sh/pattern/pattern.go at master · mozey/sh · GitHub

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// See LICENSE for licensing information

// Package pattern allows working with shell pattern matching notation, also

// known as wildcards or globbing.

// For reference, see

// https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_13.

package pattern

import (

"bytes"

"fmt"

"regexp"

"strconv"

"strings"

)

// Mode can be used to supply a number of options to the package's functions.

// Not all functions change their behavior with all of the options below.

type Mode uint

type SyntaxError struct {

msg string

err error

}

func (e SyntaxError) Error() string { return e.msg }

func (e SyntaxError) Unwrap() error { return e.err }

const (

Shortest Mode = 1 << iota // prefer the shortest match.

Filenames // "*" and "?" don't match slashes; only "**" does

Braces // support "{a,b}" and "{1..4}"

EntireString // match the entire string using ^$ delimiters

)

var numRange = regexp.MustCompile(`^([+-]?\d+)\.\.([+-]?\d+)}`)

// Regexp turns a shell pattern into a regular expression that can be used with

// [regexp.Compile]. It will return an error if the input pattern was incorrect.

// Otherwise, the returned expression can be passed to [regexp.MustCompile].

// For example, Regexp(`foo*bar?`, true) returns `foo.*bar.`.

// Note that this function (and [QuoteMeta]) should not be directly used with file

// paths if Windows is supported, as the path separator on that platform is the

// same character as the escaping character for shell patterns.

func Regexp(pat string, mode Mode) (string, error) {

needsEscaping := false

noopLoop:

for _, r := range pat {

switch r {

// including those that need escaping since they are

// regular expression metacharacters

case '*', '?', '[', '\\', '.', '+', '(', ')', '|',

']', '{', '}', '^', '$':

needsEscaping = true

break noopLoop

}

if !needsEscaping && mode&EntireString == 0 { // short-cut without a string copy

return pat, nil

}

closingBraces := []int{}

var buf bytes.Buffer

// Enable matching `\n` with the `.` metacharacter as globs match `\n`

buf.WriteString("(?s)")

dotMeta := false

if mode&EntireString != 0 {

buf.WriteString("^")

}

writeLoop:

for i := 0; i < len(pat); i++ {

switch c := pat[i]; c {

case '*':

if mode&Filenames != 0 {

if i++; i < len(pat) && pat[i] == '*' {

if i++; i < len(pat) && pat[i] == '/' {

buf.WriteString("(.*/|)")

dotMeta = true

} else {

buf.WriteString(".*")

dotMeta = true

i--

}

} else {

buf.WriteString("[^/]*")

i--

}

} else {

buf.WriteString(".*")

dotMeta = true

}

if mode&Shortest != 0 {

buf.WriteByte('?')

}

case '?':

if mode&Filenames != 0 {

buf.WriteString("[^/]")

} else {

buf.WriteByte('.')

dotMeta = true

}

case '\\':

if i++; i >= len(pat) {

return "", &SyntaxError{msg: `\ at end of pattern`}

}

buf.WriteString(regexp.QuoteMeta(string(pat[i])))

case '[':

name, err := charClass(pat[i:])

if err != nil {

return "", &SyntaxError{msg: "charClass invalid", err: err}

}

if name != "" {

buf.WriteString(name)

i += len(name) - 1

break

}

if mode&Filenames != 0 {

for _, c := range pat[i:] {

if c == ']' {

break

} else if c == '/' {

buf.WriteString("\\[")

continue writeLoop

}

buf.WriteByte(c)

if i++; i >= len(pat) {

return "", &SyntaxError{msg: "[ was not matched with a closing ]"}

}

switch c = pat[i]; c {

case '!', '^':

buf.WriteByte('^')

if i++; i >= len(pat) {

return "", &SyntaxError{msg: "[ was not matched with a closing ]"}

}

if c = pat[i]; c == ']' {

buf.WriteByte(']')

if i++; i >= len(pat) {

return "", &SyntaxError{msg: "[ was not matched with a closing ]"}

}

rangeStart := byte(0)

loopBracket:

for ; i < len(pat); i++ {

c = pat[i]

buf.WriteByte(c)

switch c {

case '\\':

if i++; i < len(pat) {

buf.WriteByte(pat[i])

}

continue

case ']':

break loopBracket

}

if rangeStart != 0 && rangeStart > c {

return "", &SyntaxError{msg: fmt.Sprintf("invalid range: %c-%c", rangeStart, c)}

}

if c == '-' {

rangeStart = pat[i-1]

