block-map and comments

[revolunet]

Hello, i'm trying to extract comments for each value in such a YAML :

# comment 1
create:
  # comment for value 1
  value1:
  # comment for value 2
  value2:

When i do

  const doc = parseDocument(file);
  console.log(doc.contents);

I get

YAMLMap {
    items: [
      Pair {
        key: Scalar {
          value: 'create',
          range: [ 12, 18, 18 ],
          source: 'create',
          type: 'PLAIN',
          commentBefore: ' comment 1'
        },
        value: YAMLMap {
          items: [
            Pair {
              key: Scalar {
                value: 'value1',
                range: [ 46, 52, 52 ],
                source: 'value1',
                type: 'PLAIN'
              },
              value: Scalar {
                value: null,
                range: [ 53, 53, 77 ],
                source: '',
                type: 'PLAIN',
                comment: ' comment for value 2'
              }
            },
            Pair {
              key: Scalar {
                value: 'value2',
                range: [ 80, 86, 86 ],
                source: 'value2',
                type: 'PLAIN',
                spaceBefore: true
              },
              value: Scalar {
                value: null,
                range: [ 87, 87, 87 ],
                source: '',
                type: 'PLAIN'
              }
            }
          ],
          range: [ 46, 87, 87 ],
          commentBefore: ' comment for value 1'
        }
      }
    ],
    range: [ 12, 87, 87 ]
  },
  range: [ 12, 87, 87 ]
}

the create has the correct commentBefore but value1 and value2 donc have such commentBefore

Not sure if this is intended behaviour or if theres a way to get the commentBefore on each value ?

[eemeli]

This is intended behaviour. The "comment for value 1" gets assigned to the collection as a whole (not sure, but adding an empty row before it may have an effect), while "comment for value 2" ends up included in the value of the value1 key -- it's empty, so we need to keep on scanning until we can be sure that there's no value (you could try dedenting it).

YAML does not specify how comments are attached, and as you see here, there isn't always just one way to attach a comment. You're welcome to suggest changes in the logic for comment attachment, but you'll probably need to submit a PR yourself. Be warned, though, the heuristics on this can get a bit hairy as it's pretty much all corner cases.

[revolunet]

yes thanks, i'm exploring these cases :)

My goal is to produce a json-schema; Since i have all the data i need here, i "just" have to reorder/remap comments to scalars. How would you iterate that tree in doc.contents.items ? Looks like CST.visit doesnt fit here

[eemeli]

https://eemeli.org/yaml/#modifying-nodes

[revolunet]

note: if i use String(doc) on the above example, i get this slightly different YAML in return :

# comment 1
create:
  # comment for value 1
  value1: # comment for value 2
    
  value2: