Split out the puthe path/filepath functions into common/paths

So they can be used from the config package without cyclic troubles.

Updates #8654

common/paths/path.go

@@ -0,0 +1,312 @@
+// Copyright 2021 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package paths
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// FilePathSeparator as defined by os.Separator.
+const FilePathSeparator = string(filepath.Separator)
+
+// filepathPathBridge is a bridge for common functionality in filepath vs path
+type filepathPathBridge interface {
+	Base(in string) string
+	Clean(in string) string
+	Dir(in string) string
+	Ext(in string) string
+	Join(elem ...string) string
+	Separator() string
+}
+
+type filepathBridge struct {
+}
+
+func (filepathBridge) Base(in string) string {
+	return filepath.Base(in)
+}
+
+func (filepathBridge) Clean(in string) string {
+	return filepath.Clean(in)
+}
+
+func (filepathBridge) Dir(in string) string {
+	return filepath.Dir(in)
+}
+
+func (filepathBridge) Ext(in string) string {
+	return filepath.Ext(in)
+}
+
+func (filepathBridge) Join(elem ...string) string {
+	return filepath.Join(elem...)
+}
+
+func (filepathBridge) Separator() string {
+	return FilePathSeparator
+}
+
+var fpb filepathBridge
+
+// ToSlashTrimLeading is just a filepath.ToSlash with an added / prefix trimmer.
+func ToSlashTrimLeading(s string) string {
+	return strings.TrimPrefix(filepath.ToSlash(s), "/")
+}
+
+// MakeTitle converts the path given to a suitable title, trimming whitespace
+// and replacing hyphens with whitespace.
+func MakeTitle(inpath string) string {
+	return strings.Replace(strings.TrimSpace(inpath), "-", " ", -1)
+}
+
+// ReplaceExtension takes a path and an extension, strips the old extension
+// and returns the path with the new extension.
+func ReplaceExtension(path string, newExt string) string {
+	f, _ := fileAndExt(path, fpb)
+	return f + "." + newExt
+}
+
+func makePathRelative(inPath string, possibleDirectories ...string) (string, error) {
+	for _, currentPath := range possibleDirectories {
+		if strings.HasPrefix(inPath, currentPath) {
+			return strings.TrimPrefix(inPath, currentPath), nil
+		}
+	}
+	return inPath, errors.New("can't extract relative path, unknown prefix")
+}
+
+// Should be good enough for Hugo.
+var isFileRe = regexp.MustCompile(`.*\..{1,6}$`)
+
+// GetDottedRelativePath expects a relative path starting after the content directory.
+// It returns a relative path with dots ("..") navigating up the path structure.
+func GetDottedRelativePath(inPath string) string {
+	inPath = filepath.Clean(filepath.FromSlash(inPath))
+
+	if inPath == "." {
+		return "./"
+	}
+
+	if !isFileRe.MatchString(inPath) && !strings.HasSuffix(inPath, FilePathSeparator) {
+		inPath += FilePathSeparator
+	}
+
+	if !strings.HasPrefix(inPath, FilePathSeparator) {
+		inPath = FilePathSeparator + inPath
+	}
+
+	dir, _ := filepath.Split(inPath)
+
+	sectionCount := strings.Count(dir, FilePathSeparator)
+
+	if sectionCount == 0 || dir == FilePathSeparator {
+		return "./"
+	}
+
+	var dottedPath string
+
+	for i := 1; i < sectionCount; i++ {
+		dottedPath += "../"
+	}
+
+	return dottedPath
+}
+
+// ExtNoDelimiter takes a path and returns the extension, excluding the delimiter, i.e. "md".
+func ExtNoDelimiter(in string) string {
+	return strings.TrimPrefix(Ext(in), ".")
+}
+
+// Ext takes a path and returns the extension, including the delimiter, i.e. ".md".
+func Ext(in string) string {
+	_, ext := fileAndExt(in, fpb)
+	return ext
+}
+
+// PathAndExt is the same as FileAndExt, but it uses the path package.
+func PathAndExt(in string) (string, string) {
+	return fileAndExt(in, pb)
+}
+
+// FileAndExt takes a path and returns the file and extension separated,
+// the extension including the delimiter, i.e. ".md".
+func FileAndExt(in string) (string, string) {
+	return fileAndExt(in, fpb)
+}
+
+// FileAndExtNoDelimiter takes a path and returns the file and extension separated,
+// the extension excluding the delimiter, e.g "md".
+func FileAndExtNoDelimiter(in string) (string, string) {
+	file, ext := fileAndExt(in, fpb)
+	return file, strings.TrimPrefix(ext, ".")
+}
+
+// Filename takes a file path, strips out the extension,
+// and returns the name of the file.
+func Filename(in string) (name string) {
+	name, _ = fileAndExt(in, fpb)
+	return
+}
+
+// PathNoExt takes a path, strips out the extension,
+// and returns the name of the file.
+func PathNoExt(in string) string {
+	return strings.TrimSuffix(in, path.Ext(in))
