rexp.go

Documentation: k8s.io/kube-openapi/pkg/validation/validate

     1  // Copyright 2015 go-swagger maintainers
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //    http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package validate
    16  
    17  import (
    18  	re "regexp"
    19  	"sync"
    20  	"sync/atomic"
    21  )
    22  
    23  // Cache for compiled regular expressions
    24  var (
    25  	cacheMutex = &sync.Mutex{}
    26  	reDict     = atomic.Value{} //map[string]*re.Regexp
    27  )
    28  
    29  func compileRegexp(pattern string) (*re.Regexp, error) {
    30  	if cache, ok := reDict.Load().(map[string]*re.Regexp); ok {
    31  		if r := cache[pattern]; r != nil {
    32  			return r, nil
    33  		}
    34  	}
    35  
    36  	r, err := re.Compile(pattern)
    37  	if err != nil {
    38  		return nil, err
    39  	}
    40  	cacheRegexp(r)
    41  	return r, nil
    42  }
    43  
    44  func mustCompileRegexp(pattern string) *re.Regexp {
    45  	if cache, ok := reDict.Load().(map[string]*re.Regexp); ok {
    46  		if r := cache[pattern]; r != nil {
    47  			return r
    48  		}
    49  	}
    50  
    51  	r := re.MustCompile(pattern)
    52  	cacheRegexp(r)
    53  	return r
    54  }
    55  
    56  func cacheRegexp(r *re.Regexp) {
    57  	cacheMutex.Lock()
    58  	defer cacheMutex.Unlock()
    59  
    60  	if cache, ok := reDict.Load().(map[string]*re.Regexp); !ok || cache[r.String()] == nil {
    61  		newCache := map[string]*re.Regexp{
    62  			r.String(): r,
    63  		}
    64  
    65  		for k, v := range cache {
    66  			newCache[k] = v
    67  		}
    68  
    69  		reDict.Store(newCache)
    70  	}
    71  }
    72
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