[librsvg: 4/8] Add support for comma-separated lists of languages

[Marge Bot <marge-bot src gnome org>]

commit 5b918a72edd55d927d124159f95c27a8fb0c31b7
Author: Michael Howell <michael notriddle com>
Date:   Wed Oct 13 14:58:34 2021 -0700

    Add support for comma-separated lists of languages
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/606>

 src/css.rs                               | 27 ++++++++++++++++++---------
 src/element.rs                           |  5 +----
 tests/fixtures/reftests/xml-lang-css.svg |  2 +-
 3 files changed, 20 insertions(+), 14 deletions(-)
---
diff --git a/src/css.rs b/src/css.rs
index 3c9f1b97..417c1219 100644
--- a/src/css.rs
+++ b/src/css.rs
@@ -224,14 +224,16 @@ impl<'i> selectors::Parser<'i> for RuleParser {
     ) -> Result<NonTSPseudoClass, cssparser::ParseError<'i, Self::Error>> {
         match &*name {
             "lang" => {
-                let language_tag = {
-                    let language_tag = arguments.expect_ident_or_string()?.clone();
+                // Comma-separated lists of languages are a Selectors 4 feature,
+                // but a pretty stable one that hasn't changed in a long time.
+                let tags = arguments.parse_comma_separated(|arg| {
+                    let language_tag = arg.expect_ident_or_string()?.clone();
                     LanguageTag::from_str(&language_tag).map_err(|_| {
-                        
arguments.new_custom_error(selectors::parser::SelectorParseErrorKind::UnsupportedPseudoClassOrElement(language_tag))
-                    })?
-                };
+                        
arg.new_custom_error(selectors::parser::SelectorParseErrorKind::UnsupportedPseudoClassOrElement(language_tag))
+                    })
+                })?;
                 arguments.expect_exhausted()?;
-                Ok(NonTSPseudoClass::Lang(language_tag))
+                Ok(NonTSPseudoClass::Lang(tags))
             }
             _ => Err(arguments.new_custom_error(
                 selectors::parser::SelectorParseErrorKind::UnsupportedPseudoClassOrElement(name),
@@ -339,7 +341,7 @@ impl<'i> AtRuleParser<'i> for RuleParser {
 pub enum NonTSPseudoClass {
     Link,
     Visited,
-    Lang(LanguageTag),
+    Lang(Vec<LanguageTag>),
 }
 
 impl ToCss for NonTSPseudoClass {
@@ -350,7 +352,14 @@ impl ToCss for NonTSPseudoClass {
         match self {
             NonTSPseudoClass::Link => write!(dest, "link"),
             NonTSPseudoClass::Visited => write!(dest, "visited"),
-            NonTSPseudoClass::Lang(lang) => write!(dest, "lang(\"{}\")", lang),
+            NonTSPseudoClass::Lang(lang) => write!(
+                dest,
+                "lang(\"{}\")",
+                lang.iter()
+                    .map(ToString::to_string)
+                    .collect::<Vec<_>>()
+                    .join("\",\"")
+            ),
         }
     }
 }
@@ -549,7 +558,7 @@ impl selectors::Element for RsvgElement {
                 .0
                 .borrow_element()
                 .get_language()
-                .map_or(false, |e_lang| css_lang.matches(e_lang)),
+                .map_or(false, |e_lang| css_lang.iter().any(|l| l.matches(e_lang))),
         }
     }
 
diff --git a/src/element.rs b/src/element.rs
index 78215028..4eb8c1b4 100644
--- a/src/element.rs
+++ b/src/element.rs
@@ -208,10 +208,7 @@ impl<T: SetAttributes + Draw> ElementInner<T> {
                 self.language = Some(
                     LanguageTag::from_str(value)
                         .map_err(|e| {
-                            ValueErrorKind::parse_error(&format!(
-                                "invalid language tag: \"{}\"",
-                                e
-                            ))
+                            ValueErrorKind::parse_error(&format!("invalid language tag: \"{}\"", e))
                         })
                         .attribute(attr)?,
                 );
diff --git a/tests/fixtures/reftests/xml-lang-css.svg b/tests/fixtures/reftests/xml-lang-css.svg
index 67b6c8ee..9267fb42 100644
--- a/tests/fixtures/reftests/xml-lang-css.svg
+++ b/tests/fixtures/reftests/xml-lang-css.svg
@@ -3,7 +3,7 @@
     /* Elements should appear in red-green-blue-yellow order.
        The :lang(en) should match en-US. It will also match en-GB,
        but that gets overridden later. */
-    :lang(en) { fill: red }
+    :lang(en, cn) { fill: red }
     /* Languages should be inherited from their parent elements. */
     :lang(es) { fill: green }
     /* Child languages should override the parent ones. */