feat: better parse URL fragment micro syntaxes

This commit introduce a new `URLFragment` class to represent URL fragments.

Fragment strings are parsed into `URLFragment` instances using MIME type-specific logic, implementing some validity checks for a few micro syntaxes
including:

- shortand bare name IDs
- scheme-based fragments
- media fragments

SVG and HTML/XHTML MIME types are supported.

The parser is tested in the `url-fragment.feature` feature file, in a new `unit-tests` directory.

src/main/java/com/adobe/epubcheck/opf/OPFChecker.java

@@ -116,6 +116,9 @@ protected boolean checkPackage()
 
     List<OPFItem> items = opfHandler.getItems();
     report.info(null, FeatureEnum.ITEMS_COUNT, Integer.toString(items.size()));
+
+    // Register package doc and items to the XRefChecker
+    xrefChecker.registerResource(context.url, context.mimeType);
     for (OPFItem item : items)
     {
       xrefChecker.registerResource(item,

src/main/java/com/adobe/epubcheck/opf/OPFChecker30.java

@@ -25,6 +25,8 @@
 import java.util.Iterator;
 import java.util.Set;
 
+import org.w3c.epubcheck.url.URLFragment;
+
 import com.adobe.epubcheck.api.EPUBLocation;
 import com.adobe.epubcheck.api.EPUBProfile;
 import com.adobe.epubcheck.api.FeatureReport.Feature;
@@ -387,7 +389,8 @@ private void checkPreviewCollection(ResourceCollection collection)
         }
         else
         {
-          if (Optional.fromNullable(resource.getURL().fragment()).or("").startsWith("epubcfi("))
+          URLFragment fragment = URLFragment.parse(resource.getURL());
+          if (fragment.exists() && "epubcfi".equals(fragment.getScheme()))
           {
             report.message(MessageId.OPF_076, EPUBLocation.of(context));
           }

src/main/java/com/adobe/epubcheck/opf/XRefChecker.java

@@ -31,8 +31,9 @@
 import java.util.Map;
 import java.util.Queue;
 import java.util.Set;
-import java.util.regex.Pattern;
 
+import org.w3c.epubcheck.constants.MIMEType;
+import org.w3c.epubcheck.url.URLFragment;
 import org.w3c.epubcheck.url.URLUtils;
 
 import com.adobe.epubcheck.api.EPUBLocation;
@@ -126,6 +127,7 @@ public static final class Builder
       private OPFItem item = null;
       private boolean hasItemFallback = false;
       private boolean hasImageFallback = false;
+      public String mimetype;
 
       public Builder url(URL url)
       {
@@ -137,6 +139,13 @@ public Builder item(OPFItem item)
       {
         this.url = item.getURL();
         this.item = item;
+        this.mimetype = item.getMimeType();
+        return this;
+      }
+
+      public Builder mimetype(String mimetype)
+      {
+        this.mimetype = mimetype;
         return this;
       }
 
@@ -231,8 +240,6 @@ public boolean isInSpine()
     }
   }
 
-  private static final Pattern REGEX_SVG_VIEW = Pattern.compile("svgView\\(.*\\)");
-
   private final Map<URL, Resource> resources = new HashMap<URL, Resource>();
 
   private final Set<URL> undeclared = new HashSet<URL>();
@@ -281,7 +288,7 @@ public Optional<OPFItem> getResource(URL url)
    * @param path
    *          the path to a publication resource
    * @return an immutable {@link EnumSet} containing the types of references to
-   *         {@code path}.
+   *           {@code path}.
    */
   public Set<Type> getTypes(URL resource)
   {
@@ -413,9 +420,15 @@ public void checkReferences()
   private void checkReference(URLReference reference)
   {
     Resource hostResource = resources.get(reference.location.url);
-    Resource targetResource = resources.get(reference.targetDoc);
+
+    // Retrieve the Resource instance representing the targeted document
     // If the resource was not declared in the manifest,
     // we build a new Resource object for the data URL.
+    Resource targetResource = resources.get(reference.targetDoc);
+    String targetMimetype = (targetResource != null) ? targetResource.getMimeType() : "";
+
+    // Parse the URL fragment
+    URLFragment fragment = URLFragment.parse(reference.url, targetMimetype);
 
     // Check remote resources
     if (container.isRemote(reference.url)
@@ -470,15 +483,18 @@ else if (!undeclared.contains(reference.targetDoc)
       return;
     }
 
