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Posted to commits@commons.apache.org by re...@apache.org on 2015/02/15 19:41:16 UTC

svn commit: r1659973 [2/3] - in /commons/sandbox/rdf/trunk: ./ api/src/main/java/org/apache/commons/rdf/ impl.sparql/ impl.sparql/src/ impl.sparql/src/main/ impl.sparql/src/main/java/ impl.sparql/src/main/java/org/ impl.sparql/src/main/java/org/apache/...

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphMatcher.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphMatcher.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphMatcher.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphMatcher.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching;
+
+
+
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+import org.apache.commons.rdf.BlankNode;
+import org.apache.commons.rdf.BlankNodeOrIri;
+import org.apache.commons.rdf.Graph;
+import org.apache.commons.rdf.RdfTerm;
+import org.apache.commons.rdf.Triple;
+import org.apache.commons.rdf.impl.utils.TripleImpl;
+import org.apache.commons.rdf.impl.utils.simple.SimpleMGraph;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * @author reto
+ * 
+ */
+public class GraphMatcher {
+
+
+    private final static Logger log = LoggerFactory.getLogger(GraphMatcher.class);
+
+    /**
+     * get a mapping from g1 to g2 or null if the graphs are not isomorphic. The
+     * returned map maps each <code>BNode</code>s from g1 to one
+     * of g2. If the graphs are ground graphs the method return an empty map if
+     * the ImmutableGraph are equals and null otherwise.
+     * <p/>
+     * NOTE: This method does not returned mapping from blank nodes to grounded
+     * nodes, a bnode in g1 is not a vraiable that may match any node, but must
+     * match a bnode in g2.
+     * <p/>
+     *
+     * On the algorithm:<br/>
+     * - In a first step it checked if every grounded triple in g1 matches one
+     * in g2<br/>
+     * - [optional] blank node blind matching</br>
+     * - in a map mbng1 bnode of g1 is mapped to a set of of its
+     * properties and inverse properties, this is the predicate and the object
+     * or subject respectively, analoguosly in mbgn2 every bnode of g2<br/>
+     * - based on the incoming and outgoing properties a hash is calculated for
+     * each bnode, in the first step when calculating the hash  aconstant value
+     * is taken for the bnodes that might be subject or object in the (inverse properties)
+     * - hash-classes:
+     * 
+     * @param g1
+     * @param g2
+     * @return a Set of NodePairs
+     */
+    public static Map<BlankNode, BlankNode> getValidMapping(Graph og1, Graph og2) {
+        Graph g1 = new SimpleMGraph(og1);
+        Graph g2 = new SimpleMGraph(og2);
+        if (!Utils.removeGrounded(g1,g2)) {
+            return null;
+        }
+        final HashMatching hashMatching;
+        try {
+            hashMatching = new HashMatching(g1, g2);
+        } catch (GraphNotIsomorphicException ex) {
+            return null;
+        }
+        Map<BlankNode, BlankNode> matchings = hashMatching.getMatchings();
+        if (g1.size() > 0) {
+            //start trial an error matching
+            //TODO (CLEREZZA-81) at least in the situation where one matching
+            //group is big (approx > 5) we should switch back to hash-based matching
+            //after a first guessed matching, rather than try all permutations
+            Map<BlankNode, BlankNode> remainingMappings = trialAndErrorMatching(g1, g2, hashMatching.getMatchingGroups());
+            if (remainingMappings == null) {
+                return null;
+            } else {
+                matchings.putAll(remainingMappings);
+            }
+        }
+        return matchings;
+    }
+
+    private static Map<BlankNode, BlankNode> trialAndErrorMatching(Graph g1, Graph g2,
+            Map<Set<BlankNode>, Set<BlankNode>> matchingGroups) {
+        if (log.isDebugEnabled()) {
+            Set<BlankNode> bn1  = Utils.getBNodes(g1);
+            log.debug("doing trial and error matching for {} bnodes, " +
+                    "in graphs of size: {}.", bn1.size(), g1.size());
+        }
+        Iterator<Map<BlankNode, BlankNode>> mappingIter
+                = GroupMappingIterator.create(matchingGroups);
+        while (mappingIter.hasNext()) {
+            Map<BlankNode, BlankNode> map = mappingIter.next();
+            if (checkMapping(g1, g2, map)) {
+                return map;
+            }
+        }
+        return null;
+    }
+
+    private static boolean checkMapping(Graph g1, Graph g2, Map<BlankNode, BlankNode> map) {
+        for (Triple triple : g1) {
+            if (!g2.contains(map(triple, map))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private static Triple map(Triple triple, Map<BlankNode, BlankNode> map) {
+        final BlankNodeOrIri oSubject = triple.getSubject();
+
+        BlankNodeOrIri subject = oSubject instanceof BlankNode ?
+            map.get((BlankNode)oSubject) : oSubject;
+
+        RdfTerm oObject = triple.getObject();
+        RdfTerm object = oObject instanceof BlankNode ?
+            map.get((BlankNode)oObject) : oObject;
+        return new TripleImpl(subject, triple.getPredicate(), object);
+    }
+
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphNotIsomorphicException.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphNotIsomorphicException.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphNotIsomorphicException.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GraphNotIsomorphicException.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,28 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching;
+
+/**
+ *
+ * @author reto
+ */
+class GraphNotIsomorphicException extends Exception {
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GroupMappingIterator.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GroupMappingIterator.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GroupMappingIterator.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/GroupMappingIterator.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,102 @@
+/*
+ *  Copyright 2010 reto.
+ * 
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ * 
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *  under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Set;
+
+/**
+ * Iterates over all mappings from each element of every Set<T> to each
+ * elemenent of their corresponding Set<U>.
