#6286 Container filtering improvements: IsNull filter

svn changeset:17812/svn branch:6.6

1 files changed, 68 insertions, 0 deletions

diff --git a/src/com/vaadin/data/util/filter/IsNull.java b/src/com/vaadin/data/util/filter/IsNull.java
new file mode 100644
index 0000000000..5d8528c736
--- /dev/null
+++ b/src/com/vaadin/data/util/filter/IsNull.java
@@ -0,0 +1,68 @@
+package com.vaadin.data.util.filter;
+
+import com.vaadin.data.Container.Filter;
+import com.vaadin.data.Item;
+import com.vaadin.data.Property;
+
+/**
+ * Simple container filter checking whether an item property value is null.
+ * 
+ * This filter also directly supports in-memory filtering.
+ * 
+ * @since 6.6
+ */
+public final class IsNull implements Filter {
+
+    private final Object propertyId;
+
+    /**
+     * Constructor for a filter that compares the value of an item property with
+     * null.
+     * 
+     * For in-memory filtering, a simple == check is performed. For other
+     * containers, the comparison implementation is container dependent but
+     * should correspond to the in-memory null check.
+     * 
+     * @param propertyId
+     *            the identifier (not null) of the property whose value to check
+     */
+    public IsNull(Object propertyId) {
+        this.propertyId = propertyId;
+    }
+
+    public boolean passesFilter(Object itemId, Item item)
+            throws UnsupportedOperationException {
+        final Property p = item.getItemProperty(getPropertyId());
+        if (null == p) {
+            return false;
+        }
+        return null == p.getValue();
+    }
+
+    public boolean appliesToProperty(Object propertyId) {
+        return this.propertyId == propertyId;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        // Only objects of the same class can be equal
+        if (!getClass().equals(obj.getClass())) {
+            return false;
+        }
+        final IsNull o = (IsNull) obj;
+
+        // Checks the properties one by one
+        return (null != getPropertyId()) ? getPropertyId().equals(
+                o.getPropertyId()) : null == o.getPropertyId();
+    }
+
+    @Override
+    public int hashCode() {
+        return (null != getPropertyId() ? getPropertyId().hashCode() : 0);
+    }
+
+    public Object getPropertyId() {
+        return propertyId;
+    }
+
+}