feat: add getChildren and getChildFields methods to Node #249
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This should make it easier to traverse ASTs when depending only on decaffeinate-parser. Also change test traversal to use this new method, so that our tests make sure every node is covered. (`stripExtraInfo` also had the wrong type before, so this makes it so the param is actually always `Node`.) Traverse function and parent pointers coming soon.
| let children: Array<Node> = []; | ||
| for (let childField of this.getChildFields()) { | ||
| if (Array.isArray(childField)) { | ||
| children.push(...childField.filter<Node>((node): node is Node => node !== null)); |
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I'm surprised this node is Node assertion filter is needed. What does just filter(node => node) do?
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Yep, it was necessary. I think it used to be that filter couldn't be used for type refinement at all, but now the current state of things is that if the callback is a type guard, then it'll work. But it won't infer your callback to be a type guard, so you need to specify the return type explicitly.
(Also, minor, but filter(node => node) also doesn't typecheck because the predicate needs to return a boolean.)
This issue has some discussion about it: microsoft/TypeScript#7657
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Should we just delete decaffeinate-traverse? In theory such a package should be able to provide more fully-featured AST traversal with mutation support and everything (like babel-traverse), but I don’t see it being needed for decaffeinate itself and I don’t really want to do any CoffeeScript-based tooling, so… I’m inclined to just delete the repo. |
Yeah, that would be fine with me. My reason for cleaning up decaffeinate-parser today is so that I can make a tool to get soak operation statistics for CoffeeScript projects, which might help inform the discussion at https://github.com/tc39/proposal-optional-chaining . But other than that, I don't really plan on working on any CoffeeScript tooling. |
This should make it easier to traverse ASTs when depending only on
decaffeinate-parser.
Also change test traversal to use this new method, so that our tests make sure
every node is covered. (
stripExtraInfoalso had the wrong type before, so thismakes it so the param is actually always
Node.)Traverse function and parent pointers coming soon.