Add PostgreSQL Support (#3)

Reviewed-on: #3

src/Count.php

@@ -36,4 +36,31 @@ class Count
         return Custom::scalar(Query\Count::byFields($tableName, $namedFields, $match),
             Parameters::addFields($namedFields, []), new CountMapper());
     }
+
+    /**
+     * Count matching documents using a JSON containment query (`@>`; PostgreSQL only)
+     *
+     * @param string $tableName The name of the table in which documents should be counted
+     * @param array|object $criteria The criteria for the JSON containment query
+     * @return int The number of documents matching the JSON containment query
+     * @throws DocumentException If the database mode is not PostgreSQL, or if an error occurs
+     */
+    public static function byContains(string $tableName, array|object $criteria): int
+    {
+        return Custom::scalar(Query\Count::byContains($tableName), Parameters::json(':criteria', $criteria),
+            new CountMapper());
+    }
+
+    /**
+     * Count matching documents using a JSON Path match query (`@?`; PostgreSQL only)
+     *
+     * @param string $tableName The name of the table in which documents should be counted
+     * @param string $path The JSON Path match string
+     * @return int The number of documents matching the given JSON Path criteria
+     * @throws DocumentException If the database mode is not PostgreSQL, or if an error occurs
+     */
+    public static function byJsonPath(string $tableName, string $path): int
+    {
+        return Custom::scalar(Query\Count::byJsonPath($tableName), [':path' => $path], new CountMapper());
+    }
 }