diff options
Diffstat (limited to 'vendor/thiserror-impl/src/attr.rs')
| -rw-r--r-- | vendor/thiserror-impl/src/attr.rs | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/vendor/thiserror-impl/src/attr.rs b/vendor/thiserror-impl/src/attr.rs new file mode 100644 index 000000000..9963fd6db --- /dev/null +++ b/vendor/thiserror-impl/src/attr.rs @@ -0,0 +1,213 @@ +use proc_macro2::{Delimiter, Group, Span, TokenStream, TokenTree}; +use quote::{format_ident, quote, ToTokens}; +use std::collections::BTreeSet as Set; +use std::iter::FromIterator; +use syn::parse::{Nothing, ParseStream}; +use syn::{ + braced, bracketed, parenthesized, token, Attribute, Error, Ident, Index, LitInt, LitStr, + Result, Token, +}; + +pub struct Attrs<'a> { + pub display: Option<Display<'a>>, + pub source: Option<&'a Attribute>, + pub backtrace: Option<&'a Attribute>, + pub from: Option<&'a Attribute>, + pub transparent: Option<Transparent<'a>>, +} + +#[derive(Clone)] +pub struct Display<'a> { + pub original: &'a Attribute, + pub fmt: LitStr, + pub args: TokenStream, + pub has_bonus_display: bool, + pub implied_bounds: Set<(usize, Trait)>, +} + +#[derive(Copy, Clone)] +pub struct Transparent<'a> { + pub original: &'a Attribute, + pub span: Span, +} + +#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Debug)] +pub enum Trait { + Debug, + Display, + Octal, + LowerHex, + UpperHex, + Pointer, + Binary, + LowerExp, + UpperExp, +} + +pub fn get(input: &[Attribute]) -> Result<Attrs> { + let mut attrs = Attrs { + display: None, + source: None, + backtrace: None, + from: None, + transparent: None, + }; + + for attr in input { + if attr.path.is_ident("error") { + parse_error_attribute(&mut attrs, attr)?; + } else if attr.path.is_ident("source") { + require_empty_attribute(attr)?; + if attrs.source.is_some() { + return Err(Error::new_spanned(attr, "duplicate #[source] attribute")); + } + attrs.source = Some(attr); + } else if attr.path.is_ident("backtrace") { + require_empty_attribute(attr)?; + if attrs.backtrace.is_some() { + return Err(Error::new_spanned(attr, "duplicate #[backtrace] attribute")); + } + attrs.backtrace = Some(attr); + } else if attr.path.is_ident("from") { + if !attr.tokens.is_empty() { + // Assume this is meant for derive_more crate or something. + continue; + } + if attrs.from.is_some() { + return Err(Error::new_spanned(attr, "duplicate #[from] attribute")); + } + attrs.from = Some(attr); + } + } + + Ok(attrs) +} + +fn parse_error_attribute<'a>(attrs: &mut Attrs<'a>, attr: &'a Attribute) -> Result<()> { + syn::custom_keyword!(transparent); + + attr.parse_args_with(|input: ParseStream| { + if let Some(kw) = input.parse::<Option<transparent>>()? { + if attrs.transparent.is_some() { + return Err(Error::new_spanned( + attr, + "duplicate #[error(transparent)] attribute", + )); + } + attrs.transparent = Some(Transparent { + original: attr, + span: kw.span, + }); + return Ok(()); + } + + let display = Display { + original: attr, + fmt: input.parse()?, + args: parse_token_expr(input, false)?, + has_bonus_display: false, + implied_bounds: Set::new(), + }; + if attrs.display.is_some() { + return Err(Error::new_spanned( + attr, + "only one #[error(...)] attribute is allowed", + )); + } + attrs.display = Some(display); + Ok(()) + }) +} + +fn parse_token_expr(input: ParseStream, mut begin_expr: bool) -> Result<TokenStream> { + let mut tokens = Vec::new(); + while !input.is_empty() { + if begin_expr && input.peek(Token![.]) { + if input.peek2(Ident) { + input.parse::<Token![.]>()?; + begin_expr = false; + continue; + } + if input.peek2(LitInt) { + input.parse::<Token![.]>()?; + let int: Index = input.parse()?; + let ident = format_ident!("_{}", int.index, span = int.span); + tokens.push(TokenTree::Ident(ident)); + begin_expr = false; + continue; + } + } + + begin_expr = input.peek(Token![break]) + || input.peek(Token![continue]) + || input.peek(Token![if]) + || input.peek(Token![in]) + || input.peek(Token![match]) + || input.peek(Token![mut]) + || input.peek(Token![return]) + || input.peek(Token![while]) + || input.peek(Token![+]) + || input.peek(Token![&]) + || input.peek(Token![!]) + || input.peek(Token![^]) + || input.peek(Token![,]) + || input.peek(Token![/]) + || input.peek(Token![=]) + || input.peek(Token![>]) + || input.peek(Token![<]) + || input.peek(Token![|]) + || input.peek(Token![%]) + || input.peek(Token![;]) + || input.peek(Token![*]) + || input.peek(Token![-]); + + let token: TokenTree = if input.peek(token::Paren) { + let content; + let delimiter = parenthesized!(content in input); + let nested = parse_token_expr(&content, true)?; + let mut group = Group::new(Delimiter::Parenthesis, nested); + group.set_span(delimiter.span); + TokenTree::Group(group) + } else if input.peek(token::Brace) { + let content; + let delimiter = braced!(content in input); + let nested = parse_token_expr(&content, true)?; + let mut group = Group::new(Delimiter::Brace, nested); + group.set_span(delimiter.span); + TokenTree::Group(group) + } else if input.peek(token::Bracket) { + let content; + let delimiter = bracketed!(content in input); + let nested = parse_token_expr(&content, true)?; + let mut group = Group::new(Delimiter::Bracket, nested); + group.set_span(delimiter.span); + TokenTree::Group(group) + } else { + input.parse()? + }; + tokens.push(token); + } + Ok(TokenStream::from_iter(tokens)) +} + +fn require_empty_attribute(attr: &Attribute) -> Result<()> { + syn::parse2::<Nothing>(attr.tokens.clone())?; + Ok(()) +} + +impl ToTokens for Display<'_> { + fn to_tokens(&self, tokens: &mut TokenStream) { + let fmt = &self.fmt; + let args = &self.args; + tokens.extend(quote! { + write!(__formatter, #fmt #args) + }); + } +} + +impl ToTokens for Trait { + fn to_tokens(&self, tokens: &mut TokenStream) { + let trait_name = format_ident!("{}", format!("{:?}", self)); + tokens.extend(quote!(std::fmt::#trait_name)); + } +} |