Struct Alphabet 

pub struct Alphabet {
    pub(crate) symbols: [u8; 64],
    pub(crate) padding: Symbol,
}

An alphabet defines the 64 ASCII characters (symbols) used for base64.

Common alphabets are provided as constants, and custom alphabets can be made via from_str or the TryFrom<str> implementation.

Examples

Building and using a custom Alphabet:

let custom = base64::alphabet::Alphabet::new("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/").unwrap();

let engine = base64::engine::GeneralPurpose::new(
    &custom,
    base64::engine::general_purpose::PAD);

Building a const:

use base64::alphabet::Alphabet;

static CUSTOM: Alphabet = {
    // Result::unwrap() isn't const yet, but panic!() is OK
    match Alphabet::new("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/") {
        Ok(x) => x,
        Err(_) => panic!("creation of alphabet failed"),
    }
};

Building lazily:

use base64::alphabet::Alphabet;
use std::sync::LazyLock;

static CUSTOM: LazyLock<Alphabet> = LazyLock::new(||
    Alphabet::new("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/").unwrap()
);

Fields

symbols: [u8; 64]

All bytes are valid symbols, but left as u8 to allow .as_str() to work.

padding: Symbol

Implementations

impl Alphabet

const fn from_str_unchecked(alphabet: &str, padding: Symbol) -> Self

Performs no checks so that it can be const. Used only for known-valid strings.

pub const fn new(alphabet: &str) -> Result<Self, ParseAlphabetError>

Create an Alphabet from a string of 64 unique printable ASCII bytes with = as the padding symbol.

The padding symbol = is not allowed in the alphabet.

See Self::new_with_padding if a non-default padding symbol is needed.

pub const fn new_with_padding( alphabet: &str, padding: Symbol, ) -> Result<Self, ParseAlphabetError>

Create an Alphabet from a string of 64 unique printable ASCII bytes, with a custom padding symbol.

The padding symbol must not appear in the alphabet.

This is meant for strange alphabets that don’t use = as the padding symbol.

pub fn as_str(&self) -> &str

A &str containing the symbols in the Alphabet (excluding padding)

pub fn symbols(&self) -> [Symbol; 64]

The 64 symbols of the alphabet (excluding padding).

pub fn padding(&self) -> Symbol

The symbol used for padding.

Trait Implementations

impl Clone for Alphabet

fn clone(&self) -> Alphabet

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Alphabet

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

Formats the value using the given formatter.

impl PartialEq for Alphabet

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

Tests for self and other values to be equal, and is used by ==.

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 TryFrom<&str> for Alphabet

type Error = ParseAlphabetError

The type returned in the event of a conversion error.

fn try_from(value: &str) -> Result<Self, Self::Error>

Performs the conversion.

impl Eq for Alphabet

impl StructuralPartialEq for Alphabet