Source file src/pkg/internal/lazyregexp/lazyre.go

     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.
     7	package lazyregexp
     8	
     9	import (
    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.
    18	type Regexp struct {
    19		str  string
    20		once sync.Once
    21		rx   *regexp.Regexp
    22	}
    23	
    24	func (r *Regexp) re() *regexp.Regexp {
    25		r.once.Do(r.build)
    26		return r.rx
    27	}
    28	
    29	func (r *Regexp) build() {
    30		r.rx = regexp.MustCompile(r.str)
    31		r.str = ""
    32	}
    33	
    34	func (r *Regexp) FindSubmatch(s []byte) [][]byte {
    35		return r.re().FindSubmatch(s)
    36	}
    37	
    38	func (r *Regexp) FindStringSubmatch(s string) []string {
    39		return r.re().FindStringSubmatch(s)
    40	}
    41	
    42	func (r *Regexp) FindStringSubmatchIndex(s string) []int {
    43		return r.re().FindStringSubmatchIndex(s)
    44	}
    45	
    46	func (r *Regexp) ReplaceAllString(src, repl string) string {
    47		return r.re().ReplaceAllString(src, repl)
    48	}
    49	
    50	func (r *Regexp) FindString(s string) string {
    51		return r.re().FindString(s)
    52	}
    53	
    54	func (r *Regexp) FindAllString(s string, n int) []string {
    55		return r.re().FindAllString(s, n)
    56	}
    57	
    58	func (r *Regexp) MatchString(s string) bool {
    59		return r.re().MatchString(s)
    60	}
    61	
    62	func (r *Regexp) SubexpNames() []string {
    63		return r.re().SubexpNames()
    64	}
    65	
    66	var inTest = len(os.Args) > 0 && strings.HasSuffix(strings.TrimSuffix(os.Args[0], ".exe"), ".test")
    67	
    68	// New creates a new lazy regexp, delaying the compiling work until it is first
    69	// needed. If the code is being run as part of tests, the regexp compiling will
    70	// happen immediately.
    71	func New(str string) *Regexp {
    72		lr := &Regexp{str: str}
    73		if inTest {
    74			// In tests, always compile the regexps early.
    75			lr.re()
    76		}
    77		return lr
    78	}
    79	

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