Implement vendor prefixing for @supports

Fixes #341

src/lib.rs

@@ -10339,6 +10339,47 @@ mod tests {
       }
     "#},
     );
+    prefix_test(
+      r#"
+      @supports (backdrop-filter: blur(10px)) {
+        div {
+          backdrop-filter: blur(10px);
+        }
+      }
+    "#,
+      indoc! { r#"
+      @supports ((-webkit-backdrop-filter: blur(10px)) or (backdrop-filter: blur(10px))) {
+        div {
+          -webkit-backdrop-filter: blur(10px);
+          backdrop-filter: blur(10px);
+        }
+      }
+    "#},
+      Browsers {
+        safari: Some(14 << 16),
+        ..Default::default()
+      },
+    );
+    minify_test(
+      r#"
+      @supports (width: calc(10px * 2)) {
+        .test {
+          width: calc(10px * 2);
+        }
+      }
+    "#,
+      "@supports (width:calc(10px * 2)){.test{width:20px}}",
+    );
+    minify_test(
+      r#"
+      @supports (color: hsl(0deg, 0%, 0%)) {
+        .test {
+          color: hsl(0deg, 0%, 0%);
+        }
+      }
+    "#,
+      "@supports (color:hsl(0deg, 0%, 0%)){.test{color:#000}}",
+    );
   }
 
   #[test]
@@ -10490,19 +10531,19 @@ mod tests {
     );
     minify_test(
       "@import url(foo.css) supports(display: flex);",
-      "@import \"foo.css\" supports(display: flex);",
+      "@import \"foo.css\" supports(display:flex);",
     );
     minify_test(
       "@import url(foo.css) supports(display: flex) print;",
-      "@import \"foo.css\" supports(display: flex) print;",
+      "@import \"foo.css\" supports(display:flex) print;",
     );
     minify_test(
       "@import url(foo.css) supports(not (display: flex));",
-      "@import \"foo.css\" supports(not (display: flex));",
+      "@import \"foo.css\" supports(not (display:flex));",
     );
     minify_test(
       "@import url(foo.css) supports((display: flex));",
-      "@import \"foo.css\" supports(display: flex);",
+      "@import \"foo.css\" supports(display:flex);",
     );
     minify_test("@charset \"UTF-8\"; @import url(foo.css);", "@import \"foo.css\";");
     minify_test("@layer foo; @import url(foo.css);", "@layer foo;@import \"foo.css\";");

src/properties/mod.rs

@@ -267,28 +267,6 @@ macro_rules! define_properties {
 
     impl<'i> ToCss for PropertyId<'i> {
       fn to_css<W>(&self, dest: &mut Printer<W>) -> Result<(), PrinterError> where W: std::fmt::Write {
-        use PropertyId::*;
-
-        let (name, prefix) = match self {
-          $(
-            $(#[$meta])*
-            $property$((vp_name!($vp, prefix)))? => {
-              macro_rules! get_prefix {
-                ($v: ty) => {
-                  *prefix
-                };
-                () => {
-                  VendorPrefix::None
-                };
-              }
-
-              ($name, get_prefix!($($vp)?))
-            },
-          )+
-          All => ("all", VendorPrefix::None),
-          Custom(name) => (name.as_ref(), VendorPrefix::None),
-        };
-
         let mut first = true;
         macro_rules! delim {
           () => {
@@ -301,27 +279,20 @@ macro_rules! define_properties {
           };
         }
 
-        macro_rules! write {
-          ($p: expr) => {
-            if prefix.contains($p) {
-              delim!();
-              $p.to_css(dest)?;
-              dest.write_str(name)?;
-            }
-          };
+        let name = self.name();
+        for p in self.prefix().or_none() {
+          delim!();
+          p.to_css(dest)?;
+          dest.write_str(name)?;
         }
 
-        write!(VendorPrefix::WebKit);
-        write!(VendorPrefix::Moz);
-        write!(VendorPrefix::Ms);
-        write!(VendorPrefix::O);
-        write!(VendorPrefix::None);
         Ok(())
       }
     }
 
     impl<'i> PropertyId<'i> {
-      fn prefix(&self) -> VendorPrefix {
+      /// Returns the vendor prefix for this property id.
+      pub fn prefix(&self) -> VendorPrefix {
         use PropertyId::*;
         match self {
           $(
@@ -366,7 +337,7 @@ macro_rules! define_properties {
         }
       }
 
