oxc_css_parser/parser/at_rule/
import.rs

1use super::Parser;
2use crate::{
3    Parse, Syntax,
4    ast::*,
5    error::{Error, ErrorKind, PResult},
6    pos::Span,
7    tokenizer::{Token, TokenWithSpan},
8};
9
10// https://www.w3.org/TR/css-cascade-5/#at-import
11//
12// @import [ <url> | <string> ]
13//         [ layer | layer( <layer-name> ) ]?
14//         <import-conditions> ;
15// <import-conditions> = [ supports( [ <supports-condition> | <declaration> ] ) ]?
16//                       <media-query-list>?
17impl<'a> Parse<'a> for ImportPrelude<'a> {
18    fn parse(input: &mut Parser<'a>) -> PResult<Self> {
19        // The indented syntax accepts an unquoted path (`@import other.css`),
20        // but an ident glued to `(` is a function href
21        // (`@import url("theme.css")`), which the `Url::parse` arm handles.
22        let sass_unquoted_path = input.syntax == Syntax::Sass
23            && matches!(input.cursor.peek()?, TokenWithSpan { token: Token::Ident(..), span }
24                if input.source.as_bytes().get(span.end) != Some(&b'('));
25        let href = match &input.cursor.peek()?.token {
26            Token::Str(..) | Token::StrTemplate(..) => input.parse().map(ImportPreludeHref::Str)?,
27            Token::Ident(..) if sass_unquoted_path => {
28                let start = input.cursor.peek()?.span.start;
29                let mut end = start;
30                while matches!(
31                    &input.cursor.peek()?.token,
32                    Token::Ident(..) | Token::Dot(..) | Token::Minus(..) | Token::Solidus(..)
33                ) && input.cursor.peek()?.span.start == end
34                {
35                    end = input.cursor.bump()?.span.end;
36                }
37                let raw = unsafe { input.source.get_unchecked(start..end) };
38                let span = Span { start, end };
39                ImportPreludeHref::Str(InterpolableStr::Literal(Str { value: raw, raw, span }))
40            }
41            _ => match input.try_parse(Url::parse) {
42                Ok(url) => ImportPreludeHref::Url(url),
43                // Sass only: the content of `url(...)` may be SassScript that
44                // is not a parsable URL, e.g. `@import url($dir+"/path");`.
45                // Mirrors the fallback in `parse_component_value_atom`.
46                Err(error) if matches!(input.syntax, Syntax::Scss | Syntax::Sass) => {
47                    let (function_name, function_name_span) = input.cursor.expect_ident()?;
48                    let function_name = input.ident(function_name, function_name_span);
49                    if !function_name.name.eq_ignore_ascii_case("url") {
50                        return Err(error);
51                    }
52                    input
53                        .parse_function(InterpolableIdent::Literal(function_name))
54                        .map(ImportPreludeHref::Function)
55                        .map_err(|_| error)?
56                }
57                Err(error) => return Err(error),
58            },
59        };
60        let mut span = href.span().clone();
61
62        let structured = input.try_parse(Self::parse_structured_tail);
63        let (layer, supports, media, modifiers) = match structured {
64            Ok((layer, supports, media)) => (layer, supports, media, None),
65            // Reference compilers accept arbitrary import modifiers (idents,
66            // unknown functions, media-ish parens, further comma-chained
67            // imports); keep the whole tail as raw component values.
68            // NOTE: Scss/Sass multi-path imports (`@import 'a', 'b';`) never
69            // get here — the at-rule dispatch claims them as
70            // `SassImportPrelude` before trying `ImportPrelude`.
71            Err(_) => {
72                let start = input.cursor.peek()?.span.start;
73                let values = input.parse_declaration_value_tokens(true)?;
74                // A trailing comma has no import after it — reference
75                // compilers reject that, so don't paper over it.