+ *
+ * @author reto
+ */
+class GroupMappingIterator<T,U> implements Iterator<Map<T, U>> {
+
+    private Iterator<Map<T, U>> firstPartIter;
+    private Map<T, U> currentFirstPart;
+    final private Map<Set<T>, Set<U>> restMap;
+    private Iterator<Map<T, U>> currentRestPartIter;
+
+    static <T,U> Iterator<Map<T, U>> create(Map<Set<T>, Set<U>> matchingGroups) {
+        if (matchingGroups.size() > 1) {
+            return new GroupMappingIterator<T, U>(matchingGroups);
+        } else {
+            if (matchingGroups.size() == 0) {
+                return new ArrayList<Map<T, U>>(0).iterator();
+            }
+            Map.Entry<Set<T>, Set<U>> entry = matchingGroups.entrySet().iterator().next();
+            return new MappingIterator<T,U>(entry.getKey(),
+                        entry.getValue());
+        }
+    }
+
+    private GroupMappingIterator(Map<Set<T>, Set<U>> matchingGroups) {
+        if (matchingGroups.size() == 0) {
+            throw new IllegalArgumentException("matchingGroups must not be empty");
+        }
+        restMap = new HashMap<Set<T>, Set<U>>();
+        boolean first = true;
+        for (Map.Entry<Set<T>, Set<U>> entry : matchingGroups.entrySet()) {
+            if (first) {
+                firstPartIter = new MappingIterator<T,U>(entry.getKey(),
+                        entry.getValue());
+                first = false;
+            } else {
+                restMap.put(entry.getKey(), entry.getValue());
+            }
+        }
+        currentRestPartIter = create(restMap);
+        currentFirstPart = firstPartIter.next();
+    }
+
+    @Override
+    public boolean hasNext() {
+        return firstPartIter.hasNext() || currentRestPartIter.hasNext();
+    }
+
+    @Override
+    public Map<T, U> next() {
+        Map<T, U> restPart;
+        if (currentRestPartIter.hasNext()) {
+            restPart = currentRestPartIter.next();
+        } else {
+            if (firstPartIter.hasNext()) {
+                currentFirstPart = firstPartIter.next();
+                currentRestPartIter = create(restMap);
+                restPart = currentRestPartIter.next();
+            } else {
+                throw new NoSuchElementException();
+            }
+        }
+        Map<T, U> result = new HashMap<T, U>(restPart);
+        result.putAll(currentFirstPart);
+        return result;
+    }
+
+    @Override
+    public void remove() {
+        throw new UnsupportedOperationException("Not supported.");
+    }
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/HashMatching.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/HashMatching.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/HashMatching.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/HashMatching.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,268 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching;
+
+
+import org.apache.commons.rdf.impl.utils.graphmatching.collections.IntHashMap;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+import org.apache.commons.rdf.BlankNode;
+import org.apache.commons.rdf.Graph;
+import org.apache.commons.rdf.BlankNodeOrIri;
+import org.apache.commons.rdf.RdfTerm;
+import org.apache.commons.rdf.Triple;
+import org.apache.commons.rdf.Graph;
+import org.apache.commons.rdf.Iri;
+import org.apache.commons.rdf.impl.utils.TripleImpl;
+import org.apache.commons.rdf.impl.utils.graphmatching.collections.IntIterator;
+
+/**
+ *
+ * @author reto
+ */
+public class HashMatching {
+
+    private Map<BlankNode, BlankNode> matchings = new HashMap<BlankNode, BlankNode>();
+    private Map<Set<BlankNode>, Set<BlankNode>> matchingGroups;
+
+    /**
+     * tc1 and tc2 will be modified: the triples containing no unmatched bnode
+     * will be removed
+     *
+     * @param tc1
+     * @param tc2
+     * @throws GraphNotIsomorphicException
+     */
+    HashMatching(Graph tc1, Graph tc2) throws GraphNotIsomorphicException {
+        int foundMatchings = 0;
+        int foundMatchingGroups = 0;
+        Map<BlankNode, Integer> bNodeHashMap = new HashMap<BlankNode, Integer>();
+        while (true) {
+            bNodeHashMap = matchByHashes(tc1, tc2, bNodeHashMap);
+            if (bNodeHashMap == null) {
+                throw new GraphNotIsomorphicException();
+            }
+            if (matchings.size() == foundMatchings) {
+                if (!(matchingGroups.size() > foundMatchingGroups)) {
+                    break;
+                }
+            }
+            foundMatchings = matchings.size();
+            foundMatchingGroups = matchingGroups.size();
+        }
+    }
+
+    /**
+     *
+     * @return a map containing set of which each bnodes mappes one of the other set
+     */
+    public Map<Set<BlankNode>, Set<BlankNode>> getMatchingGroups() {
+        return matchingGroups;
+    }
+
+    public Map<BlankNode, BlankNode> getMatchings() {
+        return matchings;
+    }
+
+    
+    private static IntHashMap<Set<BlankNode>> getHashNodes(Map<BlankNode,
+            Set<Property>> bNodePropMap, Map<BlankNode, Integer> bNodeHashMap) {
+        IntHashMap<Set<BlankNode>> result = new IntHashMap<Set<BlankNode>>();
+        for (Map.Entry<BlankNode, Set<Property>> entry : bNodePropMap.entrySet()) {
+            int hash = computeHash(entry.getValue(), bNodeHashMap);
+            Set<BlankNode> bNodeSet = result.get(hash);
+            if (bNodeSet == null) {
+                bNodeSet = new HashSet<BlankNode>();
+                result.put(hash,bNodeSet);
+            }
+            bNodeSet.add(entry.getKey());
+        }
+        return result;
+    }
+    /*
+     * returns a Map from bnodes to hash that can be used for future
+     * refinements, this could be separate for each ImmutableGraph.
+     *
+     * triples no longer containing an unmatched bnodes ae removed.
+     *
+     * Note that the matched node are not guaranteed to be equals, but only to
+     * be the correct if the graphs are isomorphic.
+     */
+    private Map<BlankNode, Integer> matchByHashes(Graph g1, Graph g2,
+            Map<BlankNode, Integer> bNodeHashMap) {
+        Map<BlankNode, Set<Property>> bNodePropMap1  = getBNodePropMap(g1);
+        Map<BlankNode, Set<Property>> bNodePropMap2  = getBNodePropMap(g2);
+        IntHashMap<Set<BlankNode>> hashNodeMap1 = getHashNodes(bNodePropMap1, bNodeHashMap);
+        IntHashMap<Set<BlankNode>> hashNodeMap2 = getHashNodes(bNodePropMap2, bNodeHashMap);
+        if (!hashNodeMap1.keySet().equals(hashNodeMap2.keySet())) {
+            return null;
+        }
+
+        matchingGroups = new HashMap<Set<BlankNode>, Set<BlankNode>>();
+        IntIterator hashIter = hashNodeMap1.keySet().intIterator();
+        while (hashIter.hasNext()) {
+            int hash = hashIter.next();
+            Set<BlankNode> nodes1 = hashNodeMap1.get(hash);
+            Set<BlankNode> nodes2 = hashNodeMap2.get(hash);
+            if (nodes1.size() != nodes2.size()) {
+                return null;
+            }
+            if (nodes1.size() != 1) {
+                matchingGroups.put(nodes1, nodes2);
+                continue;
+            }
+            final BlankNode bNode1 = nodes1.iterator().next();
+            final BlankNode bNode2 = nodes2.iterator().next();
+            matchings.put(bNode1,bNode2);
+            //in the graphs replace node occurences with grounded node,
