element-web/src/autocomplete/FuzzyMatcher.js

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import Levenshtein from 'liblevenshtein';
import _at from 'lodash/at';
import _flatMap from 'lodash/flatMap';
import _sortBy from 'lodash/sortBy';
import _sortedUniq from 'lodash/sortedUniq';
import _keys from 'lodash/keys';
class KeyMap {
keys: Array<String>;
objectMap: {[String]: Array<Object>};
priorityMap: {[String]: number}
}
const DEFAULT_RESULT_COUNT = 10;
const DEFAULT_DISTANCE = 5;
export default class FuzzyMatcher {
/**
* Given an array of objects and keys, returns a KeyMap
* Keys can refer to object properties by name and as in JavaScript (for nested properties)
*
* To use, simply presort objects by required criteria, run through this function and create a FuzzyMatcher with the
* resulting KeyMap.
*
* TODO: Handle arrays and objects (Fuse did this, RoomProvider uses it)
*/
static valuesToKeyMap(objects: Array<Object>, keys: Array<String>): KeyMap {
const keyMap = new KeyMap();
const map = {};
const priorities = {};
objects.forEach((object, i) => {
const keyValues = _at(object, keys);
console.log(object, keyValues, keys);
for (const keyValue of keyValues) {
if (!map.hasOwnProperty(keyValue)) {
map[keyValue] = [];
}
map[keyValue].push(object);
}
priorities[object] = i;
});
keyMap.objectMap = map;
keyMap.priorityMap = priorities;
keyMap.keys = _sortBy(_keys(map), [value => priorities[value]]);
return keyMap;
}
constructor(objects: Array<Object>, options: {[Object]: Object} = {}) {
this.options = options;
this.keys = options.keys;
this.setObjects(objects);
}
setObjects(objects: Array<Object>) {
this.keyMap = FuzzyMatcher.valuesToKeyMap(objects, this.keys);
console.log(this.keyMap.keys);
this.matcher = new Levenshtein.Builder()
.dictionary(this.keyMap.keys, true)
.algorithm('transposition')
.sort_candidates(false)
.case_insensitive_sort(true)
.include_distance(true)
.maximum_candidates(this.options.resultCount || DEFAULT_RESULT_COUNT) // result count 0 doesn't make much sense
.build();
}
match(query: String): Array<Object> {
const candidates = this.matcher.transduce(query, this.options.distance || DEFAULT_DISTANCE);
// TODO FIXME This is hideous. Clean up when possible.
const val = _sortedUniq(_sortBy(_flatMap(candidates, candidate => {
return this.keyMap.objectMap[candidate[0]].map(value => {
return {
distance: candidate[1],
...value,
};
});
}),
[candidate => candidate.distance, candidate => this.keyMap.priorityMap[candidate]]));
console.log(val);
return val;
}
}