Add Hugo Modules

This commit implements Hugo Modules.

This is a broad subject, but some keywords include:

* A new `module` configuration section where you can import almost anything. You can configure both your own file mounts nd the file mounts of the modules you import. This is the new recommended way of configuring what you earlier put in `configDir`, `staticDir` etc. And it also allows you to mount folders in non-Hugo-projects, e.g. the `SCSS` folder in the Bootstrap GitHub project.
* A module consists of a set of mounts to the standard 7 component types in Hugo: `static`, `content`, `layouts`, `data`, `assets`, `i18n`, and `archetypes`. Yes, Theme Components can now include content, which should be very useful, especially in bigger multilingual projects.
* Modules not in your local file cache will be downloaded automatically and even "hot replaced" while the server is running.
* Hugo Modules supports and encourages semver versioned modules, and uses the minimal version selection algorithm to resolve versions.
* A new set of CLI commands are provided to manage all of this: `hugo mod init`,  `hugo mod get`,  `hugo mod graph`,  `hugo mod tidy`, and  `hugo mod vendor`.

All of the above is backed by Go Modules.

Fixes #5973
Fixes #5996
Fixes #6010
Fixes #5911
Fixes #5940
Fixes #6074
Fixes #6082
Fixes #6092

1 files changed, 0 insertions, 346 deletions

diff --git a/hugofs/language_fs.go b/hugofs/language_fs.go
deleted file mode 100644
index db77c1fab..000000000
--- a/hugofs/language_fs.go
+++ /dev/null
@@ -1,346 +0,0 @@
-// Copyright 2018 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 hugofs
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"strings"
-
-	"github.com/spf13/afero"
-)
-
-const hugoFsMarker = "__hugofs"
-
-var (
-	_ LanguageAnnouncer = (*LanguageFileInfo)(nil)
-	_ FilePather        = (*LanguageFileInfo)(nil)
-	_ afero.Lstater     = (*LanguageFs)(nil)
-)
-
-// LanguageAnnouncer is aware of its language.
-type LanguageAnnouncer interface {
-	Lang() string
-	TranslationBaseName() string
-}
-
-// FilePather is aware of its file's location.
-type FilePather interface {
-	// Filename gets the full path and filename to the file.
-	Filename() string
-
-	// Path gets the content relative path including file name and extension.
-	// The directory is relative to the content root where "content" is a broad term.
-	Path() string
-
-	// RealName is FileInfo.Name in its original form.
-	RealName() string
-
-	BaseDir() string
-}
-
-// LanguageDirsMerger implements the afero.DirsMerger interface, which is used
-// to merge two directories.
-var LanguageDirsMerger = func(lofi, bofi []os.FileInfo) ([]os.FileInfo, error) {
-	m := make(map[string]*LanguageFileInfo)
-
-	for _, fi := range lofi {
-		fil, ok := fi.(*LanguageFileInfo)
-		if !ok {
-			return nil, fmt.Errorf("received %T, expected *LanguageFileInfo", fi)
-		}
-		m[fil.virtualName] = fil
-	}
-
-	for _, fi := range bofi {
-		fil, ok := fi.(*LanguageFileInfo)
-		if !ok {
-			return nil, fmt.Errorf("received %T, expected *LanguageFileInfo", fi)
-		}
-		existing, found := m[fil.virtualName]
-
-		if !found || existing.weight < fil.weight {
-			m[fil.virtualName] = fil
-		}
-	}
-
-	merged := make([]os.FileInfo, len(m))
-	i := 0
-	for _, v := range m {
-		merged[i] = v
-		i++
-	}
-
-	return merged, nil
-}
-
-// LanguageFileInfo is a super-set of os.FileInfo with additional information
-// about the file in relation to its Hugo language.
-type LanguageFileInfo struct {
-	os.FileInfo
-	lang                string
-	baseDir             string
-	realFilename        string
-	relFilename         string
-	name                string
-	realName            string
-	virtualName         string
-	translationBaseName string
-
-	// We add some weight to the files in their own language's content directory.
-	weight int
-}
-
-// Filename returns a file's real filename including the base (ie.
-// "/my/base/sect/page.md").
-func (fi *LanguageFileInfo) Filename() string {
-	return fi.realFilename
-}
-
-// Path returns a file's filename relative to the base (ie. "sect/page.md").
-func (fi *LanguageFileInfo) Path() string {
-	return fi.relFilename
-}
-
-// RealName returns a file's real base name (ie. "page.md").
-func (fi *LanguageFileInfo) RealName() string {
-	return fi.realName
-}
-
-// BaseDir returns a file's base directory (ie. "/my/base").
-func (fi *LanguageFileInfo) BaseDir() string {
-	return fi.baseDir
-}
-
-// Lang returns a file's language (ie. "sv").
-func (fi *LanguageFileInfo) Lang() string {
-	return fi.lang
-}
-
-// TranslationBaseName returns the base filename without any extension or language
-// identifiers (ie. "page").
-func (fi *LanguageFileInfo) TranslationBaseName() string {
-	return fi.translationBaseName
-}
-
-// Name is the name of the file within this filesystem without any path info.
-// It will be marked with language information so we can identify it as ours
-// (ie. "__hugofs_sv_page.md").
-func (fi *LanguageFileInfo) Name() string {
-	return fi.name
-}
-
-type languageFile struct {