+            BlankNodeOrIri mappedNode = new MappedNode(bNode1, bNode2);
+            replaceNode(g1,bNode1, mappedNode);
+            replaceNode(g2, bNode2, mappedNode);
+            //remove grounded triples
+            if (!Utils.removeGrounded(g1,g2)) {
+                return null;
+            }
+        }
+        Map<BlankNode, Integer> result = new HashMap<BlankNode, Integer>();
+        addInverted(result, hashNodeMap1);
+        addInverted(result, hashNodeMap2);
+        return result;
+    }
+    private static int computeHash(Set<Property> propertySet, Map<BlankNode, Integer> bNodeHashMap) {
+        int result = 0;
+        for (Property property : propertySet) {
+            result += property.hashCode(bNodeHashMap);
+        }
+        return result;
+    }
+    private static Map<BlankNode, Set<Property>> getBNodePropMap(Graph g) {
+        Set<BlankNode> bNodes = Utils.getBNodes(g);
+        Map<BlankNode, Set<Property>> result = new HashMap<BlankNode, Set<Property>>();
+        for (BlankNode bNode : bNodes) {
+            result.put(bNode, getProperties(bNode, g));
+        }
+        return result;
+    }
+    private static Set<Property> getProperties(BlankNode bNode, Graph g) {
+        Set<Property> result = new HashSet<Property>();
+        Iterator<Triple> ti = g.filter(bNode, null, null);
+        while (ti.hasNext()) {
+            Triple triple = ti.next();
+            result.add(new ForwardProperty(triple.getPredicate(), triple.getObject()));
+        }
+        ti = g.filter(null, null, bNode);
+        while (ti.hasNext()) {
+            Triple triple = ti.next();
+            result.add(new BackwardProperty(triple.getSubject(), triple.getPredicate()));
+        }
+        return result;
+    }
+    private static int nodeHash(RdfTerm resource, Map<BlankNode, Integer> bNodeHashMap) {
+        if (resource instanceof BlankNode) {
+            Integer mapValue = bNodeHashMap.get((BlankNode)resource);
+            if (mapValue == null) {
+                return 0;
+            } else {
+                return mapValue;
+            }
+        } else {
+            return resource.hashCode();
+        }
+    }
+    private static void replaceNode(Graph graph, BlankNode bNode, BlankNodeOrIri replacementNode) {
+        Set<Triple> triplesToRemove = new HashSet<Triple>();
+        for (Triple triple : graph) {
+            Triple replacementTriple = getReplacement(triple, bNode, replacementNode);
+            if (replacementTriple != null) {
+                triplesToRemove.add(triple);
+                graph.add(replacementTriple);
+            }
+        }
+        graph.removeAll(triplesToRemove);
+    }
+    private static Triple getReplacement(Triple triple, BlankNode bNode, BlankNodeOrIri replacementNode) {
+        if (triple.getSubject().equals(bNode)) {
+            if (triple.getObject().equals(bNode)) {
+                return new TripleImpl(replacementNode, triple.getPredicate(), replacementNode);
+            } else {
+                return new TripleImpl(replacementNode, triple.getPredicate(), triple.getObject());
+            }
+        } else {
+            if (triple.getObject().equals(bNode)) {
+                return new TripleImpl(triple.getSubject(), triple.getPredicate(), replacementNode);
+            } else {
+                return null;
+            }
+        }
+    }
+    private static void addInverted(Map<BlankNode, Integer> result, IntHashMap<Set<BlankNode>> hashNodeMap) {
+        for (int hash : hashNodeMap.keySet()) {
+            Set<BlankNode> bNodes = hashNodeMap.get(hash);
+            for (BlankNode bNode : bNodes) {
+                result.put(bNode, hash);
+            }
+        }
+    }
+    
+    private static class BackwardProperty implements Property {
+        private BlankNodeOrIri subject;
+        private Iri predicate;
+    
+        public BackwardProperty(BlankNodeOrIri subject, Iri predicate) {
+            this.subject = subject;
+            this.predicate = predicate;
+        }
+    
+        @Override
+        public int hashCode(Map<BlankNode, Integer> bNodeHashMap) {
+            return  0xFF ^ predicate.hashCode() ^ nodeHash(subject, bNodeHashMap);
+        }
+    
+    }
+    private static class ForwardProperty implements Property {
+        private Iri predicate;
+        private RdfTerm object;
+    
+        public ForwardProperty(Iri predicate, RdfTerm object) {
+            this.predicate = predicate;
+            this.object = object;
+        }
+    
+        @Override
+        public int hashCode(Map<BlankNode, Integer> bNodeHashMap) {
+            return predicate.hashCode() ^ nodeHash(object, bNodeHashMap);
+        }
+    }
+    private static class MappedNode implements BlankNodeOrIri {
+        private BlankNode bNode1, bNode2;
+    
+        public MappedNode(BlankNode bNode1, BlankNode bNode2) {
+            this.bNode1 = bNode1;
+            this.bNode2 = bNode2;
+        }
+        
+    }
+    private static interface Property {
+        public int hashCode(Map<BlankNode, Integer> bNodeHashMap);
+    }
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/MappingIterator.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/MappingIterator.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/MappingIterator.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/MappingIterator.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,76 @@
+package org.apache.commons.rdf.impl.utils.graphmatching;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * An iterator over all possible mapping beetween the elemnets of two sets of
+ * the same size, each mapping maps each element from set1 to a disctinct one of
+ * set2.
+ *
+ *
+ *
+ * @author reto
+ */
+class MappingIterator<T,U> implements Iterator<Map<T, U>> {
+
+    private List<T> list1;
+    private Iterator<List<U>> permutationList2Iterator;
+
+
+    public MappingIterator(Set<T> set1, Set<U> set2) {
+        if (set1.size() != set2.size()) {
+            throw new IllegalArgumentException();
+        }
+        this.list1 = new ArrayList<T>(set1);
+        permutationList2Iterator = new PermutationIterator<U>(
+                new ArrayList<U>(set2));
+    }
+
+    @Override
+    public boolean hasNext() {
+        return permutationList2Iterator.hasNext();
+    }
+
+    @Override
+    public Map<T, U> next() {
+        List<U> list2 = permutationList2Iterator.next();
+        Map<T, U> result = new HashMap<T, U>(list1.size());
+        for (int i = 0; i < list1.size(); i++) {
+            result.put(list1.get(i), list2.get(i));
+        }
+        return result;
+    }
+
+    @Override
+    public void remove() {
+        throw new UnsupportedOperationException("Not supported.");
+    }
+
+
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/PermutationIterator.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/PermutationIterator.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/PermutationIterator.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/PermutationIterator.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,107 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching;
+
+
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/**
+ *
+ * An Iterator over all permuations of a list.
