Struct FormatArena 

pub struct FormatArena { /* private fields */ }

Arena for formatted strings.

All scalar values are formatted once into this buffer and referenced by Span. This avoids per-value allocations and allows measuring display width at format time.

Implementations

impl FormatArena

pub fn with_capacity(cap: usize) -> Self

Create a new arena with pre-allocated capacity.

pub fn new() -> Self

Create a new arena with default capacity.

pub fn format<F>(&mut self, f: F) -> (Span, usize)

where F: FnOnce(&mut String) -> Result,

Format something into the arena, returning span and display width.

The closure receives a &mut String to write into. The span returned covers exactly what was written. Display width is calculated using unicode-width for proper handling of CJK characters, emoji, etc.

pub fn push_str(&mut self, s: &str) -> (Span, usize)

Push a string directly, returning span and display width.

pub fn get(&self, span: Span) -> &str

Retrieve the string for a span.

pub fn len(&self) -> usize

Current size of the buffer in bytes.

pub fn is_empty(&self) -> bool

Check if the arena is empty.

Trait Implementations

impl Default for FormatArena

fn default() -> Self

Returns the “default value” for a type.