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forgejo/modules/regexplru/regexplru.go

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// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package regexplru
import (
"regexp"
"code.gitea.io/gitea/modules/log"
lru "github.com/hashicorp/golang-lru"
)
var lruCache *lru.Cache
func init() {
var err error
lruCache, err = lru.New(1000)
if err != nil {
log.Fatal("failed to new LRU cache, err: %v", err)
}
}
// GetCompiled works like regexp.Compile, the compiled expr or error is stored in LRU cache
func GetCompiled(expr string) (r *regexp.Regexp, err error) {
v, ok := lruCache.Get(expr)
if !ok {
r, err = regexp.Compile(expr)
if err != nil {
lruCache.Add(expr, err)
return nil, err
}
lruCache.Add(expr, r)
} else {
r, ok = v.(*regexp.Regexp)
if !ok {
if err, ok = v.(error); ok {
return nil, err
}
panic("impossible")
}
}
return r, nil
}