vendor/cmd/go/internal/str/path.go

// Copyright 2018 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 str

import (
	"path/filepath"
	"strings"
)

// HasFilePathPrefix reports whether the filesystem path s begins with the
// elements in prefix.
func HasFilePathPrefix(s, prefix string) bool {
	sv := strings.ToUpper(filepath.VolumeName(s))
	pv := strings.ToUpper(filepath.VolumeName(prefix))
	s = s[len(sv):]
	prefix = prefix[len(pv):]
	switch {
	default:
		return false
	case sv != pv:
		return false
	case len(s) == len(prefix):
		return s == prefix
	case len(s) > len(prefix):
		if prefix != "" && prefix[len(prefix)-1] == filepath.Separator {
			return strings.HasPrefix(s, prefix)
		}
		return s[len(prefix)] == filepath.Separator && s[:len(prefix)] == prefix
	}
}