golang match 代码
文件路径：/src/path/match.go
/ 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
}