[Enhancement #73] Refactor OntoDriver API descriptors in preparation …

…for supporting multiple contexts per assertion/subject.

AxiomValueDescriptor has been split from AxiomDescriptor, as it can contain only one context per assertion/subject to prevent ambiguity issues when saving values.

ontodriver-api/src/main/java/cz/cvut/kbss/ontodriver/descriptor/AbstractAxiomDescriptor.java

@@ -0,0 +1,66 @@
+package cz.cvut.kbss.ontodriver.descriptor;
+
+import cz.cvut.kbss.ontodriver.model.Assertion;
+import cz.cvut.kbss.ontodriver.model.NamedResource;
+
+import java.net.URI;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Defines common API for axiom descriptors.
+ */
+public abstract class AbstractAxiomDescriptor {
+
+    private final NamedResource subject;
+
+    protected AbstractAxiomDescriptor(NamedResource subject) {
+        this.subject = Objects.requireNonNull(subject);
+    }
+
+    public NamedResource getSubject() {
+        return subject;
+    }
+
+    /**
+     * Gets the set of assertions in this descriptor.
+     *
+     * @return Set of assertions
+     */
+    public abstract Set<Assertion> getAssertions();
+
+    /**
+     * Checks whether this descriptor contains the specified assertion.
+     *
+     * @param assertion Assertion to look for
+     * @return {@code boolean} result
+     */
+    public abstract boolean containsAssertion(Assertion assertion);
+
+    /**
+     * Gets the set of repository context identifiers in which this descriptor's subject may be.
+     *
+     * @return Set of context identifiers
+     */
+    public abstract Set<URI> getSubjectContexts();
+
+    /**
+     * Gets the set of repository context identifiers in which the specified assertion values may be.
+     *
+     * @return Set of context identifiers
+     */
+    public abstract Set<URI> getAssertionContexts(Assertion assertion);
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof AbstractAxiomDescriptor)) return false;
+        AbstractAxiomDescriptor that = (AbstractAxiomDescriptor) o;
+        return subject.equals(that.subject);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(subject);
+    }
+}

ontodriver-api/src/main/java/cz/cvut/kbss/ontodriver/descriptor/AxiomDescriptor.java

@@ -26,16 +26,15 @@
  * Additionally, it can specify context URIs for both the descriptor and individual properties so that the underlying
  * driver knows where to look for the corresponding axioms.
  */
-public class AxiomDescriptor {
+public class AxiomDescriptor extends AbstractAxiomDescriptor {
 
-    private final NamedResource subject;
     private final Set<Assertion> assertions;
 
     private URI subjectContext;
     private final Map<Assertion, URI> assertionContexts;
 
     public AxiomDescriptor(NamedResource subject) {
-        this.subject = Objects.requireNonNull(subject);
+        super(subject);
         this.assertions = new HashSet<>();
         this.assertionContexts = new HashMap<>();
     }
@@ -78,10 +77,6 @@ public void setAssertionContext(Assertion assertion, URI context) {
         assertionContexts.put(assertion, context);
     }
 
-    public NamedResource getSubject() {
-        return subject;
-    }
-
     public URI getSubjectContext() {
         return subjectContext;
     }
@@ -122,39 +117,37 @@ public boolean containsAssertion(Assertion assertion) {
     }
 
     @Override
-    public int hashCode() {
-        final int prime = 31;
-        int result = 1;
-        result = prime * result + subject.hashCode();
-        result = prime * result + ((subjectContext == null) ? 0 : subjectContext.hashCode());
-        result = prime * result + assertions.hashCode();
-        result = prime * result + assertionContexts.hashCode();
-        return result;
+    public Set<URI> getSubjectContexts() {
+        // TODO
+        return Collections.singleton(getSubjectContext());
+    }
+
+    @Override
+    public Set<URI> getAssertionContexts(Assertion assertion) {
+        // TODO
+        return Collections.singleton(getAssertionContext(assertion));
     }
 
     @Override
-    public boolean equals(Object obj) {
-        if (this == obj)
-            return true;
-        if (obj == null)
-            return false;
-        if (getClass() != obj.getClass())
-            return false;
-        AxiomDescriptor other = (AxiomDescriptor) obj;
-        if (!subject.equals(other.subject))
-            return false;
-        if (subjectContext == null) {
-            if (other.subjectContext != null)
-                return false;
-        } else if (!subjectContext.equals(other.subjectContext))
-            return false;
-        return assertions.equals(other.assertions) && assertionContexts.equals(other.assertionContexts);
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof AxiomDescriptor)) return false;
+        if (!super.equals(o)) return false;
+        AxiomDescriptor that = (AxiomDescriptor) o;
+        return assertions.equals(that.assertions) &&
+                Objects.equals(subjectContext, that.subjectContext) &&
+                assertionContexts.equals(that.assertionContexts);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(super.hashCode(), assertions, subjectContext, assertionContexts);
     }
 
     @Override
     public String toString() {
         final StringBuilder sb = new StringBuilder();
-        sb.append("[").append(subject);
+        sb.append("[").append(getSubject());
         if (subjectContext != null) {
             sb.append(" - ").append(subjectContext);
         }

ontodriver-api/src/main/java/cz/cvut/kbss/ontodriver/descriptor/AxiomValueDescriptor.java

@@ -1,32 +1,120 @@
 /**
  * Copyright (C) 2020 Czech Technical University in Prague
- *
- * This program is free software: you can redistribute it and/or modify it under
- * the terms of the GNU General Public License as published by the Free Software
- * Foundation, either version 3 of the License, or (at your option) any
- * later version.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
- * details. You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ * <p>
+ * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ * <p>
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details. You should have received a copy of the GNU General Public License along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
  */
 package cz.cvut.kbss.ontodriver.descriptor;
 
 import cz.cvut.kbss.ontodriver.model.Assertion;
 import cz.cvut.kbss.ontodriver.model.NamedResource;
 import cz.cvut.kbss.ontodriver.model.Value;
 
