single code point (Char) for Int64 indexes, or a zero-copy CharsView sub-view for Range[Int64] / ClosedRange[Int64]. All access is O(n) because UTF-8 is variable-width. Panics on out-of-bounds.

public subscript[I](wrapped: I) -> I.CharsWrappedYield { get }

Reads at index with modulo wrap-around. Negative indices wrap from the end: view.chars(wrapped: -1) reads the last char. Returns None on an empty view.

ImplementsIterable

Associated Types

type Item = Char

The element type yielded by iteration — always Char.

type TargetIterator = CharsIterator

The iterator type returned by iter().

Methods

public func iter() -> CharsIterator

Returns a CharsIterator positioned at byte 0.

Each call returns a fresh iterator; the view itself is reusable.

ImplementsCloneable

Methods

public func clone() -> CharsView

Defined in lang/std/text/views.ks