time_macros/
error.rs

1use std::borrow::Cow;
2use std::fmt;
3
4use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
5
6trait WithSpan {
7    fn with_span(self, span: Span) -> Self;
8}
9
10impl WithSpan for TokenTree {
11    fn with_span(mut self, span: Span) -> Self {
12        self.set_span(span);
13        self
14    }
15}
16
17pub(crate) enum Error {
18    MissingComponent {
19        name: &'static str,
20        span_start: Option<Span>,
21        span_end: Option<Span>,
22    },
23    InvalidComponent {
24        name: &'static str,
25        value: String,
26        span_start: Option<Span>,
27        span_end: Option<Span>,
28    },
29    #[cfg(any(feature = "formatting", feature = "parsing"))]
30    ExpectedString {
31        span_start: Option<Span>,
32        span_end: Option<Span>,
33    },
34    UnexpectedToken {
35        tree: TokenTree,
36    },
37    UnexpectedEndOfInput,
38    Custom {
39        message: Cow<'static, str>,
40        span_start: Option<Span>,
41        span_end: Option<Span>,
42    },
43}
44
45impl fmt::Display for Error {
46    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
47        match self {
48            Self::MissingComponent { name, .. } => write!(f, "missing component: {name}"),
49            Self::InvalidComponent { name, value, .. } => {
50                write!(f, "invalid component: {name} was {value}")
51            }
52            #[cfg(any(feature = "formatting", feature = "parsing"))]
53            Self::ExpectedString { .. } => f.write_str("expected string literal"),
54            Self::UnexpectedToken { tree } => write!(f, "unexpected token: {tree}"),
55            Self::UnexpectedEndOfInput => f.write_str("unexpected end of input"),
56            Self::Custom { message, .. } => f.write_str(message),
57        }
58    }
59}
60
61impl Error {
62    fn span_start(&self) -> Span {
63        match self {
64            Self::MissingComponent { span_start, .. }
65            | Self::InvalidComponent { span_start, .. }
66            | Self::Custom { span_start, .. } => *span_start,
67            #[cfg(any(feature = "formatting", feature = "parsing"))]
68            Self::ExpectedString { span_start, .. } => *span_start,
69            Self::UnexpectedToken { tree } => Some(tree.span()),
70            Self::UnexpectedEndOfInput => Some(Span::mixed_site()),
71        }
72        .unwrap_or_else(Span::mixed_site)
73    }
74
75    fn span_end(&self) -> Span {
76        match self {
77            Self::MissingComponent { span_end, .. }
78            | Self::InvalidComponent { span_end, .. }
79            | Self::Custom { span_end, .. } => *span_end,
80            #[cfg(any(feature = "formatting", feature = "parsing"))]
81            Self::ExpectedString { span_end, .. } => *span_end,
82            Self::UnexpectedToken { tree, .. } => Some(tree.span()),
83            Self::UnexpectedEndOfInput => Some(Span::mixed_site()),
84        }
85        .unwrap_or_else(|| self.span_start())
86    }
87
88    pub(crate) fn to_compile_error(&self) -> TokenStream {
89        let (start, end) = (self.span_start(), self.span_end());
90
91        [
92            TokenTree::from(Punct::new(':', Spacing::Joint)).with_span(start),
93            TokenTree::from(Punct::new(':', Spacing::Alone)).with_span(start),
94            TokenTree::from(Ident::new("core", start)),
95            TokenTree::from(Punct::new(':', Spacing::Joint)).with_span(start),
96            TokenTree::from(Punct::new(':', Spacing::Alone)).with_span(start),
97            TokenTree::from(Ident::new("compile_error", start)),
98            TokenTree::from(Punct::new('!', Spacing::Alone)).with_span(start),
99            TokenTree::from(Group::new(
100                Delimiter::Parenthesis,
101                TokenStream::from(
102                    TokenTree::from(Literal::string(&self.to_string())).with_span(end),
103                ),
104            ))
105            .with_span(end),
106        ]
107        .iter()
108        .cloned()
109        .collect()
110    }
111
112    /// Like `to_compile_error`, but for use in macros that produce items.
113    #[cfg(all(feature = "serde", any(feature = "formatting", feature = "parsing")))]
114    pub(crate) fn to_compile_error_standalone(&self) -> TokenStream {
115        let end = self.span_end();
116        self.to_compile_error()
117            .into_iter()
118            .chain(std::iter::once(
119                TokenTree::from(Punct::new(';', Spacing::Alone)).with_span(end),
120            ))
121            .collect()
122    }
123}
time_macros/error.rs

time_macros/
error.rs