76                if let Some(ComponentValue::TokenWithSpan(TokenWithSpan {
77                    token: Token::Comma(..),
78                    span,
79                })) = values.last()
80                {
81                    return Err(Error { kind: ErrorKind::ExpectRule, span: span.clone() });
82                }
83                let end = values.last().map_or(start, |value| value.span().end);
84                (None, None, None, Some(ComponentValues { values, span: Span { start, end } }))
85            }
86        };
87        if let Some(layer) = &layer {
88            span.end = layer.span().end;
89        }
90        if let Some(supports) = &supports {
91            span.end = supports.span().end;
92        }
93        if let Some(media) = &media {
94            span.end = media.span.end;
95        }
96        if let Some(modifiers) = &modifiers
97            && modifiers.span.end > modifiers.span.start
98        {
99            span.end = modifiers.span.end;
100        }
101
102        Ok(ImportPrelude { href, layer, supports, media, modifiers, span })
103    }
104}
105
106impl<'a> ImportPrelude<'a> {
107    /// The standard post-URL grammar: optional `layer`/`layer(...)`, optional
108    /// `supports(...)`, optional media query list — valid only if it accounts
109    /// for everything up to the end of the statement.
110    #[allow(clippy::type_complexity)]
111    fn parse_structured_tail(
112        input: &mut Parser<'a>,
113    ) -> PResult<(
114        Option<ImportPreludeLayer<'a>>,
115        Option<ImportPreludeSupports<'a>>,
116        Option<MediaQueryList<'a>>,
117    )> {
118        let layer = match &input.cursor.peek()?.token {
119            Token::Ident(ident) if ident.name().eq_ignore_ascii_case("layer") => {
120                let ident = input.parse::<Ident>()?;
121                let layer = match input.cursor.peek()? {
122                    TokenWithSpan { token: Token::LParen(..), span }
123                        if span.start == ident.span.end =>
124                    {
125                        input.cursor.bump()?;
126                        let layer_name = input.parse().map(ComponentValue::LayerName)?;
127                        let args = input.vec1(layer_name);
128                        let end = input.cursor.expect_r_paren()?.1.end;
129                        let span = Span { start: ident.span.start, end };
130                        ImportPreludeLayer::WithName(Function {
131                            name: FunctionName::Ident(InterpolableIdent::Literal(ident)),
132                            args,
133                            span,
134                        })
135                    }
136                    _ => ImportPreludeLayer::Empty(ident),
137                };
138                Some(layer)
139            }
140            _ => None,
141        };
142
143        let supports = input.try_parse(|parser| {
144            // (kept as its own try so a non-`supports` ident rolls back)
145            let (ident, span) = parser.cursor.expect_ident()?;
146            if !ident.name().eq_ignore_ascii_case("supports") {
147                return Err(Error { kind: ErrorKind::TryParseError, span });
148            }
149
150            parser.cursor.expect_l_paren_without_ws_or_comments()?;
151
152            let kind = if let Ok(supports_condition) = parser.try_parse(SupportsCondition::parse) {
153                ImportPreludeSupportsKind::SupportsCondition(supports_condition)
154            } else {
155                parser.parse().map(ImportPreludeSupportsKind::Declaration)?
156            };
157            let (_, Span { end, .. }) = parser.cursor.expect_r_paren()?;
158            Ok(ImportPreludeSupports { kind, span: Span { start: span.start, end } })
159        });
160        // `}` ends the at-rule too, so an `@import` nested in a style rule needs no
161        // trailing `;` (`a { @import "b.css" }`); it can't start a media query.
162        let media = if at_import_prelude_end(&input.cursor.peek()?.token) {
163            None
164        } else {
165            Some(input.parse::<MediaQueryList>()?)
166        };
167
168        // Anything left over means this tail isn't the standard grammar.
169        if at_import_prelude_end(&input.cursor.peek()?.token) {
170            Ok((layer, supports.ok(), media))
171        } else {
172            let span = input.cursor.peek()?.span.clone();
173            Err(Error { kind: ErrorKind::TryParseError, span })
174        }
175    }
176}
177
178/// End of an `@import` prelude: the statement boundary tokens.
179fn at_import_prelude_end(token: &Token) -> bool {
180    matches!(
181        token,
182        Token::Semicolon(..)
183            | Token::Eof(..)
184            | Token::RBrace(..)
185            | Token::Dedent(..)
186            | Token::Linebreak(..)
187    )
188}
oxc_css_parser/parser/at_rule/import.rs

oxc_css_parser/parser/at_rule/
import.rs
