refactor(css/compat): Merge nesting into the compiler (#6686)

crates/swc_css_compat/src/compiler/mod.rs

@@ -1,4 +1,4 @@
-use swc_common::{Spanned, DUMMY_SP};
+use swc_common::{util::take::Take, Spanned, DUMMY_SP};
 use swc_css_ast::{
     AbsoluteColorBase, AtRule, ComponentValue, CompoundSelector, MediaAnd, MediaCondition,
     MediaConditionAllType, MediaConditionWithoutOr, MediaInParens, MediaQuery, Rule,
@@ -16,8 +16,8 @@ mod color_space_separated_parameters;
 mod custom_media;
 mod legacy_rgb_and_hsl;
 mod media_query_ranges;
+mod nesting;
 mod selector_not;
-mod utils;
 
 /// Compiles a modern CSS file to a CSS file which works with old browsers.
 #[derive(Debug)]
@@ -88,7 +88,29 @@ impl VisitMut for Compiler {
     }
 
     fn visit_mut_rules(&mut self, n: &mut Vec<Rule>) {
-        n.visit_mut_children_with(self);
+        if self.c.process.contains(Features::NESTING) {
+            let mut new = vec![];
+
+            for n in n.take() {
+                match n {
+                    Rule::QualifiedRule(mut n) => {
+                        let mut rules = self.extract_nested_rules(&mut n);
+
+                        rules.visit_mut_with(self);
+
+                        new.push(Rule::QualifiedRule(n));
+                        new.extend(rules);
+                    }
+                    _ => {
+                        new.push(n);
+                    }
+                }
+            }
+
+            *n = new;
+        } else {
+            n.visit_mut_children_with(self);
+        }
 
         if self.c.process.contains(Features::CUSTOM_MEDIA) {
             self.custom_media.process_rules(n);

crates/swc_css_compat/src/nesting.rs → crates/swc_css_compat/src/compiler/nesting.rs

@@ -2,15 +2,10 @@ use std::iter::once;
 
 use swc_common::{util::take::Take, DUMMY_SP};
 use swc_css_ast::*;
-use swc_css_visit::{VisitMut, VisitMutWith};
 
-pub fn nesting() -> impl VisitMut {
-    NestingHandler {}
-}
-
-struct NestingHandler {}
+use crate::compiler::Compiler;
 
-impl NestingHandler {
+impl Compiler {
     fn process_subclass_selectors(
         &mut self,
         prelude: &SelectorList,
@@ -225,7 +220,7 @@ impl NestingHandler {
         }
     }
 
-    fn extract_nested_rules(&mut self, rule: &mut QualifiedRule) -> Vec<Rule> {
+    pub(crate) fn extract_nested_rules(&mut self, rule: &mut QualifiedRule) -> Vec<Rule> {
         let mut nested_rules = vec![];
         let mut block_values = vec![];
 
@@ -262,7 +257,7 @@ impl NestingHandler {
                                         nested_of_media.extend(
                                             once(Rule::QualifiedRule(q))
                                                 .chain(rules.into_iter())
-                                                .map(rule_to_component_value),
+                                                .map(From::from),
                                         );
                                     }
 
@@ -308,54 +303,3 @@ impl NestingHandler {
         nested_rules
     }
 }
-
-impl VisitMut for NestingHandler {
-    fn visit_mut_rules(&mut self, n: &mut Vec<Rule>) {
-        let mut new = vec![];
-
-        for n in n.take() {
-            match n {
-                Rule::QualifiedRule(mut n) => {
-                    let mut rules = self.extract_nested_rules(&mut n);
-
-                    rules.visit_mut_with(self);
-
-                    new.push(Rule::QualifiedRule(n));
-                    new.extend(rules);
-                }
-                _ => {
-                    new.push(n);
-                }
-            }
-        }
-
-        *n = new;
-    }
-
-    fn visit_mut_component_values(&mut self, n: &mut Vec<ComponentValue>) {
-        let mut new = vec![];
-
-        for n in n.take() {
-            match n {
-                ComponentValue::QualifiedRule(mut n) => {
-                    let mut rules = self.extract_nested_rules(&mut n);
-
-                    rules.visit_mut_with(self);
-
-                    new.push(ComponentValue::QualifiedRule(n));
-                    new.extend(rules.into_iter().map(rule_to_component_value));
-                }
-
-                _ => {
-                    new.push(n);
-                }
-            }
-        }
-
-        *n = new;
-    }
-}
-
-fn rule_to_component_value(rule: Rule) -> ComponentValue {
-    rule.into()
-}

crates/swc_css_compat/src/lib.rs

@@ -5,4 +5,3 @@
 
 pub mod compiler;
 pub mod feature;
-pub mod nesting;

crates/swc_css_compat/tests/fixture.rs

@@ -16,7 +16,6 @@ use swc_css_codegen::{
 use swc_css_compat::{
     compiler::{Compiler, Config},
     feature::Features,
-    nesting::nesting,
 };
 use swc_css_parser::{parse_file, parser::ParserConfig};
 use swc_css_visit::VisitMutWith;
@@ -54,18 +53,17 @@ fn print_stylesheet(ss: &Stylesheet) -> String {
     s
 }
 
-fn test_nesting(input: PathBuf, suffix: Option<&str>) {
-    let parent = input.parent().unwrap();
-    let output = match suffix {
-        Some(suffix) => parent.join("output.".to_owned() + suffix + ".css"),
-        _ => parent.join("output.css"),
-    };
+#[testing::fixture("tests/nesting/**/*.css", exclude("expect.css"))]
+fn test_nesting(input: PathBuf) {
+    let output = input.with_extension("expect.css");
 
     testing::run_test(false, |cm, _| {
         let fm = cm.load_file(&input).unwrap();
         let mut ss = parse_stylesheet(&fm);
 
-        ss.visit_mut_with(&mut nesting());
+        ss.visit_mut_with(&mut Compiler::new(Config {
+            process: Features::NESTING,
+        }));
 
         let s = print_stylesheet(&ss);
 
@@ -76,11 +74,6 @@ fn test_nesting(input: PathBuf, suffix: Option<&str>) {
     .unwrap();
 }
 
-#[testing::fixture("tests/nesting/**/input.css")]
-fn test_nesting_without_env(input: PathBuf) {
-    test_nesting(input, None)
-}
-
 #[testing::fixture("tests/custom-media-query/**/*.css", exclude("expect.css"))]
 fn test_custom_media_query(input: PathBuf) {
     let output = input.with_extension("expect.css");

crates/swc_css_modules/tests/with_compat.rs

@@ -13,7 +13,10 @@ use swc_css_codegen::{
     writer::basic::{BasicCssWriter, BasicCssWriterConfig},
     CodegenConfig, Emit,
 };
-use swc_css_compat::nesting::nesting;
+use swc_css_compat::{
+    compiler::{Compiler, Config},
+    feature::Features,
+};
 use swc_css_parser::{parse_file, parser::ParserConfig};
 use swc_css_visit::VisitMutWith;
 use testing::NormalizedOutput;
@@ -48,8 +51,9 @@ fn test_full(input: PathBuf, suffix: Option<&str>) {
         }
 
         swc_css_modules::compile(&mut ss, TestConfig {});
-
-        ss.visit_mut_with(&mut nesting());
+        ss.visit_mut_with(&mut Compiler::new(Config {
+            process: Features::NESTING,
+        }));
 
         let mut s = String::new();
         {