Add support for minification of final output

Hugo Pipes added minification support for resources fetched via ´resources.Get` and similar.

This also adds support for minification of the final output for supported output formats: HTML, XML, SVG, CSS, JavaScript, JSON.

To enable, run Hugo with the `--minify` flag:

```bash
hugo --minify
```

This commit is also a major spring cleaning of the `transform` package to allow the new minification step fit into that processing chain.

Fixes #1251

commands/commands.go

@@ -177,6 +177,7 @@ Complete documentation is available at http://gohugo.io/.`,
 	cc.cmd.Flags().BoolVarP(&cc.buildWatch, "watch", "w", false, "watch filesystem for changes and recreate as needed")
 
 	cc.cmd.Flags().Bool("renderToMemory", false, "render to memory (only useful for benchmark testing)")
+	cc.cmd.Flags().Bool("minify", false, "minify any supported output format (HTML, XML etc.)")
 
 	// Set bash-completion
 	_ = cc.cmd.PersistentFlags().SetAnnotation("logFile", cobra.BashCompFilenameExt, []string{})

commands/hugo.go

@@ -209,16 +209,25 @@ func initializeFlags(cmd *cobra.Command, cfg config.Provider) {
 		"verboseLog",
 	}
 
+	// Will set a value even if it is the default.
+	flagKeysForced := []string{
+		"minify",
+	}
+
 	for _, key := range persFlagKeys {
-		setValueFromFlag(cmd.PersistentFlags(), key, cfg, "")
+		setValueFromFlag(cmd.PersistentFlags(), key, cfg, "", false)
 	}
 	for _, key := range flagKeys {
-		setValueFromFlag(cmd.Flags(), key, cfg, "")
+		setValueFromFlag(cmd.Flags(), key, cfg, "", false)
+	}
+
+	for _, key := range flagKeysForced {
+		setValueFromFlag(cmd.Flags(), key, cfg, "", true)
 	}
 
 	// Set some "config aliases"
-	setValueFromFlag(cmd.Flags(), "destination", cfg, "publishDir")
+	setValueFromFlag(cmd.Flags(), "destination", cfg, "publishDir", false)
-	setValueFromFlag(cmd.Flags(), "i18n-warnings", cfg, "logI18nWarnings")
+	setValueFromFlag(cmd.Flags(), "i18n-warnings", cfg, "logI18nWarnings", false)
 
 }
 
@@ -229,9 +238,9 @@ var deprecatedFlags = map[string]bool{
 	strings.ToLower("canonifyURLs"):          true,
 }
 
-func setValueFromFlag(flags *flag.FlagSet, key string, cfg config.Provider, targetKey string) {
+func setValueFromFlag(flags *flag.FlagSet, key string, cfg config.Provider, targetKey string, force bool) {
 	key = strings.TrimSpace(key)
-	if flags.Changed(key) {
+	if (force && flags.Lookup(key) != nil) || flags.Changed(key) {
 		if _, deprecated := deprecatedFlags[strings.ToLower(key)]; deprecated {
 			msg := fmt.Sprintf(`Set "%s = true" in your config.toml.
 If you need to set this configuration value from the command line, set it via an OS environment variable: "HUGO_%s=true hugo"`, key, strings.ToUpper(key))

deps/deps.go

@@ -162,7 +162,7 @@ func New(cfg DepsCfg) (*Deps, error) {
 		return nil, err
 	}
 
-	resourceSpec, err := resource.NewSpec(ps, logger, cfg.MediaTypes)
+	resourceSpec, err := resource.NewSpec(ps, logger, cfg.OutputFormats, cfg.MediaTypes)
 	if err != nil {
 		return nil, err
 	}
@@ -224,7 +224,7 @@ func (d Deps) ForLanguage(cfg DepsCfg) (*Deps, error) {
 	// The resource cache is global so reuse.
 	// TODO(bep) clean up these inits.
 	resourceCache := d.ResourceSpec.ResourceCache
-	d.ResourceSpec, err = resource.NewSpec(d.PathSpec, d.Log, cfg.MediaTypes)
+	d.ResourceSpec, err = resource.NewSpec(d.PathSpec, d.Log, cfg.OutputFormats, cfg.MediaTypes)
 	if err != nil {
 		return nil, err
 	}
@@ -267,6 +267,9 @@ type DepsCfg struct {
 	// The media types configured.
 	MediaTypes media.Types
 
+	// The output formats configured.
+	OutputFormats output.Formats
+
 	// Template handling.
 	TemplateProvider ResourceProvider
 	WithTemplate     func(templ tpl.TemplateHandler) error

helpers/path.go

@@ -515,6 +515,25 @@ func WriteToDisk(inpath string, r io.Reader, fs afero.Fs) (err error) {
 	return afero.WriteReader(fs, inpath, r)
 }
 
+// OpenFileForWriting opens or creates the given file. If the target directory
+// does not exist, it gets created.
+func OpenFileForWriting(fs afero.Fs, filename string) (afero.File, error) {
+	filename = filepath.Clean(filename)
+	// Create will truncate if file already exists.
+	f, err := fs.Create(filename)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return nil, err
+		}
+		if err = fs.MkdirAll(filepath.Dir(filename), 0755); err != nil {
+			return nil, err
+		}
+		f, err = fs.Create(filename)
+	}
+
+	return f, err
+}
+
 // GetTempDir returns a temporary directory with the given sub path.
 func GetTempDir(subPath string, fs afero.Fs) string {
 	return afero.GetTempDir(fs, subPath)

hugolib/alias.go

@@ -22,6 +22,8 @@ import (
 	"runtime"
 	"strings"
 
+	"github.com/gohugoio/hugo/output"
+	"github.com/gohugoio/hugo/publisher"
 	"github.com/gohugoio/hugo/tpl"
 
 	jww "github.com/spf13/jwalterweatherman"
@@ -89,11 +91,11 @@ func (a aliasHandler) renderAlias(isXHTML bool, permalink string, page *Page) (i
 	return buffer, nil
 }
 
-func (s *Site) writeDestAlias(path, permalink string, p *Page) (err error) {
+func (s *Site) writeDestAlias(path, permalink string, outputFormat output.Format, p *Page) (err error) {
-	return s.publishDestAlias(false, path, permalink, p)
+	return s.publishDestAlias(false, path, permalink, outputFormat, p)
 }
 
-func (s *Site) publishDestAlias(allowRoot bool, path, permalink string, p *Page) (err error) {
+func (s *Site) publishDestAlias(allowRoot bool, path, permalink string, outputFormat output.Format, p *Page) (err error) {
 	handler := newAliasHandler(s.Tmpl, s.Log, allowRoot)
 
 	isXHTML := strings.HasSuffix(path, ".xhtml")
@@ -110,7 +112,14 @@ func (s *Site) publishDestAlias(allowRoot bool, path, permalink string, p *Page)
 		return err
 	}
 
-	return s.publish(&s.PathSpec.ProcessingStats.Aliases, targetPath, aliasContent)
+	pd := publisher.Descriptor{
+		Src:          aliasContent,
+		TargetPath:   targetPath,
+		StatCounter:  &s.PathSpec.ProcessingStats.Aliases,
+		OutputFormat: outputFormat,
+	}
+
+	return s.publisher.Publish(pd)
 
 }
 

hugolib/hugo_sites.go

@@ -24,6 +24,7 @@ import (
 	"github.com/gohugoio/hugo/deps"
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/langs"
+	"github.com/gohugoio/hugo/publisher"
 
 	"github.com/gohugoio/hugo/i18n"
 	"github.com/gohugoio/hugo/tpl"
@@ -182,6 +183,7 @@ func applyDeps(cfg deps.DepsCfg, sites ...*Site) error {
 
 		cfg.Language = s.Language
 		cfg.MediaTypes = s.mediaTypesConfig
+		cfg.OutputFormats = s.outputFormatsConfig
 
 		if d == nil {
 			cfg.WithTemplate = s.withSiteTemplates(cfg.WithTemplate)
@@ -208,6 +210,9 @@ func applyDeps(cfg deps.DepsCfg, sites ...*Site) error {
 			s.Deps = d
 		}
 
