Initial commit of Python queries and QL libraries.

python/ql/src/Expressions/ExpectedMappingForFormatString.ql

@@ -0,0 +1,19 @@
+/**
+ * @name Formatted object is not a mapping
+ * @description The formatted object must be a mapping when the format includes a named specifier; otherwise a TypeError will be raised."
+ * @kind problem
+ * @tags reliability
+ *       correctness
+ * @problem.severity error
+ * @sub-severity low
+ * @precision high
+ * @id py/percent-format/not-mapping
+ */
+
+import python
+import semmle.python.strings
+
+from Expr e, ClassObject t
+where exists(BinaryExpr b | b.getOp() instanceof Mod and format_string(b.getLeft()) and e = b.getRight() and
+mapping_format(b.getLeft()) and e.refersTo(_, t, _) and not t.isMapping())
+select e, "Right hand side of a % operator must be a mapping, not class $@.", t, t.getName()