80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
package main
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import (
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"fmt"
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"os"
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"path"
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)
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func CommonPrefix(sep byte, paths ...string) string {
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// Handle special cases.
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switch len(paths) {
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case 0:
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return ""
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case 1:
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return path.Clean(paths[0])
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}
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// Note, we treat string as []byte, not []rune as is often
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// done in Go. (And sep as byte, not rune). This is because
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// most/all supported OS' treat paths as string of non-zero
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// bytes. A filename may be displayed as a sequence of Unicode
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// runes (typically encoded as UTF-8) but paths are
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// not required to be valid UTF-8 or in any normalized form
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// (e.g. "é" (U+00C9) and "é" (U+0065,U+0301) are different
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// file names.
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c := []byte(path.Clean(paths[0]))
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// We add a trailing sep to handle the case where the
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// common prefix directory is included in the path list
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// (e.g. /home/user1, /home/user1/foo, /home/user1/bar).
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// path.Clean will have cleaned off trailing / separators with
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// the exception of the root directory, "/" (in which case we
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// make it "//", but this will get fixed up to "/" bellow).
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c = append(c, sep)
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// Ignore the first path since it's already in c
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for _, v := range paths[1:] {
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// Clean up each path before testing it
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v = path.Clean(v) + string(sep)
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// Find the first non-common byte and truncate c
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if len(v) < len(c) {
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c = c[:len(v)]
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}
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for i := 0; i < len(c); i++ {
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if v[i] != c[i] {
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c = c[:i]
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break
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}
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}
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}
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// Remove trailing non-separator characters and the final separator
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for i := len(c) - 1; i >= 0; i-- {
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if c[i] == sep {
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c = c[:i]
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break
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}
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}
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return string(c)
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}
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func main() {
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c := CommonPrefix(os.PathSeparator,
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//"/home/user1/tmp",
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"/home/user1/tmp/coverage/test",
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"/home/user1/tmp/covert/operator",
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"/home/user1/tmp/coven/members",
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"/home//user1/tmp/coventry",
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"/home/user1/././tmp/covertly/foo",
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"/home/bob/../user1/tmp/coved/bar",
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)
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if c == "" {
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fmt.Println("No common path")
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} else {
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fmt.Println("Common path:", c)
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}
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}
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