+		// Set up the main publishing chain.
+		s.publisher = publisher.NewDestinationPublisher(d.PathSpec.BaseFs.PublishFs, s.outputFormatsConfig, s.mediaTypesConfig, cfg.Cfg.GetBool("minify"))
+
 		if err := s.initializeSiteInfo(); err != nil {
 			return err
 		}

hugolib/minify_publisher_test.go

@@ -0,0 +1,71 @@
+// 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 hugolib
+
+import (
+	"testing"
+
+	"github.com/spf13/viper"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMinifyPublisher(t *testing.T) {
+	t.Parallel()
+	assert := require.New(t)
+
+	v := viper.New()
+	v.Set("minify", true)
+	v.Set("baseURL", "https://example.org/")
+
+	htmlTemplate := `
+<!DOCTYPE html>
+<html lang="en">
+<head>
+	<meta charset="utf-8">
+	<title>HTML5 boilerplate – all you really need…</title>
+	<link rel="stylesheet" href="css/style.css">
+	<!--[if IE]>
+		<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
+	<![endif]-->
+</head>
+
+<body id="home">
+
+	<h1>{{ .Page.Title }}</h1>
+
+</body>
+</html>
+`
+
+	b := newTestSitesBuilder(t)
+	b.WithViper(v).WithContent("page.md", pageWithAlias)
+	b.WithTemplates("_default/list.html", htmlTemplate, "_default/single.html", htmlTemplate, "alias.html", htmlTemplate)
+	b.CreateSites().Build(BuildCfg{})
+
+	assert.Equal(1, len(b.H.Sites))
+	require.Len(t, b.H.Sites[0].RegularPages, 1)
+
+	// Check minification
+	// HTML
+	b.AssertFileContent("public/page/index.html", "<!doctype html><html lang=en><head><meta charset=utf-8><title>HTML5 boilerplate – all you really need…</title><link rel=stylesheet href=css/style.css></head><body id=home><h1>Has Alias</h1></body></html>")
+	// HTML alias. Note the custom template which does no redirect.
+	b.AssertFileContent("public/foo/bar/index.html", "<!doctype html><html lang=en><head><meta charset=utf-8><title>HTML5 boilerplate ")
+
+	// RSS
+	b.AssertFileContent("public/index.xml", "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\"?><rss version=\"2.0\" xmlns:atom=\"http://www.w3.org/2005/Atom\"><channel><title/><link>https://example.org/</link>")
+
+	// Sitemap
+	b.AssertFileContent("public/sitemap.xml", "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\"?><urlset xmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\" xmlns:xhtml=\"http://www.w3.org/1999/xhtml\"><url><loc>https://example.org/</loc><priority>0</priority></url><url>")
+}

hugolib/resource_chain_test.go

@@ -223,7 +223,7 @@ Min HTML: {{ ( resources.Get "mydata/html1.html" | resources.Minify ).Content |
 			b.AssertFileContent("public/index.html", `Min XML: <hello><world>Hugo Rocks!</<world></hello>`)
 			b.AssertFileContent("public/index.html", `Min SVG: <svg height="100" width="100"><path d="M5 10 20 40z"/></svg>`)
 			b.AssertFileContent("public/index.html", `Min SVG again: <svg height="100" width="100"><path d="M5 10 20 40z"/></svg>`)
-			b.AssertFileContent("public/index.html", `Min HTML: <a href=#>Cool</a>`)
+			b.AssertFileContent("public/index.html", `Min HTML: <html><a href=#>Cool</a></html>`)
 		}},
 
 		{"concat", func() bool { return true }, func(b *sitesBuilder) {

hugolib/site.go

@@ -29,6 +29,7 @@ import (
 	"time"
 
 	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/publisher"
 	"github.com/gohugoio/hugo/resource"
 
 	"github.com/gohugoio/hugo/langs"
@@ -54,15 +55,12 @@ import (
 	"github.com/gohugoio/hugo/related"
 	"github.com/gohugoio/hugo/source"
 	"github.com/gohugoio/hugo/tpl"
-	"github.com/gohugoio/hugo/transform"
 	"github.com/spf13/afero"
 	"github.com/spf13/cast"
 	"github.com/spf13/nitro"
 	"github.com/spf13/viper"
 )
 
-var _ = transform.AbsURL
-
 // used to indicate if run as a test.
 var testMode bool
 
@@ -151,6 +149,8 @@ type Site struct {
 
 	relatedDocsHandler *relatedDocsHandler
 	siteRefLinker
+
+	publisher publisher.Publisher
 }
 
 type siteRenderingContext struct {
@@ -195,6 +195,7 @@ func (s *Site) reset() *Site {
 		mediaTypesConfig:    s.mediaTypesConfig,
 		Language:            s.Language,
 		owner:               s.owner,
+		publisher:           s.publisher,
 		siteConfig:          s.siteConfig,
 		PageCollections:     newPageCollections()}
 
@@ -759,8 +760,9 @@ func (s *Site) processPartial(events []fsnotify.Event) (whatChanged, error) {
 			site := sites[i]
 			var err error
 			depsCfg := deps.DepsCfg{
-				Language:   site.Language,
+				Language:      site.Language,
-				MediaTypes: site.mediaTypesConfig,
+				MediaTypes:    site.mediaTypesConfig,
+				OutputFormats: site.outputFormatsConfig,
 			}
 			site.Deps, err = first.Deps.ForLanguage(depsCfg)
 			if err != nil {
@@ -1637,8 +1639,8 @@ func (s *Site) permalink(link string) string {
 
 }
 
-func (s *Site) renderAndWriteXML(statCounter *uint64, name string, dest string, d interface{}, layouts ...string) error {
+func (s *Site) renderAndWriteXML(statCounter *uint64, name string, targetPath string, d interface{}, layouts ...string) error {
-	s.Log.DEBUG.Printf("Render XML for %q to %q", name, dest)
+	s.Log.DEBUG.Printf("Render XML for %q to %q", name, targetPath)
 	renderBuffer := bp.GetBuffer()
 	defer bp.PutBuffer(renderBuffer)
 	renderBuffer.WriteString("<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?>\n")
@@ -1648,30 +1650,32 @@ func (s *Site) renderAndWriteXML(statCounter *uint64, name string, dest string,
 		return nil
 	}
 
-	outBuffer := bp.GetBuffer()
+	var path string
-	defer bp.PutBuffer(outBuffer)
-
-	var path []byte
 	if s.Info.relativeURLs {
-		path = []byte(helpers.GetDottedRelativePath(dest))
+		path = helpers.GetDottedRelativePath(targetPath)
 	} else {
 		s := s.PathSpec.BaseURL.String()
 		if !strings.HasSuffix(s, "/") {
 			s += "/"
 		}
-		path = []byte(s)
+		path = s
-	}
-	transformer := transform.NewChain(transform.AbsURLInXML)
-	if err := transformer.Apply(outBuffer, renderBuffer, path); err != nil {
-		s.DistinctErrorLog.Println(err)
-		return nil
 	}
 
-	return s.publish(statCounter, dest, outBuffer)
+	pd := publisher.Descriptor{
+		Src:         renderBuffer,
+		TargetPath:  targetPath,
+		StatCounter: statCounter,
+		// For the minification part of XML,
+		// we currently only use the MIME type.
+		OutputFormat: output.RSSFormat,
+		AbsURLPath:   path,
+	}
+
+	return s.publisher.Publish(pd)
 
 }
 
-func (s *Site) renderAndWritePage(statCounter *uint64, name string, dest string, p *PageOutput, layouts ...string) error {
+func (s *Site) renderAndWritePage(statCounter *uint64, name string, targetPath string, p *PageOutput, layouts ...string) error {
 	renderBuffer := bp.GetBuffer()
 	defer bp.PutBuffer(renderBuffer)
 
@@ -1684,49 +1688,44 @@ func (s *Site) renderAndWritePage(statCounter *uint64, name string, dest string,
 		return nil
 	}
 
-	outBuffer := bp.GetBuffer()
-	defer bp.PutBuffer(outBuffer)
-
-	transformLinks := transform.NewEmptyTransforms()
-
 	isHTML := p.outputFormat.IsHTML
 
-	if isHTML {
+	var path string
-		if s.Info.relativeURLs || s.Info.canonifyURLs {
-			transformLinks = append(transformLinks, transform.AbsURL)
-		}
-
-		if s.running() && s.Cfg.GetBool("watch") && !s.Cfg.GetBool("disableLiveReload") {
-			transformLinks = append(transformLinks, transform.LiveReloadInject(s.Cfg.GetInt("liveReloadPort")))
-		}
-
-		// For performance reasons we only inject the Hugo generator tag on the home page.
-		if p.IsHome() {
-			if !s.Cfg.GetBool("disableHugoGeneratorInject") {
-				transformLinks = append(transformLinks, transform.HugoGeneratorInject)
-			}
-		}
-	}
-
-	var path []byte
 
 	if s.Info.relativeURLs {
-		path = []byte(helpers.GetDottedRelativePath(dest))
+		path = helpers.GetDottedRelativePath(targetPath)
 	} else if s.Info.canonifyURLs {
 		url := s.PathSpec.BaseURL.String()
 		if !strings.HasSuffix(url, "/") {
 			url += "/"
 		}
-		path = []byte(url)
+		path = url
 	}
 
-	transformer := transform.NewChain(transformLinks...)
+	pd := publisher.Descriptor{
-	if err := transformer.Apply(outBuffer, renderBuffer, path); err != nil {
+		Src:          renderBuffer,
-		s.DistinctErrorLog.Println(err)
+		TargetPath:   targetPath,
-		return nil
+		StatCounter:  statCounter,
+		OutputFormat: p.outputFormat,
 	}
 
