github.com/graemephi/kahugo@v0.62.3-0.20211121071557-d78c0423784d/tpl/strings/regexp.go (about)

     1  // Copyright 2017 The Hugo Authors. All rights reserved.
     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  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package strings
    15  
    16  import (
    17  	"regexp"
    18  	"sync"
    19  
    20  	"github.com/spf13/cast"
    21  )
    22  
    23  // FindRE returns a list of strings that match the regular expression. By default all matches
    24  // will be included. The number of matches can be limited with an optional third parameter.
    25  func (ns *Namespace) FindRE(expr string, content interface{}, limit ...interface{}) ([]string, error) {
    26  	re, err := reCache.Get(expr)
    27  	if err != nil {
    28  		return nil, err
    29  	}
    30  
    31  	conv, err := cast.ToStringE(content)
    32  	if err != nil {
    33  		return nil, err
    34  	}
    35  
    36  	if len(limit) == 0 {
    37  		return re.FindAllString(conv, -1), nil
    38  	}
    39  
    40  	lim, err := cast.ToIntE(limit[0])
    41  	if err != nil {
    42  		return nil, err
    43  	}
    44  
    45  	return re.FindAllString(conv, lim), nil
    46  }
    47  
    48  // ReplaceRE returns a copy of s, replacing all matches of the regular
    49  // expression pattern with the replacement text repl. The number of replacements
    50  // can be limited with an optional fourth parameter.
    51  func (ns *Namespace) ReplaceRE(pattern, repl, s interface{}, n ...interface{}) (_ string, err error) {
    52  	sp, err := cast.ToStringE(pattern)
    53  	if err != nil {
    54  		return
    55  	}
    56  
    57  	sr, err := cast.ToStringE(repl)
    58  	if err != nil {
    59  		return
    60  	}
    61  
    62  	ss, err := cast.ToStringE(s)
    63  	if err != nil {
    64  		return
    65  	}
    66  
    67  	nn := -1
    68  	if len(n) > 0 {
    69  		nn, err = cast.ToIntE(n[0])
    70  		if err != nil {
    71  			return
    72  		}
    73  	}
    74  
    75  	re, err := reCache.Get(sp)
    76  	if err != nil {
    77  		return "", err
    78  	}
    79  
    80  	return re.ReplaceAllStringFunc(ss, func(str string) string {
    81  		if nn == 0 {
    82  			return str
    83  		}
    84  
    85  		nn -= 1
    86  		return re.ReplaceAllString(str, sr)
    87  	}), nil
    88  }
    89  
    90  // regexpCache represents a cache of regexp objects protected by a mutex.
    91  type regexpCache struct {
    92  	mu sync.RWMutex
    93  	re map[string]*regexp.Regexp
    94  }
    95  
    96  // Get retrieves a regexp object from the cache based upon the pattern.
    97  // If the pattern is not found in the cache, create one
    98  func (rc *regexpCache) Get(pattern string) (re *regexp.Regexp, err error) {
    99  	var ok bool
   100  
   101  	if re, ok = rc.get(pattern); !ok {
   102  		re, err = regexp.Compile(pattern)
   103  		if err != nil {
   104  			return nil, err
   105  		}
   106  		rc.set(pattern, re)
   107  	}
   108  
   109  	return re, nil
   110  }
   111  
   112  func (rc *regexpCache) get(key string) (re *regexp.Regexp, ok bool) {
   113  	rc.mu.RLock()
   114  	re, ok = rc.re[key]
   115  	rc.mu.RUnlock()
   116  	return
   117  }
   118  
   119  func (rc *regexpCache) set(key string, re *regexp.Regexp) {
   120  	rc.mu.Lock()
   121  	rc.re[key] = re
   122  	rc.mu.Unlock()
   123  }
   124  
   125  var reCache = regexpCache{re: make(map[string]*regexp.Regexp)}