Started to add filters

src/main/java/org/vizierdb/database/CellSet.java

@@ -24,11 +24,35 @@ import org.vizierdb.database.value.Value;
  */
 public class CellSet implements Iterable<Cell> {
     
-    private final HashMap<Integer, Cell> _cells = new HashMap<>();
+    private final HashMap<String, Cell> _cellIndex = new HashMap<>();
+    private final HashMap<Integer, Cell> _valueIndex = new HashMap<>();
     
     public void add(Cell cell) {
 	
-	_cells.put(cell.getValue().getIdentifier(), cell);
+	_cellIndex.put(cell.getKey(), cell);
+	_valueIndex.put(cell.getValue().getIdentifier(), cell);
+    }
+    
+    /**
+     * Cell with the given key.
+     * 
+     * @param key
+     * @return 
+     */
+    public Cell getCell(String key) {
+	
+	return _cellIndex.get(key);
+    }
+    
+    /**
+     * Cell at given coordinate position.
+     * 
+     * @param coordinates
+     * @return 
+     */
+    public Cell getCell(CellCoordinates coordinates) {
+	
+	return this.getCell(coordinates.getKey());
     }
     
     /**
@@ -39,7 +63,7 @@ public class CellSet implements Iterable<Cell> {
      */
     public Cell getCellForValue(int valueId) {
 	
-	return _cells.get(valueId);
+	return _valueIndex.get(valueId);
     }
     
     /**
@@ -50,7 +74,7 @@ public class CellSet implements Iterable<Cell> {
      */
     public Value getValue(int valueId) {
 	
-	Cell cell = _cells.get(valueId);
+	Cell cell = _valueIndex.get(valueId);
 	if (cell != null) {
 	    return cell.getValue();
 	} else {
@@ -61,6 +85,6 @@ public class CellSet implements Iterable<Cell> {
     @Override
     public Iterator<Cell> iterator() {
 
-	return _cells.values().iterator();
+	return _valueIndex.values().iterator();
     }
 }

src/main/java/org/vizierdb/database/CellSetFactory.java

@@ -17,7 +17,6 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
-import org.vizierdb.database.value.ConstantValue;
 import org.vizierdb.database.value.DependencyGraph;
 import org.vizierdb.database.value.ErrorValue;
 import org.vizierdb.database.value.Value;
@@ -34,7 +33,6 @@ import org.vizierdb.database.value.formula.Formula;
 public class CellSetFactory {
    
     private final CellSet _cells = new CellSet();
-    private final HashMap<String, Cell> _cellIndex = new HashMap<>();
     private final DependencyGraph _graph = new DependencyGraph();
     
     /**
@@ -45,7 +43,6 @@ public class CellSetFactory {
     public void add(Cell cell) {
 	
 	_cells.add(cell);
-	_cellIndex.put(cell.getKey(), cell);
 	if (cell.getValue().isDerived()) {
 	    int valueId = cell.getValue().getIdentifier();
 	    for (int sourceValueId : cell.getValue().getDependencies()) {
@@ -115,7 +112,7 @@ public class CellSetFactory {
      */
     public Cell get(String key) {
 	
-	return _cellIndex.get(key);
+	return _cells.getCell(key);
     }
     
     /**

src/main/java/org/vizierdb/database/Row.java

@@ -0,0 +1,51 @@
+/*
+ * 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.vizierdb.database;
+
+import org.vizierdb.database.value.Value;
+
+/**
+ * Row in a spreadsheet. Primarily used to group cells for evaluation in filter
+ * conditions.
+ * 
+ * @author Heiko Mueller
+ */
+public class Row {
+    
+    private final CellSet _cells;
+    private final int _rowId;
+    
+    public Row(int rowId, CellSet cells) {
+	
+	_rowId = rowId;
+	_cells = cells;
+    }
+    
+    /**
+     * Value for column with given identifier. The result is null if the row
+     * does not have a value for the given column.
+     * 
+     * @param columnId
+     * @return 
+     */
+    public Value getColumnValue(int columnId) {
+	
+	Cell cell = _cells.getCell(new CellCoordinates(columnId, _rowId));
+	if (cell != null) {
+	    return cell.getValue();
+	} else {
+	    return null;
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/ANDOp.java