-	return s.publish(statCounter, dest, outBuffer)
+	if isHTML {
+		if s.Info.relativeURLs || s.Info.canonifyURLs {
+			pd.AbsURLPath = path
+		}
+
+		if s.running() && s.Cfg.GetBool("watch") && !s.Cfg.GetBool("disableLiveReload") {
+			pd.LiveReloadPort = s.Cfg.GetInt("liveReloadPort")
+		}
+
+		// For performance reasons we only inject the Hugo generator tag on the home page.
+		if p.IsHome() {
+			pd.AddHugoGeneratorTag = !s.Cfg.GetBool("disableHugoGeneratorInject")
+		}
+
+	}
+
+	return s.publisher.Publish(pd)
 }
 
 func (s *Site) renderForLayouts(name string, d interface{}, w io.Writer, layouts ...string) (err error) {

hugolib/site_render.go

@@ -195,7 +195,7 @@ func (s *Site) renderPaginator(p *PageOutput) error {
 
 		// TODO(bep) do better
 		link := newOutputFormat(p.Page, p.outputFormat).Permalink()
-		if err := s.writeDestAlias(target, link, nil); err != nil {
+		if err := s.writeDestAlias(target, link, p.outputFormat, nil); err != nil {
 			return err
 		}
 
@@ -417,7 +417,7 @@ func (s *Site) renderAliases() error {
 					a = path.Join(lang, a)
 				}
 
-				if err := s.writeDestAlias(a, plink, p); err != nil {
+				if err := s.writeDestAlias(a, plink, f, p); err != nil {
 					return err
 				}
 			}
@@ -425,18 +425,21 @@ func (s *Site) renderAliases() error {
 	}
 
 	if s.owner.multilingual.enabled() && !s.owner.IsMultihost() {
-		mainLang := s.owner.multilingual.DefaultLang
+		html, found := s.outputFormatsConfig.GetByName("HTML")
-		if s.Info.defaultContentLanguageInSubdir {
+		if found {
-			mainLangURL := s.PathSpec.AbsURL(mainLang.Lang, false)
+			mainLang := s.owner.multilingual.DefaultLang
-			s.Log.DEBUG.Printf("Write redirect to main language %s: %s", mainLang, mainLangURL)
+			if s.Info.defaultContentLanguageInSubdir {
-			if err := s.publishDestAlias(true, "/", mainLangURL, nil); err != nil {
+				mainLangURL := s.PathSpec.AbsURL(mainLang.Lang, false)
-				return err
+				s.Log.DEBUG.Printf("Write redirect to main language %s: %s", mainLang, mainLangURL)
-			}
+				if err := s.publishDestAlias(true, "/", mainLangURL, html, nil); err != nil {
-		} else {
+					return err
-			mainLangURL := s.PathSpec.AbsURL("", false)
+				}
-			s.Log.DEBUG.Printf("Write redirect to main language %s: %s", mainLang, mainLangURL)
+			} else {
-			if err := s.publishDestAlias(true, mainLang.Lang, mainLangURL, nil); err != nil {
+				mainLangURL := s.PathSpec.AbsURL("", false)
-				return err
+				s.Log.DEBUG.Printf("Write redirect to main language %s: %s", mainLang, mainLangURL)
+				if err := s.publishDestAlias(true, mainLang.Lang, mainLangURL, html, nil); err != nil {
+					return err
+				}
 			}
 		}
 	}

hugolib/testhelpers_test.go

@@ -130,6 +130,7 @@ func (s *sitesBuilder) WithConfigTemplate(data interface{}, format, configTempla
 func (s *sitesBuilder) WithViper(v *viper.Viper) *sitesBuilder {
 	loadDefaultSettingsFor(v)
 	s.Cfg = v
+
 	return s
 }
 

minifiers/minifiers.go

@@ -0,0 +1,126 @@
+// 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 minifiers contains minifiers mapped to MIME types. This package is used
+// in both the resource transformation, i.e. resources.Minify, and in the publishing
+// chain.
+package minifiers
+
+import (
+	"io"
+
+	"github.com/gohugoio/hugo/output"
+	"github.com/gohugoio/hugo/transform"
+
+	"github.com/gohugoio/hugo/media"
+	"github.com/tdewolff/minify"
+	"github.com/tdewolff/minify/css"
+	"github.com/tdewolff/minify/html"
+	"github.com/tdewolff/minify/js"
+	"github.com/tdewolff/minify/json"
+	"github.com/tdewolff/minify/svg"
+	"github.com/tdewolff/minify/xml"
+)
+
+// Client wraps a minifier.
+type Client struct {
+	m *minify.M
+}
+
+// Transformer returns a func that can be used in the transformer publishing chain.
+// TODO(bep) minify config etc
+func (m Client) Transformer(mediatype media.Type) transform.Transformer {
+	_, params, min := m.m.Match(mediatype.Type())
+	if min == nil {
+		// No minifier for this MIME type
+		return nil
+	}
+
+	return func(ft transform.FromTo) error {
+		// Note that the source io.Reader will already be buffered, but it implements
+		// the Bytes() method, which is recognized by the Minify library.
+		return min.Minify(m.m, ft.To(), ft.From(), params)
+	}
+}
+
+// Minify tries to minify the src into dst given a MIME type.
+func (m Client) Minify(mediatype media.Type, dst io.Writer, src io.Reader) error {
+	return m.m.Minify(mediatype.Type(), dst, src)
+}
+
+// New creates a new Client with the provided MIME types as the mapping foundation.
+// The HTML minifier is also registered for additional HTML types (AMP etc.) in the
+// provided list of output formats.
+func New(mediaTypes media.Types, outputFormats output.Formats) Client {
+	m := minify.New()
+	htmlMin := &html.Minifier{
+		KeepDocumentTags: true,
+	}
+
+	// We use the Type definition of the media types defined in the site if found.
+	addMinifierFunc(m, mediaTypes, "text/css", "css", css.Minify)
+	addMinifierFunc(m, mediaTypes, "application/javascript", "js", js.Minify)
+	addMinifierFunc(m, mediaTypes, "application/json", "json", json.Minify)
+	addMinifierFunc(m, mediaTypes, "image/svg+xml", "svg", svg.Minify)
+	addMinifierFunc(m, mediaTypes, "application/xml", "xml", xml.Minify)
+	addMinifierFunc(m, mediaTypes, "application/rss", "xml", xml.Minify)
+
+	// HTML
+	addMinifier(m, mediaTypes, "text/html", "html", htmlMin)
+	for _, of := range outputFormats {
+		if of.IsHTML {
+			addMinifier(m, mediaTypes, of.MediaType.Type(), "html", htmlMin)
+		}
+	}
+	return Client{m: m}
+
+}
+
+func addMinifier(m *minify.M, mt media.Types, typeString, suffix string, min minify.Minifier) {
+	resolvedTypeStr := resolveMediaTypeString(mt, typeString, suffix)
+	m.Add(resolvedTypeStr, min)
+	if resolvedTypeStr != typeString {
+		m.Add(typeString, min)
+	}
+}
+
+func addMinifierFunc(m *minify.M, mt media.Types, typeString, suffix string, fn minify.MinifierFunc) {
+	resolvedTypeStr := resolveMediaTypeString(mt, typeString, suffix)
+	m.AddFunc(resolvedTypeStr, fn)
+	if resolvedTypeStr != typeString {
+		m.AddFunc(typeString, fn)
+	}
+}
+
+func resolveMediaTypeString(types media.Types, typeStr, suffix string) string {
+	if m, found := resolveMediaType(types, typeStr, suffix); found {
+		return m.Type()
+	}
+	// Fall back to the default.
+	return typeStr
+}
+
+// Make sure we match the matching pattern with what the user have actually defined
+// in his or hers media types configuration.
+func resolveMediaType(types media.Types, typeStr, suffix string) (media.Type, bool) {
+	if m, found := types.GetByType(typeStr); found {
+		return m, true
+	}
+
+	if m, found := types.GetFirstBySuffix(suffix); found {
+		return m, true
+	}
+
+	return media.Type{}, false
+
+}

minifiers/minifiers_test.go

@@ -0,0 +1,35 @@
+// 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 minifiers
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/gohugoio/hugo/media"
+
+	"github.com/gohugoio/hugo/output"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNew(t *testing.T) {
+	assert := require.New(t)
+	m := New(media.DefaultTypes, output.DefaultFormats)
+
+	var b bytes.Buffer
+
+	assert.NoError(m.Minify(media.CSSType, &b, strings.NewReader("body { color: blue; }")))
+	assert.Equal("body{color:blue}", b.String())
+}