-    String mimetype = targetResource.getMimeType();
-
     // Type-specific checks
     switch (reference.type)
     {
     case HYPERLINK:
+      if ("epubcfi".equals(fragment.getScheme()))
+      {
+        break; // EPUB CFI is not supported
+      }
       // if mimeType is null, we should have reported an error already
-      if (!OPFChecker.isBlessedItemType(mimetype, version)
-          && !OPFChecker.isDeprecatedBlessedItemType(mimetype) && !targetResource.hasItemFallback())
+      if (!OPFChecker.isBlessedItemType(targetMimetype, version)
+          && !OPFChecker.isDeprecatedBlessedItemType(targetMimetype)
+          && !targetResource.hasItemFallback())
       {
         report.message(MessageId.RSC_010,
             reference.location.context(container.relativize(reference.url)));
@@ -494,31 +510,35 @@ else if (!undeclared.contains(reference.targetDoc)
     case IMAGE:
     case PICTURE_SOURCE:
     case PICTURE_SOURCE_FOREIGN:
-      if (reference.url.fragment() != null && !mimetype.equals("image/svg+xml"))
+      if ("epubcfi".equals(fragment.getScheme()))
+      {
+        break; // EPUB CFI is not supported
+      }
+      if (fragment.exists() && !MIMEType.SVG.is(targetMimetype))
       {
         report.message(MessageId.RSC_009,
             reference.location.context(container.relativize(reference.url)));
         return;
       }
       // if mimeType is null, we should have reported an error already
-      if (!OPFChecker.isBlessedImageType(mimetype, version))
+      if (!OPFChecker.isBlessedImageType(targetMimetype, version))
       {
         if (version == EPUBVersion.VERSION_3 && reference.type == Type.PICTURE_SOURCE)
         {
           report.message(MessageId.MED_007, reference.location,
-              container.relativize(reference.targetDoc), mimetype);
+              container.relativize(reference.targetDoc), targetMimetype);
           return;
         }
         else if (reference.type == Type.IMAGE && !targetResource.hasImageFallback())
         {
           report.message(MessageId.MED_003, reference.location,
-              container.relativize(reference.targetDoc), mimetype);
+              container.relativize(reference.targetDoc), targetMimetype);
         }
       }
       break;
     case SEARCH_KEY:
       // TODO update when we support EPUB CFI
-      if ((reference.url.fragment() == null || !reference.url.fragment().startsWith("epubcfi("))
+      if ((!fragment.exists() || !"epubcfi".equals(fragment.getScheme()))
           && !targetResource.isInSpine())
       {
         report.message(MessageId.RSC_021, reference.location,
@@ -527,7 +547,7 @@ else if (reference.type == Type.IMAGE && !targetResource.hasImageFallback())
       }
       break;
     case STYLESHEET:
-      if (reference.url.fragment() != null)
+      if (fragment.exists())
       {
         report.message(MessageId.RSC_013,
             reference.location.context(container.relativize(reference.url)));
@@ -551,7 +571,7 @@ else if (reference.type == Type.IMAGE && !targetResource.hasImageFallback())
     case SVG_CLIP_PATH:
     case SVG_PAINT:
     case SVG_SYMBOL:
-      if (reference.url.fragment() == null)
+      if (!fragment.exists())
       {
         report.message(MessageId.RSC_015, reference.location.context(reference.url));
         return;
@@ -562,32 +582,32 @@ else if (reference.type == Type.IMAGE && !targetResource.hasImageFallback())
     }
 
     // Fragment integrity checks
-    String fragment = reference.url.fragment();
-    if (fragment != null && !fragment.isEmpty())
+    if (fragment.exists() && !fragment.isEmpty())
     {
       // EPUB CFI
-      if (fragment.startsWith("epubcfi("))
+      if ("epubcfi".equals(fragment.getScheme()))
       {
+        // FIXME HOT should warn if in MO
         // FIXME epubcfi currently not supported (see issue 150).
         return;
       }
       // Media fragments in Data Navigation Documents
-      else if (fragment.contains("=") && hostResource != null && hostResource.hasItem()
+      else if (fragment.isMediaFragment() && hostResource != null && hostResource.hasItem()
           && hostResource.getItem().getProperties()
               .contains(PackageVocabs.ITEM_VOCAB.get(PackageVocabs.ITEM_PROPERTIES.DATA_NAV)))
       {
         // Ignore,
         return;
       }
-      // SVG view fragments are ignored
-      else if (mimetype.equals("image/svg+xml") && REGEX_SVG_VIEW.matcher(fragment).matches())
+      // Non-ID-based fragments are ignored
+      else if (fragment.getId().isEmpty())
       {
         return;
       }
       // Fragment Identifier (by default)
       else if (!container.isRemote(reference.targetDoc))
       {
-        ID anchor = targetResource.ids.get(fragment);
+        ID anchor = targetResource.ids.get(fragment.getId());
         if (anchor == null)
         {
           report.message(MessageId.RSC_012, reference.location.context(reference.url.toString()));
@@ -674,7 +694,8 @@ private void checkReadingOrder(Queue<URLReference> references, int lastSpinePosi
       }
 
       // check that the fragment is in document order
-      int targetAnchorPosition = res.getIDPosition(ref.url.fragment());
+      URLFragment fragment = URLFragment.parse(ref.url, res.getMimeType());
+      int targetAnchorPosition = res.getIDPosition(fragment.getId());
       if (targetAnchorPosition < lastAnchorPosition)
       {
         String orderContext = LocalizedMessages.getInstance(locale).getSuggestion(MessageId.NAV_011,

src/main/java/com/adobe/epubcheck/ops/OPSHandler.java

@@ -141,11 +141,6 @@ else if (".".equals(href))
 
     // If the URL was not properly parsed, return early
     if (url == null) return;
-    // If the URL is an EPUB CFI, return (not implemented)
-    if (url.fragment() != null && url.fragment().matches("epubcfi\\(.*\\)"))
-    {
-      return; // temp until cfi implemented
-    }
 
     if ("file".equals(url.scheme()))
     {

src/main/java/org/w3c/epubcheck/constants/MIMEType.java

@@ -54,6 +54,6 @@ public boolean is(String string)
 
   public static MIMEType get(String name)
   {
-    return ENUM_MAP.getOrDefault(name.toLowerCase(Locale.ROOT), OTHER);
+    return (name != null) ? ENUM_MAP.getOrDefault(name.toLowerCase(Locale.ROOT), OTHER) : OTHER;
   }
 }