@@ -0,0 +1,39 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.ColumnList;
+import org.vizierdb.database.Row;
+
+/**
+ *
+ * @author heiko
+ */
+public class ANDOp extends LogicOp {
+
+    public ANDOp(Condition left, Condition right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	if (this.left().eval(row)) {
+	    return this.right().eval(row);
+	} else {
+	    return false;
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/BinaryOp.java

@@ -0,0 +1,60 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.ColumnList;
+
+/**
+ *
+ * @author heiko
+ */
+public abstract class BinaryOp implements Condition {
+
+    private final Term _left;
+    private final Term _right;
+    
+    public BinaryOp(Term left, Term right) {
+
+	_left = left;
+	_right = right;
+    }
+
+    @Override
+    public boolean isApplicable(ColumnList columns) {
+
+	Integer col = _left.getReferencedColumn();
+	if (col != null) {
+	    if (!columns.contains(col)) {
+		return false;
+	    }
+	}
+	col = _right.getReferencedColumn();
+	if (col != null) {
+	    if (!columns.contains(col)) {
+		return false;
+	    }
+	}
+	return true;
+    }
+    
+    public Term left() {
+	
+	return _left;
+    }
+    
+    public Term rigth() {
+	
+	return _right;
+    }
+}

src/main/java/org/vizierdb/database/filter/ColumnTerm.java

@@ -0,0 +1,44 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ * Term that returns value of column with specific identifier.
+ * 
+ * @author Heiko Mueller
+ */
+public class ColumnTerm implements Term {
+    
+    private final int _columnId;
+    
+    public ColumnTerm(int columnId) {
+	
+	_columnId = columnId;
+    }
+
+    @Override
+    public Value getValue(Row row) {
+
+	return row.getColumnValue(_columnId);
+    }
+
+    @Override
+    public Integer getReferencedColumn() {
+
+	return _columnId;
+    }
+}

src/main/java/org/vizierdb/database/filter/Condition.java

@@ -0,0 +1,42 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.ColumnList;
+import org.vizierdb.database.Row;
+
+/**
+ * Condition in a VizUAL filter. Conditions are evaluated over rows in a
+ * spreadsheet.
+ * 
+ * @author Heiko Mueller
+ */
+public interface Condition {
+    
+    /**
+     * Evaluate the condition on a spreadsheet row.
+     * 
+     * @param row
+     * @return 
+     */
+    public boolean eval(Row row);
+    
+    /**
+     * Test if all column terms can be evaluated over given list of columns.
+     * 
+     * @param columns
+     * @return 
+     */
+    public boolean isApplicable(ColumnList columns);
+}

src/main/java/org/vizierdb/database/filter/ConstantTerm.java

@@ -0,0 +1,45 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ * Constant value term.
+ * 
+ * @author heiko
+ */
+public class ConstantTerm implements Term{
+
+    private final Value _value;
+    
+    public ConstantTerm(Value value) {
+	
+	_value = value;
+    }
+    
+    
+    @Override
+    public Value getValue(Row row) {
+
+	return _value;
+    }
+
+    @Override
+    public Integer getReferencedColumn() {
+
+	return null;
+    }
+}

src/main/java/org/vizierdb/database/filter/EQOp.java

@@ -0,0 +1,46 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class EQOp extends BinaryOp {
+
+    public EQOp(Term left, Term right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value leftVal = this.left().getValue(row);
+	Value rightVal = this.rigth().getValue(row);
+	
+	if ((leftVal != null) && (rightVal != null)) {
+	    try {
+		return (leftVal.getAsBigDecimal().compareTo(rightVal.getAsBigDecimal()) == 0);
+	    } catch (Exception exception) {
+		return leftVal.getAsString().equals(rightVal.getAsString());
+	    }
+	} else {
+	    return ((leftVal == null) && (rightVal == null));
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/GEQOp.java

