Source: match.go in package path


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)

Trailing * matches rest of string unless it has a /.

			return bytealg.IndexByteString(name, '/') < 0, nil

Look for match at current position.

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
		}

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 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] {

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 ?.

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] {

character class

			var r rune
			if !failed {
				var n int
				r, n = utf8.DecodeRuneInString(s)
				s = s[n:]
			}

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