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use std::{borrow::Borrow, fmt};
use crate::{
error::{Error, NonEmptyStringError},
utils,
};
/// An owned structured field value [token].
///
/// Tokens must match the following regular expression:
///
/// ```re
/// ^[A-Za-z*][A-Za-z*0-9!#$%&'+\-.^_`|~]*$
/// ```
///
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Token(String);
/// A borrowed structured field value [token].
///
/// Tokens must match the following regular expression:
///
/// ```re
/// ^[A-Za-z*][A-Za-z*0-9!#$%&'+\-.^_`|~]*$
/// ```
///
/// This type is to [`Token`] as [`str`] is to [`String`].
///
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, ref_cast::RefCastCustom)]
#[repr(transparent)]
pub struct TokenRef(str);
const fn validate(v: &[u8]) -> Result<(), NonEmptyStringError> {
if v.is_empty() {
return Err(NonEmptyStringError::empty());
}
if !utils::is_allowed_start_token_char(v[0]) {
return Err(NonEmptyStringError::invalid_character(0));
}
let mut index = 1;
while index < v.len() {
if !utils::is_allowed_inner_token_char(v[index]) {
return Err(NonEmptyStringError::invalid_character(index));
}
index += 1;
}
Ok(())
}
impl TokenRef {
#[ref_cast::ref_cast_custom]
const fn cast(v: &str) -> &Self;
/// Creates a `&TokenRef` from a `&str`.
///
/// # Errors
/// The error result reports the reason for any failed validation.
#[allow(clippy::should_implement_trait)]
pub fn from_str(v: &str) -> Result<&Self, Error> {
validate(v.as_bytes())?;
Ok(Self::cast(v))
}
// Like `from_str`, but assumes that the contents of the string have already
// been validated as a token.
pub(crate) fn from_validated_str(v: &str) -> &Self {
debug_assert!(validate(v.as_bytes()).is_ok());
Self::cast(v)
}
/// Creates a `&TokenRef`, panicking if the value is invalid.
///
/// This method is intended to be called from `const` contexts in which the
/// value is known to be valid. Use [`TokenRef::from_str`] for non-panicking
/// conversions.
#[must_use]
pub const fn constant(v: &str) -> &Self {
match validate(v.as_bytes()) {
Ok(()) => Self::cast(v),
Err(err) => panic!("{}", err.msg()),
}
}
/// Returns the token as a `&str`.
#[must_use]
pub fn as_str(&self) -> &str {
&self.0
}
}
impl ToOwned for TokenRef {
type Owned = Token;
fn to_owned(&self) -> Token {
Token(self.0.to_owned())
}
fn clone_into(&self, target: &mut Token) {
self.0.clone_into(&mut target.0);
}
}
impl Borrow<TokenRef> for Token {
fn borrow(&self) -> &TokenRef {
self
}
}
impl std::ops::Deref for Token {
type Target = TokenRef;
fn deref(&self) -> &TokenRef {
TokenRef::cast(&self.0)
}
}
impl From<Token> for String {
fn from(v: Token) -> String {
v.0
}
}
impl TryFrom<String> for Token {
type Error = Error;
fn try_from(v: String) -> Result<Token, Error> {
validate(v.as_bytes())?;
Ok(Token(v))
}
}
impl Token {
/// Creates a `Token` from a `String`.
///
/// Returns the original value if the conversion failed.
///
/// # Errors
/// The error result reports the reason for any failed validation.
pub fn from_string(v: String) -> Result<Self, (Error, String)> {
match validate(v.as_bytes()) {
Ok(()) => Ok(Self(v)),
Err(err) => Err((err.into(), v)),
}
}
}
/// Creates a `&TokenRef`, panicking if the value is invalid.
///
/// This is a convenience free function for [`TokenRef::constant`].
///
/// This method is intended to be called from `const` contexts in which the
/// value is known to be valid. Use [`TokenRef::from_str`] for non-panicking
/// conversions.
#[must_use]
pub const fn token_ref(v: &str) -> &TokenRef {
TokenRef::constant(v)
}
impl fmt::Display for TokenRef {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(self.as_str())
}
}
impl fmt::Display for Token {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
<TokenRef as fmt::Display>::fmt(self, f)
}
}
macro_rules! impl_eq {
($a: ty, $b: ty) => {
impl PartialEq<$a> for $b {
fn eq(&self, other: &$a) -> bool {
<TokenRef as PartialEq>::eq(self, other)
}
}
impl PartialEq<$b> for $a {
fn eq(&self, other: &$b) -> bool {
<TokenRef as PartialEq>::eq(self, other)
}
}
};
}
impl_eq!(Token, TokenRef);
impl_eq!(Token, &TokenRef);
impl<'a> TryFrom<&'a str> for &'a TokenRef {
type Error = Error;
fn try_from(v: &'a str) -> Result<&'a TokenRef, Error> {
TokenRef::from_str(v)
}
}
impl Borrow<str> for Token {
fn borrow(&self) -> &str {
self.as_str()
}
}
impl Borrow<str> for TokenRef {
fn borrow(&self) -> &str {
self.as_str()
}
}
#[cfg(feature = "arbitrary")]
impl<'a> arbitrary::Arbitrary<'a> for &'a TokenRef {
fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
TokenRef::from_str(<&str>::arbitrary(u)?).map_err(|_| arbitrary::Error::IncorrectFormat)
}
}
#[cfg(feature = "arbitrary")]
impl<'a> arbitrary::Arbitrary<'a> for Token {
fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
<&TokenRef>::arbitrary(u).map(ToOwned::to_owned)
}
}