[css-shadow-parts-1] use "split on commas" #2412

Author: fergald

css-shadow-parts-1/Overview.bs

@@ -364,18 +364,19 @@ The rules for parsing a list of part mappings are as follow:
 
 1. Let <var>input</var> be the string being parsed.
 
-1. Let <var>position</var> be a pointer into <var>input</var>, initially pointing at the start of the string.
+1. <span data-x="split a string on commas">Split the string <var>input</var> on
+    commas</span>. Let <var>unparsed mappings</var> be the resulting list of strings.
 
 1. Let <var>mappings</var> be an initially empty [=list=] of [=pairs=] of tokens.
     This [=list=] will be the result of this algorithm.
 
-1. [=Collect a sequence of code points=] that are space characters, U+002C COMMA.
-    This skips past any leading delimiters.
-
-1. While <var>position</var> is not past the end of <var>input</var>:
+1. For each string <var>unparsed mapping</var> in <var>unparsed mappings</var>,
+    run the following substeps:
 
-  1. [=Collect a sequence of code points=] that are not U+002C COMMA characters,
-      and let <var>unparsed mapping</var> be the result.
-  1. Let <var>mapping</var> be the result of parsing <var>unparsed mapping</var> using the <span>rules for parsing part mappings</span>.
-  1. If <var>mapping</var> is an error, continue.
-  1. Append <var>mapping</var> to <var>mappings</var>.
+    1. If <var>unparsed mapping</var> is empty or contains only space characters,
+        continue to the next iteration of the loop.
+    1. Let <var>mapping</var> be the result of parsing <var>unparsed mapping</var>
+        using the <span>rules for parsing part mappings</span>.
+    1. If <var>mapping</var> is an error then continue to the next iteration of the loop.
+        This allows clients to skip over new syntax that is not understood.
+    1. Append <var>mapping</var> to <var>mappings</var>.