@@ -0,0 +1,46 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class GEQOp extends BinaryOp {
+
+    public GEQOp(Term left, Term right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value leftVal = this.left().getValue(row);
+	Value rightVal = this.rigth().getValue(row);
+	
+	if ((leftVal != null) && (rightVal != null)) {
+	    try {
+		return (leftVal.getAsBigDecimal().compareTo(rightVal.getAsBigDecimal()) >= 0);
+	    } catch (Exception exception) {
+		return (leftVal.getAsString().compareTo(rightVal.getAsString()) >= 0);
+	    }
+	} else {
+	    return ((leftVal == null) && (rightVal == null));
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/GTOp.java

@@ -0,0 +1,46 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class GTOp extends BinaryOp {
+
+    public GTOp(Term left, Term right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value leftVal = this.left().getValue(row);
+	Value rightVal = this.rigth().getValue(row);
+	
+	if ((leftVal != null) && (rightVal != null)) {
+	    try {
+		return (leftVal.getAsBigDecimal().compareTo(rightVal.getAsBigDecimal()) > 0);
+	    } catch (Exception exception) {
+		return (leftVal.getAsString().compareTo(rightVal.getAsString()) > 0);
+	    }
+	} else {
+	    return false;
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/LEQOp.java

@@ -0,0 +1,46 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class LEQOp extends BinaryOp {
+
+    public LEQOp(Term left, Term right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value leftVal = this.left().getValue(row);
+	Value rightVal = this.rigth().getValue(row);
+	
+	if ((leftVal != null) && (rightVal != null)) {
+	    try {
+		return (leftVal.getAsBigDecimal().compareTo(rightVal.getAsBigDecimal()) <= 0);
+	    } catch (Exception exception) {
+		return (leftVal.getAsString().compareTo(rightVal.getAsString()) <= 0);
+	    }
+	} else {
+	    return ((leftVal == null) && (rightVal == null));
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/LTOp.java

@@ -0,0 +1,46 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class LTOp extends BinaryOp {
+
+    public LTOp(Term left, Term right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value leftVal = this.left().getValue(row);
+	Value rightVal = this.rigth().getValue(row);
+	
+	if ((leftVal != null) && (rightVal != null)) {
+	    try {
+		return (leftVal.getAsBigDecimal().compareTo(rightVal.getAsBigDecimal()) < 0);
+	    } catch (Exception exception) {
+		return (leftVal.getAsString().compareTo(rightVal.getAsString()) < 0);
+	    }
+	} else {
+	    return false;
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/LogicOp.java

@@ -0,0 +1,52 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.ColumnList;
+
+/**
+ *
+ * @author heiko
+ */
+public abstract class LogicOp implements Condition {
+
+    private final Condition _left;
+    private final Condition _right;
+    
+    public LogicOp(Condition left, Condition right) {
+
+	_left = left;
+	_right = right;
+    }
+    
+    @Override
+    public boolean isApplicable(ColumnList columns) {
+
+	if (_left.isApplicable(columns)) {
+	    return _right.isApplicable(columns);
+	} else {
+	    return false;
+	}
+    }
+    
+    public Condition left() {
+	
+	return _left;
+    }
+    
+    public Condition right() {
+	
+	return _right;
+    } 
+}

src/main/java/org/vizierdb/database/filter/MatchesOp.java

@@ -0,0 +1,61 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import java.util.regex.Pattern;
+import org.vizierdb.database.ColumnList;
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class MatchesOp implements Condition {
+
+    private final Pattern _pattern;
+    private final Term _term;
+    
+    public MatchesOp(Term term, Pattern pattern) {
+
+	_term = term;
+	_pattern = pattern;
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value val = _term.getValue(row);
+	
+	if (val != null) {
+	    try {
+		return _pattern.matcher(val.getAsString()).matches();
+	    } catch (Exception exception) {
+		return false;
+	    }
+	} else {
+	    return false;
+	}
+    }
+
+    @Override
+    public boolean isApplicable(ColumnList columns) {
+
+	Integer col = _term.getReferencedColumn();
+	if (col != null) {
+	    return (columns.contains(col));
+	}
+	return false;
+    }
+}