+}
+
+// FileAndExt returns the filename and any extension of a file path as
+// two separate strings.
+//
+// If the path, in, contains a directory name ending in a slash,
+// then both name and ext will be empty strings.
+//
+// If the path, in, is either the current directory, the parent
+// directory or the root directory, or an empty string,
+// then both name and ext will be empty strings.
+//
+// If the path, in, represents the path of a file without an extension,
+// then name will be the name of the file and ext will be an empty string.
+//
+// If the path, in, represents a filename with an extension,
+// then name will be the filename minus any extension - including the dot
+// and ext will contain the extension - minus the dot.
+func fileAndExt(in string, b filepathPathBridge) (name string, ext string) {
+	ext = b.Ext(in)
+	base := b.Base(in)
+
+	return extractFilename(in, ext, base, b.Separator()), ext
+}
+
+func extractFilename(in, ext, base, pathSeparator string) (name string) {
+	// No file name cases. These are defined as:
+	// 1. any "in" path that ends in a pathSeparator
+	// 2. any "base" consisting of just an pathSeparator
+	// 3. any "base" consisting of just an empty string
+	// 4. any "base" consisting of just the current directory i.e. "."
+	// 5. any "base" consisting of just the parent directory i.e. ".."
+	if (strings.LastIndex(in, pathSeparator) == len(in)-1) || base == "" || base == "." || base == ".." || base == pathSeparator {
+		name = "" // there is NO filename
+	} else if ext != "" { // there was an Extension
+		// return the filename minus the extension (and the ".")
+		name = base[:strings.LastIndex(base, ".")]
+	} else {
+		// no extension case so just return base, which willi
+		// be the filename
+		name = base
+	}
+	return
+}
+
+// GetRelativePath returns the relative path of a given path.
+func GetRelativePath(path, base string) (final string, err error) {
+	if filepath.IsAbs(path) && base == "" {
+		return "", errors.New("source: missing base directory")
+	}
+	name := filepath.Clean(path)
+	base = filepath.Clean(base)
+
+	name, err = filepath.Rel(base, name)
+	if err != nil {
+		return "", err
+	}
+
+	if strings.HasSuffix(filepath.FromSlash(path), FilePathSeparator) && !strings.HasSuffix(name, FilePathSeparator) {
+		name += FilePathSeparator
+	}
+	return name, nil
+}
+
+// PathPrep prepares the path using the uglify setting to create paths on
+// either the form /section/name/index.html or /section/name.html.
+func PathPrep(ugly bool, in string) string {
+	if ugly {
+		return Uglify(in)
+	}
+	return PrettifyPath(in)
+}
+
+// PrettifyPath is the same as PrettifyURLPath but for file paths.
+//     /section/name.html       becomes /section/name/index.html
+//     /section/name/           becomes /section/name/index.html
+//     /section/name/index.html becomes /section/name/index.html
+func PrettifyPath(in string) string {
+	return prettifyPath(in, fpb)
+}
+
+func prettifyPath(in string, b filepathPathBridge) string {
+	if filepath.Ext(in) == "" {
+		// /section/name/  -> /section/name/index.html
+		if len(in) < 2 {
+			return b.Separator()
+		}
+		return b.Join(in, "index.html")
+	}
+	name, ext := fileAndExt(in, b)
+	if name == "index" {
+		// /section/name/index.html -> /section/name/index.html
+		return b.Clean(in)
+	}
+	// /section/name.html -> /section/name/index.html
+	return b.Join(b.Dir(in), name, "index"+ext)
+}
+
+type NamedSlice struct {
+	Name  string
+	Slice []string
+}
+
+func (n NamedSlice) String() string {
+	if len(n.Slice) == 0 {
+		return n.Name
+	}
+	return fmt.Sprintf("%s%s{%s}", n.Name, FilePathSeparator, strings.Join(n.Slice, ","))
+}
+
+// FindCWD returns the current working directory from where the Hugo
+// executable is run.
+func FindCWD() (string, error) {
+	serverFile, err := filepath.Abs(os.Args[0])
+	if err != nil {
+		return "", fmt.Errorf("can't get absolute path for executable: %v", err)
+	}
+
+	path := filepath.Dir(serverFile)
+	realFile, err := filepath.EvalSymlinks(serverFile)
+	if err != nil {
+		if _, err = os.Stat(serverFile + ".exe"); err == nil {
+			realFile = filepath.Clean(serverFile + ".exe")
+		}
+	}
+
+	if err == nil && realFile != serverFile {
+		path = filepath.Dir(realFile)
+	}
+
+	return path, nil
+}
+
+// AddTrailingSlash adds a trailing Unix styled slash (/) if not already
+// there.
+func AddTrailingSlash(path string) string {
+	if !strings.HasSuffix(path, "/") {
+		path += "/"
+	}
+	return path
+}