The following queries provide results that do not match those of other implementations of JSONPath
(compare https://cburgmer.github.io/json-path-comparison/):

• $.2
  Input:

  {"a": "first", "2": "second", "b": "third"}
  

  Expected output:

  ["second"]
  

  Error:

  line 1:2 mismatched input '2' expecting {'*', ID}
  ValueError("line 1:2 mismatched input '2' expecting {'*', ID}")
  

• $[::2]
  Input:

  ["first", "second", "third", "forth", "fifth"]
  

  Expected output:

  ["first", "third", "fifth"]
  

  Actual output:

  ["first", "second"]
  

• $[?(@.key==42)]
  Input:

  [{"key": 0}, {"key": 42}, {"key": -1}, {"key": 41}, {"key": 43}, {"key": 42.0001}, {"key": 41.9999}, {"key": 100}, {"some": "value"}]
  

  Expected output:

  [{"key": 42}]
  

  Error:

  line 1:10 extraneous input '=' expecting {'@', '$', 'true', 'false', 'null', '{', '[', STRING, NUMBER}
  ValueError("line 1:10 extraneous input '=' expecting {'@', '$', 'true', 'false', 'null', '{', '[', STRING, NUMBER}")
  

• $[?(@.key>42)]
  Input:

  [{"key": 0}, {"key": 42}, {"key": -1}, {"key": 41}, {"key": 43}, {"key": 42.0001}, {"key": 41.9999}, {"key": 100}]
  

  Expected output:

  [{"key": 43}, {"key": 42.0001}, {"key": 100}]
  

  Actual output:

  []
  

• $[?(@.key)]
  Input:

  [{"some": "some value"}, {"key": "value"}]
  

  Expected output:

  [{"key": "value"}]
  

  Actual output:

  []
  

• $['key']
  Input:

  {"key": "value"}
  

  Expected output:

  ["value"]
  

  Error:

  line 1:2 token recognition error at: '''
  ValueError("line 1:2 token recognition error at: '''")
  

For reference, the output was generated by the program in https://github.com/cburgmer/json-path-comparison/tree/master/implementations/Python_jsonpath2.