src/main/java/org/vizierdb/database/filter/NEQOp.java

@@ -0,0 +1,46 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ *
+ * @author heiko
+ */
+public class NEQOp extends BinaryOp {
+
+    public NEQOp(Term left, Term right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	Value leftVal = this.left().getValue(row);
+	Value rightVal = this.rigth().getValue(row);
+	
+	if ((leftVal != null) && (rightVal != null)) {
+	    try {
+		return (leftVal.getAsBigDecimal().compareTo(rightVal.getAsBigDecimal()) != 0);
+	    } catch (Exception exception) {
+		return !leftVal.getAsString().equals(rightVal.getAsString());
+	    }
+	} else {
+	    return !((leftVal == null) && (rightVal == null));
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/OROp.java

@@ -0,0 +1,38 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+
+/**
+ *
+ * @author heiko
+ */
+public class OROp extends LogicOp {
+
+    public OROp(Condition left, Condition right) {
+
+	super(left, right);
+    }
+    
+    @Override
+    public boolean eval(Row row) {
+
+	if (this.left().eval(row)) {
+	    return true;
+	} else {
+	    return this.right().eval(row);
+	}
+    }
+}

src/main/java/org/vizierdb/database/filter/Term.java

@@ -0,0 +1,41 @@
+/*
+ * 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.vizierdb.database.filter;
+
+import org.vizierdb.database.Row;
+import org.vizierdb.database.value.Value;
+
+/**
+ * Value expression in a filter condition operator. Returns a value. Could
+ * either be a constant value or the value of a cell in a spreadsheet row.
+ * 
+ * @author Heiko Mueller
+ */
+public interface Term {
+    
+    /**
+     * The value that the term evaluates to for the given row.
+     * 
+     * @param row
+     * @return 
+     */
+    public Value getValue(Row row);
+    
+    /**
+     * The identifier of the column from which the value is extracted. The
+     * result is null if the term represents a constant value.
+     * @return 
+     */
+    public Integer getReferencedColumn();
+}

src/main/java/org/vizierdb/database/script/OperationType.java

@@ -62,6 +62,7 @@ public enum OperationType {
    
     DeleteColumn,
     DeleteRow,
+    Filter,
     InsertColumn,
     InsertRow,
     LoadFile,

src/main/java/org/vizierdb/database/script/op/RowFilter.java

@@ -0,0 +1,85 @@
+/*
+ * 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.vizierdb.database.script.op;
+
+import java.util.ArrayList;
+import org.vizierdb.database.Cell;
+import org.vizierdb.database.CellSetFactory;
+import org.vizierdb.database.Notebook;
+import org.vizierdb.database.Row;
+import org.vizierdb.database.RowList;
+import org.vizierdb.database.Snapshot;
+import org.vizierdb.database.filter.Condition;
+import org.vizierdb.database.script.Operation;
+import org.vizierdb.database.script.OperationType;
+import org.vizierdb.database.script.VizUALStatement;
+
+/**
+ *
+ * @author heiko
+ */
+public class RowFilter extends Operation {
+
+    private final Condition _filter;
+    
+    public RowFilter(Condition filter) {
+	
+	super(OperationType.Filter);
+	
+	_filter = filter;
+    }
+    
+    @Override
+    public Snapshot exec(Notebook notebook, Snapshot snapshot, int resultIdentifier) {
+
+	RowList rows = new RowList();
+	for (int rowId : snapshot.getRows()) {
+	    Row row = new Row(rowId, snapshot.getCells());
+	    if (_filter.eval(row)) {
+		rows.add(rowId);
+		
+	    }
+	}
+	
+	CellSetFactory cells = new CellSetFactory();
+	ArrayList<Integer> deletedValues = new ArrayList<>();
+	for (Cell cell : snapshot.getCells()) {
+	    if (rows.contains(cell.getRowId())) {
+		cells.add(cell);
+	    } else {
+		deletedValues.add(cell.getValue().getIdentifier());
+	    }
+	}
+	/*
+	 * Create new snapshot and update values that depend on values in
+	 * the deleted row.
+	 */
+	Snapshot nextSnapshot = new Snapshot(resultIdentifier, snapshot.getColumns(), rows, cells.getSet());
+	if (!deletedValues.isEmpty()) {
+	    cells.evalForDeletedValues(nextSnapshot, deletedValues);
+	}
+	return nextSnapshot;
+    }
+
+    @Override
+    public VizUALStatement getStatement(Snapshot snapshot) {
+	throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+    }
+
+    @Override
+    public boolean isApplicable(Snapshot snapshot) {
+
+	return _filter.isApplicable(snapshot.getColumns());
+    }
+}

