Merge pull request #9 from jmespath-community/jep/string-slices

JEP-15 String Slices

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'])
@@ -271,6 +277,17 @@ def visit_pipe(self, node, value):
 
     def visit_projection(self, node, value):
         base = self.visit(node['children'][0], value)
+
+        allow_string = False
+        first_child = node['children'][0]
+        if first_child['type'] == 'index_expression':
+            nested_children = first_child['children']
+            if len(nested_children) > 1 and nested_children[1]['type'] == 'slice':
+                allow_string = True
+
+        if isinstance(base, string_type) and allow_string:
+            return base
+
         if not isinstance(base, list):
             return None
         collected = []

tests/compliance/slice.json

@@ -184,4 +184,12 @@
       "result": []
     }
   ]
+}, {
+  "given": null,
+  "cases": [
+    {
+      "expression": "'e\u0301le\u0301ment'[::-1]",
+      "result": "tnem\u0301el\u0301e"
+    }
+  ]
 }]