Allow preprocessing of the input stream to be skipped

This change adds an optional isPreprocessed boolean parameter to the
StyleSheetParser() constructor; if the value of that parameter is true,
the steps from https://drafts.csswg.org/css-syntax/#input-preprocessing
for preprocessing the input stream are skipped — so UnescapeFilterReader()
is not called.

This is useful in a context where the input stream has already been
preprocessed — for example, if the contents of the stylesheet being
parsed are from an HTML document that has already been parsed by a
conformant HTML parser (which is the case, for example, when the
https://github.com/validator/validator HTML checker calls the code).

Author: sideshowbarker

org/w3c/css/css/StyleSheetParser.java

@@ -50,6 +50,7 @@ public final class StyleSheetParser
         implements CssValidatorListener, CssParser {
 
     private static Constructor co = null;
+    private static boolean isPreprocessed;
 
     static {
         try {
@@ -64,10 +65,15 @@ public final class StyleSheetParser
     CssFouffa cssFouffa;
     StyleSheet style = new StyleSheet();
 
-    public StyleSheetParser(ApplContext ac) {
+    public StyleSheetParser(ApplContext ac, boolean isPreprocessed) {
+        this.isPreprocessed = isPreprocessed;
         ac.setStyleSheet(getStyleSheet());
     }
 
+    public StyleSheetParser(ApplContext ac) {
+        new StyleSheetParser(ac, false);
+    }
+
     public void reInit() {
         style = new StyleSheet();
     }
@@ -293,7 +299,8 @@ public void parseStyleElement(ApplContext ac, Reader reader,
 
 //	    if (cssFouffa == null) {
             String charset = ac.getCharsetForURL(url);
-            if (ac.getCssVersion().compareTo(CssVersion.CSS2) >=0 ) {
+            if (ac.getCssVersion().compareTo(CssVersion.CSS2) >=0
+                    && !isPreprocessed) {
                 cssFouffa = new CssFouffa(ac, new UnescapeFilterReader(new BufferedReader(reader)), url, lineno);
             } else {
                 cssFouffa = new CssFouffa(ac, reader, url, lineno);