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|
use proc_macro2::TokenStream;
use quote::{quote, ToTokens};
use syn::{Attribute, LitStr, Meta, Result};
#[derive(Clone)]
pub(crate) struct Display {
pub(crate) fmt: LitStr,
pub(crate) args: TokenStream,
}
pub(crate) struct VariantDisplay {
pub(crate) r#enum: Option<Display>,
pub(crate) variant: Display,
}
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 VariantDisplay {
fn to_tokens(&self, tokens: &mut TokenStream) {
if let Some(ref r#enum) = self.r#enum {
r#enum.to_tokens(tokens);
tokens.extend(quote! { ?; write!(formatter, ": ")?; });
}
self.variant.to_tokens(tokens);
}
}
pub(crate) struct AttrsHelper {
ignore_extra_doc_attributes: bool,
prefix_enum_doc_attributes: bool,
}
impl AttrsHelper {
pub(crate) fn new(attrs: &[Attribute]) -> Self {
let ignore_extra_doc_attributes = attrs
.iter()
.any(|attr| attr.path().is_ident("ignore_extra_doc_attributes"));
let prefix_enum_doc_attributes = attrs
.iter()
.any(|attr| attr.path().is_ident("prefix_enum_doc_attributes"));
Self {
ignore_extra_doc_attributes,
prefix_enum_doc_attributes,
}
}
pub(crate) fn display(&self, attrs: &[Attribute]) -> Result<Option<Display>> {
let displaydoc_attr = attrs.iter().find(|attr| attr.path().is_ident("displaydoc"));
if let Some(displaydoc_attr) = displaydoc_attr {
let lit = displaydoc_attr
.parse_args()
.expect("#[displaydoc(\"foo\")] must contain string arguments");
let mut display = Display {
fmt: lit,
args: TokenStream::new(),
};
display.expand_shorthand();
return Ok(Some(display));
}
let num_doc_attrs = attrs
.iter()
.filter(|attr| attr.path().is_ident("doc"))
.count();
if !self.ignore_extra_doc_attributes && num_doc_attrs > 1 {
panic!("Multi-line comments are disabled by default by displaydoc. Please consider using block doc comments (/** */) or adding the #[ignore_extra_doc_attributes] attribute to your type next to the derive.");
}
for attr in attrs {
if attr.path().is_ident("doc") {
let lit = match &attr.meta {
Meta::NameValue(syn::MetaNameValue {
value:
syn::Expr::Lit(syn::ExprLit {
lit: syn::Lit::Str(lit),
..
}),
..
}) => lit,
_ => unimplemented!(),
};
// Make an attempt at cleaning up multiline doc comments.
let doc_str = lit
.value()
.lines()
.map(|line| line.trim().trim_start_matches('*').trim())
.collect::<Vec<&str>>()
.join("\n");
let lit = LitStr::new(doc_str.trim(), lit.span());
let mut display = Display {
fmt: lit,
args: TokenStream::new(),
};
display.expand_shorthand();
return Ok(Some(display));
}
}
Ok(None)
}
pub(crate) fn display_with_input(
&self,
r#enum: &[Attribute],
variant: &[Attribute],
) -> Result<Option<VariantDisplay>> {
let r#enum = if self.prefix_enum_doc_attributes {
let result = self
.display(r#enum)?
.expect("Missing doc comment on enum with #[prefix_enum_doc_attributes]. Please remove the attribute or add a doc comment to the enum itself.");
Some(result)
} else {
None
};
Ok(self
.display(variant)?
.map(|variant| VariantDisplay { r#enum, variant }))
}
}
|
