I have the following yaml snippet
I want to resolve the pointer to the anchor and also I don’t want to lose !flatten and !ref which are to be processed by another program.

Input:

_ip_context: &ip_context
  ip_restriction: !flatten
  - !ref 'constant::public_cidr_blocks'

policies:
- file: policies/somepolicy.json
  context:
    <<: *ip_context

Desired output:

policies:
- file: policies/somepolicy.json
  context:
    ip_restriction: !flatten
    - !ref 'constant::public_cidr_blocks'

I tried this program which is produced by ChatGpt. But it didn’t get me what I wanted:

import sys
import yaml

yaml_content = """
_ip_context: &ip_context
  ip_restriction: !flatten
  - !ref 'constant::public_cidr_blocks'

policies:
- file: policies/somepolicy.json
  context:
    <<: *ip_context
"""

class FlattenConstructor(yaml.constructor.SafeConstructor):
    def construct_flatten(self, node):
        return self.construct_sequence(node)

class RefConstructor(yaml.constructor.SafeConstructor):
    def construct_ref(self, node):
        return self.construct_scalar(node)

yaml.add_constructor('!flatten', FlattenConstructor.construct_flatten, Loader=yaml.SafeLoader)
yaml.add_constructor('!ref', RefConstructor.construct_ref, Loader=yaml.SafeLoader)

data = yaml.load(yaml_content, Loader=yaml.SafeLoader)

class FlattenRepresenter(yaml.representer.SafeRepresenter):
    def represent_flatten(self, data):
        return self.represent_sequence('!flatten', data)

class RefRepresenter(yaml.representer.SafeRepresenter):
    def represent_ref(self, data):
        return self.represent_scalar('!ref', data)

yaml.add_representer(list, FlattenRepresenter.represent_flatten)
yaml.add_representer(str, RefRepresenter.represent_ref)

#with open('output.yaml', 'w') as outfile:
yaml.dump(data, sys.stdout, default_flow_style=False,Dumper=yaml.SafeDumper)

This is the output:

_ip_context:
  ip_restriction: &id001
  - constant::public_cidr_blocks
policies:
- context:
    ip_restriction: *id001
  file: policies/somepolicy.json