Flatten a nested JSON object

Problem

You are given a JSON-like value representing an object that may contain:

• Objects / dictionaries (string keys)
• Arrays / lists
• Primitive values (string/number/boolean/null)

Return a flattened map from path to primitive value.

Path rules

• Use . to join object keys.
• Use [i] for array indices.
• The root has no leading separator.

Examples

Input

{
  "a": 1,
  "b": {"c": 2, "d": [3, 4]},
  "e": [ {"f": 5}, 6 ]
}

Output

a -> 1
b.c -> 2
b.d[0] -> 3
b.d[1] -> 4
e[0].f -> 5
e[1] -> 6

Notes / constraints

• Keys are strings and may contain any characters except . and [ ] (you may assume this to avoid escaping).
• The output can be returned as a dictionary/map of string -> primitive .
• Order does not matter.

Implement a function to perform this flattening.