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lib.rs
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lib.rs
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//! Implementation details for the `uuid!` macro.
//!
//! This crate is not meant to be used directly. Instead,
//! you can use the `macro-diagnostics` feature of `uuid`:
//!
//! ```toml
//! [dependencies.uuid]
//! features = ["macro-diagnostics"]
//! ```
use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::{quote, quote_spanned};
use std::fmt;
use syn::{spanned::Spanned, LitStr};
mod error;
mod parser;
#[proc_macro]
#[doc(hidden)]
pub fn parse_lit(input: TokenStream) -> TokenStream {
build_uuid(input.clone()).unwrap_or_else(|e| {
let msg = e.to_string();
let span = match e {
Error::UuidParse(lit, error::Error(error::ErrorKind::Char { character, index })) => {
let mut bytes = character as u32;
let mut width = 0;
while bytes != 0 {
bytes >>= 4;
width += 1;
}
let mut s = proc_macro2::Literal::string("");
s.set_span(lit.span());
s.subspan(index..index + width - 1)
}
Error::UuidParse(
lit,
error::Error(error::ErrorKind::GroupLength { index, len, .. }),
) => {
let mut s = proc_macro2::Literal::string("");
s.set_span(lit.span());
s.subspan(index..index + len)
}
_ => None,
}
.unwrap_or_else(|| TokenStream2::from(input).span());
TokenStream::from(quote_spanned! {span=>
compile_error!(#msg)
})
})
}
enum Error {
NonStringLiteral,
UuidParse(LitStr, error::Error),
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Error::NonStringLiteral => f.write_str("expected string literal"),
Error::UuidParse(_, ref e) => write!(f, "{}", e),
}
}
}
fn build_uuid(input: TokenStream) -> Result<TokenStream, Error> {
let str_lit = match syn::parse::<syn::Lit>(input) {
Ok(syn::Lit::Str(literal)) => literal,
_ => return Err(Error::NonStringLiteral),
};
let bytes =
parser::try_parse(&str_lit.value()).map_err(|e| Error::UuidParse(str_lit, e.into_err()))?;
let tokens = bytes
.iter()
.map(|byte| quote! { #byte, })
.collect::<TokenStream2>();
Ok(quote! {[#tokens]}.into())
}