-      fn set_prefixes_for_targets(&mut self, targets: Option<Browsers>) {
+      pub(crate) fn set_prefixes_for_targets(&mut self, targets: Browsers) {
         match self {
           $(
             $(#[$meta])*
@@ -376,9 +347,7 @@ macro_rules! define_properties {
                 ($v: ty, $u: literal) => {};
                 ($v: ty) => {{
                   if prefix.contains(VendorPrefix::None) {
-                    if let Some(targets) = targets {
-                      *prefix = Feature::$property.prefixes_for(targets);
-                    }
+                    *prefix = Feature::$property.prefixes_for(targets);
                   };
                 }};
                 () => {};
@@ -677,25 +646,14 @@ macro_rules! define_properties {
             return Ok(())
           }
         };
-
-        macro_rules! write {
-          ($p: expr) => {
-            if prefix.contains($p) {
-              start!();
-              $p.to_css(dest)?;
-              dest.write_str(name)?;
-              dest.delim(':', false)?;
-              self.value_to_css(dest)?;
-              write_important!();
-            }
-          }
+        for p in prefix {
+          start!();
+          p.to_css(dest)?;
+          dest.write_str(name)?;
+          dest.delim(':', false)?;
+          self.value_to_css(dest)?;
+          write_important!();
         }
-
-        write!(VendorPrefix::WebKit);
-        write!(VendorPrefix::Moz);
-        write!(VendorPrefix::Ms);
-        write!(VendorPrefix::O);
-        write!(VendorPrefix::None);
         Ok(())
       }
 

src/properties/transition.rs

@@ -267,16 +267,10 @@ impl<'i> TransitionHandler<'i> {
               };
 
               // Expand vendor prefixes into multiple transitions.
-              let prefix = property_id.prefix();
-              let mut b = 1 << (7 - prefix.bits().leading_zeros());
-              while b != 0 {
-                let p = VendorPrefix::from_bits_truncate(b);
-                if prefix.contains(p) {
-                  let mut t = transition.clone();
-                  t.property = property_id.with_prefix(p);
-                  transitions.push(t);
-                }
-                b >>= 1;
+              for p in property_id.prefix().or_none() {
+                let mut t = transition.clone();
+                t.property = property_id.with_prefix(p);
+                transitions.push(t);
               }
             }
             transitions
@@ -398,7 +392,9 @@ fn expand_properties<'i>(
       }
       _ => {
         // Expand vendor prefixes for targets.
-        properties[i].set_prefixes_for_targets(targets);
+        if let Some(targets) = targets {
+          properties[i].set_prefixes_for_targets(targets);
+        }
 
         // Expand mask properties, which use different vendor-prefixed names.
         if let (Some(targets), Some(property_id)) = (targets, get_webkit_mask_property(&properties[i])) {
@@ -409,7 +405,9 @@ fn expand_properties<'i>(
         }
 
         if let Some(rtl_properties) = &mut rtl_properties {
-          rtl_properties[i].set_prefixes_for_targets(targets);
+          if let Some(targets) = targets {
+            rtl_properties[i].set_prefixes_for_targets(targets);
+          }
 
           if let (Some(targets), Some(property_id)) = (targets, get_webkit_mask_property(&rtl_properties[i])) {
             if Feature::MaskBorder.prefixes_for(targets).contains(VendorPrefix::WebKit) {

src/rules/import.rs

@@ -68,7 +68,7 @@ impl<'i> ToCss for ImportRule<'i> {
       dest.write_str(" supports")?;
       if matches!(
         supports,
-        SupportsCondition::Declaration(_) | SupportsCondition::Parens(_)
+        SupportsCondition::Declaration { .. } | SupportsCondition::Parens(_)
       ) {
         supports.to_css(dest)?;
       } else {

src/rules/supports.rs

@@ -5,9 +5,12 @@ use super::{CssRuleList, MinifyContext};
 use crate::error::{MinifyError, ParserError, PrinterError};
 use crate::parser::DefaultAtRule;
 use crate::printer::Printer;
+use crate::properties::PropertyId;
 use crate::rules::{StyleContext, ToCssWithContext};
+use crate::targets::Browsers;
 use crate::traits::{Parse, ToCss};
 use crate::values::string::CowArcStr;
+use crate::vendor_prefix::VendorPrefix;
 use crate::visitor::Visit;
 use cssparser::*;
 
