Is it possible to do recursive types?

[calebsander]

It is currently impossible to instantiate a recursive type because types are immutable, so you would have to have the type already created in order to pass it into its own construction.

Idea:

• Have a global registry of named types
• To use a type in its own definition, would use new sb.RecursiveType(typeName)
• Then add the type to the global registry

Example:

sb.registerType({
  type: new sb.SetType(
    new sb.RecursiveType('node')
  ),
  name: 'node'
})

When the type is written, the name (or equivalent identifier) probably has to be written with the first instance, and then when it is repeated, it would refer to that identifier to specify what type to use.

Each value write buffer would need to keep track of the positions in which recursive types' values were written. If the value was already written, a pointer would be created to it. Otherwise, the value would have to be added to the set of pointers to fill in later.

[calebsander]

To fix issues where a recursive type's definition contains a REPEATED_TYPE pointing to a parent of the recursive type, REPEATED_TYPE should be avoided if writing a descendant of a recursive type where it would point to before the recursive type

[calebsander]

Can a WeakMap be used instead of adding properties to write buffers?

[calebsander]

Todo still:

• Documentation of RecursiveType and registerType(), with examples
• Comments
• Increase coverage
• Version bump to 2.16.9