StringBuilder

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No import is needed.

Read the usage guide for examples and common tasks. This reference lists the public declarations for this part of the library. See Reading API signatures for parameter and result notation.

StringBuilder

StringBuilder — growable UTF-16 string construction. Lives in the bootstrap core so every package (collections included) can build strings in O(n); always available without imports.

public class StringBuilder

constructor

Allocates an empty builder with an initial backing buffer capacity in payload bytes (defaults to 16).

public constructor(capacity: int = 16)

length

Number of UTF-16 code units appended so far (count is always even).

public get length(): int

is_empty

True when nothing has been appended yet.

public fun is_empty(): bool

append_char

Appends a Unicode scalar as one or two UTF-16 units.

public fun append_char(c: char): void

append

Appends every UTF-16 unit of text, growing at most once.

public fun append(borrow text: string): void

append

Appends the units a ReadOnlySpan<char> views, with no intermediate string.

public fun append(span: ReadOnlySpan<char>): void

append_utf8_slice

Appends byte_len payload bytes starting at byte index start of text.

public fun append_utf8_slice(borrow text: string, start: int, byte_len: int): void

append_int

Appends a decimal integer without allocating an intermediate string.

public fun append_int(n: int): void

append_bool

Appends "true" or "false" without allocating an intermediate string.

public fun append_bool(v: bool): void

append_long

Appends a decimal long without allocating an intermediate string.

public fun append_long(n: long): void

append_double

Appends the same text as n.to_string() without allocating an intermediate string.

public fun append_double(n: double): void

append_line

Appends text followed by a newline character.

public fun append_line(borrow text: string): void

clear

Removes every appended character, keeping the backing buffer for reuse.

public fun clear(): void

as_span

A view of everything appended so far, without copying the units. Later appends and clear leave the view unchanged: it is a snapshot.

public fun as_span(): ReadOnlySpan<char>

build

Snapshot into a new string. from_builder copies once; do not stage through a second byte[] (that doubled the finish memcpy).

public fun build(): string

to_string

Supplies text to object formatting. Use build() when finishing a builder.

public override fun to_string(): string