+ *
+ * @author reto
+ */
+class PermutationIterator<T> implements Iterator<List<T>> {
+
+    private Iterator<List<T>> restIterator;
+    private List<T> list;
+    private List<T> next;
+    int posInList = 0; //the position of the last element of next returned list
+    //with list, this is the one excluded from restIterator
+
+    PermutationIterator(List<T> list) {
+        this.list = Collections.unmodifiableList(list);
+        if (list.size() > 1) {
+            createRestList();
+        }
+        prepareNext();
+    }
+
+    @Override
+    public boolean hasNext() {
+        return next != null;
+    }
+
+    @Override
+    public List<T> next() {
+        List<T> result = next;
+        if (result == null) {
+            throw new NoSuchElementException();
+        }
+        prepareNext();
+        return result;
+    }
+
+    @Override
+    public void remove() {
+        throw new UnsupportedOperationException("Not supported");
+    }
+
+    private void createRestList() {
+        List<T> restList = new ArrayList<T>(list);
+        restList.remove(posInList);
+        restIterator = new PermutationIterator<T>(restList);
+    }
+
+    private void prepareNext() {
+        next = getNext();
+        
+    }
+    private List<T> getNext() {
+        if (list.size() == 0) {
+            return null;
+        }
+        if (list.size() == 1) {
+            if (posInList++ == 0) {
+                return new ArrayList<T>(list);
+            } else {
+                return null;
+            }
+        } else {
+            if (!restIterator.hasNext()) {
+                if (posInList < (list.size()-1)) {
+                    posInList++;
+                    createRestList();
+                } else {
+                    return null;
+                }
+            }
+            List<T> result = restIterator.next();
+            result.add(list.get(posInList));
+            return result;
+        }
+    }
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/Utils.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/Utils.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/Utils.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/Utils.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,82 @@
+package org.apache.commons.rdf.impl.utils.graphmatching;
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+*/
+
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+
+import org.apache.commons.rdf.BlankNode;
+import org.apache.commons.rdf.Triple;
+
+public class Utils {
+
+    static Set<BlankNode> getBNodes(Collection<Triple> s) {
+        Set<BlankNode> result = new HashSet<BlankNode>();
+        for (Triple triple : s) {
+            if (triple.getSubject() instanceof BlankNode) {
+                result.add((BlankNode) triple.getSubject());
+            }
+            if (triple.getObject() instanceof BlankNode) {
+                result.add((BlankNode) triple.getObject());
+            }
+        }
+        return result;
+    }
+
+    /**
+     * removes the common grounded triples from s1 and s2. returns false if
+     * a grounded triple is not in both sets, true otherwise
+     */
+    static boolean removeGrounded(Collection<Triple> s1, Collection<Triple> s2) {
+        Iterator<Triple> triplesIter = s1.iterator();
+        while (triplesIter.hasNext()) {
+            Triple triple = triplesIter.next();
+            if (!isGrounded(triple)) {
+                continue;
+            }
+            if (!s2.remove(triple)) {
+                return false;
+            }
+            triplesIter.remove();
+        }
+        //for efficiency we might skip this (redefine method)
+        for (Triple triple : s2) {
+            if (isGrounded(triple)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private static boolean isGrounded(Triple triple) {
+        if (triple.getSubject() instanceof BlankNode) {
+            return false;
+        }
+        if (triple.getObject() instanceof BlankNode) {
+            return false;
+        }
+        return true;
+    }
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashMap.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashMap.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashMap.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashMap.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,377 @@
+/*
+ * Copyright 2002-2004 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Note: originally released under the GNU LGPL v2.1, 
+ * but rereleased by the original author under the ASF license (above).
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching.collections;
+
+
+
+/**
+ * <p>A hash map that uses primitive ints for the key rather than objects.</p>
+ *
+ * <p>Note that this class is for internal optimization purposes only, and may
+ * not be supported in future releases of Jakarta Commons Lang.  Utilities of
+ * this sort may be included in future releases of Jakarta Commons Collections.</p>
+ *
+ * @author Justin Couch
+ * @author Alex Chaffee (alex@apache.org)
+ * @author Stephen Colebourne
+ * @since 2.0
+ * @version $Revision: 1.2 $
+ * @see java.util.HashMap
+ */
+public class IntHashMap<T> {
+
+
+    private IntSet keySet = new IntHashSet();
+
+    /**
+     * The hash table data.
+     */
+    private transient Entry<T> table[];
+
+    /**
+     * The total number of entries in the hash table.
+     */
+    private transient int count;
+
+    /**
+     * The table is rehashed when its size exceeds this threshold.  (The
+     * value of this field is (int)(capacity * loadFactor).)
+     *
+     * @serial
+     */
+    private int threshold;
+
+    /**
+     * The load factor for the hashtable.
+     *
+     * @serial
+     */
+    private float loadFactor;
+
+    /**
+     * <p>Innerclass that acts as a datastructure to create a new entry in the
+     * table.</p>
+     */
+    private static class Entry<T> {
+        int hash;
+        int key;
+        T value;
+        Entry<T> next;
+
+        /**
+         * <p>Create a new entry with the given values.</p>
+         *
+         * @param hash The code used to hash the object with
+         * @param key The key used to enter this in the table
+         * @param value The value for this key
+         * @param next A reference to the next entry in the table
+         */
+        protected Entry(int hash, int key, T value, Entry<T> next) {
+            this.hash = hash;
+            this.key = key;
+            this.value = value;
+            this.next = next;
+        }
+    }
+
+    /**
+     * <p>Constructs a new, empty hashtable with a default capacity and load
+     * factor, which is <code>20</code> and <code>0.75</code> respectively.</p>
+     */
+    public IntHashMap() {
+        this(20, 0.75f);
+    }
+
+    /**
+     * <p>Constructs a new, empty hashtable with the specified initial capacity
+     * and default load factor, which is <code>0.75</code>.</p>
+     *
+     * @param  initialCapacity the initial capacity of the hashtable.
+     * @throws IllegalArgumentException if the initial capacity is less
+     *   than zero.
+     */
+    public IntHashMap(int initialCapacity) {
+        this(initialCapacity, 0.75f);
+    }
+
+    /**
+     * <p>Constructs a new, empty hashtable with the specified initial
+     * capacity and the specified load factor.</p>
+     *
+     * @param initialCapacity the initial capacity of the hashtable.
+     * @param loadFactor the load factor of the hashtable.
+     * @throws IllegalArgumentException  if the initial capacity is less
+     *             than zero, or if the load factor is nonpositive.
+     */
+    public IntHashMap(int initialCapacity, float loadFactor) {
+        super();
+        if (initialCapacity < 0) {
+            throw new IllegalArgumentException("Illegal Capacity: " + initialCapacity);
+        }
+        if (loadFactor <= 0) {
+            throw new IllegalArgumentException("Illegal Load: " + loadFactor);
+        }
+        if (initialCapacity == 0) {
+            initialCapacity = 1;
+        }
+
+        this.loadFactor = loadFactor;
+        table = new Entry[initialCapacity];
+        threshold = (int) (initialCapacity * loadFactor);
+    }
+
+    /**
+     * <p>Returns the number of keys in this hashtable.</p>
+     *
+     * @return  the number of keys in this hashtable.
+     */
+    public int size() {
+        return count;
+    }
+
+    /**
+     * <p>Tests if this hashtable maps no keys to values.</p>
+     *
+     * @return  <code>true</code> if this hashtable maps no keys to values;
+     *          <code>false</code> otherwise.
