Struct FormatSpec

pub struct FormatSpec {
    pub fill: Option<char>,
    pub align: Option<Align>,
    pub sign: Option<Sign>,
    pub alternate: bool,
    pub zero: bool,
    pub width: Option<usize>,
    pub precision: Option<usize>,
    pub ty: FmtType,
}

A complete format specification for dynamic formatting.

FormatSpec represents all the components of a format specification that can appear between the colons in a format string: "{:<5.2}". It controls how values are formatted including alignment, padding, width, precision, and type-specific formatting.

Format String Components

A format specification in a string typically looks like: :[fill][align][sign][#][0][width][.precision][type]

Fields

fill: Option<char>

The fill character to use for padding.

If None, spaces will be used for padding.

align: Option<Align>

The alignment of the formatted value within the field.

If None, the default alignment (typically right for numbers, left for text) will be used.

sign: Option<Sign>

The sign display option for numeric values.

If None, signs will only be shown for negative numbers.

alternate: bool

Whether to use alternate formatting.

For example, adding 0x prefix to hexadecimal numbers or always showing the decimal point.

zero: bool

Whether to pad with zeros instead of the fill character.

This is typically used for numeric types to ensure a minimum number of digits.

width: Option<usize>

The minimum width of the formatted field.

If the formatted value is shorter than this width, it will be padded according to the alignment.

precision: Option<usize>

The precision for floating-point numbers or maximum length for strings.

ty: FmtType

The format type specification.

Implementations

impl FormatSpec

pub fn fill_and_align(&self, s: String, default_align: Align) -> String

Applies fill and alignment to a string according to this format specification.

Arguments

• s - The string to format
• default_align - The default alignment to use if none is specified

Trait Implementations

impl Clone for FormatSpec

fn clone(&self) -> FormatSpec

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FormatSpec

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

Formats the value using the given formatter.

impl Default for FormatSpec

fn default() -> Self

Returns the “default value” for a type.

impl Display for FormatSpec

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

Formats the value using the given formatter.