1// Copyright 2018 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Package lazyregexp is a thin wrapper over regexp, allowing the use of global 6// regexp variables without forcing them to be compiled at init. 7package lazyregexp 8 9import ( 10 "os" 11 "regexp" 12 "strings" 13 "sync" 14) 15 16// Regexp is a wrapper around regexp.Regexp, where the underlying regexp will be 17// compiled the first time it is needed. 18type Regexp struct { 19 str string 20 once sync.Once 21 rx *regexp.Regexp 22} 23 24func (r *Regexp) re() *regexp.Regexp { 25 r.once.Do(r.build) 26 return r.rx 27} 28 29func (r *Regexp) build() { 30 r.rx = regexp.MustCompile(r.str) 31 r.str = "" 32} 33 34func (r *Regexp) MatchString(s string) bool { 35 return r.re().MatchString(s) 36} 37 38var inTest = len(os.Args) > 0 && strings.HasSuffix(strings.TrimSuffix(os.Args[0], ".exe"), ".test") 39 40// New creates a new lazy regexp, delaying the compiling work until it is first 41// needed. If the code is being run as part of tests, the regexp compiling will 42// happen immediately. 43func New(str string) *Regexp { 44 lr := &Regexp{str: str} 45 if inTest { 46 // In tests, always compile the regexps early. 47 lr.re() 48 } 49 return lr 50} 51