} else {

rangeStart = 0

}

if i >= len(pat) {

return "", &SyntaxError{msg: "[ was not matched with a closing ]"}

}

case '{':

if mode&Braces == 0 {

buf.WriteString(regexp.QuoteMeta(string(c)))

break

}

innerLevel := 1

commas := false

peekBrace:

for j := i + 1; j < len(pat); j++ {

switch c := pat[j]; c {

case '{':

innerLevel++

case ',':

commas = true

case '\\':

j++

case '}':

if innerLevel--; innerLevel > 0 {

continue

}

if !commas {

break peekBrace

}

closingBraces = append(closingBraces, j)

buf.WriteString("(?:")

continue writeLoop

}

if match := numRange.FindStringSubmatch(pat[i+1:]); len(match) == 3 {

start, err1 := strconv.Atoi(match[1])

end, err2 := strconv.Atoi(match[2])

if err1 != nil || err2 != nil || start > end {

return "", &SyntaxError{msg: fmt.Sprintf("invalid range: %q", match[0])}

}

// TODO: can we do better here?

buf.WriteString("(?:")

for n := start; n <= end; n++ {

if n > start {

buf.WriteByte('|')

}

fmt.Fprintf(&buf, "%d", n)

}

buf.WriteByte(')')

i += len(match[0])

break

}

buf.WriteString(regexp.QuoteMeta(string(c)))

case ',':

if len(closingBraces) == 0 {

buf.WriteString(regexp.QuoteMeta(string(c)))

} else {

buf.WriteByte('|')

}

case '}':

if len(closingBraces) > 0 && closingBraces[len(closingBraces)-1] == i {

buf.WriteByte(')')

closingBraces = closingBraces[:len(closingBraces)-1]

} else {

buf.WriteString(regexp.QuoteMeta(string(c)))

}

default:

if c > 128 {

buf.WriteByte(c)

} else {

buf.WriteString(regexp.QuoteMeta(string(c)))

}

if mode&EntireString != 0 {

buf.WriteString("$")

}

// No `.` metacharacters were used, so don't return the flag.

if !dotMeta {

return string(buf.Bytes()[4:]), nil

}

return buf.String(), nil

}

func charClass(s string) (string, error) {

if strings.HasPrefix(s, "[[.") || strings.HasPrefix(s, "[[=") {

return "", fmt.Errorf("collating features not available")

}

if !strings.HasPrefix(s, "[[:") {

return "", nil

}

name := s[3:]

end := strings.Index(name, ":]]")

if end < 0 {

return "", fmt.Errorf("[[: was not matched with a closing :]]")

}

name = name[:end]

switch name {

case "alnum", "alpha", "ascii", "blank", "cntrl", "digit", "graph",

"lower", "print", "punct", "space", "upper", "word", "xdigit":

default:

return "", fmt.Errorf("invalid character class: %q", name)

}

return s[:len(name)+6], nil

}

// HasMeta returns whether a string contains any unescaped pattern

// metacharacters: '*', '?', or '['. When the function returns false, the given

// pattern can only match at most one string.

// For example, HasMeta(`foo\*bar`) returns false, but HasMeta(`foo*bar`)

// returns true.

// This can be useful to avoid extra work, like TranslatePattern. Note that this

// function cannot be used to avoid QuotePattern, as backslashes are quoted by

// that function but ignored here.

func HasMeta(pat string, mode Mode) bool {

for i := 0; i < len(pat); i++ {

switch pat[i] {

case '\\':

i++

case '*', '?', '[':

return true

case '{':

if mode&Braces != 0 {

return true

}

return false

}

// QuoteMeta returns a string that quotes all pattern metacharacters in the

// given text. The returned string is a pattern that matches the literal text.

// For example, QuoteMeta(`foo*bar?`) returns `foo\*bar\?`.

func QuoteMeta(pat string, mode Mode) string {

needsEscaping := false

loop:

for _, r := range pat {

switch r {

case '{':

if mode&Braces == 0 {

continue

}

fallthrough

case '*', '?', '[', '\\':

needsEscaping = true

break loop

}

if !needsEscaping { // short-cut without a string copy

return pat

}

var buf bytes.Buffer

for _, r := range pat {

switch r {

case '*', '?', '[', '\\':

buf.WriteByte('\\')

case '{':

if mode&Braces != 0 {

buf.WriteByte('\\')

}

buf.WriteRune(r)

}

return buf.String()

}

sh/pattern/pattern.go at master · mozey/sh · GitHub

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