1 files changed, 96 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/basicdeferred/Equality.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/basicdeferred/Equality.java
new file mode 100644
index 00000000..b978b62c
--- /dev/null
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/basicdeferred/Equality.java
@@ -0,0 +1,96 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2010 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.matchers.psystem.basicdeferred;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.context.IQueryMetaContext;
+import tools.refinery.viatra.runtime.matchers.planning.SubPlan;
+import tools.refinery.viatra.runtime.matchers.psystem.DeferredPConstraint;
+import tools.refinery.viatra.runtime.matchers.psystem.PBody;
+import tools.refinery.viatra.runtime.matchers.psystem.PVariable;
+
+/**
+ * @author Gabor Bergmann
+ * 
+ */
+public class Equality extends DeferredPConstraint {
+
+    private PVariable who;
+    private PVariable withWhom;
+
+    public Equality(PBody pBody, PVariable who, PVariable withWhom) {
+        super(pBody, buildSet(who, withWhom));
+        this.who = who;
+        this.withWhom = withWhom;
+    }
+
+    private static Set<PVariable> buildSet(PVariable who, PVariable withWhom) {
+        Set<PVariable> set = new HashSet<PVariable>();
+        set.add(who);
+        set.add(withWhom);
+        return set;
+    }
+
+    /**
+     * An equality is moot if it compares the a variable with itself.
+     * 
+     * @return true, if the equality is moot
+     */
+    public boolean isMoot() {
+        return who.equals(withWhom);
+    }
+
+    @Override
+    public void doReplaceVariable(PVariable obsolete, PVariable replacement) {
+        if (obsolete.equals(who))
+            who = replacement;
+        if (obsolete.equals(withWhom))
+            withWhom = replacement;
+    }
+
+    @Override
+    protected String toStringRest() {
+        return who.getName() + "=" + withWhom.getName();
+    }
+
+    public PVariable getWho() {
+        return who;
+    }
+
+    public PVariable getWithWhom() {
+        return withWhom;
+    }
+
+    @Override
+    public Set<PVariable> getDeducedVariables() {
+        return Collections.emptySet();
+    }
+    
+    @Override
+    public Map<Set<PVariable>, Set<PVariable>> getFunctionalDependencies(IQueryMetaContext context) {
+        final Map<Set<PVariable>, Set<PVariable>> result = new HashMap<Set<PVariable>, Set<PVariable>>();
+        result.put(Collections.singleton(who), Collections.singleton(withWhom));
+        result.put(Collections.singleton(withWhom), Collections.singleton(who));
+        return result;
+    }
+
+    @Override
+    public boolean isReadyAt(SubPlan plan, IQueryMetaContext context) {
+        return plan.getVisibleVariables().contains(who) && plan.getVisibleVariables().contains(withWhom);
+        // will be replaced by || if copierNode is available;
+        // until then, LayoutHelper.unifyVariablesAlongEqualities(PSystem<PatternDescription, StubHandle, Collector>) is
+        // recommended.
+    }
+}