Merge pull request #5 from jmespath-community/feature/pipe-expression

JEP-19 Evaluation of Pipe Expressions

Author: springcomp

jmespath/visitor.py

@@ -129,6 +129,8 @@ def visit_subexpression(self, node, value):
         result = value
         for node in node['children']:
             result = self.visit(node, result)
+            if (result is None):
+                return None
         return result
 
     def visit_field(self, node, value):
@@ -234,16 +236,12 @@ def visit_literal(self, node, value):
         return node['value']
 
     def visit_multi_select_dict(self, node, value):
-        if value is None:
-            return None
         collected = self._dict_cls()
         for child in node['children']:
             collected[child['value']] = self.visit(child, value)
         return collected
 
     def visit_multi_select_list(self, node, value):
-        if value is None:
-            return None
         collected = []
         for child in node['children']:
             collected.append(self.visit(child, value))

tests/compliance/pipe.json

@@ -126,6 +126,10 @@
     {
       "expression": "foo[*].bar[*] | [0][0]",
       "result": {"baz": "one"}
+    },
+    {
+      "expression": "`null`|[@]",
+      "result": [ null ]
     }
   ]
 }]