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Diffstat (limited to 'src/path/match.go')
| -rw-r--r-- | src/path/match.go | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/src/path/match.go b/src/path/match.go new file mode 100644 index 0000000..673bbc7 --- /dev/null +++ b/src/path/match.go @@ -0,0 +1,230 @@ +// 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 +} |