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

use crate::priv_prelude::*;

#[derive(Clone, Debug)]
pub struct ItemUse {
    pub visibility: Option<PubToken>,
    pub use_token: UseToken,
    pub root_import: Option<DoubleColonToken>,
    pub tree: UseTree,
    pub semicolon_token: SemicolonToken,
}

impl Spanned for ItemUse {
    fn span(&self) -> Span {
        let start = match &self.visibility {
            Some(pub_token) => pub_token.span(),
            None => self.use_token.span(),
        };
        let end = self.semicolon_token.span();
        Span::join(start, end)
    }
}

#[derive(Clone, Debug)]
pub enum UseTree {
    Group {
        imports: Braces<Punctuated<UseTree, CommaToken>>,
    },
    Name {
        name: Ident,
    },
    Rename {
        name: Ident,
        as_token: AsToken,
        alias: Ident,
    },
    Glob {
        star_token: StarToken,
    },
    Path {
        prefix: Ident,
        double_colon_token: DoubleColonToken,
        suffix: Box<UseTree>,
    },
}

impl Parse for UseTree {
    fn parse(parser: &mut Parser) -> ParseResult<UseTree> {
        if let Some(imports) = Braces::try_parse(parser)? {
            return Ok(UseTree::Group { imports });
        }
        if let Some(star_token) = parser.take() {
            return Ok(UseTree::Glob { star_token });
        }
        let name = match parser.take() {
            Some(name) => name,
            None => return Err(parser.emit_error(ParseErrorKind::ExpectedImportNameGroupOrGlob)),
        };
        if let Some(as_token) = parser.take() {
            let alias = parser.parse()?;
            return Ok(UseTree::Rename {
                name,
                as_token,
                alias,
            });
        }
        if let Some(double_colon_token) = parser.take() {
            let suffix = parser.parse()?;
            return Ok(UseTree::Path {
                prefix: name,
                double_colon_token,
                suffix,
            });
        }
        Ok(UseTree::Name { name })
    }
}

impl Parse for ItemUse {
    fn parse(parser: &mut Parser) -> ParseResult<ItemUse> {
        let visibility = parser.take();
        let use_token = parser.parse()?;
        let root_import = parser.take();
        let tree = parser.parse()?;
        let semicolon_token = parser.parse()?;
        Ok(ItemUse {
            visibility,
            use_token,
            root_import,
            tree,
            semicolon_token,
        })
    }
}