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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175

use crate::ast;
use crate::shared::Description;
use crate::{Parse, ParseError, Parser, Peek, Peeker, Spanned, ToTokens, TokenStream};

/// Attribute like `#[derive(Debug)]`
#[derive(Debug, Clone, PartialEq, Eq, ToTokens, Spanned)]
pub struct Attribute {
    /// The `#` character
    pub hash: T![#],
    /// Specify if the attribute is outer `#!` or inner `#`
    pub style: AttrStyle,
    /// The `[` character
    pub open: T!['['],
    /// The path of the attribute
    pub path: ast::Path,
    /// The input to the input of the attribute
    #[rune(optional)]
    pub input: TokenStream,
    /// The `]` character
    pub close: T![']'],
}

/// Parsing an Attribute
///
/// # Examples
///
/// ```rust
/// use rune::{testing, ast};
///
/// testing::roundtrip::<ast::Attribute>("#[foo = \"foo\"]");
/// testing::roundtrip::<ast::Attribute>("#[foo()]");
/// testing::roundtrip::<ast::Attribute>("#![foo]");
/// testing::roundtrip::<ast::Attribute>("#![cfg(all(feature = \"potato\"))]");
/// testing::roundtrip::<ast::Attribute>("#[x+1]");
/// ```
impl Parse for Attribute {
    fn parse(p: &mut Parser<'_>) -> Result<Self, ParseError> {
        let hash = p.parse()?;
        let style = p.parse()?;
        let open = p.parse()?;
        let path = p.parse()?;

        let close;

        let mut level = 1;
        let mut input = TokenStream::new();

        loop {
            let token = p.next()?;

            match token.kind {
                K!['['] => level += 1,
                K![']'] => {
                    level -= 1;
                }
                _ => (),
            }

            if level == 0 {
                close = ast::CloseBracket { token };
                break;
            }

            input.push(token);
        }

        Ok(Attribute {
            hash,
            style,
            open,
            path,
            input,
            close,
        })
    }
}

impl Peek for Attribute {
    fn peek(p: &mut Peeker<'_>) -> bool {
        match (p.nth(0), p.nth(1)) {
            (K![#], K![!]) => true,
            (K![#], K!['[']) => true,
            _ => false,
        }
    }
}

impl Description for &Attribute {
    fn description(self) -> &'static str {
        match &self.style {
            AttrStyle::Inner => "inner attribute",
            AttrStyle::Outer(_) => "outer attribute",
        }
    }
}

/// Whether or not the attribute is an outer `#!` or inner `#` attribute
#[derive(Debug, Clone, Copy, PartialEq, Eq, ToTokens)]
pub enum AttrStyle {
    /// `#`
    Inner,
    /// `#!`
    Outer(T![!]),
}

impl Parse for AttrStyle {
    fn parse(p: &mut Parser) -> Result<Self, ParseError> {
        Ok(if p.peek::<T![!]>()? {
            Self::Outer(p.parse()?)
        } else {
            Self::Inner
        })
    }
}

/// Helper struct to only parse inner attributes.
pub(crate) struct InnerAttribute(pub(crate) Attribute);

impl Parse for InnerAttribute {
    fn parse(p: &mut Parser) -> Result<Self, ParseError> {
        let attribute: Attribute = p.parse()?;

        match attribute.style {
            AttrStyle::Inner => Ok(Self(attribute)),
            _ => Err(ParseError::expected(
                &attribute,
                "inner attribute like `#![allow(unused)]`",
            )),
        }
    }
}

/// Tag struct to assist peeking for an outer `#![...]` attributes at the top of
/// a module/file
pub struct OuterAttribute;

impl Peek for OuterAttribute {
    fn peek(p: &mut Peeker<'_>) -> bool {
        match (p.nth(0), p.nth(1)) {
            (K![#], K![!]) => true,
            _ => false,
        }
    }
}

#[test]
fn test_parse_attribute() {
    const TEST_STRINGS: &[&'static str] = &[
        "#[foo]",
        "#[a::b::c]",
        "#[foo = \"hello world\"]",
        "#[foo = 1]",
        "#[foo = 1.3]",
        "#[foo = true]",
        "#[foo = b\"bytes\"]",
        "#[foo = (1, 2, \"string\")]",
        "#[foo = #{\"a\": 1} ]",
        r#"#[foo = Fred {"a": 1} ]"#,
        r#"#[foo = a::Fred {"a": #{ "b": 2 } } ]"#,
        "#[bar()]",
        "#[bar(baz)]",
        "#[derive(Debug, PartialEq, PartialOrd)]",
        "#[tracing::instrument(skip(non_debug))]",
        "#[zanzibar(a = \"z\", both = false, sasquatch::herring)]",
        r#"#[doc = "multiline \
                  docs are neat"
          ]"#,
    ];

    for s in TEST_STRINGS.iter() {
        crate::parse_all::<ast::Attribute>(s).expect(s);
        let withbang = s.replacen("#[", "#![", 1);
        crate::parse_all::<ast::Attribute>(&withbang).expect(&withbang);
    }
}