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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package path
import (
"errors"
"internal/bytealg"
"unicode/utf8"
)
// ErrBadPattern indicates a pattern was malformed.
var ErrBadPattern = errors.New("syntax error in pattern")
// Match reports whether name matches the shell pattern.
// The pattern syntax is:
//
// pattern:
// { term }
// term:
// '*' matches any sequence of non-/ characters
// '?' matches any single non-/ character
// '[' [ '^' ] { character-range } ']'
// character class (must be non-empty)
// c matches character c (c != '*', '?', '\\', '[')
// '\\' c matches character c
//
// character-range:
// c matches character c (c != '\\', '-', ']')
// '\\' c matches character c
// lo '-' hi matches character c for lo <= c <= hi
//
// Match requires pattern to match all of name, not just a substring.
// The only possible returned error is [ErrBadPattern], when pattern
// is malformed.
func Match(pattern, name string) (matched bool, err error) {
Pattern:
for len(pattern) > 0 {
var star bool
var chunk string
star, chunk, pattern = scanChunk(pattern)
if star && chunk == "" {
// Trailing * matches rest of string unless it has a /.
return bytealg.IndexByteString(name, '/') < 0, nil
}
// Look for match at current position.
t, ok, err := matchChunk(chunk, name)
// if we're the last chunk, make sure we've exhausted the name
// otherwise we'll give a false result even if we could still match
// using the star
if ok && (len(t) == 0 || len(pattern) > 0) {
name = t
continue
}
if err != nil {
return false, err
}
if star {
// Look for match skipping i+1 bytes.
// Cannot skip /.
for i := 0; i < len(name) && name[i] != '/'; i++ {
t, ok, err := matchChunk(chunk, name[i+1:])
if ok {
// if we're the last chunk, make sure we exhausted the name
if len(pattern) == 0 && len(t) > 0 {
continue
}
name = t
continue Pattern
}
if err != nil {
return false, err
}
}
}
// Before returning false with no error,
// check that the remainder of the pattern is syntactically valid.
for len(pattern) > 0 {
_, chunk, pattern = scanChunk(pattern)
if _, _, err := matchChunk(chunk, ""); err != nil {
return false, err
}
}
return false, nil
}
return len(name) == 0, nil
}
// scanChunk gets the next segment of pattern, which is a non-star string
// possibly preceded by a star.
func scanChunk(pattern string) (star bool, chunk, rest string) {
for len(pattern) > 0 && pattern[0] == '*' {
pattern = pattern[1:]
star = true
}
inrange := false
var i int
Scan:
for i = 0; i < len(pattern); i++ {
switch pattern[i] {
case '\\':
// error check handled in matchChunk: bad pattern.
if i+1 < len(pattern) {
i++
}
case '[':
inrange = true
case ']':
inrange = false
case '*':
if !inrange {
break Scan
}
}
}
return star, pattern[0:i], pattern[i:]
}
// matchChunk checks whether chunk matches the beginning of s.
// If so, it returns the remainder of s (after the match).
// Chunk is all single-character operators: literals, char classes, and ?.
func matchChunk(chunk, s string) (rest string, ok bool, err error) {
// failed records whether the match has failed.
// After the match fails, the loop continues on processing chunk,
// checking that the pattern is well-formed but no longer reading s.
failed := false
for len(chunk) > 0 {
if !failed && len(s) == 0 {
failed = true
}
switch chunk[0] {
case '[':
// character class
var r rune
if !failed {
var n int
r, n = utf8.DecodeRuneInString(s)
s = s[n:]
}
chunk = chunk[1:]
// possibly negated
negated := false
if len(chunk) > 0 && chunk[0] == '^' {
negated = true
chunk = chunk[1:]
}
// parse all ranges
match := false
nrange := 0
for {
if len(chunk) > 0 && chunk[0] == ']' && nrange > 0 {
chunk = chunk[1:]
break
}
var lo, hi rune
if lo, chunk, err = getEsc(chunk); err != nil {
return "", false, err
}
hi = lo
if chunk[0] == '-' {
if hi, chunk, err = getEsc(chunk[1:]); err != nil {
return "", false, err
}
}
if lo <= r && r <= hi {
match = true
}
nrange++
}
if match == negated {
failed = true
}
case '?':
if !failed {
if s[0] == '/' {
failed = true
}
_, n := utf8.DecodeRuneInString(s)
s = s[n:]
}
chunk = chunk[1:]
case '\\':
chunk = chunk[1:]
if len(chunk) == 0 {
return "", false, ErrBadPattern
}
fallthrough
default:
if !failed {
if chunk[0] != s[0] {
failed = true
}
s = s[1:]
}
chunk = chunk[1:]
}
}
if failed {
return "", false, nil
}
return s, true, nil
}
// getEsc gets a possibly-escaped character from chunk, for a character class.
func getEsc(chunk string) (r rune, nchunk string, err error) {
if len(chunk) == 0 || chunk[0] == '-' || chunk[0] == ']' {
err = ErrBadPattern
return
}
if chunk[0] == '\\' {
chunk = chunk[1:]
if len(chunk) == 0 {
err = ErrBadPattern
return
}
}
r, n := utf8.DecodeRuneInString(chunk)
if r == utf8.RuneError && n == 1 {
err = ErrBadPattern
}
nchunk = chunk[n:]
if len(nchunk) == 0 {
err = ErrBadPattern
}
return
}
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