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#![allow(
clippy::missing_const_for_fn, // irrelevant for proc macros
clippy::missing_docs_in_private_items, // TODO remove
clippy::std_instead_of_core, // irrelevant for proc macros
clippy::std_instead_of_alloc, // irrelevant for proc macros
clippy::alloc_instead_of_core, // irrelevant for proc macros
missing_docs, // TODO remove
)]
#[allow(unused_macros)]
macro_rules! bug {
() => { compile_error!("provide an error message to help fix a possible bug") };
($descr:literal $($rest:tt)?) => {
unreachable!(concat!("internal error: ", $descr) $($rest)?)
}
}
#[macro_use]
mod quote;
mod date;
mod datetime;
mod error;
#[cfg(any(feature = "formatting", feature = "parsing"))]
mod format_description;
mod helpers;
mod offset;
#[cfg(all(feature = "serde", any(feature = "formatting", feature = "parsing")))]
mod serde_format_description;
mod time;
mod to_tokens;
#[cfg(any(feature = "formatting", feature = "parsing"))]
use std::iter::Peekable;
use proc_macro::TokenStream;
#[cfg(any(feature = "formatting", feature = "parsing"))]
use proc_macro::{Ident, TokenTree};
use self::error::Error;
macro_rules! impl_macros {
($($name:ident)*) => {$(
#[proc_macro]
pub fn $name(input: TokenStream) -> TokenStream {
use crate::to_tokens::ToTokenTree;
let mut iter = input.into_iter().peekable();
match $name::parse(&mut iter) {
Ok(value) => match iter.peek() {
Some(tree) => Error::UnexpectedToken { tree: tree.clone() }.to_compile_error(),
None => TokenStream::from(value.into_token_tree()),
},
Err(err) => err.to_compile_error(),
}
}
)*};
}
impl_macros![date datetime offset time];
#[cfg(any(feature = "formatting", feature = "parsing"))]
enum FormatDescriptionVersion {
V1,
V2,
}
#[cfg(any(feature = "formatting", feature = "parsing"))]
enum VersionOrModuleName {
Version(FormatDescriptionVersion),
#[cfg_attr(not(feature = "serde"), allow(dead_code))]
ModuleName(Ident),
}
#[cfg(any(feature = "formatting", feature = "parsing"))]
fn parse_format_description_version<const NO_EQUALS_IS_MOD_NAME: bool>(
iter: &mut Peekable<proc_macro::token_stream::IntoIter>,
) -> Result<Option<VersionOrModuleName>, Error> {
let version_ident = match iter.peek() {
Some(TokenTree::Ident(ident)) if ident.to_string() == "version" => match iter.next() {
Some(TokenTree::Ident(ident)) => ident,
_ => unreachable!(),
},
_ => return Ok(None),
};
match iter.peek() {
Some(TokenTree::Punct(punct)) if punct.as_char() == '=' => iter.next(),
_ if NO_EQUALS_IS_MOD_NAME => {
return Ok(Some(VersionOrModuleName::ModuleName(version_ident)));
}
Some(token) => {
return Err(Error::Custom {
message: "expected `=`".into(),
span_start: Some(token.span()),
span_end: Some(token.span()),
});
}
None => {
return Err(Error::Custom {
message: "expected `=`".into(),
span_start: None,
span_end: None,
});
}
};
let version_literal = match iter.next() {
Some(TokenTree::Literal(literal)) => literal,
Some(token) => {
return Err(Error::Custom {
message: "expected 1 or 2".into(),
span_start: Some(token.span()),
span_end: Some(token.span()),
});
}
None => {
return Err(Error::Custom {
message: "expected 1 or 2".into(),
span_start: None,
span_end: None,
});
}
};
let version = match version_literal.to_string().as_str() {
"1" => FormatDescriptionVersion::V1,
"2" => FormatDescriptionVersion::V2,
_ => {
return Err(Error::Custom {
message: "invalid format description version".into(),
span_start: Some(version_literal.span()),
span_end: Some(version_literal.span()),
});
}
};
helpers::consume_punct(',', iter)?;
Ok(Some(VersionOrModuleName::Version(version)))
}
#[cfg(any(feature = "formatting", feature = "parsing"))]
#[proc_macro]
pub fn format_description(input: TokenStream) -> TokenStream {
(|| {
let mut input = input.into_iter().peekable();
let version = match parse_format_description_version::<false>(&mut input)? {
Some(VersionOrModuleName::Version(version)) => Some(version),
None => None,
// This branch should never occur here, as `false` is the provided as a const parameter.