-	afero.File
-	fs *LanguageFs
-}
-
-// Readdir creates FileInfo entries by calling Lstat if possible.
-func (l *languageFile) Readdir(c int) (ofi []os.FileInfo, err error) {
-	names, err := l.File.Readdirnames(c)
-	if err != nil {
-		return nil, err
-	}
-
-	fis := make([]os.FileInfo, len(names))
-
-	for i, name := range names {
-		fi, _, err := l.fs.LstatIfPossible(filepath.Join(l.Name(), name))
-
-		if err != nil {
-			return nil, err
-		}
-		fis[i] = fi
-	}
-
-	return fis, err
-}
-
-// LanguageFs represents a language filesystem.
-type LanguageFs struct {
-	// This Fs is usually created with a BasePathFs
-	basePath   string
-	lang       string
-	nameMarker string
-	languages  map[string]bool
-	afero.Fs
-}
-
-// NewLanguageFs creates a new language filesystem.
-func NewLanguageFs(lang string, languages map[string]bool, fs afero.Fs) *LanguageFs {
-	if lang == "" {
-		panic("no lang set for the language fs")
-	}
-	var basePath string
-
-	if bfs, ok := fs.(*afero.BasePathFs); ok {
-		basePath, _ = bfs.RealPath("")
-	}
-
-	marker := hugoFsMarker + "_" + lang + "_"
-
-	return &LanguageFs{lang: lang, languages: languages, basePath: basePath, Fs: fs, nameMarker: marker}
-}
-
-// Lang returns a language filesystem's language (ie. "sv").
-func (fs *LanguageFs) Lang() string {
-	return fs.lang
-}
-
-// Stat returns the os.FileInfo of a given file.
-func (fs *LanguageFs) Stat(name string) (os.FileInfo, error) {
-	name, err := fs.realName(name)
-	if err != nil {
-		return nil, err
-	}
-
-	fi, err := fs.Fs.Stat(name)
-	if err != nil {
-		return nil, err
-	}
-
-	return fs.newLanguageFileInfo(name, fi)
-}
-
-// Open opens the named file for reading.
-func (fs *LanguageFs) Open(name string) (afero.File, error) {
-	name, err := fs.realName(name)
-	if err != nil {
-		return nil, err
-	}
-	f, err := fs.Fs.Open(name)
-
-	if err != nil {
-		return nil, err
-	}
-	return &languageFile{File: f, fs: fs}, nil
-}
-
-// LstatIfPossible returns the os.FileInfo structure describing a given file.
-// It attempts to use Lstat if supported or defers to the os.  In addition to
-// the FileInfo, a boolean is returned telling whether Lstat was called.
-func (fs *LanguageFs) LstatIfPossible(name string) (os.FileInfo, bool, error) {
-	name, err := fs.realName(name)
-	if err != nil {
-		return nil, false, err
-	}
-
-	var fi os.FileInfo
-	var b bool
-
-	if lif, ok := fs.Fs.(afero.Lstater); ok {
-		fi, b, err = lif.LstatIfPossible(name)
-	} else {
-		fi, err = fs.Fs.Stat(name)
-	}
-
-	if err != nil {
-		return nil, b, err
-	}
-
-	lfi, err := fs.newLanguageFileInfo(name, fi)
-
-	return lfi, b, err
-}
-
-func (fs *LanguageFs) realPath(name string) (string, error) {
-	if baseFs, ok := fs.Fs.(*afero.BasePathFs); ok {
-		return baseFs.RealPath(name)
-	}
-	return name, nil
-}
-
-func (fs *LanguageFs) realName(name string) (string, error) {
-	if strings.Contains(name, hugoFsMarker) {
-		if !strings.Contains(name, fs.nameMarker) {
-			return "", os.ErrNotExist
-		}
-		return strings.Replace(name, fs.nameMarker, "", 1), nil
-	}
-
-	if fs.basePath == "" {
-		return name, nil
-	}
-
-	return strings.TrimPrefix(name, fs.basePath), nil
-}
-
-func (fs *LanguageFs) newLanguageFileInfo(filename string, fi os.FileInfo) (*LanguageFileInfo, error) {
-	filename = filepath.Clean(filename)
-	_, name := filepath.Split(filename)
-
-	realName := name
-	virtualName := name
-
-	realPath, err := fs.realPath(filename)
-	if err != nil {
-		return nil, err
-	}
-
-	lang := fs.Lang()
-
-	baseNameNoExt := ""
-
-	if !fi.IsDir() {
-
-		// Try to extract the language from the file name.
-		// Any valid language identificator in the name will win over the
-		// language set on the file system, e.g. "mypost.en.md".
-		baseName := filepath.Base(name)
-		ext := filepath.Ext(baseName)
-		baseNameNoExt = baseName
-
-		if ext != "" {
-			baseNameNoExt = strings.TrimSuffix(baseNameNoExt, ext)
-		}
-
-		fileLangExt := filepath.Ext(baseNameNoExt)
-		fileLang := strings.TrimPrefix(fileLangExt, ".")
-
-		if fs.languages[fileLang] {
-			lang = fileLang
-			baseNameNoExt = strings.TrimSuffix(baseNameNoExt, fileLangExt)
-		}
-
-		// This connects the filename to the filesystem, not the language.
-		virtualName = baseNameNoExt + "." + lang + ext
-
-		name = fs.nameMarker + name
-	}
-
-	weight := 1
-	// If this file's language belongs in this directory, add some weight to it
-	// to make it more important.
-	if lang == fs.Lang() {
-		weight = 2
-	}
-
-	if fi.IsDir() {
-		// For directories we always want to start from the union view.
-		realPath = strings.TrimPrefix(realPath, fs.basePath)
-	}
-
-	return &LanguageFileInfo{
-		lang:                lang,
-		weight:              weight,
-		realFilename:        realPath,
-		realName:            realName,
-		relFilename:         strings.TrimPrefix(strings.TrimPrefix(realPath, fs.basePath), string(os.PathSeparator)),
-		name:                name,
-		virtualName:         virtualName,
-		translationBaseName: baseNameNoExt,
-		baseDir:             fs.basePath,
-		FileInfo:            fi}, nil
-}