publisher/publisher.go

@@ -0,0 +1,160 @@
+// 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 publisher
+
+import (
+	"errors"
+	"io"
+	"sync/atomic"
+
+	"github.com/gohugoio/hugo/media"
+
+	"github.com/gohugoio/hugo/minifiers"
+
+	bp "github.com/gohugoio/hugo/bufferpool"
+	"github.com/gohugoio/hugo/helpers"
+
+	"github.com/spf13/afero"
+
+	"github.com/gohugoio/hugo/output"
+	"github.com/gohugoio/hugo/transform"
+	"github.com/gohugoio/hugo/transform/livereloadinject"
+	"github.com/gohugoio/hugo/transform/metainject"
+	"github.com/gohugoio/hugo/transform/urlreplacers"
+)
+
+// Descriptor describes the needed publishing chain for an item.
+type Descriptor struct {
+	// The content to publish.
+	Src io.Reader
+
+	// The OutputFormat of the this content.
+	OutputFormat output.Format
+
+	// Where to publish this content. This is a filesystem-relative path.
+	TargetPath string
+
+	// Counter for the end build summary.
+	StatCounter *uint64
+
+	// Configuration that trigger pre-processing.
+	// LiveReload script will be injected if this is > 0
+	LiveReloadPort int
+
+	// Enable to inject the Hugo generated tag in the header. Is currently only
+	// injected on the home page for HTML type of output formats.
+	AddHugoGeneratorTag bool
+
+	// If set, will replace all relative URLs with this one.
+	AbsURLPath string
+
+	// Enable to minify the output using the OutputFormat defined above to
+	// pick the correct minifier configuration.
+	Minify bool
+}
+
+// DestinationPublisher is the default and currently only publisher in Hugo. This
+// publisher prepares and publishes an item to the defined destination, e.g. /public.
+type DestinationPublisher struct {
+	fs     afero.Fs
+	minify bool
+	min    minifiers.Client
+}
+
+func NewDestinationPublisher(fs afero.Fs, outputFormats output.Formats, mediaTypes media.Types, minify bool) DestinationPublisher {
+	pub := DestinationPublisher{fs: fs}
+	if minify {
+		pub.min = minifiers.New(mediaTypes, outputFormats)
+		pub.minify = true
+	}
+	return pub
+}
+
+// Publish applies any relevant transformations and writes the file
+// to its destination, e.g. /public.
+func (p DestinationPublisher) Publish(d Descriptor) error {
+	if d.TargetPath == "" {
+		return errors.New("must provide a TargetPath")
+	}
+
+	src := d.Src
+
+	transformers := p.createTransformerChain(d)
+
+	if len(transformers) != 0 {
+		b := bp.GetBuffer()
+		defer bp.PutBuffer(b)
+
+		if err := transformers.Apply(b, d.Src); err != nil {
+			return err
+		}
+
+		// This is now what we write to disk.
+		src = b
+	}
+
+	f, err := helpers.OpenFileForWriting(p.fs, d.TargetPath)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(f, src)
+	if err == nil && d.StatCounter != nil {
+		atomic.AddUint64(d.StatCounter, uint64(1))
+	}
+	return err
+}
+
+// Publisher publishes a result file.
+type Publisher interface {
+	Publish(d Descriptor) error
+}
+
+// XML transformer := transform.New(urlreplacers.NewAbsURLInXMLTransformer(path))
+func (p DestinationPublisher) createTransformerChain(f Descriptor) transform.Chain {
+	transformers := transform.NewEmpty()
+
+	isHTML := f.OutputFormat.IsHTML
+
+	if f.AbsURLPath != "" {
+		if isHTML {
+			transformers = append(transformers, urlreplacers.NewAbsURLTransformer(f.AbsURLPath))
+		} else {
+			// Assume XML.
+			transformers = append(transformers, urlreplacers.NewAbsURLInXMLTransformer(f.AbsURLPath))
+		}
+	}
+
+	if isHTML {
+		if f.LiveReloadPort > 0 {
+			transformers = append(transformers, livereloadinject.New(f.LiveReloadPort))
+		}
+
+		// This is only injected on the home page.
+		if f.AddHugoGeneratorTag {
+			transformers = append(transformers, metainject.HugoGenerator)
+		}
+
+	}
+
+	if p.minify {
+		minifyTransformer := p.min.Transformer(f.OutputFormat.MediaType)
+		if minifyTransformer != nil {
+			transformers = append(transformers, minifyTransformer)
+		}
+	}
+
+	return transformers
+
+}

publisher/publisher_test.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Hugo Authors. All rights reserved.
+// 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.
@@ -11,18 +11,4 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package transform
+package publisher
-
-var ar = newAbsURLReplacer()
-
-// AbsURL replaces relative URLs with absolute ones
-// in HTML files, using the baseURL setting.
-var AbsURL = func(ct contentTransformer) {
-	ar.replaceInHTML(ct)
-}
-
-// AbsURLInXML replaces relative URLs with absolute ones
-// in XML files, using the baseURL setting.
-var AbsURLInXML = func(ct contentTransformer) {
-	ar.replaceInXML(ct)
-}

resource/image.go

@@ -464,7 +464,7 @@ func (i *Image) copyToDestination(src string) error {
 		}
 		defer in.Close()
 
-		out, err := openFileForWriting(i.spec.BaseFs.PublishFs, target)
+		out, err := helpers.OpenFileForWriting(i.spec.BaseFs.PublishFs, target)
 
 		if err != nil {
 			res = err
@@ -487,7 +487,7 @@ func (i *Image) copyToDestination(src string) error {
 
 func (i *Image) encodeToDestinations(img image.Image, conf imageConfig, resourceCacheFilename, targetFilename string) error {
 
-	file1, err := openFileForWriting(i.spec.BaseFs.PublishFs, targetFilename)
+	file1, err := helpers.OpenFileForWriting(i.spec.BaseFs.PublishFs, targetFilename)
 	if err != nil {
 		return err
 	}
@@ -498,7 +498,7 @@ func (i *Image) encodeToDestinations(img image.Image, conf imageConfig, resource
 
 	if resourceCacheFilename != "" {
 		// Also save it to the image resource cache for later reuse.
-		file2, err := openFileForWriting(i.spec.BaseFs.Resources.Fs, resourceCacheFilename)
+		file2, err := helpers.OpenFileForWriting(i.spec.BaseFs.Resources.Fs, resourceCacheFilename)
 		if err != nil {
 			return err
 		}

resource/minifier/minify.go

@@ -0,0 +1,58 @@
+// 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 minifier
+
+import (
+	"github.com/gohugoio/hugo/minifiers"
+	"github.com/gohugoio/hugo/resource"
+)
+
+// Client for minification of Resource objects. Supported minfiers are:
+// css, html, js, json, svg and xml.
+type Client struct {
+	rs *resource.Spec
+	m  minifiers.Client
+}
+
+// New creates a new Client given a specification. Note that it is the media types
+// configured for the site that is used to match files to the correct minifier.
+func New(rs *resource.Spec) *Client {
+	return &Client{rs: rs, m: minifiers.New(rs.MediaTypes, rs.OutputFormats)}
+}
+
+type minifyTransformation struct {
+	rs *resource.Spec
+	m  minifiers.Client
+}
+
+func (t *minifyTransformation) Key() resource.ResourceTransformationKey {
+	return resource.NewResourceTransformationKey("minify")
+}
+
+func (t *minifyTransformation) Transform(ctx *resource.ResourceTransformationCtx) error {
+	if err := t.m.Minify(ctx.InMediaType, ctx.To, ctx.From); err != nil {
+		return err
+	}
+	ctx.AddOutPathIdentifier(".min")
+	return nil
+}
+
+func (c *Client) Minify(res resource.Resource) (resource.Resource, error) {
+	return c.rs.Transform(
+		res,
+		&minifyTransformation{
+			rs: c.rs,
+			m:  c.m},
+	)
+}

resource/minifiers/minify.go

@@ -1,115 +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 minifiers
-
-import (
-	"github.com/gohugoio/hugo/helpers"
-	"github.com/gohugoio/hugo/media"
-
-	"github.com/gohugoio/hugo/resource"
-	"github.com/tdewolff/minify"
-	"github.com/tdewolff/minify/css"
-	"github.com/tdewolff/minify/html"
-	"github.com/tdewolff/minify/js"
-	"github.com/tdewolff/minify/json"
-	"github.com/tdewolff/minify/svg"
-	"github.com/tdewolff/minify/xml"
-)
-
-// Client for minification of Resource objects. Supported minfiers are:
-// css, html, js, json, svg and xml.
-type Client struct {
-	rs *resource.Spec
-	m  *minify.M
-}
-
-// New creates a new Client given a specification. Note that it is the media types
-// configured for the site that is used to match files to the correct minifier.
-func New(rs *resource.Spec) *Client {
-	m := minify.New()
-	mt := rs.MediaTypes
-
-	// We use the Type definition of the media types defined in the site if found.
-	addMinifierFunc(m, mt, "text/css", "css", css.Minify)
-	addMinifierFunc(m, mt, "text/html", "html", html.Minify)
-	addMinifierFunc(m, mt, "application/javascript", "js", js.Minify)
-	addMinifierFunc(m, mt, "application/json", "json", json.Minify)
-	addMinifierFunc(m, mt, "image/svg+xml", "svg", svg.Minify)
-	addMinifierFunc(m, mt, "application/xml", "xml", xml.Minify)
-	addMinifierFunc(m, mt, "application/rss", "xml", xml.Minify)
-
-	return &Client{rs: rs, m: m}
-}
-
-func addMinifierFunc(m *minify.M, mt media.Types, typeString, suffix string, fn minify.MinifierFunc) {
-	resolvedTypeStr := resolveMediaTypeString(mt, typeString, suffix)
-	m.AddFunc(resolvedTypeStr, fn)
-	if resolvedTypeStr != typeString {
-		m.AddFunc(typeString, fn)
-	}
-}
-
-type minifyTransformation struct {
-	rs *resource.Spec
-	m  *minify.M
-}
-
-func (t *minifyTransformation) Key() resource.ResourceTransformationKey {
-	return resource.NewResourceTransformationKey("minify")
-}
-
-func (t *minifyTransformation) Transform(ctx *resource.ResourceTransformationCtx) error {
-	mtype := resolveMediaTypeString(
-		t.rs.MediaTypes,
-		ctx.InMediaType.Type(),
-		helpers.ExtNoDelimiter(ctx.InPath),
-	)
-	if err := t.m.Minify(mtype, ctx.To, ctx.From); err != nil {
-		return err
-	}
-	ctx.AddOutPathIdentifier(".min")
-	return nil
-}
-
-func (c *Client) Minify(res resource.Resource) (resource.Resource, error) {
-	return c.rs.Transform(
-		res,
-		&minifyTransformation{
-			rs: c.rs,
-			m:  c.m},
-	)
-}
-
-func resolveMediaTypeString(types media.Types, typeStr, suffix string) string {
-	if m, found := resolveMediaType(types, typeStr, suffix); found {
-		return m.Type()
-	}
-	// Fall back to the default.
-	return typeStr
-}
-
-// Make sure we match the matching pattern with what the user have actually defined
-// in his or hers media types configuration.
-func resolveMediaType(types media.Types, typeStr, suffix string) (media.Type, bool) {
-	if m, found := types.GetByType(typeStr); found {
-		return m, true
-	}
-
-	if m, found := types.GetFirstBySuffix(suffix); found {
-		return m, true
-	}
-
-	return media.Type{}, false
-
-}

