Parse empty node in YAML (many languages)

parse-yaml-empty-node.js

var yamlParser = require("yaml-parser")
yamlParser.safeLoadAll("---\nfoo: #@ data.value\n", (doc) => { console.log(doc); });

// https://runkit.com/embed/oipcfk86vcq2

// output:
//   Object{foo:null}

parse-yaml-empty-node.rb

require 'yaml'
puts YAML.load("---\nfoo: #@ data.value\n")

# output:
# {"foo"=>nil}

parse-yaml-empty-node.rs

extern crate yaml_rust;
use yaml_rust::{YamlLoader};

fn main() {
    let s =
"---
foo: #@ data.value
";
    let docs = YamlLoader::load_from_str(s).unwrap();

    let doc = &docs[0];
    println!("{:?}", doc);
}
// https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=50b2343706643e84cb4114f9add6189c

// output:
//  Hash({String("foo"): Null})

ParseYamlEmptyNode.java

// on classpath: https://repo1.maven.org/maven2/org/yaml/snakeyaml/1.27/snakeyaml-1.27.jar
package emptynode;

import org.yaml.snakeyaml.Yaml;
import java.util.Map;

public class ParseYaml {
  public static void main(String[] args) {
    Yaml yaml = new Yaml();
    Map<String, Object> obj = yaml.load("---\nfoo: #@ data.value\n");
    System.out.println(obj);
  }
}

// output:
// {foo=null}