Can field indexer be simplify?

[linonetwo]

https://github.com/Jermolene/TiddlyWiki5/blob/95dc56d8508109a76c232cfbcd858889d32916a9/core/modules/indexers/field-indexer.js#L35-L41

Can it be

	this.wiki.each.byField = function(name,value) {
		var lookup = self.lookup(name,value);
		return lookup;
	};

Why check against the whole wiki? This is the most time consuming part. I'm not sure I understand this, so this is a discussion.

The lookup here is already a list of tiddler titles.

If you want to update the indexer by removing titles that is not longer exist, we can do this in an deferred async task.

[pmario]

Did you run the tests with your changes applied?

[linonetwo]

I have tried, and It works without any obvious bug, and the speed is dramatically increased.

[linonetwo]

Oh, you mean tw test set, I'm trying.

[linonetwo]

Randomized with seed 29235
Started
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775 specs, 0 failures
Finished in 3.369 seconds
Randomized with seed 29235 (jasmine --random=true --seed=29235)
To run the tests in a browser, open editions/test/output/test.html

[Jermolene]

Hi @linonetwo I think that the issue is that self.lookup(name,value); includes shadow tiddlers in the index, and wiki.each.byField() is intended to only return non-shadow tiddlers.

[linonetwo]

But titles.indexOf make it O(n^2) , can we use simplier approach here, e.g. $tw.wiki.isShadowTiddler which use hasOwnProperty is O(1).

Or we can just index non-shadow, just replace this.wiki.eachTiddlerPlusShadows with this.wiki.forEachTiddler as long as we don't need shadow.

If we need shadow, we can even create this.index and this.shadowIndex, exchange time with space.

[linonetwo]

I see, we have wiki.eachShadowPlusTiddlers.byField. So we also need to index shadow tiddlers.

Let me create this.index and this.shadowIndex? Because wiki.each.byField used more frequently by plugin, we need to make it efficient.

[linonetwo]

Oh, that is too complicated, use $tw.wiki.isShadowTiddler instead.

[pmario]

But titles.indexOf make it O(n^2)

IMO titles.indexOf is O(n) ... titles is an array. .. but anyway O(1) is preferable.

[linonetwo]

By n^2 I mean it was .filter's n x .indexOf's n. This is the case we might optimize for in the future.

If we have a situation to do so, build an object outside of .filter as hash map will make it faster too. Thankfully in this case we already have a hash map to use (used by isShadowTiddler).