+     */
+    public boolean isEmpty() {
+        return count == 0;
+    }
+
+    /**
+     * <p>Tests if some key maps into the specified value in this hashtable.
+     * This operation is more expensive than the <code>containsKey</code>
+     * method.</p>
+     *
+     * <p>Note that this method is identical in functionality to containsValue,
+     * (which is part of the Map interface in the collections framework).</p>
+     *
+     * @param      value   a value to search for.
+     * @return     <code>true</code> if and only if some key maps to the
+     *             <code>value</code> argument in this hashtable as
+     *             determined by the <tt>equals</tt> method;
+     *             <code>false</code> otherwise.
+     * @throws  NullPointerException  if the value is <code>null</code>.
+     * @see        #containsKey(int)
+     * @see        #containsValue(Object)
+     * @see        java.util.Map
+     */
+    public boolean contains(Object value) {
+        if (value == null) {
+            throw new NullPointerException();
+        }
+
+        Entry tab[] = table;
+        for (int i = tab.length; i-- > 0;) {
+            for (Entry e = tab[i]; e != null; e = e.next) {
+                if (e.value.equals(value)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    /**
+     * <p>Returns <code>true</code> if this HashMap maps one or more keys
+     * to this value.</p>
+     *
+     * <p>Note that this method is identical in functionality to contains
+     * (which predates the Map interface).</p>
+     *
+     * @param value value whose presence in this HashMap is to be tested.
+     * @see    java.util.Map
+     * @since JDK1.2
+     */
+    public boolean containsValue(Object value) {
+        return contains(value);
+    }
+
+    /**
+     * <p>Tests if the specified object is a key in this hashtable.</p>
+     *
+     * @param  key  possible key.
+     * @return <code>true</code> if and only if the specified object is a
+     *    key in this hashtable, as determined by the <tt>equals</tt>
+     *    method; <code>false</code> otherwise.
+     * @see #contains(Object)
+     */
+    public boolean containsKey(int key) {
+        Entry tab[] = table;
+        int hash = key;
+        int index = (hash & 0x7FFFFFFF) % tab.length;
+        for (Entry e = tab[index]; e != null; e = e.next) {
+            if (e.hash == hash) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * <p>Returns the value to which the specified key is mapped in this map.</p>
+     *
+     * @param   key   a key in the hashtable.
+     * @return  the value to which the key is mapped in this hashtable;
+     *          <code>null</code> if the key is not mapped to any value in
+     *          this hashtable.
+     * @see     #put(int, Object)
+     */
+    public T get(int key) {
+        Entry<T> tab[] = table;
+        int hash = key;
+        int index = (hash & 0x7FFFFFFF) % tab.length;
+        for (Entry<T> e = tab[index]; e != null; e = e.next) {
+            if (e.hash == hash) {
+                return e.value;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * <p>Increases the capacity of and internally reorganizes this
+     * hashtable, in order to accommodate and access its entries more
+     * efficiently.</p>
+     *
+     * <p>This method is called automatically when the number of keys
+     * in the hashtable exceeds this hashtable's capacity and load
+     * factor.</p>
+     */
+    protected void rehash() {
+        int oldCapacity = table.length;
+        Entry<T> oldMap[] = table;
+
+        int newCapacity = oldCapacity * 2 + 1;
+        Entry<T> newMap[] = new Entry[newCapacity];
+
+        threshold = (int) (newCapacity * loadFactor);
+        table = newMap;
+
+        for (int i = oldCapacity; i-- > 0;) {
+            for (Entry<T> old = oldMap[i]; old != null;) {
+                Entry<T> e = old;
+                old = old.next;
+
+                int index = (e.hash & 0x7FFFFFFF) % newCapacity;
+                e.next = newMap[index];
+                newMap[index] = e;
+            }
+        }
+    }
+
+    /**
+     * <p>Maps the specified <code>key</code> to the specified
+     * <code>value</code> in this hashtable. The key cannot be
+     * <code>null</code>. </p>
+     *
+     * <p>The value can be retrieved by calling the <code>get</code> method
+     * with a key that is equal to the original key.</p>
+     *
+     * @param key     the hashtable key.
+     * @param value   the value.
+     * @return the previous value of the specified key in this hashtable,
+     *         or <code>null</code> if it did not have one.
+     * @throws  NullPointerException  if the key is <code>null</code>.
+     * @see     #get(int)
+     */
+    public Object put(int key, T value) {
+            keySet.add(key);
+        // Makes sure the key is not already in the hashtable.
+        Entry<T> tab[] = table;
+        int hash = key;
+        int index = (hash & 0x7FFFFFFF) % tab.length;
+        for (Entry<T> e = tab[index]; e != null; e = e.next) {
+            if (e.hash == hash) {
+                T old = e.value;
+                e.value = value;
+                return old;
+            }
+        }
+
+        if (count >= threshold) {
+            // Rehash the table if the threshold is exceeded
+            rehash();
+
+            tab = table;
+            index = (hash & 0x7FFFFFFF) % tab.length;
+        }
+
+        // Creates the new entry.
+        Entry<T> e = new Entry<T>(hash, key, value, tab[index]);
+        tab[index] = e;
+        count++;
+        return null;
+    }
+
+    /**
+     * <p>Removes the key (and its corresponding value) from this
+     * hashtable.</p>
+     *
+     * <p>This method does nothing if the key is not present in the
+     * hashtable.</p>
+     *
+     * @param   key   the key that needs to be removed.
+     * @return  the value to which the key had been mapped in this hashtable,
+     *          or <code>null</code> if the key did not have a mapping.
+     */
+    /*public Object remove(int key) {
+        Entry tab[] = table;
+        int hash = key;
+        int index = (hash & 0x7FFFFFFF) % tab.length;
+        for (Entry e = tab[index], prev = null; e != null; prev = e, e = e.next) {
+            if (e.hash == hash) {
+                if (prev != null) {
+                    prev.next = e.next;
+                } else {
+                    tab[index] = e.next;
+                }
+                count--;
+                Object oldValue = e.value;
+                e.value = null;
+                return oldValue;
+            }
+        }
+        return null;
+    }*/
+
+    /**
+     * <p>Clears this hashtable so that it contains no keys.</p>
+     */
+    public synchronized void clear() {
+            keySet.clear();
+        Entry tab[] = table;
+        for (int index = tab.length; --index >= 0;) {
+            tab[index] = null;
+        }
+        count = 0;
+    }
+    
+    public IntSet keySet() {
+            return keySet;
+    }
+    
+    
+    
+}
+

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashSet.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashSet.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashSet.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntHashSet.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2002-2004 The Apache Software Foundation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching.collections;
+
+import java.util.HashSet;
+import java.util.Iterator;
+
+/**
+ * This is currently just a placeholder implementation based onm HashSet<Integer>
+ * an efficient implementation is to store the primitives directly.