+import java.net.URI;
 import java.util.*;
 
-public class AxiomValueDescriptor extends AxiomDescriptor {
+public class AxiomValueDescriptor extends AbstractAxiomDescriptor {
 
-    private final Map<Assertion, List<Value<?>>> values;
+    private URI subjectContext;
+
+    private final Map<Assertion, AssertionData> assertionData;
 
     public AxiomValueDescriptor(NamedResource subject) {
         super(subject);
-        this.values = new HashMap<>();
+        this.assertionData = new HashMap<>();
+    }
+
+    /**
+     * Sets subject context.
+     *
+     * @param context The context to use for subject
+     */
+    public void setSubjectContext(URI context) {
+        this.subjectContext = context;
+    }
+
+    public URI getSubjectContext() {
+        return subjectContext;
+    }
+
+    /**
+     * Adds the specified assertion to this descriptor.
+     *
+     * @param assertion The assertion to add
+     * @throws NullPointerException When {@code assertion} is {@code null}
+     */
+    public void addAssertion(Assertion assertion) {
+        Objects.requireNonNull(assertion);
+        assertionData.put(assertion, new AssertionData());
+    }
+
+    /**
+     * Gets unmodifiable view of the properties in this descriptor.
+     *
+     * @return Set of assertions in this descriptor
+     */
+    public Set<Assertion> getAssertions() {
+        return Collections.unmodifiableSet(assertionData.keySet());
+    }
+
+    /**
+     * Checks whether this descriptor contains the specified assertion.
+     *
+     * @param assertion The assertion to check
+     * @return True if the assertion is already present in this descriptor, false otherwise
+     */
+    public boolean containsAssertion(Assertion assertion) {
+        return assertionData.containsKey(assertion);
+    }
+
+    @Override
+    public Set<URI> getSubjectContexts() {
+        return Collections.singleton(getSubjectContext());
+    }
+
+    @Override
+    public Set<URI> getAssertionContexts(Assertion assertion) {
+        return Collections.singleton(getAssertionContext(assertion));
+    }
+
+    /**
+     * Gets context of the specified assertion.
+     * <p>
+     * If the context was not explicitly set, the same context as the subject's is returned.
+     *
+     * @param assertion Assertion for which context should be resolved
+     * @return Assertion context
+     */
+    public URI getAssertionContext(Assertion assertion) {
+        Objects.requireNonNull(assertion);
+        if (!assertionData.containsKey(assertion) || !assertionData.get(assertion).hasContext) {
+            return subjectContext;
+        }
+        return assertionData.get(assertion).context;
+    }
+
+    /**
+     * Sets context for the specified assertion.
+     * <p>
+     * Note that the assertion has to be already present in this descriptor.
+     *
+     * @param assertion The property to set context for
+     * @param context   Context URI
+     * @throws IllegalArgumentException If there is no such assertion in this descriptor
+     * @throws NullPointerException     When {@code assertion} is {@code null}
+     */
+    public void setAssertionContext(Assertion assertion, URI context) {
+        Objects.requireNonNull(assertion);
+        if (!assertionData.containsKey(assertion)) {
+            throw new IllegalArgumentException("Assertion " + assertion + " is not present in this descriptor.");
+        }
+        assertionData.get(assertion).setContext(context);
     }
 
     /**
@@ -55,43 +143,48 @@ public AxiomValueDescriptor addAssertionValue(Assertion assertion, Value<?> valu
      */
     public List<Value<?>> getAssertionValues(Assertion assertion) {
         Objects.requireNonNull(assertion);
-        if (!values.containsKey(assertion)) {
+        if (!assertionData.containsKey(assertion)) {
             return Collections.emptyList();
         }
-        return Collections.unmodifiableList(values.get(assertion));
+        return Collections.unmodifiableList(assertionData.get(assertion).values);
     }
 
     private List<Value<?>> getAssertionList(Assertion assertion) {
         assert assertion != null;
-        if (!values.containsKey(assertion)) {
-            values.put(assertion, new ArrayList<>());
+        if (!assertionData.containsKey(assertion)) {
             addAssertion(assertion);
         }
-        return values.get(assertion);
+        return assertionData.get(assertion).values;
     }
 
     @Override
-    public int hashCode() {
-        final int prime = 31;
-        int result = super.hashCode();
-        result = prime * result + values.hashCode();
-        return result;
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof AxiomValueDescriptor)) return false;
+        if (!super.equals(o)) return false;
+        AxiomValueDescriptor that = (AxiomValueDescriptor) o;
+        return Objects.equals(subjectContext, that.subjectContext) &&
+                assertionData.equals(that.assertionData);
     }
 
     @Override
-    public boolean equals(Object obj) {
-        if (this == obj)
-            return true;
-        if (!super.equals(obj))
-            return false;
-        if (getClass() != obj.getClass())
-            return false;
-        AxiomValueDescriptor other = (AxiomValueDescriptor) obj;
-        return values.equals(other.values);
+    public int hashCode() {
+        return Objects.hash(super.hashCode(), subjectContext, assertionData);
     }
 
     @Override
     public String toString() {
-        return super.toString() + ", property values: " + values;
+        return "AxiomValueDescriptor{<" + getSubject() + "> - " + assertionData + '}';
+    }
+
+    private static class AssertionData {
+        private final List<Value<?>> values = new ArrayList<>();
+        private URI context;
+        private boolean hasContext;
+
+        private void setContext(URI context) {
+            this.context = context;
+            this.hasContext = true;
+        }
     }
 }