Initial data commit

Task/Find-common-directory-path/Go/find-common-directory-path.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path"
+)
+
+func CommonPrefix(sep byte, paths ...string) string {
+	// Handle special cases.
+	switch len(paths) {
+	case 0:
+		return ""
+	case 1:
+		return path.Clean(paths[0])
+	}
+
+	// Note, we treat string as []byte, not []rune as is often
+	// done in Go. (And sep as byte, not rune). This is because
+	// most/all supported OS' treat paths as string of non-zero
+	// bytes. A filename may be displayed as a sequence of Unicode
+	// runes (typically encoded as UTF-8) but paths are
+	// not required to be valid UTF-8 or in any normalized form
+	// (e.g. "é" (U+00C9) and "é" (U+0065,U+0301) are different
+	// file names.
+	c := []byte(path.Clean(paths[0]))
+
+	// We add a trailing sep to handle the case where the
+	// common prefix directory is included in the path list
+	// (e.g. /home/user1, /home/user1/foo, /home/user1/bar).
+	// path.Clean will have cleaned off trailing / separators with
+	// the exception of the root directory, "/" (in which case we
+	// make it "//", but this will get fixed up to "/" bellow).
+	c = append(c, sep)
+
+	// Ignore the first path since it's already in c
+	for _, v := range paths[1:] {
+		// Clean up each path before testing it
+		v = path.Clean(v) + string(sep)
+
+		// Find the first non-common byte and truncate c
+		if len(v) < len(c) {
+			c = c[:len(v)]
+		}
+		for i := 0; i < len(c); i++ {
+			if v[i] != c[i] {
+				c = c[:i]
+				break
+			}
+		}
+	}
+
+	// Remove trailing non-separator characters and the final separator
+	for i := len(c) - 1; i >= 0; i-- {
+		if c[i] == sep {
+			c = c[:i]
+			break
+		}
+	}
+
+	return string(c)
+}
+
+func main() {
+	c := CommonPrefix(os.PathSeparator,
+		//"/home/user1/tmp",
+		"/home/user1/tmp/coverage/test",
+		"/home/user1/tmp/covert/operator",
+		"/home/user1/tmp/coven/members",
+		"/home//user1/tmp/coventry",
+		"/home/user1/././tmp/covertly/foo",
+		"/home/bob/../user1/tmp/coved/bar",
+	)
+	if c == "" {
+		fmt.Println("No common path")
+	} else {
+		fmt.Println("Common path:", c)
+	}
+}