gitea/modules/indexer/code/bleve/token/path/path.go

102 lines
2.3 KiB
Go

// Copyright 2024 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package path
import (
"slices"
"strings"
"github.com/blevesearch/bleve/v2/analysis"
"github.com/blevesearch/bleve/v2/registry"
)
const (
Name = "gitea/path"
)
type TokenFilter struct{}
func NewTokenFilter() *TokenFilter {
return &TokenFilter{}
}
func TokenFilterConstructor(config map[string]any, cache *registry.Cache) (analysis.TokenFilter, error) {
return NewTokenFilter(), nil
}
func (s *TokenFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
if len(input) == 1 {
// if there is only one token, we dont need to generate the reversed chain
return generatePathTokens(input, false)
}
normal := generatePathTokens(input, false)
reversed := generatePathTokens(input, true)
return append(normal, reversed...)
}
// Generates path tokens from the input tokens.
// This mimics the behavior of the path hierarchy tokenizer in ES. It takes the input tokens and combine them, generating a term for each component
// in tree (e.g., foo/bar/baz.md will generate foo, foo/bar, and foo/bar/baz.md).
//
// If the reverse flag is set, the order of the tokens is reversed (the same input will generate baz.md, baz.md/bar, baz.md/bar/foo). This is useful
// to efficiently search for filenames without supplying the fullpath.
func generatePathTokens(input analysis.TokenStream, reversed bool) analysis.TokenStream {
terms := make([]string, 0, len(input))
longestTerm := 0
if reversed {
slices.Reverse(input)
}
for i := 0; i < len(input); i++ {
var sb strings.Builder
sb.WriteString(string(input[0].Term))
for j := 1; j < i; j++ {
sb.WriteString("/")
sb.WriteString(string(input[j].Term))
}
term := sb.String()
if longestTerm < len(term) {
longestTerm = len(term)
}
terms = append(terms, term)
}
output := make(analysis.TokenStream, 0, len(terms))
for _, term := range terms {
var start, end int
if reversed {
start = 0
end = len(term)
} else {
start = longestTerm - len(term)
end = longestTerm
}
token := analysis.Token{
Position: 1,
Start: start,
End: end,
Type: analysis.AlphaNumeric,
Term: []byte(term),
}
output = append(output, &token)
}
return output
}
func init() {
registry.RegisterTokenFilter(Name, TokenFilterConstructor)
}