Wrong parse result from single scalar document

[fktn-k]

Description

Parsing a YAML document which contains only one scalar produces a mapping with the scalar as a key to a null scalar, but the parse result must be a scalar.

Reproduction steps

Run the following code:

char input[] = “foo“;
auto n = fkyaml::node::deserialize(input);
auto scalar = n.get_value<std::string>(); // This line throws a fkyaml::type_error since n is a mapping.

Expected vs. actual results

The parse result must be a scalar, but is a mapping.

Minimal code example

See the reproduction steps.

Error messages

type_error: The node value is not a string. type=mapping

Compiler and operating system

GCC 11.4.0 on Ubuntu 22.04 LTS

Library version

develop HEAD

Validation

• [X] The bug also occurs if the latest version from the develop branch is used.
• [X] I can successfully compile and run the unit tests.

[fktn-k]

This bug was found when trying to reproduce the issue #405.