displaydoc/
attr.rs

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1use proc_macro2::TokenStream;
2use quote::{quote, ToTokens};
3use syn::{Attribute, LitStr, Meta, Result};
4
5#[derive(Clone)]
6pub(crate) struct Display {
7    pub(crate) fmt: LitStr,
8    pub(crate) args: TokenStream,
9}
10
11pub(crate) struct VariantDisplay {
12    pub(crate) r#enum: Option<Display>,
13    pub(crate) variant: Display,
14}
15
16impl ToTokens for Display {
17    fn to_tokens(&self, tokens: &mut TokenStream) {
18        let fmt = &self.fmt;
19        let args = &self.args;
20        tokens.extend(quote! {
21            write!(formatter, #fmt #args)
22        });
23    }
24}
25
26impl ToTokens for VariantDisplay {
27    fn to_tokens(&self, tokens: &mut TokenStream) {
28        if let Some(ref r#enum) = self.r#enum {
29            r#enum.to_tokens(tokens);
30            tokens.extend(quote! { ?; write!(formatter, ": ")?; });
31        }
32        self.variant.to_tokens(tokens);
33    }
34}
35
36pub(crate) struct AttrsHelper {
37    ignore_extra_doc_attributes: bool,
38    prefix_enum_doc_attributes: bool,
39}
40
41impl AttrsHelper {
42    pub(crate) fn new(attrs: &[Attribute]) -> Self {
43        let ignore_extra_doc_attributes = attrs
44            .iter()
45            .any(|attr| attr.path().is_ident("ignore_extra_doc_attributes"));
46        let prefix_enum_doc_attributes = attrs
47            .iter()
48            .any(|attr| attr.path().is_ident("prefix_enum_doc_attributes"));
49
50        Self {
51            ignore_extra_doc_attributes,
52            prefix_enum_doc_attributes,
53        }
54    }
55
56    pub(crate) fn display(&self, attrs: &[Attribute]) -> Result<Option<Display>> {
57        let displaydoc_attr = attrs.iter().find(|attr| attr.path().is_ident("displaydoc"));
58
59        if let Some(displaydoc_attr) = displaydoc_attr {
60            let lit = displaydoc_attr
61                .parse_args()
62                .expect("#[displaydoc(\"foo\")] must contain string arguments");
63            let mut display = Display {
64                fmt: lit,
65                args: TokenStream::new(),
66            };
67
68            display.expand_shorthand();
69            return Ok(Some(display));
70        }
71
72        let num_doc_attrs = attrs
73            .iter()
74            .filter(|attr| attr.path().is_ident("doc"))
75            .count();
76
77        if !self.ignore_extra_doc_attributes && num_doc_attrs > 1 {
78            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.");
79        }
80
81        for attr in attrs {
82            if attr.path().is_ident("doc") {
83                let lit = match &attr.meta {
84                    Meta::NameValue(syn::MetaNameValue {
85                        value:
86                            syn::Expr::Lit(syn::ExprLit {
87                                lit: syn::Lit::Str(lit),
88                                ..
89                            }),
90                        ..
91                    }) => lit,
92                    _ => unimplemented!(),
93                };
94
95                // Make an attempt at cleaning up multiline doc comments.
96                let doc_str = lit
97                    .value()
98                    .lines()
99                    .map(|line| line.trim().trim_start_matches('*').trim())
100                    .collect::<Vec<&str>>()
101                    .join("\n");
102
103                let lit = LitStr::new(doc_str.trim(), lit.span());
104
105                let mut display = Display {
106                    fmt: lit,
107                    args: TokenStream::new(),
108                };
109
110                display.expand_shorthand();
111                return Ok(Some(display));
112            }
113        }
114
115        Ok(None)
116    }
117
118    pub(crate) fn display_with_input(
119        &self,
120        r#enum: &[Attribute],
121        variant: &[Attribute],
122    ) -> Result<Option<VariantDisplay>> {
123        let r#enum = if self.prefix_enum_doc_attributes {
124            let result = self
125                .display(r#enum)?
126                .expect("Missing doc comment on enum with #[prefix_enum_doc_attributes]. Please remove the attribute or add a doc comment to the enum itself.");
127
128            Some(result)
129        } else {
130            None
131        };
132
133        Ok(self
134            .display(variant)?
135            .map(|variant| VariantDisplay { r#enum, variant }))
136    }
137}
displaydoc/attr.rs

displaydoc/
attr.rs
