[Enhancement #43] Properly handle term mapping conflicts in contexts.

kbss-cvut · Feb 7, 2023 · ac25191 · ac25191
1 parent 1842067
commit ac25191
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Showing 7 changed files with 60 additions and 3 deletions.
diff --git a/src/main/java/cz/cvut/kbss/jsonld/serialization/ContextBuildingJsonLdSerializer.java b/src/main/java/cz/cvut/kbss/jsonld/serialization/ContextBuildingJsonLdSerializer.java
@@ -4,10 +4,12 @@
 import cz.cvut.kbss.jsonld.ConfigParam;
 import cz.cvut.kbss.jsonld.Configuration;
 import cz.cvut.kbss.jsonld.JsonLd;
+import cz.cvut.kbss.jsonld.exception.AmbiguousTermMappingException;
 import cz.cvut.kbss.jsonld.serialization.context.JsonLdContext;
 import cz.cvut.kbss.jsonld.serialization.context.JsonLdContextFactory;
 import cz.cvut.kbss.jsonld.serialization.context.MappingJsonLdContextFactory;
 import cz.cvut.kbss.jsonld.serialization.model.CollectionNode;
+import cz.cvut.kbss.jsonld.serialization.model.CompositeNode;
 import cz.cvut.kbss.jsonld.serialization.model.JsonNode;
 import cz.cvut.kbss.jsonld.serialization.model.ObjectNode;
 import cz.cvut.kbss.jsonld.serialization.serializer.LiteralValueSerializers;
@@ -24,6 +26,7 @@
 import java.time.*;
 import java.util.Collection;
 import java.util.Date;
+import java.util.Optional;
 
 /**
  * JSON-LD serializer outputting compacted JSON-LD with context.
@@ -77,10 +80,20 @@ protected JsonNode buildJsonTree(Object root) {
         final JsonLdTreeBuilder treeBuilder = initTreeBuilder(traverser, jsonLdContextFactory);
         traverser.setVisitor(treeBuilder);
         traverser.traverse(root);
+        ensureContextNodeNotPresent(treeBuilder.getTreeRoot(), rootContext.getContextNode());
         treeBuilder.getTreeRoot().prependItem(rootContext.getContextNode());
         return treeBuilder.getTreeRoot();
     }
 
+    private void ensureContextNodeNotPresent(CompositeNode<?> root, JsonNode rootCtx) {
+        final Optional<JsonNode> ctxNode =
+                root.getItems().stream().filter(n -> JsonLd.CONTEXT.equals(n.getName())).findAny();
+        if (ctxNode.isPresent()) {
+            throw new AmbiguousTermMappingException(
+                    "Unable to build context hierarchy. Attempted to add two root contexts. Original root context: " + rootCtx + ", conflicting: " + ctxNode.get());
+        }
+    }
+
     private JsonLdTreeBuilder initTreeBuilder(ObjectGraphTraverser traverser,
                                               JsonLdContextFactory jsonLdContextFactory) {
         return new JsonLdTreeBuilder(new ObjectGraphValueSerializers(serializers,

diff --git a/src/main/java/cz/cvut/kbss/jsonld/serialization/context/DummyTermMappingHolder.java b/src/main/java/cz/cvut/kbss/jsonld/serialization/context/DummyTermMappingHolder.java
@@ -48,4 +48,9 @@ boolean hasTermMapping(String term, JsonNode mappedNode) {
     boolean isEmpty() {
         return true;
     }
+
+    @Override
+    boolean isRoot() {
+        return true;
+    }
 }
diff --git a/src/main/java/cz/cvut/kbss/jsonld/serialization/context/EmbeddedTermMappingHolder.java b/src/main/java/cz/cvut/kbss/jsonld/serialization/context/EmbeddedTermMappingHolder.java
@@ -1,5 +1,6 @@
 package cz.cvut.kbss.jsonld.serialization.context;
 
+import cz.cvut.kbss.jsonld.exception.AmbiguousTermMappingException;
 import cz.cvut.kbss.jsonld.serialization.model.JsonNode;
 
 import java.util.*;
@@ -28,14 +29,21 @@ void registerTermMapping(String term, JsonNode mappedNode) {
         if (!isRoot() && !parentContext.hasTermMapping(term)) {
             parentContext.registerTermMapping(term, mappedNode);
         } else {
+            verifyMappingUnique(term, mappedNode);
             mapping.put(term, mappedNode);
         }
     }
 
