Implement local version of position() and last()

.gitignore

@@ -1,3 +1,4 @@
 .idea/
 target/
 *.iml
+/bin/

src/main/java/sparksoniq/exceptions/AbsentPartOfDynamicContextException.java

@@ -0,0 +1,35 @@
+/*
+ * 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.
+ *
+ * Authors: Stefan Irimescu, Can Berker Cikis
+ *
+ */
+
+
+package sparksoniq.exceptions;
+
+import sparksoniq.exceptions.codes.ErrorCodes;
+import sparksoniq.jsoniq.compiler.translator.metadata.ExpressionMetadata;
+import sparksoniq.jsoniq.runtime.metadata.IteratorMetadata;
+
+public class AbsentPartOfDynamicContextException extends SparksoniqRuntimeException {
+
+	private static final long serialVersionUID = 1L;
+
+	public AbsentPartOfDynamicContextException(String message, IteratorMetadata iteratorMetadata) {
+        super(message, ErrorCodes.AbsentPartOfDynamicContextCode, iteratorMetadata.getExpressionMetadata());
+    }
+}

src/main/java/sparksoniq/exceptions/codes/ErrorCodes.java

@@ -45,6 +45,7 @@ public class ErrorCodes {
     public static final String UnimplementedErrorCode = "SPRKIQ0002";
 
 
+    public static final String AbsentPartOfDynamicContextCode = "XPDY0002";
     public static final String DynamicTypeTreatErrorCode = "XPDY0050";
     public static final String RuntimeExceptionErrorCode = "XPDY0130";
 

src/main/java/sparksoniq/jsoniq/runtime/iterator/functions/base/Functions.java

@@ -35,6 +35,8 @@
 import sparksoniq.jsoniq.runtime.iterator.functions.binaries.HexBinaryFunctionIterator;
 import sparksoniq.jsoniq.runtime.iterator.functions.booleans.BooleanFunctionIterator;
 import sparksoniq.jsoniq.runtime.iterator.functions.io.JsonDocFunctionIterator;
+import sparksoniq.jsoniq.runtime.iterator.functions.context.PositionFunctionIterator;
+import sparksoniq.jsoniq.runtime.iterator.functions.context.LastFunctionIterator;
 import sparksoniq.jsoniq.runtime.iterator.functions.datetime.DateFunctionIterator;
 import sparksoniq.jsoniq.runtime.iterator.functions.datetime.DateTimeFunctionIterator;
 import sparksoniq.jsoniq.runtime.iterator.functions.datetime.TimeFunctionIterator;
@@ -131,6 +133,9 @@ public class Functions {
         userDefinedFunctions = new HashMap<>();
         builtInFunctions = new HashMap<>();
 
+        builtInFunctions.put(new FunctionIdentifier(POSITION, 0), PositionFunctionIterator.class);
+        builtInFunctions.put(new FunctionIdentifier(LAST, 0), LastFunctionIterator.class);
+
         builtInFunctions.put(new FunctionIdentifier(JSON_FILE, 1), ParseJsonFunctionIterator.class);
         builtInFunctions.put(new FunctionIdentifier(JSON_FILE, 2), ParseJsonFunctionIterator.class);
         builtInFunctions.put(new FunctionIdentifier(JSON_DOC, 1), JsonDocFunctionIterator.class);
@@ -310,6 +315,14 @@ public static FunctionItem getUserDefinedFunction(FunctionIdentifier identifier,
     }
 
     public static class FunctionNames {
+        /**
+         * function that returns the context position
+         */
+        public static final String POSITION = "position";
+        /**
+         * function that returns the context size
+         */
+        public static final String LAST  = "last";
 
         /**
          * function that parses a JSON lines file

src/main/java/sparksoniq/jsoniq/runtime/iterator/functions/context/LastFunctionIterator.java

@@ -0,0 +1,77 @@
+/*
+ * 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.
+ *
+ * Authors: Stefan Irimescu, Can Berker Cikis
+ *
+ */
+
+package sparksoniq.jsoniq.runtime.iterator.functions.context;
+
+import sparksoniq.exceptions.AbsentPartOfDynamicContextException;
+import sparksoniq.jsoniq.item.ItemFactory;
+import sparksoniq.jsoniq.runtime.iterator.RuntimeIterator;
+import sparksoniq.jsoniq.runtime.iterator.functions.base.LocalFunctionCallIterator;
+import sparksoniq.jsoniq.runtime.metadata.IteratorMetadata;
+import sparksoniq.semantics.DynamicContext;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+import org.rumbledb.api.Item;
+
+public class LastFunctionIterator extends LocalFunctionCallIterator {
+
+
+	private static final long serialVersionUID = 1L;
+
+    public LastFunctionIterator(List<RuntimeIterator> arguments, IteratorMetadata iteratorMetadata) {
+        super(arguments, iteratorMetadata);
+    }
+
+    @Override
+    public void open(DynamicContext context) {
+        super.open(context);
+        this._hasNext = true;
+    }
+
+    @Override
+    public Item next() {
+        if (this._hasNext) {
+            this._hasNext = false;
+            long last = _currentDynamicContext.getLast();
+            if(last == -1)
+            {
+	            throw new AbsentPartOfDynamicContextException("Context indefined (last) ", getMetadata());
+            }
+            if(last < Integer.MAX_VALUE)
+            {
+            	return ItemFactory.getInstance().createIntegerItem((int)last);
+            } else {
+            	return ItemFactory.getInstance().createDecimalItem(new BigDecimal(last));
+            }
+        }
+        return null;
+    }
+
+    public Map<String, DynamicContext.VariableDependency> getVariableDependencies() {
+        Map<String, DynamicContext.VariableDependency> result = new TreeMap<String, DynamicContext.VariableDependency>();
+        result.put("$last", DynamicContext.VariableDependency.FULL);
+        return result;
+    }
+
+}

src/main/java/sparksoniq/jsoniq/runtime/iterator/functions/context/PositionFunctionIterator.java

