Filter: Implement hasNotValue() & matchHasnotValue() methods

src/Filter.php

@@ -182,6 +182,34 @@ protected function matchHasValue($rule, $row)
         return ! empty($this->extractValue($rule->getColumn(), $row));
     }
 
+    /**
+     * Create a rule that applies rows where a column has no values, i.e. to all
+     * rows where this column hasn't been set.
+     *
+     * Performs ! isset() | IS NULL actions
+     *
+     * @param string $column
+     *
+     * @return HasNotValue
+     */
+    public static function hasNotValue($column)
+    {
+        return new HasNotValue($column, '');
+    }
+
+    /**
+     * Get whether the given rule's column is null|doesn't contain any values
+     *
+     * @param  HasNotValue $rule
+     * @param  object $row
+     *
+     * @return bool
+     */
+    public function matchHasNotValue(HasNotValue $rule, $row)
+    {
+        return ! $this->matchHasValue($rule, $row);
+    }
+
     /**
      * Create a rule that matches rows with a column that **equals** the given value
      *
@@ -449,6 +477,8 @@ protected function performMatch(Rule $rule, $row)
                 return $this->matchUnequal($rule, $row);
             case $rule instanceof HasValue:
                 return $this->matchHasValue($rule, $row);
+            case $rule instanceof HasNotValue:
+                return $this->matchHasNotValue($rule, $row);
             default:
                 throw new InvalidArgumentException(sprintf(
                     'Unable to match filter. Rule type %s is unknown',