resource/resource.go

@@ -24,6 +24,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/gohugoio/hugo/output"
 	"github.com/gohugoio/hugo/tpl"
 
 	"github.com/gohugoio/hugo/common/loggers"
@@ -259,7 +260,8 @@ func (r1 Resources) MergeByLanguageInterface(in interface{}) (interface{}, error
 type Spec struct {
 	*helpers.PathSpec
 
-	MediaTypes media.Types
+	MediaTypes    media.Types
+	OutputFormats output.Formats
 
 	Logger *jww.Notepad
 
@@ -275,7 +277,7 @@ type Spec struct {
 	GenAssetsPath string
 }
 
-func NewSpec(s *helpers.PathSpec, logger *jww.Notepad, mimeTypes media.Types) (*Spec, error) {
+func NewSpec(s *helpers.PathSpec, logger *jww.Notepad, outputFormats output.Formats, mimeTypes media.Types) (*Spec, error) {
 
 	imaging, err := decodeImaging(s.Cfg.GetStringMap("imaging"))
 	if err != nil {
@@ -296,6 +298,7 @@ func NewSpec(s *helpers.PathSpec, logger *jww.Notepad, mimeTypes media.Types) (*
 		GenAssetsPath: genAssetsPath,
 		imaging:       &imaging,
 		MediaTypes:    mimeTypes,
+		OutputFormats: outputFormats,
 		imageCache: newImageCache(
 			s,
 			// We're going to write a cache pruning routine later, so make it extremely

resource/resource_cache.go

@@ -16,12 +16,12 @@ package resource
 import (
 	"encoding/json"
 	"io/ioutil"
-	"os"
 	"path"
 	"path/filepath"
 	"strings"
 	"sync"
 
+	"github.com/gohugoio/hugo/helpers"
 	"github.com/spf13/afero"
 
 	"github.com/BurntSushi/locker"
@@ -176,26 +176,7 @@ func (c *ResourceCache) writeMeta(key string, meta transformedResourceMetadata)
 }
 
 func (c *ResourceCache) openResourceFileForWriting(filename string) (afero.File, error) {
-	return openFileForWriting(c.rs.Resources.Fs, filename)
+	return helpers.OpenFileForWriting(c.rs.Resources.Fs, filename)
-}
-
-// openFileForWriting opens or creates the given file. If the target directory
-// does not exist, it gets created.
-func openFileForWriting(fs afero.Fs, filename string) (afero.File, error) {
-	filename = filepath.Clean(filename)
-	// Create will truncate if file already exists.
-	f, err := fs.Create(filename)
-	if err != nil {
-		if !os.IsNotExist(err) {
-			return nil, err
-		}
-		if err = fs.MkdirAll(filepath.Dir(filename), 0755); err != nil {
-			return nil, err
-		}
-		f, err = fs.Create(filename)
-	}
-
-	return f, err
 }
 
 func (c *ResourceCache) set(key string, r Resource) {

resource/testhelpers_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/media"
+	"github.com/gohugoio/hugo/output"
 	"github.com/spf13/afero"
 	"github.com/spf13/viper"
 	"github.com/stretchr/testify/require"
@@ -51,7 +52,7 @@ func newTestResourceSpecForBaseURL(assert *require.Assertions, baseURL string) *
 
 	assert.NoError(err)
 
-	spec, err := NewSpec(s, nil, media.DefaultTypes)
+	spec, err := NewSpec(s, nil, output.DefaultFormats, media.DefaultTypes)
 	assert.NoError(err)
 	return spec
 }
@@ -85,7 +86,7 @@ func newTestResourceOsFs(assert *require.Assertions) *Spec {
 
 	assert.NoError(err)
 
-	spec, err := NewSpec(s, nil, media.DefaultTypes)
+	spec, err := NewSpec(s, nil, output.DefaultFormats, media.DefaultTypes)
 	assert.NoError(err)
 	return spec
 
@@ -110,7 +111,7 @@ func fetchResourceForSpec(spec *Spec, assert *require.Assertions, name string) C
 	src, err := os.Open(filepath.FromSlash("testdata/" + name))
 	assert.NoError(err)
 
-	out, err := openFileForWriting(spec.BaseFs.Content.Fs, name)
+	out, err := helpers.OpenFileForWriting(spec.BaseFs.Content.Fs, name)
 	assert.NoError(err)
 	_, err = io.Copy(out, src)
 	out.Close()

resource/transform.go

@@ -267,7 +267,7 @@ func (r *transformedResource) initContent() error {
 func (r *transformedResource) transform(setContent bool) (err error) {
 
 	openPublishFileForWriting := func(relTargetPath string) (io.WriteCloser, error) {
-		return openFileForWriting(r.cache.rs.PublishFs, r.linker.relTargetPathFor(relTargetPath))
+		return helpers.OpenFileForWriting(r.cache.rs.PublishFs, r.linker.relTargetPathFor(relTargetPath))
 	}
 
 	// This can be the last resource in a chain.

tpl/resources/resources.go

@@ -23,7 +23,7 @@ import (
 	"github.com/gohugoio/hugo/resource/bundler"
 	"github.com/gohugoio/hugo/resource/create"
 	"github.com/gohugoio/hugo/resource/integrity"
-	"github.com/gohugoio/hugo/resource/minifiers"
+	"github.com/gohugoio/hugo/resource/minifier"
 	"github.com/gohugoio/hugo/resource/postcss"
 	"github.com/gohugoio/hugo/resource/templates"
 	"github.com/gohugoio/hugo/resource/tocss/scss"
@@ -42,7 +42,7 @@ func New(deps *deps.Deps) (*Namespace, error) {
 		createClient:    create.New(deps.ResourceSpec),
 		bundlerClient:   bundler.New(deps.ResourceSpec),
 		integrityClient: integrity.New(deps.ResourceSpec),
-		minifyClient:    minifiers.New(deps.ResourceSpec),
+		minifyClient:    minifier.New(deps.ResourceSpec),
 		postcssClient:   postcss.New(deps.ResourceSpec),
 		templatesClient: templates.New(deps.ResourceSpec, deps.TextTmpl),
 	}, nil
@@ -56,7 +56,7 @@ type Namespace struct {
 	bundlerClient   *bundler.Client
 	scssClient      *scss.Client
 	integrityClient *integrity.Client
-	minifyClient    *minifiers.Client
+	minifyClient    *minifier.Client
 	postcssClient   *postcss.Client
 	templatesClient *templates.Client
 }

transform/chain.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Hugo Authors. All rights reserved.
+// 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.
@@ -20,67 +20,74 @@ import (
 	bp "github.com/gohugoio/hugo/bufferpool"
 )
 
-type trans func(rw contentTransformer)
+// Transformer is the func that needs to be implemented by a transformation step.
+type Transformer func(ft FromTo) error
 
-type link trans
+// BytesReader wraps the Bytes method, usually implemented by bytes.Buffer, and an
+// io.Reader.
+type BytesReader interface {
+	// The slice given by Bytes is valid for use only until the next buffer modification.
+	// That is, if you want to use this value outside of the current transformer step,
+	// you need to take a copy.
+	Bytes() []byte
 
-type chain []link
+	io.Reader
+}
 
-// NewChain creates a chained content transformer given the provided transforms.
+// FromTo is sent to each transformation step in the chain.
-func NewChain(trs ...link) chain {
+type FromTo interface {
+	From() BytesReader
+	To() io.Writer
+}
+
+// Chain is an ordered processing chain. The next transform operation will
+// receive the output from the previous.
+type Chain []Transformer
+
+// New creates a content transformer chain given the provided transform funcs.
+func New(trs ...Transformer) Chain {
 	return trs
 }
 
