swc_css_compat/compiler/
mod.rs

1use swc_common::{util::take::Take, Spanned, DUMMY_SP};
2use swc_css_ast::{
3    AbsoluteColorBase, AtRule, ComponentValue, CompoundSelector, MediaAnd, MediaCondition,
4    MediaConditionAllType, MediaConditionWithoutOr, MediaInParens, MediaQuery, Rule,
5    SupportsCondition,
6};
7use swc_css_visit::{VisitMut, VisitMutWith};
8
9use self::custom_media::CustomMediaHandler;
10use crate::feature::Features;
11
12mod color_alpha_parameter;
13mod color_hex_alpha;
14mod color_hwb;
15mod color_space_separated_parameters;
16mod custom_media;
17mod legacy_rgb_and_hsl;
18mod media_query_ranges;
19mod nesting;
20mod selector_not;
21
22/// Compiles a modern CSS file to a CSS file which works with old browsers.
23#[derive(Debug)]
24pub struct Compiler {
25    #[allow(unused)]
26    c: Config,
27    custom_media: CustomMediaHandler,
28    in_supports_condition: bool,
29}
30
31#[derive(Debug)]
32pub struct Config {
33    /// The list of features to **process**.
34    pub process: Features,
35}
36
37impl Compiler {
38    pub fn new(config: Config) -> Self {
39        Self {
40            c: config,
41            custom_media: Default::default(),
42            in_supports_condition: Default::default(),
43        }
44    }
45}
46
47impl VisitMut for Compiler {
48    fn visit_mut_at_rule(&mut self, n: &mut AtRule) {
49        n.visit_mut_children_with(self);
50
51        if self.c.process.contains(Features::CUSTOM_MEDIA) {
52            self.custom_media.store_custom_media(n);
53        }
54    }
55
56    fn visit_mut_supports_condition(&mut self, n: &mut SupportsCondition) {
57        let old_in_support_condition = self.in_supports_condition;
58
59        self.in_supports_condition = true;
60
61        n.visit_mut_children_with(self);
62
63        self.in_supports_condition = old_in_support_condition;
64    }
65
66    fn visit_mut_media_query(&mut self, n: &mut MediaQuery) {
67        n.visit_mut_children_with(self);
68
69        if self.c.process.contains(Features::CUSTOM_MEDIA) {
70            self.custom_media.process_media_query(n);
71        }
72    }
73
74    fn visit_mut_media_condition(&mut self, n: &mut MediaCondition) {
75        n.visit_mut_children_with(self);
76
77        if self.c.process.contains(Features::CUSTOM_MEDIA) {
78            self.custom_media.process_media_condition(n);
79        }
80    }
81
82    fn visit_mut_media_condition_without_or(&mut self, n: &mut MediaConditionWithoutOr) {
83        n.visit_mut_children_with(self);
84
85        if self.c.process.contains(Features::CUSTOM_MEDIA) {
86            self.custom_media.process_media_condition_without_or(n);
87        }
88    }
89
90    fn visit_mut_rules(&mut self, n: &mut Vec<Rule>) {
91        if self.c.process.contains(Features::NESTING) {
92            let mut new = Vec::new();
93
94            for n in n.take() {
95                match n {
96                    Rule::QualifiedRule(mut n) => {
97                        let mut rules = self.extract_nested_rules(&mut n);
98
99                        rules.visit_mut_with(self);
100
101                        new.push(Rule::QualifiedRule(n));
102                        new.extend(rules);
103                    }
104                    _ => {
105                        new.push(n);
106                    }
107                }
108            }
109
110            *n = new;
111        } else {
112            n.visit_mut_children_with(self);
113        }
114
115        if self.c.process.contains(Features::CUSTOM_MEDIA) {
116            self.custom_media.process_rules(n);
117        }
118    }
119
120    fn visit_mut_media_in_parens(&mut self, n: &mut MediaInParens) {
121        n.visit_mut_children_with(self);
122
123        if self.c.process.contains(Features::MEDIA_QUERY_RANGES) {
124            if let MediaInParens::Feature(media_feature) = n {
125                if let Some(legacy_media_feature) = self.get_legacy_media_feature(media_feature) {
126                    match legacy_media_feature {
127                        (legacy_media_feature, None) => {
128                            *media_feature = Box::new(legacy_media_feature);
129                        }
130                        (left, Some(right)) => {
131                            *n = MediaInParens::MediaCondition(MediaCondition {
132                                span: n.span(),
133                                conditions: vec![
134                                    MediaConditionAllType::MediaInParens(*Box::new(
135                                        MediaInParens::Feature(Box::new(left)),
136                                    )),
137                                    MediaConditionAllType::And(MediaAnd {
138                                        span: DUMMY_SP,
139                                        keyword: None,
140                                        condition: MediaInParens::Feature(Box::new(right)),
141                                    }),
142                                ],
143                            });
144                        }
145                    }
146                }
147            }
148        }
149    }
150
151    fn visit_mut_compound_selector(&mut self, n: &mut CompoundSelector) {
152        n.visit_mut_children_with(self);
153
154        if self.in_supports_condition {
155            return;
156        }
157
158        if self.c.process.contains(Features::SELECTOR_NOT) {
159            self.process_selector_not(n);
160        }
161    }
162
163    fn visit_mut_component_value(&mut self, n: &mut ComponentValue) {
164        n.visit_mut_children_with(self);
165
166        if self.in_supports_condition {
167            return;
168        }
169
170        if self.c.process.contains(Features::COLOR_HEX_ALPHA) {
171            self.process_color_hex_alpha(n);
172        }
173    }
174
175    fn visit_mut_absolute_color_base(&mut self, n: &mut AbsoluteColorBase) {
176        n.visit_mut_children_with(self);
177
178        if self.in_supports_condition {
179            return;
180        }
181
182        // TODO handle color functions in custom variables under the option
183        // TODO implement the `preserve` option to preserve the original color
184
185        let process = self.c.process;
186
187        if process.contains(Features::COLOR_SPACE_SEPARATED_PARAMETERS) {
188            self.process_color_space_separated_function_notation(n);
189        }
190
191        if process.contains(Features::COLOR_ALPHA_PARAMETER) {
192            self.process_color_alpha_parameter(n);
193        }
194
195        if process.contains(Features::COLOR_LEGACY_RGB_AND_HSL) {
196            self.process_rgb_and_hsl(n);
197        }
198
199        if process.contains(Features::COLOR_HWB) {
200            self.process_color_hwb(n);
201        }
202    }
203}
swc_css_compat/compiler/mod.rs

swc_css_compat/compiler/
mod.rs