+ *
+ * @author reto
+ */
+public class IntHashSet extends HashSet<Integer> implements IntSet {
+
+    @Override
+    public IntIterator intIterator() {
+        final Iterator<Integer> base = iterator();
+        return new IntIterator() {
+
+            @Override
+            public int nextInt() {
+                return base.next();
+            }
+
+            @Override
+            public boolean hasNext() {
+                return base.hasNext();
+            }
+
+            @Override
+            public Integer next() {
+                return base.next();
+            }
+
+            @Override
+            public void remove() {
+                base.remove();
+            }
+        };
+    }
+
+    @Override
+    public void add(int i) {
+        super.add((Integer)i);
+    }
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntIterator.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntIterator.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntIterator.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntIterator.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2002-2004 The Apache Software Foundation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching.collections;
+
+import java.util.Iterator;
+
+
+/**
+ * An iterator allowing to iterate over ints, Iterator<Integer> is extended for
+ * compatibility, however accessing nextInt allows faster implementations.
+ *
+ * @author reto
+ */
+public interface IntIterator extends Iterator<Integer> {
+    public int nextInt();
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntSet.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntSet.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntSet.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/graphmatching/collections/IntSet.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2002-2004 The Apache Software Foundation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.rdf.impl.utils.graphmatching.collections;
+
+import java.util.Set;
+
+/**
+ * A IntSet allows directly adding primitive ints to a set, Set<Integer> is 
+ * extended, but accessingt he respective methods is less efficient.
+ *
+ * @author reto
+ */
+public interface IntSet extends Set<Integer> {
+    /**
+     *
+     * @return an iterator over the primitive int
+     */
+    public IntIterator intIterator();
+    
+    public void add(int i);
+}

Copied: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/package-info.java (from r1651181, commons/sandbox/rdf/trunk/src/main/java/org/apache/commons/rdf/package-info.java)
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/package-info.java?p2=commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/package-info.java&p1=commons/sandbox/rdf/trunk/src/main/java/org/apache/commons/rdf/package-info.java&r1=1651181&r2=1659973&rev=1659973&view=diff
==============================================================================
--- commons/sandbox/rdf/trunk/src/main/java/org/apache/commons/rdf/package-info.java (original)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/package-info.java Sun Feb 15 18:41:15 2015
@@ -16,6 +16,6 @@
  */
 
 /**
- * Common RDF API
+ * Common RDF API Implementation utilities.
  */
-package org.apache.commons.rdf;
\ No newline at end of file
+package org.apache.commons.rdf.impl.utils;
\ No newline at end of file

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraph.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraph.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraph.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraph.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,221 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.rdf.impl.utils.simple;
+
+import org.apache.commons.rdf.impl.utils.AbstractGraph;
+import java.lang.ref.SoftReference;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.ConcurrentModificationException;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.commons.rdf.BlankNodeOrIri;
+import org.apache.commons.rdf.ImmutableGraph;
+import org.apache.commons.rdf.RdfTerm;
+import org.apache.commons.rdf.Triple;
+import org.apache.commons.rdf.Iri;
+
+/**
+ * For now this is a minimalistic implementation, without any indexes or other
+ * optimizations.
+ *
+ * This class is not public, implementations should use {@link SimpleGraph} or
+ * {@link SimpleMGraph}.
+ *
+ * @author reto
+ */
+class SimpleGraph extends AbstractGraph {
+
+    final Set<Triple> triples;
+
+    private boolean checkConcurrency = false;
+
+    class SimpleIterator implements Iterator<Triple> {
+
+        private Iterator<Triple> listIter;
+        private boolean isValid = true;
+
+        public SimpleIterator(Iterator<Triple> listIter) {
+            this.listIter = listIter;
+        }
+        private Triple currentNext;
+
+        @Override
+        public boolean hasNext() {
+            checkValidity();
+            return listIter.hasNext();
+        }
+
+        @Override
+        public Triple next() {
+            checkValidity();
+            currentNext = listIter.next();
+            return currentNext;
+        }        
+
+        @Override
+        public void remove() {
+            checkValidity();
+            listIter.remove();
+            triples.remove(currentNext);            
+            invalidateIterators(this);            
+        }
+
+        private void checkValidity() throws ConcurrentModificationException {
+            if (checkConcurrency && !isValid) {
+                throw new ConcurrentModificationException();
+            }
+        }
+
+        private void invalidate() {
+            isValid = false;
+        }
+    }    
+    
+    private final Set<SoftReference<SimpleIterator>> iterators =
+            Collections.synchronizedSet(new HashSet<SoftReference<SimpleIterator>>());
+    
+    /**
+     * Creates an empty SimpleGraph
+     */
+    public SimpleGraph() {
+        triples = Collections.synchronizedSet(new HashSet<Triple>());
+    }
+
+    /**
+     * Creates a SimpleGraph using the passed iterator, the iterator 
+     * is consumed before the constructor returns
+     * 
+     * @param iterator
+     */
+    public SimpleGraph(Iterator<Triple> iterator) {
+        triples = new HashSet<Triple>();
+        while (iterator.hasNext()) {
+            Triple triple = iterator.next();
+            triples.add(triple);
+        }
+    }
+
+    /**
+     * Creates a SimpleGraph for the specified set of triples, 
+     * subsequent modification of baseSet do affect the created instance.
+     * 
+     * @param baseSet
+     */
+    public SimpleGraph(Set<Triple> baseSet) {
+        this.triples = baseSet;
+    }
+
+    /**
+     * Creates a SimpleGraph for the specified collection of triples,
+     * subsequent modification of baseSet do not affect the created instance.