-// NewEmptyTransforms creates a new slice of transforms with a capacity of 20.
+// NewEmpty creates a new slice of transformers with a capacity of 20.
-func NewEmptyTransforms() []link {
+func NewEmpty() Chain {
-	return make([]link, 0, 20)
+	return make(Chain, 0, 20)
-}
-
-// contentTransformer is an interface that enables rotation  of pooled buffers
-// in the transformer chain.
-type contentTransformer interface {
-	Path() []byte
-	Content() []byte
-	io.Writer
 }
 
 // Implements contentTransformer
 // Content is read from the from-buffer and rewritten to to the to-buffer.
 type fromToBuffer struct {
-	path []byte
 	from *bytes.Buffer
 	to   *bytes.Buffer
 }
 
-func (ft fromToBuffer) Path() []byte {
+func (ft fromToBuffer) From() BytesReader {
-	return ft.path
+	return ft.from
 }
 
-func (ft fromToBuffer) Write(p []byte) (n int, err error) {
+func (ft fromToBuffer) To() io.Writer {
-	return ft.to.Write(p)
+	return ft.to
 }
 
-func (ft fromToBuffer) Content() []byte {
+// Apply passes the given from io.Reader through the transformation chain.
-	return ft.from.Bytes()
+// The result is written to to.
-}
+func (c *Chain) Apply(to io.Writer, from io.Reader) error {
-
-func (c *chain) Apply(w io.Writer, r io.Reader, p []byte) error {
 	if len(*c) == 0 {
-		_, err := io.Copy(w, r)
+		_, err := io.Copy(to, from)
 		return err
 	}
 
 	b1 := bp.GetBuffer()
 	defer bp.PutBuffer(b1)
 
-	if _, err := b1.ReadFrom(r); err != nil {
+	if _, err := b1.ReadFrom(from); err != nil {
 		return err
 	}
 
 	b2 := bp.GetBuffer()
 	defer bp.PutBuffer(b2)
 
-	fb := &fromToBuffer{path: p, from: b1, to: b2}
+	fb := &fromToBuffer{from: b1, to: b2}
 
 	for i, tr := range *c {
 		if i > 0 {
@@ -95,9 +102,11 @@ func (c *chain) Apply(w io.Writer, r io.Reader, p []byte) error {
 			}
 		}
 
-		tr(fb)
+		if err := tr(fb); err != nil {
+			return err
+		}
 	}
 
-	_, err := fb.to.WriteTo(w)
+	_, err := fb.to.WriteTo(to)
 	return err
 }

transform/chain_test.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Hugo Authors. All rights reserved.
+// 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.
@@ -15,142 +15,44 @@ package transform
 
 import (
 	"bytes"
-	"path/filepath"
 	"strings"
 	"testing"
 
-	bp "github.com/gohugoio/hugo/bufferpool"
-	"github.com/gohugoio/hugo/helpers"
 	"github.com/stretchr/testify/assert"
 )
 
-const (
-	h5JsContentDoubleQuote      = "<!DOCTYPE html><html><head><script src=\"foobar.js\"></script><script src=\"/barfoo.js\"></script></head><body><nav><h1>title</h1></nav><article>content <a href=\"foobar\">foobar</a>. <a href=\"/foobar\">Follow up</a></article></body></html>"
-	h5JsContentSingleQuote      = "<!DOCTYPE html><html><head><script src='foobar.js'></script><script src='/barfoo.js'></script></head><body><nav><h1>title</h1></nav><article>content <a href='foobar'>foobar</a>. <a href='/foobar'>Follow up</a></article></body></html>"
-	h5JsContentAbsURL           = "<!DOCTYPE html><html><head><script src=\"http://user@host:10234/foobar.js\"></script></head><body><nav><h1>title</h1></nav><article>content <a href=\"https://host/foobar\">foobar</a>. Follow up</article></body></html>"
-	h5JsContentAbsURLSchemaless = "<!DOCTYPE html><html><head><script src=\"//host/foobar.js\"></script><script src='//host2/barfoo.js'></head><body><nav><h1>title</h1></nav><article>content <a href=\"//host/foobar\">foobar</a>. <a href='//host2/foobar'>Follow up</a></article></body></html>"
-	corectOutputSrcHrefDq       = "<!DOCTYPE html><html><head><script src=\"foobar.js\"></script><script src=\"http://base/barfoo.js\"></script></head><body><nav><h1>title</h1></nav><article>content <a href=\"foobar\">foobar</a>. <a href=\"http://base/foobar\">Follow up</a></article></body></html>"
-	corectOutputSrcHrefSq       = "<!DOCTYPE html><html><head><script src='foobar.js'></script><script src='http://base/barfoo.js'></script></head><body><nav><h1>title</h1></nav><article>content <a href='foobar'>foobar</a>. <a href='http://base/foobar'>Follow up</a></article></body></html>"
-
-	h5XMLXontentAbsURL        = "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?><feed xmlns=\"http://www.w3.org/2005/Atom\"><entry><content type=\"html\">&lt;p&gt;&lt;a href=&#34;/foobar&#34;&gt;foobar&lt;/a&gt;&lt;/p&gt; &lt;p&gt;A video: &lt;iframe src=&#39;/foo&#39;&gt;&lt;/iframe&gt;&lt;/p&gt;</content></entry></feed>"
-	correctOutputSrcHrefInXML = "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?><feed xmlns=\"http://www.w3.org/2005/Atom\"><entry><content type=\"html\">&lt;p&gt;&lt;a href=&#34;http://base/foobar&#34;&gt;foobar&lt;/a&gt;&lt;/p&gt; &lt;p&gt;A video: &lt;iframe src=&#39;http://base/foo&#39;&gt;&lt;/iframe&gt;&lt;/p&gt;</content></entry></feed>"
-	h5XMLContentGuarded       = "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?><feed xmlns=\"http://www.w3.org/2005/Atom\"><entry><content type=\"html\">&lt;p&gt;&lt;a href=&#34;//foobar&#34;&gt;foobar&lt;/a&gt;&lt;/p&gt; &lt;p&gt;A video: &lt;iframe src=&#39;//foo&#39;&gt;&lt;/iframe&gt;&lt;/p&gt;</content></entry></feed>"
-)
-
-const (
-	// additional sanity tests for replacements testing
-	replace1 = "No replacements."
-	replace2 = "ᚠᛇᚻ ᛒᛦᚦ ᚠᚱᚩᚠᚢᚱ\nᚠᛁᚱᚪ ᚷᛖᚻᚹᛦᛚᚳᚢᛗ"
-	replace3 = `End of file: src="/`
-	replace4 = `End of file: srcset="/`
-	replace5 = `Srcsett with no closing quote: srcset="/img/small.jpg do be do be do.`
-
-	// Issue: 816, schemaless links combined with others
-	replaceSchemalessHTML        = `Pre. src='//schemaless' src='/normal'  <a href="//schemaless">Schemaless</a>. <a href="/normal">normal</a>. Post.`
-	replaceSchemalessHTMLCorrect = `Pre. src='//schemaless' src='http://base/normal'  <a href="//schemaless">Schemaless</a>. <a href="http://base/normal">normal</a>. Post.`
-	replaceSchemalessXML         = `Pre. src=&#39;//schemaless&#39; src=&#39;/normal&#39;  <a href=&#39;//schemaless&#39;>Schemaless</a>. <a href=&#39;/normal&#39;>normal</a>. Post.`
-	replaceSchemalessXMLCorrect  = `Pre. src=&#39;//schemaless&#39; src=&#39;http://base/normal&#39;  <a href=&#39;//schemaless&#39;>Schemaless</a>. <a href=&#39;http://base/normal&#39;>normal</a>. Post.`
-)
-
-const (
-	// srcset=
-	srcsetBasic                 = `Pre. <img srcset="/img/small.jpg 200w, /img/medium.jpg 300w, /img/big.jpg 700w" alt="text" src="/img/foo.jpg">`
-	srcsetBasicCorrect          = `Pre. <img srcset="http://base/img/small.jpg 200w, http://base/img/medium.jpg 300w, http://base/img/big.jpg 700w" alt="text" src="http://base/img/foo.jpg">`
-	srcsetSingleQuote           = `Pre. <img srcset='/img/small.jpg 200w, /img/big.jpg 700w' alt="text" src="/img/foo.jpg"> POST.`
-	srcsetSingleQuoteCorrect    = `Pre. <img srcset='http://base/img/small.jpg 200w, http://base/img/big.jpg 700w' alt="text" src="http://base/img/foo.jpg"> POST.`
-	srcsetXMLBasic              = `Pre. <img srcset=&#34;/img/small.jpg 200w, /img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;/img/foo.jpg&#34;>`
-	srcsetXMLBasicCorrect       = `Pre. <img srcset=&#34;http://base/img/small.jpg 200w, http://base/img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;http://base/img/foo.jpg&#34;>`
-	srcsetXMLSingleQuote        = `Pre. <img srcset=&#34;/img/small.jpg 200w, /img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;/img/foo.jpg&#34;>`
-	srcsetXMLSingleQuoteCorrect = `Pre. <img srcset=&#34;http://base/img/small.jpg 200w, http://base/img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;http://base/img/foo.jpg&#34;>`
-	srcsetVariations            = `Pre. 
-Missing start quote: <img srcset=/img/small.jpg 200w, /img/big.jpg 700w" alt="text"> src='/img/foo.jpg'> FOO. 
-<img srcset='/img.jpg'> 
-schemaless: <img srcset='//img.jpg' src='//basic.jpg'>
-schemaless2: <img srcset="//img.jpg" src="//basic.jpg2> POST
-`
-)
-
-const (
-	srcsetVariationsCorrect = `Pre. 
-Missing start quote: <img srcset=/img/small.jpg 200w, /img/big.jpg 700w" alt="text"> src='http://base/img/foo.jpg'> FOO. 
-<img srcset='http://base/img.jpg'> 
-schemaless: <img srcset='//img.jpg' src='//basic.jpg'>
-schemaless2: <img srcset="//img.jpg" src="//basic.jpg2> POST
-`
-	srcsetXMLVariations = `Pre. 
-Missing start quote: &lt;img srcset=/img/small.jpg 200w /img/big.jpg 700w&quot; alt=&quot;text&quot;&gt; src=&#39;/img/foo.jpg&#39;&gt; FOO. 
-&lt;img srcset=&#39;/img.jpg&#39;&gt; 
-schemaless: &lt;img srcset=&#39;//img.jpg&#39; src=&#39;//basic.jpg&#39;&gt;
-schemaless2: &lt;img srcset=&quot;//img.jpg&quot; src=&quot;//basic.jpg2&gt; POST
-`
-	srcsetXMLVariationsCorrect = `Pre. 
-Missing start quote: &lt;img srcset=/img/small.jpg 200w /img/big.jpg 700w&quot; alt=&quot;text&quot;&gt; src=&#39;http://base/img/foo.jpg&#39;&gt; FOO. 
-&lt;img srcset=&#39;http://base/img.jpg&#39;&gt; 
-schemaless: &lt;img srcset=&#39;//img.jpg&#39; src=&#39;//basic.jpg&#39;&gt;
-schemaless2: &lt;img srcset=&quot;//img.jpg&quot; src=&quot;//basic.jpg2&gt; POST
-`
-
-	relPathVariations        = `PRE. a href="/img/small.jpg" POST.`
-	relPathVariationsCorrect = `PRE. a href="../../img/small.jpg" POST.`
-
-	testBaseURL = "http://base/"
-)
-
-var (
-	absURLlBenchTests = []test{
-		{h5JsContentDoubleQuote, corectOutputSrcHrefDq},
-		{h5JsContentSingleQuote, corectOutputSrcHrefSq},
-		{h5JsContentAbsURL, h5JsContentAbsURL},
-		{h5JsContentAbsURLSchemaless, h5JsContentAbsURLSchemaless},
-	}
-
-	xmlAbsURLBenchTests = []test{
-		{h5XMLXontentAbsURL, correctOutputSrcHrefInXML},
-		{h5XMLContentGuarded, h5XMLContentGuarded},
-	}
-
-	sanityTests    = []test{{replace1, replace1}, {replace2, replace2}, {replace3, replace3}, {replace3, replace3}, {replace5, replace5}}
-	extraTestsHTML = []test{{replaceSchemalessHTML, replaceSchemalessHTMLCorrect}}
-	absURLTests    = append(absURLlBenchTests, append(sanityTests, extraTestsHTML...)...)
-	extraTestsXML  = []test{{replaceSchemalessXML, replaceSchemalessXMLCorrect}}
-	xmlAbsURLTests = append(xmlAbsURLBenchTests, append(sanityTests, extraTestsXML...)...)
-	srcsetTests    = []test{{srcsetBasic, srcsetBasicCorrect}, {srcsetSingleQuote, srcsetSingleQuoteCorrect}, {srcsetVariations, srcsetVariationsCorrect}}
-	srcsetXMLTests = []test{
-		{srcsetXMLBasic, srcsetXMLBasicCorrect},
-		{srcsetXMLSingleQuote, srcsetXMLSingleQuoteCorrect},
-		{srcsetXMLVariations, srcsetXMLVariationsCorrect}}
-
-	relurlTests = []test{{relPathVariations, relPathVariationsCorrect}}
-)
-
 func TestChainZeroTransformers(t *testing.T) {
-	tr := NewChain()
+	tr := New()
 	in := new(bytes.Buffer)
 	out := new(bytes.Buffer)
-	if err := tr.Apply(in, out, []byte("")); err != nil {
+	if err := tr.Apply(in, out); err != nil {
 		t.Errorf("A zero transformer chain returned an error.")
 	}
 }
 
