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// Copyright 2017 The Hugo Authors. All rights reserved.
//
// 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 strings
import (
"regexp"
"sync"
"github.com/spf13/cast"
)
// FindRE returns a list of strings that match the regular expression. By default all matches
// will be included. The number of matches can be limited with an optional third parameter.
func (ns *Namespace) FindRE(expr string, content interface{}, limit ...interface{}) ([]string, error) {
re, err := reCache.Get(expr)
if err != nil {
return nil, err
}
conv, err := cast.ToStringE(content)
if err != nil {
return nil, err
}
if len(limit) == 0 {
return re.FindAllString(conv, -1), nil
}
lim, err := cast.ToIntE(limit[0])
if err != nil {
return nil, err
}
return re.FindAllString(conv, lim), nil
}
// ReplaceRE returns a copy of s, replacing all matches of the regular
// expression pattern with the replacement text repl. The number of replacements
// can be limited with an optional fourth parameter.
func (ns *Namespace) ReplaceRE(pattern, repl, s interface{}, n ...interface{}) (_ string, err error) {
sp, err := cast.ToStringE(pattern)
if err != nil {
return
}
sr, err := cast.ToStringE(repl)
if err != nil {
return
}
ss, err := cast.ToStringE(s)
if err != nil {
return
}
nn := -1
if len(n) > 0 {
nn, err = cast.ToIntE(n[0])
if err != nil {
return
}
}
re, err := reCache.Get(sp)
if err != nil {
return "", err
}
return re.ReplaceAllStringFunc(ss, func(str string) string {
if nn == 0 {
return str
}
nn -= 1
return re.ReplaceAllString(str, sr)
}), nil
}
// regexpCache represents a cache of regexp objects protected by a mutex.
type regexpCache struct {
mu sync.RWMutex
re map[string]*regexp.Regexp
}
// Get retrieves a regexp object from the cache based upon the pattern.
// If the pattern is not found in the cache, create one
func (rc *regexpCache) Get(pattern string) (re *regexp.Regexp, err error) {
var ok bool
if re, ok = rc.get(pattern); !ok {
re, err = regexp.Compile(pattern)
if err != nil {
return nil, err
}
rc.set(pattern, re)
}
return re, nil
}
func (rc *regexpCache) get(key string) (re *regexp.Regexp, ok bool) {
rc.mu.RLock()
re, ok = rc.re[key]
rc.mu.RUnlock()
return
}
func (rc *regexpCache) set(key string, re *regexp.Regexp) {
rc.mu.Lock()
rc.re[key] = re
rc.mu.Unlock()
}
var reCache = regexpCache{re: make(map[string]*regexp.Regexp)}
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