uuid_macro_internal/
lib.rs

1//! Implementation details for the `uuid!` macro.
2//!
3//! This crate is not meant to be used directly. Instead,
4//! you can use the `macro-diagnostics` feature of `uuid`:
5//!
6//! ```toml
7//! [dependencies.uuid]
8//! features = ["macro-diagnostics"]
9//! ```
10
11use proc_macro::TokenStream;
12use proc_macro2::TokenStream as TokenStream2;
13use quote::{quote, quote_spanned};
14use std::fmt;
15use syn::{spanned::Spanned, LitStr};
16
17mod error;
18mod parser;
19
20#[proc_macro]
21#[doc(hidden)]
22pub fn parse_lit(input: TokenStream) -> TokenStream {
23    build_uuid(input.clone()).unwrap_or_else(|e| {
24        let msg = e.to_string();
25        let span = match e {
26            Error::UuidParse(lit, error::Error(error::ErrorKind::Char { character, index })) => {
27                let mut bytes = character as u32;
28                let mut width = 0;
29                while bytes != 0 {
30                    bytes >>= 4;
31                    width += 1;
32                }
33                let mut s = proc_macro2::Literal::string("");
34                s.set_span(lit.span());
35                s.subspan(index..index + width - 1)
36            }
37            Error::UuidParse(
38                lit,
39                error::Error(error::ErrorKind::GroupLength { index, len, .. }),
40            ) => {
41                let mut s = proc_macro2::Literal::string("");
42                s.set_span(lit.span());
43                s.subspan(index..index + len)
44            }
45            _ => None,
46        }
47        .unwrap_or_else(|| TokenStream2::from(input).span());
48
49        TokenStream::from(quote_spanned! {span=>
50            compile_error!(#msg)
51        })
52    })
53}
54
55enum Error {
56    NonStringLiteral,
57    UuidParse(LitStr, error::Error),
58}
59
60impl fmt::Display for Error {
61    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
62        match *self {
63            Error::NonStringLiteral => f.write_str("expected string literal"),
64            Error::UuidParse(_, ref e) => write!(f, "{}", e),
65        }
66    }
67}
68
69fn build_uuid(input: TokenStream) -> Result<TokenStream, Error> {
70    let str_lit = match syn::parse::<syn::Lit>(input) {
71        Ok(syn::Lit::Str(literal)) => literal,
72        _ => return Err(Error::NonStringLiteral),
73    };
74
75    let bytes =
76        parser::try_parse(&str_lit.value()).map_err(|e| Error::UuidParse(str_lit, e.into_err()))?;
77
78    let tokens = bytes
79        .iter()
80        .map(|byte| quote! { #byte, })
81        .collect::<TokenStream2>();
82
83    Ok(quote! {[#tokens]}.into())
84}
uuid_macro_internal/lib.rs

uuid_macro_internal/
lib.rs
