Fixed issue 49: Add Edit Cells / Set Null.

Added support for "null" literal.

git-svn-id: http://google-refine.googlecode.com/svn/trunk@855 7d457c2a-affb-35e4-300a-418c747d4874

CHANGES.txt

@@ -19,6 +19,7 @@ Fixes:
   Supported by the function facetCount()
 - Issue 14: "Limiting Freebase load to starred records"
   We load whatever rows that are filtered through, not particularly starred rows.
+- Issue 49: "Add Edit Cells / Set Null"
 
 Features:
 - Row/record sorting (Issue 32)

src/main/java/com/metaweb/gridworks/gel/Parser.java

@@ -165,7 +165,7 @@ public class Parser {
             next(false);
             
             if (_token == null || _token.type != TokenType.Delimiter || !_token.text.equals("(")) {
-                eval = new VariableExpr(text);
+                eval = "null".equals(text) ? new LiteralExpr(null) : new VariableExpr(text);
             } else {
                 Function f = ControlFunctionRegistry.getFunction(text);
                 Control c = ControlFunctionRegistry.getControl(text);

src/main/java/com/metaweb/gridworks/operations/cell/TextTransformOperation.java

@@ -141,7 +141,12 @@ public class TextTransformOperation extends EngineDependentMassCellOperation {
                 ExpressionUtils.bind(bindings, row, rowIndex, _columnName, cell);
                 
                 Object o = eval.evaluate(bindings);
-                if (o != null) {
+                if (o == null) {
+                	if (oldValue != null) {
+                        CellChange cellChange = new CellChange(rowIndex, cellIndex, cell, null);
+                        cellChanges.add(cellChange);
+                	}
+                } else {
                     if (o instanceof Cell) {
                         newCell = (Cell) o;
                     } else if (o instanceof WrappedCell) {

src/main/webapp/scripts/views/data-table-column-header-ui.js

@@ -271,6 +271,10 @@ DataTableColumnHeaderUI.prototype._createMenuForColumnHeader = function(elmt) {
                         {
                             label: "To Lowercase",
                             click: function() { self._doTextTransform("toLowercase(value)", "store-blank", false, ""); }
+                        },
+                        {
+                            label: "To Blank",
+                            click: function() { self._doTextTransform("null", "store-blank", false, ""); }
                         }
                     ]
                 },