rune 0.14.2

The Rune Language, an embeddable dynamic programming language for Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

use crate::ast::prelude::*;

#[test]
#[cfg(not(miri))]
fn ast_parse() {
    rt::<ast::LitChar>("'a'");
    rt::<ast::LitChar>("'\\0'");
    rt::<ast::LitChar>("'\\n'");
    rt::<ast::LitChar>("'\\r'");
    rt::<ast::LitChar>("'\\''");
}

/// A character literal.
#[derive(Debug, TryClone, Clone, Copy, PartialEq, Eq, Spanned)]
#[try_clone(copy)]
#[non_exhaustive]
pub struct LitChar {
    /// The span corresponding to the literal.
    pub span: Span,
    /// The source of the literal character.
    #[rune(skip)]
    pub source: ast::CopySource<char>,
}

impl ToAst for LitChar {
    fn to_ast(span: Span, kind: ast::Kind) -> compile::Result<Self> {
        match kind {
            K![char(source)] => Ok(LitChar { span, source }),
            _ => Err(compile::Error::expected(
                ast::Token { span, kind },
                Self::into_expectation(),
            )),
        }
    }

    #[inline]
    fn matches(kind: &ast::Kind) -> bool {
        matches!(kind, K![char])
    }

    #[inline]
    fn into_expectation() -> Expectation {
        Expectation::Description("char")
    }
}

impl Parse for LitChar {
    fn parse(parser: &mut Parser<'_>) -> Result<Self> {
        let t = parser.next()?;
        Self::to_ast(t.span, t.kind)
    }
}

impl<'a> Resolve<'a> for LitChar {
    type Output = char;

    fn resolve(&self, cx: ResolveContext<'a>) -> Result<char> {
        let source_id = match self.source {
            ast::CopySource::Inline(c) => return Ok(c),
            ast::CopySource::Text(source_id) => source_id,
        };

        let span = self.span;

        let string = cx
            .sources
            .source(source_id, span.narrow(1u32))
            .ok_or_else(|| compile::Error::new(span, ErrorKind::BadSlice))?;

        let start = span.start.into_usize();

        let mut it = string
            .char_indices()
            .map(|(n, c)| (start + n, c))
            .peekable();

        let (start, c) = match it.next() {
            Some(c) => c,
            None => {
                return Err(compile::Error::new(span, ErrorKind::BadCharLiteral));
            }
        };

        let c = match c {
            '\\' => {
                let c = match ast::unescape::parse_char_escape(
                    &mut it,
                    ast::unescape::WithTemplate(false),
                    ast::unescape::WithLineCont(false),
                ) {
                    Ok(c) => c,
                    Err(kind) => {
                        let end = it
                            .next()
                            .map(|n| n.0)
                            .unwrap_or_else(|| span.end.into_usize());
                        return Err(compile::Error::new(Span::new(start, end), kind));
                    }
                };

                match c {
                    Some(c) => c,
                    None => {
                        let end = it
                            .next()
                            .map(|n| n.0)
                            .unwrap_or_else(|| span.end.into_usize());
                        return Err(compile::Error::new(
                            Span::new(start, end),
                            ErrorKind::BadCharLiteral,
                        ));
                    }
                }
            }
            c => c,
        };

        // Too many characters in literal.
        if it.next().is_some() {
            return Err(compile::Error::new(span, ErrorKind::BadCharLiteral));
        }

        Ok(c)
    }
}

impl ToTokens for LitChar {
    fn to_tokens(
        &self,
        _: &mut MacroContext<'_, '_, '_>,
        stream: &mut TokenStream,
    ) -> alloc::Result<()> {
        stream.push(ast::Token {
            span: self.span,
            kind: ast::Kind::Char(self.source),
        })
    }
}