mirror of
https://github.com/go-gitea/gitea.git
synced 2024-11-01 08:47:40 -04:00
106 lines
2.7 KiB
Go
106 lines
2.7 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
|
||
//
|
||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
// you may not use this file except in compliance with the License.
|
||
// You may obtain a copy of the License at
|
||
//
|
||
// http://www.apache.org/licenses/LICENSE-2.0
|
||
//
|
||
// Unless required by applicable law or agreed to in writing, software
|
||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
// See the License for the specific language governing permissions and
|
||
// limitations under the License.
|
||
|
||
// Package lowercase implements a TokenFilter which converts
|
||
// tokens to lower case according to unicode rules.
|
||
package lowercase
|
||
|
||
import (
|
||
"bytes"
|
||
"unicode"
|
||
"unicode/utf8"
|
||
|
||
"github.com/blevesearch/bleve/analysis"
|
||
"github.com/blevesearch/bleve/registry"
|
||
)
|
||
|
||
// Name is the name used to register LowerCaseFilter in the bleve registry
|
||
const Name = "to_lower"
|
||
|
||
type LowerCaseFilter struct {
|
||
}
|
||
|
||
func NewLowerCaseFilter() *LowerCaseFilter {
|
||
return &LowerCaseFilter{}
|
||
}
|
||
|
||
func (f *LowerCaseFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
|
||
for _, token := range input {
|
||
token.Term = toLowerDeferredCopy(token.Term)
|
||
}
|
||
return input
|
||
}
|
||
|
||
func LowerCaseFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
|
||
return NewLowerCaseFilter(), nil
|
||
}
|
||
|
||
func init() {
|
||
registry.RegisterTokenFilter(Name, LowerCaseFilterConstructor)
|
||
}
|
||
|
||
// toLowerDeferredCopy will function exactly like
|
||
// bytes.ToLower() only it will reuse (overwrite)
|
||
// the original byte array when possible
|
||
// NOTE: because its possible that the lower-case
|
||
// form of a rune has a different utf-8 encoded
|
||
// length, in these cases a new byte array is allocated
|
||
func toLowerDeferredCopy(s []byte) []byte {
|
||
j := 0
|
||
for i := 0; i < len(s); {
|
||
wid := 1
|
||
r := rune(s[i])
|
||
if r >= utf8.RuneSelf {
|
||
r, wid = utf8.DecodeRune(s[i:])
|
||
}
|
||
|
||
l := unicode.ToLower(r)
|
||
|
||
// If the rune is already lowercased, just move to the
|
||
// next rune.
|
||
if l == r {
|
||
i += wid
|
||
j += wid
|
||
continue
|
||
}
|
||
|
||
// Handles the Unicode edge-case where the last
|
||
// rune in a word on the greek Σ needs to be converted
|
||
// differently.
|
||
if l == 'σ' && i+2 == len(s) {
|
||
l = 'ς'
|
||
}
|
||
|
||
lwid := utf8.RuneLen(l)
|
||
if lwid > wid {
|
||
// utf-8 encoded replacement is wider
|
||
// for now, punt and defer
|
||
// to bytes.ToLower() for the remainder
|
||
// only known to happen with chars
|
||
// Rune Ⱥ(570) width 2 - Lower ⱥ(11365) width 3
|
||
// Rune Ⱦ(574) width 2 - Lower ⱦ(11366) width 3
|
||
rest := bytes.ToLower(s[i:])
|
||
rv := make([]byte, j+len(rest))
|
||
copy(rv[:j], s[:j])
|
||
copy(rv[j:], rest)
|
||
return rv
|
||
} else {
|
||
utf8.EncodeRune(s[j:], l)
|
||
}
|
||
i += wid
|
||
j += lwid
|
||
}
|
||
return s[:j]
|
||
}
|