@@ -0,0 +1,77 @@
+/*
+ * 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.
+ *
+ * Authors: Stefan Irimescu, Can Berker Cikis
+ *
+ */
+
+package sparksoniq.jsoniq.runtime.iterator.functions.context;
+
+import sparksoniq.exceptions.AbsentPartOfDynamicContextException;
+import sparksoniq.jsoniq.item.ItemFactory;
+import sparksoniq.jsoniq.runtime.iterator.RuntimeIterator;
+import sparksoniq.jsoniq.runtime.iterator.functions.base.LocalFunctionCallIterator;
+import sparksoniq.jsoniq.runtime.metadata.IteratorMetadata;
+import sparksoniq.semantics.DynamicContext;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+import org.rumbledb.api.Item;
+
+public class PositionFunctionIterator extends LocalFunctionCallIterator {
+
+
+	private static final long serialVersionUID = 1L;
+
+    public PositionFunctionIterator(List<RuntimeIterator> arguments, IteratorMetadata iteratorMetadata) {
+        super(arguments, iteratorMetadata);
+    }
+
+    @Override
+    public void open(DynamicContext context) {
+        super.open(context);
+        this._hasNext = true;
+    }
+
+    @Override
+    public Item next() {
+        if (this._hasNext) {
+            this._hasNext = false;
+            long position = _currentDynamicContext.getPosition();
+            if(position == -1)
+            {
+	            throw new AbsentPartOfDynamicContextException("Context indefined (position) ", getMetadata());
+            }
+            if(position < Integer.MAX_VALUE)
+            {
+            	return ItemFactory.getInstance().createIntegerItem((int)position);
+            } else {
+            	return ItemFactory.getInstance().createDecimalItem(new BigDecimal(position));
+            }
+        }
+        return null;
+    }
+
+    public Map<String, DynamicContext.VariableDependency> getVariableDependencies() {
+        Map<String, DynamicContext.VariableDependency> result = new TreeMap<String, DynamicContext.VariableDependency>();
+        result.put("$position", DynamicContext.VariableDependency.FULL);
+        return result;
+    }
+
+}

src/main/java/sparksoniq/jsoniq/runtime/iterator/postfix/PredicateIterator.java

@@ -43,12 +43,16 @@ public class PredicateIterator extends HybridRuntimeIterator {
     private RuntimeIterator _iterator;
     private RuntimeIterator _filter;
     private Item _nextResult;
+    private long _position;
+    private boolean _mustMaintainPosition;
+    private DynamicContext _filterDynamicContext;
 
 
     public PredicateIterator(RuntimeIterator sequence, RuntimeIterator filterExpression, IteratorMetadata iteratorMetadata) {
         super(Arrays.asList(sequence, filterExpression), iteratorMetadata);
         _iterator = sequence;
         _filter = filterExpression;
+        _filterDynamicContext = null;
     }
 
     @Override
@@ -68,7 +72,18 @@ protected boolean hasNextLocal() {
 
     @Override
     protected void resetLocal(DynamicContext context) {
-        _iterator.reset(_currentDynamicContext);
+        _iterator.close();
+        _filterDynamicContext = new DynamicContext(_currentDynamicContext);
+        if(_filter.getVariableDependencies().containsKey("$last"))
+    	{
+    		setLast();
+    	}
+    	if(_filter.getVariableDependencies().containsKey("$position"))
+    	{
+            _position = 0;
+    		_mustMaintainPosition = true;
+    	}
+        _iterator.open(_currentDynamicContext);
         setNextResult();
     }
 
@@ -82,9 +97,31 @@ protected void openLocal() {
         if (this._children.size() < 2) {
             throw new SparksoniqRuntimeException("Invalid Predicate! Must initialize filter before calling next");
         }
+        _filterDynamicContext = new DynamicContext(_currentDynamicContext);
+    	if(_filter.getVariableDependencies().containsKey("$last"))
+    	{
+    		setLast();
+    	}
+    	if(_filter.getVariableDependencies().containsKey("$position"))
+    	{
+            _position = 0;
+    		_mustMaintainPosition = true;
+    	}
         _iterator.open(_currentDynamicContext);
         setNextResult();
     }
+
+    private void setLast() {
+    	long last = 0;
+        _iterator.open(_currentDynamicContext);
+        while(_iterator.hasNext())
+        {
+        	_iterator.next();
+        	++last;
+        }
+        _iterator.close();
+        _filterDynamicContext.setLast(last);
+    }
 
     private void setNextResult() {
         _nextResult = null;
@@ -93,9 +130,11 @@ private void setNextResult() {
             Item item = _iterator.next();
             List<Item> currentItems = new ArrayList<>();
             currentItems.add(item);
-            _currentDynamicContext.addVariableValue("$$", currentItems);
+            _filterDynamicContext.addVariableValue("$$", currentItems);
+            if(_mustMaintainPosition)
+            	_filterDynamicContext.setPosition(++_position);
 
-            _filter.open(_currentDynamicContext);
+            _filter.open(_filterDynamicContext);
             Item fil = null;
             if (_filter.hasNext()) {
                 fil = _filter.next();
@@ -118,7 +157,7 @@ private void setNextResult() {
             }
             _filter.close();
         }
-        _currentDynamicContext.removeVariable("$$");
+        _filterDynamicContext.removeVariable("$$");
 
         if (_nextResult == null) {
             this._hasNext = false;