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use proc_macro2::Span;
use quote::{ToTokens, TokenStreamExt};
use serde::{Deserialize, Serialize};
use std::borrow::{Borrow, Cow};
use std::fmt;
/// An identifier, analogous to `syn::Ident` and `proc_macro2::Ident`.
#[derive(Hash, Eq, PartialEq, Serialize, Clone, Debug, Ord, PartialOrd)]
#[serde(transparent)]
pub struct Ident(Cow<'static, str>);
impl Ident {
/// Validate a string
fn validate(string: &str) -> syn::Result<()> {
syn::parse_str::<syn::Ident>(string).map(|_| {})
}
/// Attempt to create a new `Ident`.
///
/// This function fails if the input isn't valid according to
/// `proc_macro2::Ident`'s invariants.
pub fn try_new(string: String) -> syn::Result<Self> {
Self::validate(&string).map(|_| Self(Cow::from(string)))
}
pub fn to_syn(&self) -> syn::Ident {
syn::Ident::new(self.as_str(), Span::call_site())
}
/// Get the `&str` representation.
pub fn as_str(&self) -> &str {
&self.0
}
/// An [`Ident`] containing "this".
pub const THIS: Self = Ident(Cow::Borrowed("this"));
}
impl From<&'static str> for Ident {
fn from(string: &'static str) -> Self {
Self::validate(string).unwrap();
Self(Cow::from(string))
}
}
impl From<String> for Ident {
fn from(string: String) -> Self {
Self::validate(&string).unwrap();
Self(Cow::from(string))
}
}
impl<'de> Deserialize<'de> for Ident {
/// The derived `Deserialize` allows for creating `Ident`s that do not uphold
/// the proper invariants. This custom impl ensures that this cannot happen.
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: serde::Deserializer<'de>,
{
Ok(Ident::from(String::deserialize(deserializer)?))
}
}
impl Borrow<str> for Ident {
fn borrow(&self) -> &str {
self.as_str()
}
}
impl fmt::Display for Ident {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.as_str().fmt(f)
}
}
impl From<&syn::Ident> for Ident {
fn from(ident: &syn::Ident) -> Self {
Self(Cow::from(ident.to_string()))
}
}
impl ToTokens for Ident {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
tokens.append(self.to_syn());
}
}