Allow custom implementation of EditableStyledDocument

[JordanMartinez]

Tomas originally said in #181

I eventually want to support custom implementations of what is now called EditableStyledDocument....

[JordanMartinez]

@TomasMikula
Do you care to elaborate more on what would be customizeable?

[TomasMikula]

My idea is that EditableStyledDocument should be an interface, something like

public interface EditableStyledDocument<PS, S> {
    EventStream<RichTextChange<PS, S>> changes();
    ObservableList<Paragraph<PS, S>> getParagraphs();
    ReadOnlyStyledDocument<PS, S> subDocument(Position from, Position to);
    void replace(Position from, Position to, ReadOnlyStyledDocument<PS, S> replacement);
}

The implementation can use any represent of a document (e.g. a parse tree), as long as it publishes changes, provides a view as a list of paragraphs, and handles edits.

[JordanMartinez]

That sounds good! Should StyledDocumentBase be public too then? Additionally, shouldn't the interface also include EventStream<PlainTextChange> plainTextChanges();?

[TomasMikula]

Should StyledDocumentBase be public too then?

For now, I would say no.

Additionally, shouldn't the interface also include EventStream<PlainTextChange> plainTextChanges()?

Yeah, but with a default implementation based on rich text changes. Currently the implementation tries to optimize for the case when plain text changes are observed, but rich text changes are not. The current implementation tries to avoid creating instances of RichTextChange at all when no-one is observing them. I don't think the actual savings make any substantial difference, but they come with a price of higher complexity of the code. I would like to simplify that part.

[JordanMartinez]

Yeah, but with a default implementation based on rich text changes.

Ok.

[JordanMartinez]

Just another thought: since there is now an interface for EditableStyledDocument, should there be a public interface for its counterpart: ReadOnlyStyledDocument? If we're going to allow custom ESD, it seems necessary to do the same for its counterpart.

[TomasMikula]

If we're going to allow custom ESD, it seems necessary to do the same for its counterpart.

Why?

[JordanMartinez]

On second thought... I guess that isn't necessary. :-)

[JordanMartinez]

This is now technically possible due to #277. However, it is quite a hassle to implement. EditableStyledDocumentImpl could be made public temporarily until some better long-term solution is made. This would be easy and quick to implement. However, people might rely on it too much and it might cause problems later on when it's made package-private again and some other long-term approach is implemented. Other thoughts are to make StyledDocumentBase public so that the implementation isn't as difficult.

Still, for now, this issue has been resolved and discussions for this new hassle can be discussed in a new issue.