+     *
+     * @param baseSet
+     */
+    public SimpleGraph(Collection<Triple> baseCollection) {
+        this.triples = new HashSet<Triple>(baseCollection);
+    }
+
+    @Override
+    public int performSize() {
+        return triples.size();
+    }
+
+    @Override
+    public Iterator<Triple> performFilter(final BlankNodeOrIri subject, final Iri predicate, final RdfTerm object) {
+        final List<Triple> tripleList = new ArrayList<Triple>();
+        synchronized (triples) {
+            Iterator<Triple> baseIter = triples.iterator();
+            while (baseIter.hasNext()) {
+                Triple triple = baseIter.next();
+                if ((subject != null)
+                        && (!triple.getSubject().equals(subject))) {
+                    continue;
+                }
+                if ((predicate != null)
+                        && (!triple.getPredicate().equals(predicate))) {
+                    continue;
+                }
+                if ((object != null)
+                        && (!triple.getObject().equals(object))) {
+                    continue;
+                }
+                tripleList.add(triple);
+            }
+
+            final Iterator<Triple> listIter = tripleList.iterator();
+            SimpleIterator resultIter = new SimpleIterator(listIter);
+            if (checkConcurrency) {
+                iterators.add(new SoftReference<SimpleIterator>(resultIter));
+            }
+            return resultIter;
+        }
+    }
+
+
+    @Override
+    public boolean performAdd(Triple e) {
+        boolean modified = triples.add(e);
+        if (modified) {
+            invalidateIterators(null);
+        }
+        return modified;
+    }
+    
+    private void invalidateIterators(SimpleIterator caller) {
+        if (!checkConcurrency) {
+            return;
+        }
+        Set<SoftReference> oldReferences = new HashSet<SoftReference>();
+        synchronized(iterators) {
+            for (SoftReference<SimpleGraph.SimpleIterator> softReference : iterators) {
+                SimpleIterator simpleIterator = softReference.get();
+                if (simpleIterator == null) {
+                    oldReferences.add(softReference);
+                    continue;
+                }
+                if (simpleIterator != caller) {
+                    simpleIterator.invalidate();
+                }
+            }
+        }
+        iterators.removeAll(oldReferences);
+    }
+
+    /**
+     * Specifies whether or not to throw <code>ConcurrentModificationException</code>s,
+     * if this simple triple collection is modified concurrently. Concurrency
+     * check is set to false by default.
+     *
+     * @param bool Specifies whether or not to check concurrent modifications.
+     */
+    public void setCheckConcurrency(boolean bool) {
+        checkConcurrency = bool;
+    }
+    
+    
+    @Override
+    public ImmutableGraph getImmutableGraph() {
+        return new SimpleImmutableGraph(this);
+    }
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleImmutableGraph.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleImmutableGraph.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleImmutableGraph.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleImmutableGraph.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,79 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.rdf.impl.utils.simple;
+
+import org.apache.commons.rdf.impl.utils.AbstractImmutableGraph;
+import java.util.Iterator;
+
+import org.apache.commons.rdf.BlankNodeOrIri;
+import org.apache.commons.rdf.RdfTerm;
+import org.apache.commons.rdf.Triple;
+import org.apache.commons.rdf.Graph;
+import org.apache.commons.rdf.Iri;
+
+/**
+ *
+ * @author reto
+ */
+public class SimpleImmutableGraph extends AbstractImmutableGraph {
+
+    private Graph graph;
+    
+    /**
+     * Creates a ImmutableGraph with the triples in Graph
+     * 
+     * @param Graph the collection of triples this ImmutableGraph shall consist of
+     */
+    public SimpleImmutableGraph(Graph Graph) {
+        this.graph = new SimpleGraph(Graph.iterator());
+    }
+
+    /**
+     * Creates a ImmutableGraph with the triples in Graph.
+     *
+     * This construction allows to specify if the Graph might change
+     * in future. If GraphWillNeverChange is set to true it will
+     * assume that the collection never changes, in this case the collection
+     * isn't copied making things more efficient.
+     *
+     * @param Graph the collection of triples this ImmutableGraph shall consist of
+     * @param GraphWillNeverChange true if the caller promises Graph will never change
+     */
+    public SimpleImmutableGraph(Graph Graph, boolean GraphWillNeverChange) {
+        if (!GraphWillNeverChange) {
+            this.graph = new SimpleGraph(Graph.iterator());
+        } else {
+            this.graph = Graph;
+        }
+    }
+    
+    public SimpleImmutableGraph(Iterator<Triple> tripleIter) {
+        this.graph = new SimpleGraph(tripleIter);
+    }
+
+    @Override
+    public int performSize() {
+        return graph.size();
+    }
+
+    @Override
+    public Iterator<Triple> performFilter(BlankNodeOrIri subject, Iri predicate, RdfTerm object) {
+        return graph.filter(subject, predicate, object);
+    }
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleMGraph.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleMGraph.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleMGraph.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/main/java/org/apache/commons/rdf/impl/utils/simple/SimpleMGraph.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.rdf.impl.utils.simple;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Set;
+
+import org.apache.commons.rdf.ImmutableGraph;
+import org.apache.commons.rdf.Graph;
+import org.apache.commons.rdf.Triple;
+
+/**
+ *
+ * @author reto
+ */
+public class SimpleMGraph extends SimpleGraph implements Graph {
+
+    /**
+     * Creates an empty SimpleMGraph
+     */
+    public SimpleMGraph() {
+    }
+
+    public SimpleMGraph(Set<Triple> baseSet) {
+        super(baseSet);
+    }
+
+    public SimpleMGraph(Collection<Triple> baseCollection) {
+        super(baseCollection);
+    }
+
+    public SimpleMGraph(Iterator<Triple> iterator) {
+        super(iterator);
+    }
+
+}
+
+    
\ No newline at end of file

Added: commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/PlainLiteralImplTest.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/PlainLiteralImplTest.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/PlainLiteralImplTest.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/PlainLiteralImplTest.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.rdf.impl.utils.simple;
+
+import org.apache.commons.rdf.impl.utils.PlainLiteralImpl;
+import org.junit.Test;
+import junit.framework.Assert;
+
+import org.apache.commons.rdf.Language;
+import org.apache.commons.rdf.Literal;
+/**
+ *
+ * @author reto
+ *
+ */
+
+public class PlainLiteralImplTest {
+
+    
+    @Test public void plainLiteralEquality() {
+        String stringValue = "some text";
+        Literal literal1 = new PlainLiteralImpl(stringValue);
+        Literal literal2 = new PlainLiteralImpl(stringValue);        
+        Assert.assertEquals(literal1, literal2);
+        Assert.assertEquals(literal1.hashCode(), literal2.hashCode());
+        Literal literal3 = new PlainLiteralImpl("something else");
+        Assert.assertFalse(literal1.equals(literal3));
+    }
+    
+    @Test public void languageLiteralEquality() {
+        String stringValue = "some text";
+        Language lang = new Language("en-ca");
+        Literal literal1 = new PlainLiteralImpl(stringValue, lang);
