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use std::fmt;
use std::hash::{Hash, Hasher};
use proc_macro2::{Span, TokenStream};
use quote::ToTokens;
use syn::{Ident, Meta};
use crate::{FromMeta, Result};
/// A wrapper for an `Ident` which also keeps the value as a string.
///
/// This struct can be used to perform string comparisons and operations.
#[derive(Clone, PartialOrd, Ord)]
pub struct IdentString {
ident: Ident,
string: String,
}
impl IdentString {
/// Create a new `IdentString`.
pub fn new(ident: Ident) -> Self {
IdentString {
string: ident.to_string(),
ident,
}
}
/// Get the ident as a `proc_macro2::Ident`.
pub fn as_ident(&self) -> &Ident {
&self.ident
}
/// Get the ident as a string.
pub fn as_str(&self) -> &str {
&self.string
}
/// Get the location of this `Ident` in source.
pub fn span(&self) -> Span {
self.ident.span()
}
/// Apply some transform to the ident's string representation.
///
/// # Panics
/// This will panic if the transform produces an invalid ident.
pub fn map<F, S>(self, map_fn: F) -> Self
where
F: FnOnce(String) -> S,
S: AsRef<str>,
{
let span = self.span();
let string = map_fn(self.string);
Ident::new(string.as_ref(), span).into()
}
}
impl AsRef<Ident> for IdentString {
fn as_ref(&self) -> &Ident {
self.as_ident()
}
}
impl AsRef<str> for IdentString {
fn as_ref(&self) -> &str {
self.as_str()
}
}
impl From<Ident> for IdentString {
fn from(ident: Ident) -> Self {
IdentString::new(ident)
}
}
impl From<IdentString> for Ident {
fn from(v: IdentString) -> Ident {
v.ident
}
}
impl From<IdentString> for String {
fn from(v: IdentString) -> String {
v.string
}
}
impl Eq for IdentString {}
impl PartialEq for IdentString {
fn eq(&self, rhs: &Self) -> bool {
self.ident == rhs.ident
}
}
impl PartialEq<String> for IdentString {
fn eq(&self, rhs: &String) -> bool {
self.as_str() == rhs
}
}
impl<'a> PartialEq<&'a str> for IdentString {
fn eq(&self, rhs: &&str) -> bool {
self.as_str() == *rhs
}
}
impl Hash for IdentString {
fn hash<H: Hasher>(&self, state: &mut H) {
self.ident.hash(state);
}
}
impl ToTokens for IdentString {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
}
}
impl fmt::Debug for IdentString {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{:?}", self.ident)
}
}
impl fmt::Display for IdentString {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.ident)
}
}
impl FromMeta for IdentString {
fn from_meta(item: &Meta) -> Result<Self> {
Ident::from_meta(item).map(IdentString::from)
}
}
#[cfg(test)]
mod tests {
use syn::parse_quote;
use super::IdentString;
#[test]
fn convert() {
let i_str = IdentString::new(parse_quote!(t));
assert_eq!(i_str.as_str(), "t");
}
#[test]
fn map_transform() {
let i = IdentString::new(parse_quote!(my));
let after = i.map(|v| format!("var_{}", v));
assert_eq!(after, "var_my");
assert_eq!(after, String::from("var_my"));
}
}