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91 lines
2.6 KiB
Go
91 lines
2.6 KiB
Go
// Copyright 2023 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package bleve
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import (
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"errors"
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"os"
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"unicode"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/setting"
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"code.gitea.io/gitea/modules/util"
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"github.com/blevesearch/bleve/v2"
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unicode_tokenizer "github.com/blevesearch/bleve/v2/analysis/tokenizer/unicode"
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"github.com/blevesearch/bleve/v2/index/upsidedown"
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"github.com/ethantkoenig/rupture"
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)
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const (
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maxFuzziness = 2
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)
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// openIndexer open the index at the specified path, checking for metadata
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// updates and bleve version updates. If index needs to be created (or
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// re-created), returns (nil, nil)
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func openIndexer(path string, latestVersion int) (bleve.Index, int, error) {
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_, err := os.Stat(path)
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if err != nil && os.IsNotExist(err) {
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return nil, 0, nil
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} else if err != nil {
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return nil, 0, err
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}
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metadata, err := rupture.ReadIndexMetadata(path)
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if err != nil {
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return nil, 0, err
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}
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if metadata.Version < latestVersion {
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// the indexer is using a previous version, so we should delete it and
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// re-populate
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return nil, metadata.Version, util.RemoveAll(path)
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}
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index, err := bleve.Open(path)
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if err != nil {
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if errors.Is(err, upsidedown.IncompatibleVersion) {
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log.Warn("Indexer was built with a previous version of bleve, deleting and rebuilding")
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return nil, 0, util.RemoveAll(path)
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}
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return nil, 0, err
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}
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return index, 0, nil
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}
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// GuessFuzzinessByKeyword guesses fuzziness based on the levenshtein distance and determines how many chars
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// may be different on two string, and they still be considered equivalent.
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// Given a phrase, its shortest word determines its fuzziness. If a phrase uses CJK (eg: `갃갃갃` `啊啊啊`), the fuzziness is zero.
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func GuessFuzzinessByKeyword(s string) int {
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tokenizer := unicode_tokenizer.NewUnicodeTokenizer()
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tokens := tokenizer.Tokenize([]byte(s))
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if len(tokens) > 0 {
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fuzziness := maxFuzziness
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for _, token := range tokens {
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fuzziness = min(fuzziness, guessFuzzinessByKeyword(string(token.Term)))
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}
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return fuzziness
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}
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return 0
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}
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func guessFuzzinessByKeyword(s string) int {
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// according to https://github.com/blevesearch/bleve/issues/1563, the supported max fuzziness is 2
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// magic number 4 was chosen to determine the levenshtein distance per each character of a keyword
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// BUT, when using CJK (eg: `갃갃갃` `啊啊啊`), it mismatches a lot.
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// Likewise, queries whose terms contains characters that are *not* letters should not use fuzziness
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for _, r := range s {
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if r >= 128 || !unicode.IsLetter(r) {
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return 0
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}
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}
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return min(min(setting.Indexer.TypeBleveMaxFuzzniess, maxFuzziness), len(s)/4)
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}
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