feat(stemmer): adds english stemmer #109
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ShogunPanda
approved these changes
Aug 29, 2022
| @@ -0,0 +1,189 @@ | |||
| const step2List = { | |||
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Non blocking comment on this file.
If you can, it would be great to extract all constant RegExp expression at the module level and declare them as RegExp when possible so we might get a small to tiny performance improvement.
ShogunPanda
approved these changes
Aug 29, 2022
| stemmingFn?: (word: string) => string; | ||
| }; | ||
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| export type TokenizerConfigExec = { |
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You can streamline this as export type TokenizerConfigExec = Required<TokenizerConfig>
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Oh, one problem is that stemmingFn can be undefined (to fallback to the default stemming function). Required is not compatible with undefined values
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This PR aims to add an English stemmer to Lyra.
The API is designed in such a way that if a stemmer is not available for a selected language, the stemming process will be skipped.
The stemming algorithm is based on the following paper: https://tartarus.org/martin/PorterStemmer/def.txt.
A clear example of how stemming works can be found in this file: tap-snapshots/tests/tokenizer.test.ts.test.cjs
Benefits:
Lucky,Luck,Luckilyshares the same meaning and will give the same resultsQuestion, should we add an option to disable stemming?
Update
This PR also adds a list of stop-words in English, which gets removed as they carry very little meaning to the search context. I will add the possibility to merge, replace, and delete stop-words with a simple API