 func TestChaingMultipleTransformers(t *testing.T) {
-	f1 := func(ct contentTransformer) {
+	f1 := func(ct FromTo) error {
-		ct.Write(bytes.Replace(ct.Content(), []byte("f1"), []byte("f1r"), -1))
+		_, err := ct.To().Write(bytes.Replace(ct.From().Bytes(), []byte("f1"), []byte("f1r"), -1))
+		return err
 	}
-	f2 := func(ct contentTransformer) {
+	f2 := func(ct FromTo) error {
-		ct.Write(bytes.Replace(ct.Content(), []byte("f2"), []byte("f2r"), -1))
+		_, err := ct.To().Write(bytes.Replace(ct.From().Bytes(), []byte("f2"), []byte("f2r"), -1))
+		return err
 	}
-	f3 := func(ct contentTransformer) {
+	f3 := func(ct FromTo) error {
-		ct.Write(bytes.Replace(ct.Content(), []byte("f3"), []byte("f3r"), -1))
+		_, err := ct.To().Write(bytes.Replace(ct.From().Bytes(), []byte("f3"), []byte("f3r"), -1))
+		return err
 	}
 
-	f4 := func(ct contentTransformer) {
+	f4 := func(ct FromTo) error {
-		ct.Write(bytes.Replace(ct.Content(), []byte("f4"), []byte("f4r"), -1))
+		_, err := ct.To().Write(bytes.Replace(ct.From().Bytes(), []byte("f4"), []byte("f4r"), -1))
+		return err
 	}
 
-	tr := NewChain(f1, f2, f3, f4)
+	tr := New(f1, f2, f3, f4)
 
 	out := new(bytes.Buffer)
-	if err := tr.Apply(out, strings.NewReader("Test: f4 f3 f1 f2 f1 The End."), []byte("")); err != nil {
+	if err := tr.Apply(out, strings.NewReader("Test: f4 f3 f1 f2 f1 The End.")); err != nil {
 		t.Errorf("Multi transformer chain returned an error: %s", err)
 	}
 
@@ -161,107 +63,7 @@ func TestChaingMultipleTransformers(t *testing.T) {
 	}
 }
 
-func BenchmarkAbsURL(b *testing.B) {
-	tr := NewChain(AbsURL)
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		apply(b.Errorf, tr, absURLlBenchTests)
-	}
-}
-
-func BenchmarkAbsURLSrcset(b *testing.B) {
-	tr := NewChain(AbsURL)
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		apply(b.Errorf, tr, srcsetTests)
-	}
-}
-
-func BenchmarkXMLAbsURLSrcset(b *testing.B) {
-	tr := NewChain(AbsURLInXML)
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		apply(b.Errorf, tr, srcsetXMLTests)
-	}
-}
-
-func TestAbsURL(t *testing.T) {
-	tr := NewChain(AbsURL)
-
-	apply(t.Errorf, tr, absURLTests)
-
-}
-
-func TestRelativeURL(t *testing.T) {
-	tr := NewChain(AbsURL)
-
-	applyWithPath(t.Errorf, tr, relurlTests, helpers.GetDottedRelativePath(filepath.FromSlash("/post/sub/")))
-
-}
-
-func TestAbsURLSrcSet(t *testing.T) {
-	tr := NewChain(AbsURL)
-
-	apply(t.Errorf, tr, srcsetTests)
-}
-
-func TestAbsXMLURLSrcSet(t *testing.T) {
-	tr := NewChain(AbsURLInXML)
-
-	apply(t.Errorf, tr, srcsetXMLTests)
-}
-
-func BenchmarkXMLAbsURL(b *testing.B) {
-	tr := NewChain(AbsURLInXML)
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		apply(b.Errorf, tr, xmlAbsURLBenchTests)
-	}
-}
-
-func TestXMLAbsURL(t *testing.T) {
-	tr := NewChain(AbsURLInXML)
-	apply(t.Errorf, tr, xmlAbsURLTests)
-}
-
 func TestNewEmptyTransforms(t *testing.T) {
-	transforms := NewEmptyTransforms()
+	transforms := NewEmpty()
 	assert.Equal(t, 20, cap(transforms))
 }
-
-type errorf func(string, ...interface{})
-
-func applyWithPath(ef errorf, tr chain, tests []test, path string) {
-	out := bp.GetBuffer()
-	defer bp.PutBuffer(out)
-
-	in := bp.GetBuffer()
-	defer bp.PutBuffer(in)
-
-	for _, test := range tests {
-		var err error
-		in.WriteString(test.content)
-		err = tr.Apply(out, in, []byte(path))
-		if err != nil {
-			ef("Unexpected error: %s", err)
-		}
-		if test.expected != out.String() {
-			ef("Expected:\n%s\nGot:\n%s", test.expected, out.String())
-		}
-		out.Reset()
-		in.Reset()
-	}
-}
-
-func apply(ef errorf, tr chain, tests []test) {
-	applyWithPath(ef, tr, tests, testBaseURL)
-}
-
-type test struct {
-	content  string
-	expected string
-}

transform/livereloadinject/livereloadinject.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Hugo Authors. All rights reserved.
+// 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.
@@ -11,30 +11,37 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package transform
+package livereloadinject
 
 import (
 	"bytes"
 	"fmt"
+
+	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/transform"
 )
 
