Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.db.layer0 / src / org / simantics / db / layer0 / genericrelation / combinators / Intersection.java

diff --git a/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/combinators/Intersection.java b/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/combinators/Intersection.java
new file mode 100644 (file)
index 0000000..24e085d
--- /dev/null
+++ b/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/combinators/Intersection.java
@@ -0,0 +1,96 @@
+/*******************************************************************************\r
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
+ * in Industry THTH ry.\r
+ * All rights reserved. This program and the accompanying materials\r
+ * are made available under the terms of the Eclipse Public License v1.0\r
+ * which accompanies this distribution, and is available at\r
+ * http://www.eclipse.org/legal/epl-v10.html\r
+ *\r
+ * Contributors:\r
+ *     VTT Technical Research Centre of Finland - initial API and implementation\r
+ *******************************************************************************/\r
+package org.simantics.db.layer0.genericrelation.combinators;\r
+\r
+import java.util.ArrayList;\r
+import java.util.Collection;\r
+import java.util.List;\r
+\r
+import org.simantics.db.ReadGraph;\r
+import org.simantics.db.exception.DatabaseException;\r
+import org.simantics.db.layer0.adapter.GenericRelation;\r
+import org.simantics.db.layer0.genericrelation.AbstractRelation;\r
+import org.simantics.utils.datastructures.Pair;\r
+\r
+/**\r
+ * Takes the intersection of multiple relations.\r
+ */\r
+public class Intersection extends AbstractRelation {\r
+\r
+       GenericRelation realizable = null;\r
+       Collection<GenericRelation> constraints;\r
+       \r
+       public Intersection(Collection<GenericRelation> relations) {\r
+               for(GenericRelation relation : relations)\r
+                       if(realizable == null && relation.isRealizable()) {\r
+                               realizable = relation;\r
+                       }\r
+                       else\r
+                               constraints.add(relation);\r
+       }\r
+       \r
+       public Intersection(GenericRelation realizable, Collection<GenericRelation> constraints) {\r
+               assert(realizable.isRealizable());\r
+               this.realizable = realizable;\r
+               this.constraints = constraints;\r
+       }\r
+\r
+       @Override\r
+       public boolean contains(ReadGraph g, Object[] tuple) throws DatabaseException {\r
+               if(!realizable.contains(g, tuple))\r
+                       return false;\r
+               for(GenericRelation relation : constraints)\r
+                       if(!relation.contains(g, tuple))\r
+                               return false;\r
+               return true;\r
+       }\r
+\r
+       @Override\r
+       public boolean isRealizable() {\r
+               return realizable != null;\r
+       }\r
+\r
+       @Override\r
+       public List<Object[]> realize(ReadGraph g) throws DatabaseException {\r
+               ArrayList<Object[]> result = new ArrayList<Object[]>();\r
+               loop:\r
+               for(Object[] tuple : realizable.realize(g)) {\r
+                       for(GenericRelation constraint : constraints)\r
+                               if(!constraint.contains(g, tuple))\r
+                                       continue loop;\r
+                       result.add(tuple);\r
+               }\r
+               return result;\r
+       }       \r
+\r
+       // TODO optimize select\r
+       \r
+       @Override\r
+       public GenericRelation selectByRelation(String bindingPattern,\r
+                       GenericRelation constraint) {\r
+               if(realizable != null)\r
+                       return new Intersection(realizable.selectByRelation(bindingPattern, constraint),\r
+                                       constraints);\r
+               else\r
+                       return super.selectByRelation(bindingPattern, constraint);\r
+       }\r
+       \r
+       @Override\r
+       public Pair<String, String>[] getFields() {\r
+               if(realizable != null)\r
+                       return realizable.getFields();\r
+               for(GenericRelation relation : constraints)\r
+                       return relation.getFields();\r
+               return null;\r
+       }\r
+\r
+}\r