+        Literal literal2 = new PlainLiteralImpl(stringValue, lang);        
+        Assert.assertEquals(literal1, literal2);
+        Assert.assertEquals(literal1.hashCode(), literal2.hashCode());
+        Language lang2 = new Language("de");
+        Literal literal3 = new PlainLiteralImpl(stringValue, lang2);
+        Assert.assertFalse(literal1.equals(literal3));
+        Literal literal4 = new PlainLiteralImpl(stringValue, null);
+        Assert.assertFalse(literal3.equals(literal4));
+        Assert.assertFalse(literal4.equals(literal3));
+    }
+
+    /**
+     * hashCode of the lexical form plus the hashCode of the locale
+     */
+    @Test public void checkHashCode() {
+        String stringValue = "some text";
+        Language language = new Language("en");
+        Literal literal = new PlainLiteralImpl(stringValue, language);
+        Assert.assertEquals(stringValue.hashCode() + language.hashCode(), literal.hashCode());
+    }
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraphTest.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraphTest.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraphTest.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/SimpleGraphTest.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,109 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.rdf.impl.utils.simple;
+
+import org.apache.commons.rdf.impl.utils.TripleImpl;
+import java.util.ConcurrentModificationException;
+import java.util.Iterator;
+import org.junit.Assert;
+import org.junit.Test;
+import org.apache.commons.rdf.Triple;
+import org.apache.commons.rdf.Iri;
+import org.apache.commons.rdf.impl.utils.simple.SimpleGraph;
+
+/**
+ *
+ * @author mir
+ */
+public class SimpleGraphTest {
+
+    private Iri uriRef1 = new Iri("http://example.org/foo");
+    private Iri uriRef2 = new Iri("http://example.org/bar");
+    private Iri uriRef3 = new Iri("http://example.org/test");
+    private Triple triple1 = new TripleImpl(uriRef1, uriRef2, uriRef3);
+    private Triple triple2 = new TripleImpl(uriRef2, uriRef2, uriRef1);
+    private Triple triple3 = new TripleImpl(uriRef3, uriRef1, uriRef3);
+    private Triple triple4 = new TripleImpl(uriRef1, uriRef3, uriRef2);
+    private Triple triple5 = new TripleImpl(uriRef2, uriRef3, uriRef2);
+        
+    @Test
+    public void iteratorRemove() {
+        SimpleGraph stc = new SimpleGraph();
+        stc.add(triple1);
+        stc.add(triple2);
+        stc.add(triple3);
+        stc.add(triple4);
+        stc.add(triple5);
+        Iterator<Triple> iter = stc.iterator();
+        while (iter.hasNext()) {
+            Triple triple = iter.next();
+            iter.remove();
+        }
+        Assert.assertEquals(0, stc.size());
+    }
+
+    @Test
+    public void removeAll() {
+        SimpleGraph stc = new SimpleGraph();
+        stc.add(triple1);
+        stc.add(triple2);
+        stc.add(triple3);
+        stc.add(triple4);
+        stc.add(triple5);
+        SimpleGraph stc2 = new SimpleGraph();
+        stc2.add(triple1);
+        stc2.add(triple3);
+        stc2.add(triple5);
+        stc.removeAll(stc2);
+        Assert.assertEquals(2, stc.size());
+    }
+    
+    @Test
+    public void filterIteratorRemove() {
+        SimpleGraph stc = new SimpleGraph();
+        stc.add(triple1);
+        stc.add(triple2);
+        stc.add(triple3);
+        stc.add(triple4);
+        stc.add(triple5);        
+        Iterator<Triple> iter = stc.filter(uriRef1, null, null);
+        while (iter.hasNext()) {
+            Triple triple = iter.next();
+            iter.remove();
+        }
+        Assert.assertEquals(3, stc.size());
+    }
+
+    @Test(expected=ConcurrentModificationException.class)
+    public void remove() {
+        SimpleGraph stc = new SimpleGraph();
+        stc.setCheckConcurrency(true);
+        stc.add(triple1);
+        stc.add(triple2);
+        stc.add(triple3);
+        stc.add(triple4);
+        stc.add(triple5);
+        Iterator<Triple> iter = stc.filter(uriRef1, null, null);
+        while (iter.hasNext()) {
+            Triple triple = iter.next();
+            stc.remove(triple);
+        }
+        Assert.assertEquals(3, stc.size());
+    }
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TripleImplTest.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TripleImplTest.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TripleImplTest.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TripleImplTest.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,57 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+package org.apache.commons.rdf.impl.utils.simple;
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+*/
+
+
+import org.junit.Test;
+import junit.framework.Assert;
+
+import org.apache.commons.rdf.BlankNodeOrIri;
+import org.apache.commons.rdf.RdfTerm;
+import org.apache.commons.rdf.Triple;
+import org.apache.commons.rdf.Iri;
+import org.apache.commons.rdf.impl.utils.PlainLiteralImpl;
+import org.apache.commons.rdf.impl.utils.TripleImpl;
+/**
+ *
+ * @author reto
+ *
+ */
+
+public class TripleImplTest {
+    
+    
+    @Test public void tripleEquality() {
+        BlankNodeOrIri subject = new Iri("http://example.org/");
+        Iri predicate = new Iri("http://example.org/property");
+        RdfTerm object = new PlainLiteralImpl("property value");
+        Triple triple1 = new TripleImpl(subject, predicate, object);
+        Triple triple2 = new TripleImpl(subject, predicate, object);
+        Assert.assertEquals(triple1.hashCode(), triple2.hashCode());
+        Assert.assertEquals(triple1, triple2);    
+    }
+
+}

Added: commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TypedLiteralImplTest.java
URL: http://svn.apache.org/viewvc/commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TypedLiteralImplTest.java?rev=1659973&view=auto
==============================================================================
--- commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TypedLiteralImplTest.java (added)
+++ commons/sandbox/rdf/trunk/impl.utils/src/test/java/org/apache/commons/rdf/impl/utils/simple/TypedLiteralImplTest.java Sun Feb 15 18:41:15 2015
@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.rdf.impl.utils.simple;
+
+import org.apache.commons.rdf.impl.utils.TypedLiteralImpl;
+import org.junit.Test;
+import junit.framework.Assert;
+
+import org.apache.commons.rdf.Iri;
+import org.apache.commons.rdf.Literal;
+/**
+ *
+ * @author reto/**
+ *
+ * @author reto/**
+ *
+ * @author reto/**
+ *
+ * @author reto
+ *
+ */
+
+public class TypedLiteralImplTest {
+    
+    
+    @Test public void typedLiteralEquality() {
+        String stringValue = "some text";
+        Iri uriRef = new Iri("http://example.org/datatypes/magic");
+        Literal literal1 = new TypedLiteralImpl(stringValue, uriRef);
+        Literal literal2 = new TypedLiteralImpl(stringValue, uriRef);        
+        Assert.assertEquals(literal1, literal2);
+        Assert.assertEquals(literal1.hashCode(), literal2.hashCode());
+        Literal literal3 = new TypedLiteralImpl("something else", uriRef);
+        Assert.assertFalse(literal1.equals(literal3));
+        Iri uriRef2 = new Iri("http://example.org/datatypes/other");
+        Literal literal4 = new TypedLiteralImpl(stringValue, uriRef2);
+        Assert.assertFalse(literal1.equals(literal4));
+    }
+
+
+    /**
+     * The hascode is equals to the hascode of the lexical form plus the hashcode of the dataTyp
+     */
+    @Test public void checkHashCode() {
+        String stringValue = "some text";
+        Iri uriRef = new Iri("http://example.org/datatypes/magic");
+        Literal literal =  new TypedLiteralImpl(stringValue, uriRef);
+        Assert.assertEquals(stringValue.hashCode() + uriRef.hashCode(), literal.hashCode());
+    }
+
+}