Don't trigger feedback/recursion on JSON-LD keywords

See https://gitlab.com/oersi/oersi-etl/-/issues/29

Author: fsteeg

org.metafacture.fix/src/main/java/org/metafacture/metamorph/FixBuilder.java

@@ -50,6 +50,8 @@
  *
  */
 public class FixBuilder { // checkstyle-disable-line ClassDataAbstractionCoupling|ClassFanOutComplexity
+
+    static final String ARRAY_MARKER = "[]";
     private static final String FLUSH_WITH = "flushWith";
     private static final String RECORD = "record";
     private final Deque<StackFrame> stack = new LinkedList<>();
@@ -91,7 +93,7 @@ private void processBind(final Expression expression, final EList<String> params
                 collect = createEntity(firstParam);
                 break;
             case "array":
-                collect = createEntity(firstParam + "[]");
+                collect = createEntity(firstParam + ARRAY_MARKER);
                 break;
             case "map":
                 final NamedValuePipe enterDataMap = enterDataMap(params, false);

org.metafacture.fix/src/main/java/org/metafacture/metamorph/Metafix.java

@@ -57,6 +57,7 @@
 import java.io.Reader;
 import java.io.StringReader;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Deque;
@@ -88,6 +89,12 @@ public class Metafix implements StreamPipe<StreamReceiver>, NamedValuePipe, Maps
     private static final InterceptorFactory NULL_INTERCEPTOR_FACTORY = new NullInterceptorFactory();
     private static final Map<String, String> NO_VARS = Collections.emptyMap();
 
+    // See https://www.w3.org/TR/json-ld11/#keywords
+    private static final List<String> JSONLD_KEYWORDS = Arrays.asList(
+            "@base", "@container", "@context", "@direction", "@graph", "@id", "@import", "@included", "@index", "@json",
+            "@language", "@list", "@nest", "@none", "@prefix", "@propagate", "@protected", "@reverse", "@set", "@type",
+            "@value", "@version", "@vocab");
+
     // warning: auxiliary class WildcardRegistry in WildcardDataRegistry.java should not be accessed from outside its own source file
     //private final Registry<NamedValueReceiver> dataRegistry = new WildcardRegistry<>();
     private final Registry<NamedValueReceiver> dataRegistry = new Registry<NamedValueReceiver>() {
@@ -370,8 +377,9 @@ public void receive(final String name, final String value, final NamedValueSourc
             throw new IllegalArgumentException(
                     "encountered literal with name='null'. This indicates a bug in a function or a collector.");
         }
-
-        if (name.length() != 0 && name.charAt(0) == FEEDBACK_CHAR) {
+        final int end = Math.min(name.indexOf(flattener.getEntityMarker()), name.indexOf(FixBuilder.ARRAY_MARKER));
+        final String firstNameSegment = end == -1 ? name : name.substring(0, end);
+        if (name.length() != 0 && name.charAt(0) == FEEDBACK_CHAR && !JSONLD_KEYWORDS.contains(firstNameSegment)) {
             dispatch(name, value, null);
             return;
         }

org.metafacture.fix/src/test/java/org/metafacture/metamorph/MetafixDslTest.java

@@ -869,6 +869,19 @@ public void shouldMatchCharactersInCharacterClass() {
         Mockito.verify(streamReceiver, Mockito.times(2)).literal(ArgumentMatchers.any(), ArgumentMatchers.any());
     }
 
+    @Test
+    public void shouldNotFeedbackJsonLdKeywords() {
+        final Metafix metafix = fix(
+                "map(_else)"
+        );
+
+        metafix.startRecord("1");
+        metafix.literal("@id", LITERAL_HAWAII);
+        metafix.endRecord();
+
+        Mockito.verify(streamReceiver).literal("@id", LITERAL_HAWAII);
+    }
+
     @Test
     @Disabled("Fix syntax")
     public void shouldReplaceVariables() {