-    private boolean isRoot() {
+    boolean isRoot() {
         return parentContext == DummyTermMappingHolder.INSTANCE;
     }
 
+    private void verifyMappingUnique(String term, JsonNode value) {
+        if (mapping.containsKey(term) && !Objects.equals(mapping.get(term), value)) {
+            throw new AmbiguousTermMappingException("Context already contains mapping for term '" + term + "'.");
+        }
+    }
+
     @Override
     public Map<String, JsonNode> getMapping() {
         return Collections.unmodifiableMap(mapping);

diff --git a/src/main/java/cz/cvut/kbss/jsonld/serialization/context/MappingJsonLdContext.java b/src/main/java/cz/cvut/kbss/jsonld/serialization/context/MappingJsonLdContext.java
@@ -31,15 +31,15 @@ public MappingJsonLdContext(JsonLdContext parent) {
     @Override
     public void registerTermMapping(String term, String iri) {
         final JsonNode value = JsonNodeFactory.createStringLiteralNode(term, iri);
-        if (!mappingHolder.canRegisterTermMapping(term, value)) {
+        if (!mappingHolder.canRegisterTermMapping(term, value) && !mappingHolder.isRoot()) {
             this.mappingHolder = new EmbeddedTermMappingHolder(mappingHolder);
         }
         mappingHolder.registerTermMapping(term, value);
     }
 
     @Override
     public void registerTermMapping(String term, ObjectNode mappedNode) {
-        if (!mappingHolder.canRegisterTermMapping(term, mappedNode)) {
+        if (!mappingHolder.canRegisterTermMapping(term, mappedNode) && !mappingHolder.isRoot()) {
             this.mappingHolder = new EmbeddedTermMappingHolder(mappingHolder);
         }
         mappingHolder.registerTermMapping(term, mappedNode);

diff --git a/src/main/java/cz/cvut/kbss/jsonld/serialization/context/TermMappingHolder.java b/src/main/java/cz/cvut/kbss/jsonld/serialization/context/TermMappingHolder.java
@@ -31,6 +31,8 @@ abstract class TermMappingHolder {
 
     abstract boolean isEmpty();
 
+    abstract boolean isRoot();
+
     public Optional<String> getMappedTerm(String iri) {
         Objects.requireNonNull(iri);
         for (Map.Entry<String, JsonNode> e : getMapping().entrySet()) {

diff --git a/src/main/java/cz/cvut/kbss/jsonld/serialization/context/WriteThroughTermMappingHolder.java b/src/main/java/cz/cvut/kbss/jsonld/serialization/context/WriteThroughTermMappingHolder.java
@@ -46,4 +46,9 @@ Map<String, JsonNode> getMapping() {
     boolean isEmpty() {
         return true;
     }
+
+    @Override
+    boolean isRoot() {
+        return false;
+    }
 }
diff --git a/src/test/java/cz/cvut/kbss/jsonld/serialization/context/EmbeddedTermMappingHolderTest.java b/src/test/java/cz/cvut/kbss/jsonld/serialization/context/EmbeddedTermMappingHolderTest.java
@@ -0,0 +1,24 @@
+package cz.cvut.kbss.jsonld.serialization.context;
+
+import cz.cvut.kbss.jopa.vocabulary.DC;
+import cz.cvut.kbss.jopa.vocabulary.RDFS;
+import cz.cvut.kbss.jsonld.exception.AmbiguousTermMappingException;
+import cz.cvut.kbss.jsonld.serialization.JsonNodeFactory;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class EmbeddedTermMappingHolderTest {
+
+    private final EmbeddedTermMappingHolder sut = new EmbeddedTermMappingHolder();
+
+    @Test
+    void registerTermMappingThrowsAmbiguousTermMappingExceptionWhenRootHolderAlreadyContainsTermMapping() {
+        final String term = "name";
+        sut.registerTermMapping(term, JsonNodeFactory.createStringLiteralNode(term, RDFS.LABEL));
+        assertThrows(AmbiguousTermMappingException.class,
+                     () -> sut.registerTermMapping(term,
+                                                   JsonNodeFactory.createStringLiteralNode(term, DC.Terms.TITLE)));
+    }
+
+}