Some(VersionOrModuleName::ModuleName(_)) => bug!("branch should never occur"),
};
let (span, string) = helpers::get_string_literal(input)?;
let items = format_description::parse_with_version(version, &string, span)?;
Ok(quote! {{
const DESCRIPTION: &[::time::format_description::BorrowedFormatItem<'_>] = &[#S(
items
.into_iter()
.map(|item| quote! { #S(item), })
.collect::<TokenStream>()
)];
DESCRIPTION
}})
})()
.unwrap_or_else(|err: Error| err.to_compile_error())
}
#[cfg(all(feature = "serde", any(feature = "formatting", feature = "parsing")))]
#[proc_macro]
pub fn serde_format_description(input: TokenStream) -> TokenStream {
(|| {
let mut tokens = input.into_iter().peekable();
// First, the optional format description version.
let version = parse_format_description_version::<true>(&mut tokens)?;
let (version, mod_name) = match version {
Some(VersionOrModuleName::ModuleName(module_name)) => (None, Some(module_name)),
Some(VersionOrModuleName::Version(version)) => (Some(version), None),
None => (None, None),
};
// Next, an identifier (the desired module name)
// Only parse this if it wasn't parsed when attempting to get the version.
let mod_name = match mod_name {
Some(mod_name) => mod_name,
None => match tokens.next() {
Some(TokenTree::Ident(ident)) => Ok(ident),
Some(tree) => Err(Error::UnexpectedToken { tree }),
None => Err(Error::UnexpectedEndOfInput),
}?,
};
// Followed by a comma
helpers::consume_punct(',', &mut tokens)?;
// Then, the type to create serde serializers for (e.g., `OffsetDateTime`).
let formattable = match tokens.next() {
Some(tree @ TokenTree::Ident(_)) => Ok(tree),
Some(tree) => Err(Error::UnexpectedToken { tree }),
None => Err(Error::UnexpectedEndOfInput),
}?;
// Another comma
helpers::consume_punct(',', &mut tokens)?;
// We now have two options. The user can either provide a format description as a string or
// they can provide a path to a format description. If the latter, all remaining tokens are
// assumed to be part of the path.
let (format, format_description_display) = match tokens.peek() {
// string literal
Some(TokenTree::Literal(_)) => {
let (span, format_string) = helpers::get_string_literal(tokens)?;
let items = format_description::parse_with_version(version, &format_string, span)?;
let items: TokenStream =
items.into_iter().map(|item| quote! { #S(item), }).collect();
let items = quote! {
const ITEMS: &[::time::format_description::BorrowedFormatItem<'_>]
= &[#S(items)];
ITEMS
};
(items, String::from_utf8_lossy(&format_string).into_owned())
}
// path
Some(_) => {
let tokens = tokens.collect::<TokenStream>();
let tokens_string = tokens.to_string();
(
quote! {{
// We can't just do `super::path` because the path could be an absolute
// path. In that case, we'd be generating `super::::path`, which is invalid.
// Even if we took that into account, it's not possible to know if it's an
// external crate, which would just require emitting `path` directly. By
// taking this approach, we can leave it to the compiler to do the actual
// resolution.
mod __path_hack {
pub(super) use super::super::*;
pub(super) use #S(tokens) as FORMAT;
}
__path_hack::FORMAT
}},
tokens_string,
)
}
None => return Err(Error::UnexpectedEndOfInput),
};
Ok(serde_format_description::build(
mod_name,
formattable,
format,
format_description_display,
))
})()
.unwrap_or_else(|err: Error| err.to_compile_error_standalone())
}