How to convert YAML duplicate keys into arrays

Question

I have a file that's almost YAML, with the exception of duplicate keys. Is there a existing method to convert duplicate keys into arrays?

My code looks like:

use Data::Dumper;
use YAML::XS;

local $YAML::XS::ForbidDuplicateKeys = 1;
 
my $x = YAML::XS::Load($yaml_string);
print Dumper $x;

Sample input file:

info:
    family: skywalker

    person:
        id: 1
        status: active

        details:
            gender: male

            name:
                first: Anakin
                last: Skywalker

        children: Leia
        children: Han Solo

    person:
        id: 58
        status: active

        details:
            gender: female

            name:
                first: Padme
                last: Amidala

        children: Leia
        children: Han Solo

Desired input file:

info:
    family: skywalker

    person:
    -
        id: 1
        status: active

        details:
            gender: male

            name:
                first: Anakin
                last: Skywalker
        children:
        - Leia
        - Han Solo

    -
        id: 58
        status: active

        details:
            gender: female

            name:
                first: Padme
                last: Amidala
        children:
        - Leia
        - Han Solo

Answer 1

The specification for YAML mappings says:

The content of a mapping node is an unordered set of key/value node pairs, with the restriction that each of the keys is unique.

Your keys are not unique and therefore you do not have a valid YAML (as you already know - "I have a file that's almost YAML"). Therefore, you should not expect to be able to parse that file with a YAML parser.

I guess you would need to write some kind of parser for your "almost YAML" which produces a Perl data structure in the format that you want. You could then use a standard YAML library to convert that data structure to YAML.