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