[Internal, New Feature, No Breaking] Rewrite constructor part 1

[Paalon]

Abstract

• This is no breaking PR.
• This adds new features.
• This is internal change.
• This is required to develop other features.

Detail

Rewrite construct functions in src/constructor.jl. Add constructor functions for the three essential YAML schemata. However this is not completed because processing for tag !!merge and !!value are still tightly connected to construct_mapping etc.

• Organize constructors of ConstructorError.
• Add TODO comments.
• Change function flatten_mapping to always return nothing.
• The following are the list of renamed and relocated functions from src/constructor.jl to src/constructor_yaml_jl_0_4_10.jl for the YAML.jl 0.4.10 schema:
  • construct_yaml_null→ construct_yaml_jl_0_4_10_schema_null
  • bool_values → yaml_jl_0_4_10_schema_bool_values
  • construct_yaml_bool → construct_yaml_jl_0_4_10_schema_bool
  • construct_yaml_int → construct_yaml_jl_0_4_10_schema_int
  • construct_yaml_float → construct_yaml_jl_0_4_10_schema_float
  • timestamp_pat → yaml_jl_0_4_10_schema_timestamp_regex
  • construct_yaml_timestamp → construct_yaml_jl_0_4_10_schema_timestamp
  • construct_yaml_omap → construct_yaml_jl_0_4_10_schema_timestamp
  • construct_yaml_pairs → construct_yaml_jl_0_4_10_schema_timestamp
  • construct_yaml_set → construct_yaml_jl_0_4_10_schema_set
  • construct_yaml_str → construct_yaml_jl_0_4_10_schema_str
  • construct_yaml_seq → construct_yaml_jl_0_4_10_schema_seq
  • construct_yaml_map → construct_yaml_jl_0_4_10_schema_map
  • construct_yaml_object → construct_yaml_jl_0_4_10_schema_object
  • construct_yaml_binary → construct_yaml_jl_0_4_10_schema_binary
  • construct_undefined → construct_undefined_yaml_jl_0_4_10_schema: this requires test's modification.
  • default_yaml_constructors → yaml_jl_0_4_10_schema_constructors: this requires test's modification.
• Similar functions are defined for the failsafe, the JSON and the Core schemata in src/constructor_failsafe.jl, src/constructor_json.jl and src/constructor_core.jl.
• Add tests for the four schemata.

This PR does not change any commonly used API (load, load_all, write, etc.).

[kescobo]

Is this still live?

[GunnarFarneback]

I believe unsafe refers to things like this that you can do in pyyaml:

$ python
Python 3.10.12 (main, Nov 20 2023, 15:14:05) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import yaml
>>> yaml.load("""!!python/object/apply:subprocess.Popen\n- [echo, hello]\n""", Loader=yaml.Loader)
<Popen: returncode: None args: ['echo', 'hello']>
>>> hello