style_map components should be given data on render

[thibaudcolas]

At the moment, style_map components do not receive any data beyond the text to style (as props['children]).

draftjs_exporter/draftjs_exporter/style_state.py

Lines 26 to 32 in 209631a

	def render_styles(self, text_node):
	node = text_node
	if not self.is_empty():
	# Nest the tags.
	for s in sorted(self.styles, reverse=True):
	opt = Options.for_style(self.style_map, s)
	node = DOM.create_element(opt.element, opt.props, node)

This is ok for common use cases (BOLD, ITALIC, etc), but it makes the style_map fallback rather useless – there is no way to know what style needs the fallback, or have any other information about the context to adjust the fallback behavior.

Here's what the block_map fallback has access to for comparison:

props['block'] = {
        'type': type_,
        'depth': depth,
        'data': data,
}

In retrospect I think this could've been all of the block's attributes, not just a cherry-picked shortlist, so for inline styles we could pass the following exhaustive props:

{
    # The style range to render.
    "range": 
        "offset": 10,
        "length": 17,
        "style": "BOLD"
    },
    # The full block data, eg.
    "block": {
            "key": "t7k7",
            "text": "Unstyled test test test test test",
            "type": "unstyled",
            "depth": 0,
            "inlineStyleRanges": [
                {
                    "offset": 10,
                    "length": 17,
                    "style": "BOLD"
                }
            ],
            "entityRanges": [
                {
                    "offset": 0,
                    "length": 4,
                    "key": 6
                }
            ],
            "data": {}
        },
}

Here's the approximative change:

-    def render_styles(self, text_node):
+    def render_styles(self, text_node, block):
        node = text_node
        if not self.is_empty():
            # Nest the tags.
            for s in sorted(self.styles, reverse=True):
                opt = Options.for_style(self.style_map, s)
+                props['block'] = block
+                props['range'] = s
                node = DOM.create_element(opt.element, opt.props, node)

        return node

---

Ideally I'd like entities and blocks to also be given more data (enough data to recreate the whole ContentState, thus making the exporter usable to create content migrations), but that's a separate issue.