Better guess the cell type based on its value

src/Spout/Writer/Helper/XLSX/CellHelper.php

@@ -34,4 +34,38 @@ class CellHelper
 
         return $cellIndex;
     }
+
+    /**
+     * @param $value
+     * @return bool Whether the given value is a non empty string
+     */
+    public static function isNonEmptyString($value)
+    {
+        return (gettype($value) === 'string' && $value !== '');
+    }
+
+    /**
+     * Returns whether the given value is numeric.
+     * A numeric value is from type "integer" or "double" ("float" is not returned by gettype).
+     *
+     * @param $value
+     * @return bool Whether the given value is numeric
+     */
+    public static function isNumeric($value)
+    {
+        $valueType = gettype($value);
+        return ($valueType === 'integer' || $valueType === 'double');
+    }
+
+    /**
+     * Returns whether the given value is boolean.
+     * "true"/"false" and 0/1 are not booleans.
+     *
+     * @param $value
+     * @return bool Whether the given value is boolean
+     */
+    public static function isBoolean($value)
+    {
+        return gettype($value) === 'boolean';
+    }
 }