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    ByteStringNotPermitted {
39        span_start: Option<Span>,
40        span_end: Option<Span>,
41    },
42    Custom {
43        message: Cow<'static, str>,
44        span_start: Option<Span>,
45        span_end: Option<Span>,
46    },
47}
48
49impl fmt::Display for Error {
50    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
51        match self {
52            Self::MissingComponent { name, .. } => write!(f, "missing component: {name}"),
53            Self::InvalidComponent { name, value, .. } => {
54                write!(f, "invalid component: {name} was {value}")
55            }
56            #[cfg(any(feature = "formatting", feature = "parsing"))]
57            Self::ExpectedString { .. } => f.write_str("expected string literal"),
58            Self::UnexpectedToken { tree } => write!(f, "unexpected token: {tree}"),
59            Self::UnexpectedEndOfInput => f.write_str("unexpected end of input"),
60            Self::ByteStringNotPermitted { .. } => f.write_str("byte strings are not permitted"),
61            Self::Custom { message, .. } => f.write_str(message),
62        }
63    }
64}
65
66impl Error {
67    fn span_start(&self) -> Span {
68        match self {
69            Self::MissingComponent { span_start, .. }
70            | Self::InvalidComponent { span_start, .. }
71            | Self::ByteStringNotPermitted { span_start, .. }
72            | Self::Custom { span_start, .. } => *span_start,
73            #[cfg(any(feature = "formatting", feature = "parsing"))]
74            Self::ExpectedString { span_start, .. } => *span_start,
75            Self::UnexpectedToken { tree } => Some(tree.span()),
76            Self::UnexpectedEndOfInput => Some(Span::mixed_site()),
77        }
78        .unwrap_or_else(Span::mixed_site)
79    }
80
81    fn span_end(&self) -> Span {
82        match self {
83            Self::MissingComponent { span_end, .. }
84            | Self::InvalidComponent { span_end, .. }
85            | Self::ByteStringNotPermitted { span_end, .. }
86            | Self::Custom { span_end, .. } => *span_end,
87            #[cfg(any(feature = "formatting", feature = "parsing"))]
88            Self::ExpectedString { span_end, .. } => *span_end,
89            Self::UnexpectedToken { tree, .. } => Some(tree.span()),
90            Self::UnexpectedEndOfInput => Some(Span::mixed_site()),
91        }
92        .unwrap_or_else(|| self.span_start())
93    }
94
95    pub(crate) fn to_compile_error(&self) -> TokenStream {
96        let (start, end) = (self.span_start(), self.span_end());
97
98        [
99            TokenTree::from(Punct::new(':', Spacing::Joint)).with_span(start),
100            TokenTree::from(Punct::new(':', Spacing::Alone)).with_span(start),
101            TokenTree::from(Ident::new("core", start)),
102            TokenTree::from(Punct::new(':', Spacing::Joint)).with_span(start),
103            TokenTree::from(Punct::new(':', Spacing::Alone)).with_span(start),
104            TokenTree::from(Ident::new("compile_error", start)),
105            TokenTree::from(Punct::new('!', Spacing::Alone)).with_span(start),
106            TokenTree::from(Group::new(
107                Delimiter::Parenthesis,
108                TokenStream::from(
109                    TokenTree::from(Literal::string(&self.to_string())).with_span(end),
110                ),
111            ))
112            .with_span(end),
113        ]
114        .iter()
115        .cloned()
116        .collect()
117    }
118
119    /// Like `to_compile_error`, but for use in macros that produce items.
120    #[cfg(all(feature = "serde", any(feature = "formatting", feature = "parsing")))]
121    pub(crate) fn to_compile_error_standalone(&self) -> TokenStream {
122        let end = self.span_end();
123        self.to_compile_error()
124            .into_iter()
125            .chain(std::iter::once(
126                TokenTree::from(Punct::new(';', Spacing::Alone)).with_span(end),
127            ))
128            .collect()
129    }
130}
time_macros/error.rs

time_macros/
error.rs
