Supports slicing strings

Author: springcomp

jmespath/visitor.py

@@ -216,6 +216,12 @@ def visit_index_expression(self, node, value):
         return result
 
     def visit_slice(self, node, value):
+        if isinstance(value, string_type):
+            start = node['children'][0]
+            end = node['children'][1]
+            step = node['children'][2]
+            return value[start:end:step]
+
         if not isinstance(value, list):
             return None
         s = slice(*node['children'])