src/main/java/org/vizierdb/database/value/ConstantValue.java

@@ -48,6 +48,12 @@ public class ConstantValue extends Value {
 	return new BigDecimal(_value);
     }
 
+    @Override
+    public String getAsString() {
+
+	return _value;
+    }
+
     @Override
     public List<Integer> getDependencies() {
 
@@ -57,13 +63,7 @@ public class ConstantValue extends Value {
     @Override
     public String getFormula(Snapshot snapshot) {
 
-	return this.getText();
-    }
-
-    @Override
-    public String getText() {
-
-	return _value;
+	return this.getAsString();
     }
 
     @Override

src/main/java/org/vizierdb/database/value/ErrorValue.java

@@ -47,6 +47,12 @@ public class ErrorValue extends Value {
 	
 	throw new java.lang.NumberFormatException();
     }
+
+    @Override
+    public String getAsString() {
+
+	return _message;
+    }
     
     @Override
     public List<Integer> getDependencies() {
@@ -60,12 +66,6 @@ public class ErrorValue extends Value {
 	return _formula;
     }
 
-    @Override
-    public String getText() {
-
-	return _message;
-    }
-
     @Override
     public boolean isDerived() {
 

src/main/java/org/vizierdb/database/value/FormulaValue.java

@@ -65,6 +65,12 @@ public class FormulaValue extends Value {
 	    return _value;
 	}
     }
+
+    @Override
+    public String getAsString() {
+
+	return _text;
+    }
     
     @Override
     public List<Integer> getDependencies() {
@@ -78,12 +84,6 @@ public class FormulaValue extends Value {
 	return "=" + _formula.toExternalForm(snapshot);
     }
 
-    @Override
-    public String getText() {
-
-	return _text;
-    }
-
     @Override
     public boolean isDerived() {
 

src/main/java/org/vizierdb/database/value/Value.java

@@ -56,6 +56,13 @@ public abstract class Value {
      */
     public abstract BigDecimal getAsBigDecimal();
     
+    /**
+     * Text representation of the value.
+     * 
+     * @return 
+     */
+    public abstract String getAsString();
+    
     /**
      * Text representation of the values formula. The value is the same as the
      * text for constant values.
@@ -75,13 +82,6 @@ public abstract class Value {
 	return _identifier;
     }
     
-    /**
-     * Text representation of the value.
-     * 
-     * @return 
-     */
-    public abstract String getText();
-    
     /**
      * Flag indicating whether the value is constant (false) or derived using
      * a formula (true).

src/main/java/org/vizierdb/server/io/ResourceStreamWriter.java

@@ -222,7 +222,7 @@ public class ResourceStreamWriter implements AutoCloseable {
 	    _out.name("row").value(rowMapping.get(cell.getRowId()));
 	    _out.name("value").beginObject();
 	    Value value = cell.getValue();
-	    _out.name("text").value(value.getText());
+	    _out.name("text").value(value.getAsString());
 	    if (value.isDerived()) {
 		_out.name("formula").value(value.getFormula(snapshot));
 	    }

src/main/webapp/index.html

@@ -25,7 +25,7 @@
     <script src="./js/ie-emulation-modes-warning.js"></script>
 
     <!-- D3.js -->
-    <script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
+    <script src="./js/d3.v3.min.js" charset="utf-8"></script>
     <script src="./js/dagre-d3.min.js"></script>
 
     <!-- Bootstrap core JavaScript