atruleExpression always null

[strarsis]

The this.atruleExpression is always null, even with Atrule expressions, even not inside an Atrule expression.
There isn't any node of type 'atruleExpression' or of similar name either.
It would be very convenient if the atruleExpression is available for all its child nodes.

var csstree  = require('css-tree');

var testCss = '@media screen{.st1{fill:red;}}';
var cssAst = csstree.parse(testCss);
csstree.walk(cssAst, function(node, item, list) {
  // this.atruleExpression is always null, even inside node with type == 'Atrule'.
});

[lahmatiy]

Yep, it's because Atrule.expression is MediaQueryList type, not an AtruleExpression. Not sure it's a bug, but agree it's confusing.
I'm planning to change solution to provide access to upper nodes (via the stack or something like that). But still thinking about a better way to do that.
Until new solution I added contextWalker marker for MediaQueryList, it should help right now. Will publish patch version later.

[strarsis]

I want to filter selectors by their parent Atrule expression (media query),
this is only possible when the parent Atrule is known for each selector.
Is this possible with the current csstree release already or do I have to wait until the next release?

[lahmatiy]

Well, for your task you need a this.atrule reference rather than a this.atruleExpression. We need to add this marker also. That's why I dislike current solution.
Yep, you need wait until next release. Or use csstree/csstree in you package.json instead of version (in this case, csstree will be installed from master branch).

[lahmatiy]

I added this.atrule reference in context. Also, I've created an issue #41 to track status on changes in walker implementation.

[lahmatiy]

Start with 1.0.0-alpha20 at-rule prelude is always wraps into AtruleExpression. So this.atruleExpression now works as expected.