mirror of
https://github.com/Jermolene/TiddlyWiki5
synced 2024-12-27 18:40:28 +00:00
55 lines
2.5 KiB
Plaintext
55 lines
2.5 KiB
Plaintext
created: 20201002010134640
|
|
modified: 20201002012758239
|
|
tags: moduletypes dev
|
|
title: indexer modules
|
|
|
|
Indexer modules maintain indexes of tiddlers organized in a manner that's more efficient for different types of access, typically to speed up things like certain filter operators. An example of this would be the tag indexer - it's much faster to maintain a lookup table listing which tiddlers have a given tag than to iterate over //all// of the tiddlers in a wiki and ask each of them if they have the tag you're interested in!
|
|
|
|
Indexer modules have a `module-type` of `indexer`, and the indexers that are included with TiddlyWiki can be found under `core/modules/indexers`.
|
|
|
|
! Methods
|
|
|
|
Indexer modules must export a constructor function, which takes the current wiki object as its only argument. The object built by the construction function must implement the following methods:
|
|
|
|
!! `init()`
|
|
|
|
This performs any initial setup required by an indexer.
|
|
|
|
!! `rebuild()`
|
|
|
|
This rebuilds an index from scratch, usually after a large number of changes have happened to a wiki.
|
|
|
|
!! `update(updateDescriptor)`
|
|
|
|
This is called every time a tiddler is added, changed, or deleted. The `updateDescriptor` value is an object with two fields - `old` and `new` - which represent the pre-update and post-update state of the tiddler, respectively. Each of these has three fields of their own:
|
|
|
|
* `tiddler` - the state of the tiddler (may be `null`)
|
|
* `shadow` - a boolean indicating whether or not the tiddler is a shadow
|
|
* `exists` - a boolean indicating whether or not the tiddler exists
|
|
|
|
For example, let's say you have an indexer `idx` and you create a tiddler T with the text "test" - that would result in your indexer's `update` method being called like this:
|
|
|
|
```javascript
|
|
idx.update({
|
|
old: { tiddler: null, shadow: false, exists: false },
|
|
new: { tiddler: new $tw.Tiddler({title: 'T', text: 'test'}), shadow: false, exists: true }
|
|
});
|
|
```
|
|
|
|
If you then change the text from "test" to "testing", `update` would be called like this:
|
|
|
|
```javascript
|
|
idx.update({
|
|
old: { tiddler: new $tw.Tiddler({title: 'T', text: 'test'}), shadow: false, exists: true },
|
|
new: { tiddler: new $tw.Tiddler({title: 'T', text: 'testing'}), shadow: false, exists: true }
|
|
});
|
|
```
|
|
|
|
And finally, if you delete T, `update` will be called like this:
|
|
|
|
```javascript
|
|
idx.update({
|
|
old: { tiddler: new $tw.Tiddler({title: 'T', text: 'testing'}), shadow: false, exists: true },
|
|
new: { tiddler: null, shadow: false, exists: false }
|
|
});
|
|
``` |