Conversion: Allows specyfing the priority for view element

[pomek]

When I was working on https://github.com/ckeditor/ckeditor5-highlight/issues/17 I noticed that there is no option for specifying the priority for the view element that will be created.

It means we cannot use two-way conversion methods like elementToElement(), attributeToElement() or attributeToAttribute(). Instead of we have to care about upcast and downcast conversion manually. It means we cannot use the helpers that are using in two-way conversion.

Would be nice to have an option for that. It simplify changes the priority element. We will have a single property instead of the whole block of code (which does not care about upcastAlso option.

[pomek]

How should we call the parameter? I thought about viewPriority:

const definition = { 
  model: { },
  view: { },
  priority: 'normal', /* by default */
  viewPriority: AttributeElement.DEFAULT_PRIORITY /* by default */
}

WDYT?

[Reinmar]

Could we add it to the view: {} object? Where is it defined in downcast and upcast converters?

[pomek]

Could we add it to the view: {} object?

Yes, we can. In such case it would be called priority.

Where is it defined in downcast and upcast converters?

I guess here – https://github.com/ckeditor/ckeditor5-engine/blob/70cc0f5976e3a2e9862f6550ad18b1886df83a37/src/conversion/downcast-converters.js#L377