@@ -31,6 +34,10 @@ impl<'i, T> SupportsRule<'i, T> {
     context: &mut MinifyContext<'_, 'i>,
     parent_is_unused: bool,
   ) -> Result<(), MinifyError> {
+    if let Some(targets) = context.targets {
+      self.condition.set_prefixes_for_targets(targets)
+    }
+
     self.rules.minify(context, parent_is_unused)
   }
 }
@@ -78,8 +85,13 @@ pub enum SupportsCondition<'i> {
   #[skip_type]
   Or(Vec<SupportsCondition<'i>>),
   /// A declaration to evaluate.
-  #[cfg_attr(feature = "serde", serde(borrow))]
-  Declaration(CowArcStr<'i>),
+  Declaration {
+    /// The property id for the declaration.
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    property_id: PropertyId<'i>,
+    /// The raw value of the declaration.
+    value: CowArcStr<'i>,
+  },
   /// A selector to evaluate.
   Selector(CowArcStr<'i>),
   // FontTechnology()
@@ -112,6 +124,24 @@ impl<'i> SupportsCondition<'i> {
       *self = SupportsCondition::Parens(Box::new(SupportsCondition::Or(vec![self.clone(), b.clone()])))
     }
   }
+
+  fn set_prefixes_for_targets(&mut self, targets: &Browsers) {
+    match self {
+      SupportsCondition::Not(cond) | SupportsCondition::Parens(cond) => cond.set_prefixes_for_targets(targets),
+      SupportsCondition::And(items) | SupportsCondition::Or(items) => {
+        for item in items {
+          item.set_prefixes_for_targets(targets);
+        }
+      }
+      SupportsCondition::Declaration { property_id, .. } => {
+        let prefix = property_id.prefix();
+        if prefix.is_empty() || prefix.contains(VendorPrefix::None) {
+          property_id.set_prefixes_for_targets(*targets);
+        }
+      }
+      _ => {}
+    }
+  }
 }
 
 impl<'i> Parse<'i> for SupportsCondition<'i> {
@@ -213,11 +243,15 @@ impl<'i> SupportsCondition<'i> {
   pub(crate) fn parse_declaration<'t>(
     input: &mut Parser<'i, 't>,
   ) -> Result<Self, ParseError<'i, ParserError<'i>>> {
-    let pos = input.position();
-    input.expect_ident()?;
+    let property_id = PropertyId::parse(input)?;
     input.expect_colon()?;
+    input.skip_whitespace();
+    let pos = input.position();
     input.expect_no_error_token()?;
-    Ok(SupportsCondition::Declaration(input.slice_from(pos).into()))
+    Ok(SupportsCondition::Declaration {
+      property_id,
+      value: input.slice_from(pos).into(),
+    })
   }
 }
 
@@ -260,9 +294,33 @@ impl<'i> ToCss for SupportsCondition<'i> {
         condition.to_css(dest)?;
         dest.write_char(')')
       }
-      SupportsCondition::Declaration(decl) => {
+      SupportsCondition::Declaration { property_id, value } => {
         dest.write_char('(')?;
-        dest.write_str(&decl)?;
+
+        let prefix = property_id.prefix().or_none();
+        if prefix != VendorPrefix::None {
+          dest.write_char('(')?;
+        }
+
+        let name = property_id.name();
+        let mut first = true;
+        for p in prefix {
+          if first {
+            first = false;
+          } else {
+            dest.write_str(") or (")?;
+          }
+
+          p.to_css(dest)?;
+          serialize_name(name, dest)?;
+          dest.delim(':', false)?;
+          dest.write_str(value)?;
+        }
+
+        if prefix != VendorPrefix::None {
+          dest.write_char(')')?;
+        }
+
         dest.write_char(')')
       }
       SupportsCondition::Selector(sel) => {

src/values/color.rs

@@ -10,6 +10,7 @@ use crate::compat::Feature;
 use crate::error::{ParserError, PrinterError};
 use crate::macros::enum_property;
 use crate::printer::Printer;
+use crate::properties::PropertyId;
 use crate::rules::supports::SupportsCondition;
 use crate::targets::Browsers;
 use crate::traits::{FallbackValues, Parse, ToCss};
@@ -194,12 +195,15 @@ impl ColorFallbackKind {
 
   pub(crate) fn supports_condition<'i>(&self) -> SupportsCondition<'i> {
     let s = match *self {
-      ColorFallbackKind::P3 => "color: color(display-p3 0 0 0)",
-      ColorFallbackKind::LAB => "color: lab(0% 0 0)",
+      ColorFallbackKind::P3 => "color(display-p3 0 0 0)",
+      ColorFallbackKind::LAB => "lab(0% 0 0)",
       _ => unreachable!(),
     };
 
-    SupportsCondition::Declaration(s.into())
+    SupportsCondition::Declaration {
+      property_id: PropertyId::Color,
+      value: s.into(),
+    }
   }
 }