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|
// Match provides a simple pattern matcher with unicode support.
package match
import "unicode/utf8"
// Match returns true if str matches pattern. This is a very
// simple wildcard match where '*' matches on any number characters
// and '?' matches on any one character.
// pattern:
// { term }
// term:
// '*' matches any sequence of non-Separator characters
// '?' matches any single non-Separator character
// c matches character c (c != '*', '?', '\\')
// '\\' c matches character c
//
func Match(str, pattern string) bool {
if pattern == "*" {
return true
}
return deepMatch(str, pattern)
}
func deepMatch(str, pattern string) bool {
for len(pattern) > 0 {
if pattern[0] > 0x7f {
return deepMatchRune(str, pattern)
}
switch pattern[0] {
default:
if len(str) == 0 {
return false
}
if str[0] > 0x7f {
return deepMatchRune(str, pattern)
}
if str[0] != pattern[0] {
return false
}
case '?':
if len(str) == 0 {
return false
}
case '*':
return deepMatch(str, pattern[1:]) ||
(len(str) > 0 && deepMatch(str[1:], pattern))
}
str = str[1:]
pattern = pattern[1:]
}
return len(str) == 0 && len(pattern) == 0
}
func deepMatchRune(str, pattern string) bool {
var sr, pr rune
var srsz, prsz int
// read the first rune ahead of time
if len(str) > 0 {
if str[0] > 0x7f {
sr, srsz = utf8.DecodeRuneInString(str)
} else {
sr, srsz = rune(str[0]), 1
}
} else {
sr, srsz = utf8.RuneError, 0
}
if len(pattern) > 0 {
if pattern[0] > 0x7f {
pr, prsz = utf8.DecodeRuneInString(pattern)
} else {
pr, prsz = rune(pattern[0]), 1
}
} else {
pr, prsz = utf8.RuneError, 0
}
// done reading
for pr != utf8.RuneError {
switch pr {
default:
if srsz == utf8.RuneError {
return false
}
if sr != pr {
return false
}
case '?':
if srsz == utf8.RuneError {
return false
}
case '*':
return deepMatchRune(str, pattern[prsz:]) ||
(srsz > 0 && deepMatchRune(str[srsz:], pattern))
}
str = str[srsz:]
pattern = pattern[prsz:]
// read the next runes
if len(str) > 0 {
if str[0] > 0x7f {
sr, srsz = utf8.DecodeRuneInString(str)
} else {
sr, srsz = rune(str[0]), 1
}
} else {
sr, srsz = utf8.RuneError, 0
}
if len(pattern) > 0 {
if pattern[0] > 0x7f {
pr, prsz = utf8.DecodeRuneInString(pattern)
} else {
pr, prsz = rune(pattern[0]), 1
}
} else {
pr, prsz = utf8.RuneError, 0
}
// done reading
}
return srsz == 0 && prsz == 0
}
var maxRuneBytes = func() []byte {
b := make([]byte, 4)
if utf8.EncodeRune(b, '\U0010FFFF') != 4 {
panic("invalid rune encoding")
}
return b
}()
// Allowable parses the pattern and determines the minimum and maximum allowable
// values that the pattern can represent.
// When the max cannot be determined, 'true' will be returned
// for infinite.
func Allowable(pattern string) (min, max string) {
if pattern == "" || pattern[0] == '*' {
return "", ""
}
minb := make([]byte, 0, len(pattern))
maxb := make([]byte, 0, len(pattern))
var wild bool
for i := 0; i < len(pattern); i++ {
if pattern[i] == '*' {
wild = true
break
}
if pattern[i] == '?' {
minb = append(minb, 0)
maxb = append(maxb, maxRuneBytes...)
} else {
minb = append(minb, pattern[i])
maxb = append(maxb, pattern[i])
}
}
if wild {
r, n := utf8.DecodeLastRune(maxb)
if r != utf8.RuneError {
if r < utf8.MaxRune {
r++
if r > 0x7f {
b := make([]byte, 4)
nn := utf8.EncodeRune(b, r)
maxb = append(maxb[:len(maxb)-n], b[:nn]...)
} else {
maxb = append(maxb[:len(maxb)-n], byte(r))
}
}
}
}
return string(minb), string(maxb)
}
// IsPattern returns true if the string is a pattern.
func IsPattern(str string) bool {
for i := 0; i < len(str); i++ {
if str[i] == '*' || str[i] == '?' {
return true
}
}
return false
}
|
