fix: allow CSS custom properties with no value

rdeltour · rdeltour · commit d60da300263b · 2024-12-23T11:11:09.000+01:00
Fix the built-in CSS parser to allow custom properties with empty values, as this is valid CSS. See https://www.w3.org/TR/css-variables/#guaranteed-invalid Fixes #1538
diff --git a/src/main/java/org/idpf/epubcheck/util/css/CssParser.java b/src/main/java/org/idpf/epubcheck/util/css/CssParser.java
@@ -373,7 +373,7 @@ private CssDeclaration handleDeclaration(CssToken name, CssTokenIterator iter,
         CssToken value = iter.next();
         if (MATCH_SEMI_CLOSEBRACE.apply(value))
         {
-          if (declaration.components.size() < 1)
+          if (declaration.components.size() < 1 && !declaration.name.or("").startsWith("--"))
           {
             err.error(new CssGrammarException(GRAMMAR_EXPECTING_TOKEN, iter.last.location,
                 messages.getLocale(), value.getChar(), messages.get("a_property_value")));
diff --git a/src/test/java/org/idpf/epubcheck/util/css/CssParserTest.java b/src/test/java/org/idpf/epubcheck/util/css/CssParserTest.java
@@ -178,6 +178,13 @@ public void testParser015() throws Exception {
     HandlerImpl handler = checkBasics(exec(s));
     assertEquals(0, handler.errors.size());
   }
+
+  @Test
+  public void testParser016() throws Exception {
+    String s = "E { --my-property: ; } ";
+    HandlerImpl handler = checkBasics(exec(s));
+    assertEquals(0, handler.errors.size());
+  }
 			
 	@Test
 	public void testParserAtRule001() throws Exception {
diff --git a/src/test/resources/css/custom-properties.css b/src/test/resources/css/custom-properties.css
@@ -4,6 +4,7 @@
 
 :root {
   --main-bg-color: brown;
+  --empty:;
 }
 
 .one {

Original file line number	Diff line number	Diff line change
`@@ -373,7 +373,7 @@ private CssDeclaration handleDeclaration(CssToken name, CssTokenIterator iter,`
`373`	`373`	`CssToken value = iter.next();`
`374`	`374`	`if (MATCH_SEMI_CLOSEBRACE.apply(value))`
`375`	`375`	`{`
`376`		`- if (declaration.components.size() < 1)`
	`376`	`+ if (declaration.components.size() < 1 && !declaration.name.or("").startsWith("--"))`
`377`	`377`	`{`
`378`	`378`	`err.error(new CssGrammarException(GRAMMAR_EXPECTING_TOKEN, iter.last.location,`
`379`	`379`	`messages.getLocale(), value.getChar(), messages.get("a_property_value")));`
Original file line number	Diff line number	Diff line change
`@@ -4,6 +4,7 @@`
`4`	`4`
`5`	`5`	`:root {`
`6`	`6`	`--main-bg-color: brown;`
	`7`	`+ --empty:;`
`7`	`8`	`}`
`8`	`9`
`9`	`10`	`.one {`