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| 1 | +// SPDX-License-Identifier: GPL-2.0 |
| 2 | + |
| 3 | +use proc_macro::{Ident, TokenStream, TokenTree}; |
| 4 | +use std::collections::BTreeSet; |
| 5 | + |
| 6 | +/// Please see [`crate::fmt`] for documentation. |
| 7 | +pub(crate) fn fmt(input: TokenStream) -> TokenStream { |
| 8 | + let mut input = input.into_iter(); |
| 9 | + |
| 10 | + let first_opt = input.next(); |
| 11 | + let first_owned_str; |
| 12 | + let mut names = BTreeSet::new(); |
| 13 | + let first_span = { |
| 14 | + let Some((mut first_str, first_span)) = (match first_opt.as_ref() { |
| 15 | + Some(TokenTree::Literal(first_lit)) => { |
| 16 | + first_owned_str = first_lit.to_string(); |
| 17 | + Some(first_owned_str.as_str()).and_then(|first| { |
| 18 | + let first = first.strip_prefix('"')?; |
| 19 | + let first = first.strip_suffix('"')?; |
| 20 | + Some((first, first_lit.span())) |
| 21 | + }) |
| 22 | + } |
| 23 | + _ => None, |
| 24 | + }) else { |
| 25 | + return first_opt.into_iter().chain(input).collect(); |
| 26 | + }; |
| 27 | + |
| 28 | + // Parse `identifier`s from the format string. |
| 29 | + // |
| 30 | + // See https://doc.rust-lang.org/std/fmt/index.html#syntax. |
| 31 | + while let Some((_, rest)) = first_str.split_once('{') { |
| 32 | + first_str = rest; |
| 33 | + if let Some(rest) = first_str.strip_prefix('{') { |
| 34 | + first_str = rest; |
| 35 | + continue; |
| 36 | + } |
| 37 | + if let Some((name, rest)) = first_str.split_once('}') { |
| 38 | + first_str = rest; |
| 39 | + let name = name.split_once(':').map_or(name, |(name, _)| name); |
| 40 | + if !name.is_empty() && !name.chars().all(|c| c.is_ascii_digit()) { |
| 41 | + names.insert(name); |
| 42 | + } |
| 43 | + } |
| 44 | + } |
| 45 | + first_span |
| 46 | + }; |
| 47 | + |
| 48 | + let adapter = quote_spanned!(first_span => ::kernel::fmt::Adapter); |
| 49 | + |
| 50 | + let mut args = TokenStream::from_iter(first_opt); |
| 51 | + { |
| 52 | + let mut flush = |args: &mut TokenStream, current: &mut TokenStream| { |
| 53 | + let current = std::mem::take(current); |
| 54 | + if !current.is_empty() { |
| 55 | + let (lhs, rhs) = (|| { |
| 56 | + let mut current = current.into_iter(); |
| 57 | + let mut acc = TokenStream::new(); |
| 58 | + while let Some(tt) = current.next() { |
| 59 | + // Split on `=` only once to handle cases like `a = b = c`. |
| 60 | + if matches!(&tt, TokenTree::Punct(p) if p.as_char() == '=') { |
| 61 | + names.remove(acc.to_string().as_str()); |
| 62 | + // Include the `=` itself to keep the handling below uniform. |
| 63 | + acc.extend([tt]); |
| 64 | + return (Some(acc), current.collect::<TokenStream>()); |
| 65 | + } |
| 66 | + acc.extend([tt]); |
| 67 | + } |
| 68 | + (None, acc) |
| 69 | + })(); |
| 70 | + args.extend(quote_spanned!(first_span => #lhs #adapter(&#rhs))); |
| 71 | + } |
| 72 | + }; |
| 73 | + |
| 74 | + let mut current = TokenStream::new(); |
| 75 | + for tt in input { |
| 76 | + match &tt { |
| 77 | + TokenTree::Punct(p) if p.as_char() == ',' => { |
| 78 | + flush(&mut args, &mut current); |
| 79 | + &mut args |
| 80 | + } |
| 81 | + _ => &mut current, |
| 82 | + } |
| 83 | + .extend([tt]); |
| 84 | + } |
| 85 | + flush(&mut args, &mut current); |
| 86 | + } |
| 87 | + |
| 88 | + for name in names { |
| 89 | + let name = Ident::new(name, first_span); |
| 90 | + args.extend(quote_spanned!(first_span => , #name = #adapter(&#name))); |
| 91 | + } |
| 92 | + |
| 93 | + quote_spanned!(first_span => ::core::format_args!(#args)) |
| 94 | +} |
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