Struct Cell 

pub struct Cell { /* private fields */ }

A single terminal cell.

This is the atomic unit of display in Flywheel. Each cell contains:

• A grapheme (the character to display)
• Foreground and background colors
• Text modifiers (bold, italic, etc.)

Memory Layout

The struct is carefully laid out to be exactly 16 bytes:

• 4 bytes for inline grapheme storage
• 2 bytes for grapheme metadata (length + display width)
• 6 bytes for colors (3 bytes fg + 3 bytes bg)
• 1 byte for modifiers
• 1 byte for flags
• 2 bytes padding (power-of-2 alignment)

Grapheme Handling

Most characters (ASCII, Latin, CJK) fit within the 4-byte inline storage. For complex graphemes like emoji ZWJ sequences (👨‍👩‍👧‍👦), we set the OVERFLOW flag and store an index in the grapheme bytes that points to an external overflow storage.

Implementations

impl Cell

pub const EMPTY: Self

An empty cell (space character with default colors).

pub fn new(c: char) -> Self

Create a new cell with a single ASCII character.

Panics

Panics if the character is not ASCII.

pub fn from_char(c: char) -> Self

Create a cell from any character.

Returns None if the character’s UTF-8 encoding exceeds 4 bytes (which never happens for a single char, but may happen for grapheme clusters when using from_grapheme).

pub fn from_grapheme(s: &str) -> Option<Self>

Create a cell from a grapheme string.

If the grapheme fits in 4 bytes, it’s stored inline. Otherwise, returns None and the caller should use overflow storage.

pub const fn overflow(index: u32, display_width: u8) -> Self

Create an overflow cell with an index to external storage.

The index is stored in the grapheme bytes as a little-endian u32.

pub const fn wide_continuation() -> Self

Create a wide-character continuation cell.

This is placed after a wide CJK character that takes 2 columns.

pub fn grapheme(&self) -> Option<&str>

Get the grapheme as a string slice.

Returns None if this is an overflow cell (caller should check is_overflow() and look up the grapheme in the overflow storage).

pub const fn overflow_index(&self) -> Option<u32>

Get the overflow index if this is an overflow cell.

pub const fn is_overflow(&self) -> bool

Check if this cell uses overflow storage.

pub const fn is_wide_continuation(&self) -> bool

Check if this is a wide-character continuation.

pub const fn display_width(&self) -> u8

Get the display width (0, 1, or 2).

pub const fn fg(&self) -> Rgb

Get the foreground color.

pub const fn bg(&self) -> Rgb

Get the background color.

pub const fn modifiers(&self) -> Modifiers

Get the modifiers.

pub const fn flags(&self) -> CellFlags

Get the flags.

pub const fn set_fg(&mut self, fg: Rgb) -> &mut Self

Set the foreground color.

pub const fn set_bg(&mut self, bg: Rgb) -> &mut Self

Set the background color.

pub const fn set_modifiers(&mut self, modifiers: Modifiers) -> &mut Self

Set the modifiers.

pub const fn with_fg(self, fg: Rgb) -> Self

Set the foreground color (builder pattern).

pub const fn with_bg(self, bg: Rgb) -> Self

Set the background color (builder pattern).

pub const fn with_modifiers(self, modifiers: Modifiers) -> Self

Set the modifiers (builder pattern).

pub const fn reset(&mut self)

Reset the cell to empty (space with default colors).

Trait Implementations

impl Clone for Cell

fn clone(&self) -> Cell

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Cell

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Cell

fn default() -> Self

Returns the “default value” for a type.

impl Hash for Cell

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Cell

fn eq(&self, other: &Self) -> bool

Optimized equality check.

We compare in order of most likely difference:

1. Grapheme bytes (most frequently changing)
2. Colors (next most common)
3. Modifiers and flags (rarely differ)

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Cell

impl Eq for Cell