Generalize current filter function inside search.

[muendlein]

Allow any arbitrary node function to be applied here, e.g. when node index shall be inserted somewhere else.

flatbush/index.js

Lines 239 to 241 in 3a6f0f0

	} else if (filterFn === undefined || filterFn(index)) {
	results.push(index); // leaf item
	}

[mourner]

Can you expand on this with an example? Not sure I'm following...

[muendlein]

Suppose you already have a boolean array place that stores the information which indices are inside a query box. In this case you would want to directly adjust this array and avoid a separate result array that is growing during search (and therefore is slower).

My proposal is therefore to have a generalized search function that does not return anything but rather works via dependency injection, meaning a leafNodeFunction (index, nodeMinX, nodeMinY, nodeMaxX, nodeMaxY) => void will be injected.

[mourner]

Ah, I see. In theory, the existing filterFn semantics can be used for this — e.g. if you return false in the function, it won't add the index to the array (but you can do custom handling of the index instead). Would that work? I'd just update the docs about it then.

[muendlein]

Ah, I see. In theory, the existing filterFn semantics can be used for this — e.g. if you return false in the function, it won't add the index to the array (but you can do custom handling of the index instead). Would that work? I'd just update the docs about it then.

In theory it could work, however I see one issue which is that the function would still return an (empty) array which can be quite confusing.
One idea is to have a separate seach_apply function which contains the logic and does not return anything (only generalizated custom handling via dependency injection). The existing search function would call this function and have the current behavior embedded in the custom function (push to array). Overall this would yield a consistent behavior.