Generated patch incorrect for Array replacement

[tamalsaha]

Here is a case that produces buggy patch:

src = {
  "spec": {
    "loadBalancerSourceRanges": [
      "192.101.0.0/16",
      "192.0.0.0/24"
    ]
  }
}

dst = {
  "spec": {
    "loadBalancerSourceRanges": [
      "192.101.0.0/24"
    ]
  }
}

The generated patch is:

[
  {
    "op": "remove",
    "path": "/spec/loadBalancerSourceRanges/0"
  },  
  {
    "op": "remove",
    "path": "/spec/loadBalancerSourceRanges/1"
  },
  {
    "op": "add",
    "path": "/spec/loadBalancerSourceRanges/0",
    "value": "192.101.0.0/24"
  }
]

This results in an error. The problem seems to be that index 1 should be removed before index 0. If I reverse the order the generated patch works.

I tested patch generation using https://github.com/stefankoegl/python-json-patch library . This produces a valid patch:

[{"path": "/spec/loadBalancerSourceRanges/1", "op": "remove"}, {"path": "/spec/loadBalancerSourceRanges/0", "value": "192.101.0.0/24", "op": "replace"}]

https://gist.github.com/tamalsaha/e8b313aec8f8d8191bc01ba504247e30

I also tested against a node.js library here: https://json8.github.io/patch/demos/apply/ . I get the same issue.

[nylon22]

I was having the same issue, so I used your fork in my project, but it didn't fix it for me.

The issue I had, which seems to be the same as this, was if src was ["A", "B", "C"] and to was ["D"], the patch that was generated causes the library I'm using to apply the patch to try to replace "A" with "D", and then remove index 1 and then index 2. But after index 1 is removed, there is no index 2 anymore, causing an "Index out of bounds exception" trying to apply the patch.

My fix was to sort "remove" operations alphabetically by path and also numerically by path index (in case index >=10) in descending order, so that in the scenario above, index 2 gets removed before index 1.

Here are my changes. Would you be interested in a PR?

[tamalsaha]

Patch is welcome!

[tamalsaha]

@nylon22 , I have created #6 to address this issue. Can you take a look?