-// LiveReloadInject returns a function that can be used
+// New creates a function that can be used
 // to inject a script tag for the livereload JavaScript in a HTML document.
-func LiveReloadInject(port int) func(ct contentTransformer) {
+func New(port int) transform.Transformer {
-	return func(ct contentTransformer) {
+	return func(ft transform.FromTo) error {
+		b := ft.From().Bytes()
 		endBodyTag := "</body>"
 		match := []byte(endBodyTag)
 		replaceTemplate := `<script data-no-instant>document.write('<script src="/livereload.js?port=%d&mindelay=10"></' + 'script>')</script>%s`
 		replace := []byte(fmt.Sprintf(replaceTemplate, port, endBodyTag))
 
-		newcontent := bytes.Replace(ct.Content(), match, replace, 1)
+		newcontent := bytes.Replace(b, match, replace, 1)
-		if len(newcontent) == len(ct.Content()) {
+		if len(newcontent) == len(b) {
 			endBodyTag = "</BODY>"
 			replace := []byte(fmt.Sprintf(replaceTemplate, port, endBodyTag))
 			match := []byte(endBodyTag)
-			newcontent = bytes.Replace(ct.Content(), match, replace, 1)
+			newcontent = bytes.Replace(b, match, replace, 1)
 		}
 
-		ct.Write(newcontent)
+		if _, err := ft.To().Write(newcontent); err != nil {
+			helpers.DistinctWarnLog.Println("Failed to inject LiveReload script:", err)
+		}
+		return nil
 	}
 }

transform/livereloadinject/livereloadinject_test.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Hugo Authors. All rights reserved.
+// 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.
@@ -11,13 +11,15 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package transform
+package livereloadinject
 
 import (
 	"bytes"
 	"fmt"
 	"strings"
 	"testing"
+
+	"github.com/gohugoio/hugo/transform"
 )
 
 func TestLiveReloadInject(t *testing.T) {
@@ -29,8 +31,8 @@ func doTestLiveReloadInject(t *testing.T, bodyEndTag string) {
 	out := new(bytes.Buffer)
 	in := strings.NewReader(bodyEndTag)
 
-	tr := NewChain(LiveReloadInject(1313))
+	tr := transform.New(New(1313))
-	tr.Apply(out, in, []byte("path"))
+	tr.Apply(out, in)
 
 	expected := fmt.Sprintf(`<script data-no-instant>document.write('<script src="/livereload.js?port=1313&mindelay=10"></' + 'script>')</script>%s`, bodyEndTag)
 	if string(out.Bytes()) != expected {

transform/metainject/hugogenerator.go

@@ -1,4 +1,4 @@
-// Copyright 2016 The Hugo Authors. All rights reserved.
+// 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.
@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package transform
+package metainject
 
 import (
 	"bytes"
@@ -19,32 +19,36 @@ import (
 	"regexp"
 
 	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/transform"
 )
 
 var metaTagsCheck = regexp.MustCompile(`(?i)<meta\s+name=['|"]?generator['|"]?`)
 var hugoGeneratorTag = fmt.Sprintf(`<meta name="generator" content="Hugo %s" />`, helpers.CurrentHugoVersion)
 
-// HugoGeneratorInject injects a meta generator tag for Hugo if none present.
+// HugoGenerator injects a meta generator tag for Hugo if none present.
-func HugoGeneratorInject(ct contentTransformer) {
+func HugoGenerator(ft transform.FromTo) error {
-	if metaTagsCheck.Match(ct.Content()) {
+	b := ft.From().Bytes()
-		if _, err := ct.Write(ct.Content()); err != nil {
+	if metaTagsCheck.Match(b) {
+		if _, err := ft.To().Write(b); err != nil {
 			helpers.DistinctWarnLog.Println("Failed to inject Hugo generator tag:", err)
 		}
-		return
+		return nil
 	}
 
 	head := "<head>"
 	replace := []byte(fmt.Sprintf("%s\n\t%s", head, hugoGeneratorTag))
-	newcontent := bytes.Replace(ct.Content(), []byte(head), replace, 1)
+	newcontent := bytes.Replace(b, []byte(head), replace, 1)
 
-	if len(newcontent) == len(ct.Content()) {
+	if len(newcontent) == len(b) {
 		head := "<HEAD>"
 		replace := []byte(fmt.Sprintf("%s\n\t%s", head, hugoGeneratorTag))
-		newcontent = bytes.Replace(ct.Content(), []byte(head), replace, 1)
+		newcontent = bytes.Replace(b, []byte(head), replace, 1)
 	}
 
-	if _, err := ct.Write(newcontent); err != nil {
+	if _, err := ft.To().Write(newcontent); err != nil {
 		helpers.DistinctWarnLog.Println("Failed to inject Hugo generator tag:", err)
 	}
 
+	return nil
+
 }

transform/metainject/hugogenerator_test.go

@@ -1,4 +1,4 @@
-// Copyright 2016 The Hugo Authors. All rights reserved.
+// 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.
@@ -11,12 +11,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package transform
+package metainject
 
 import (
 	"bytes"
 	"strings"
 	"testing"
+
+	"github.com/gohugoio/hugo/transform"
 )
 
 func TestHugoGeneratorInject(t *testing.T) {
@@ -48,8 +50,8 @@ func TestHugoGeneratorInject(t *testing.T) {
 		in := strings.NewReader(this.in)
 		out := new(bytes.Buffer)
 
-		tr := NewChain(HugoGeneratorInject)
+		tr := transform.New(HugoGenerator)
-		tr.Apply(out, in, []byte(""))
+		tr.Apply(out, in)
 
 		if out.String() != this.expect {
 			t.Errorf("[%d] Expected \n%q got \n%q", i, this.expect, out.String())

transform/urlreplacers/absurl.go

@@ -0,0 +1,36 @@
+// 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 urlreplacers
+
+import "github.com/gohugoio/hugo/transform"
+
+var ar = newAbsURLReplacer()
+
+// NewAbsURLTransformer replaces relative URLs with absolute ones
+// in HTML files, using the baseURL setting.
+func NewAbsURLTransformer(path string) transform.Transformer {
+	return func(ft transform.FromTo) error {
+		ar.replaceInHTML(path, ft)
+		return nil
+	}
+}
+
+// NewAbsURLInXMLTransformer replaces relative URLs with absolute ones
+// in XML files, using the baseURL setting.
+func NewAbsURLInXMLTransformer(path string) transform.Transformer {
+	return func(ft transform.FromTo) error {
+		ar.replaceInXML(path, ft)
+		return nil
+	}
+}

transform/urlreplacers/absurlreplacer.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Hugo Authors. All rights reserved.
+// 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.
@@ -11,12 +11,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package transform
+package urlreplacers
 
 import (
 	"bytes"
 	"io"
 	"unicode/utf8"
+
+	"github.com/gohugoio/hugo/transform"
 )
 
 type matchState int
@@ -260,12 +262,12 @@ func (l *absurllexer) replace() {
 	}
 }
 
-func doReplace(ct contentTransformer, matchers []absURLMatcher) {
+func doReplace(path string, ct transform.FromTo, matchers []absURLMatcher) {
 
 	lexer := &absurllexer{
-		content:  ct.Content(),
+		content:  ct.From().Bytes(),
-		w:        ct,
+		w:        ct.To(),
-		path:     ct.Path(),
+		path:     []byte(path),
 		matchers: matchers}
 
 	lexer.replace()
@@ -303,10 +305,10 @@ func newAbsURLReplacer() *absURLReplacer {
 		}}
 }
 
-func (au *absURLReplacer) replaceInHTML(ct contentTransformer) {
+func (au *absURLReplacer) replaceInHTML(path string, ct transform.FromTo) {
-	doReplace(ct, au.htmlMatchers)
+	doReplace(path, ct, au.htmlMatchers)
 }
 
-func (au *absURLReplacer) replaceInXML(ct contentTransformer) {
+func (au *absURLReplacer) replaceInXML(path string, ct transform.FromTo) {
-	doReplace(ct, au.xmlMatchers)
+	doReplace(path, ct, au.xmlMatchers)
 }

transform/urlreplacers/absurlreplacer_test.go

@@ -0,0 +1,223 @@
+// 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 urlreplacers
+
+import (
+	"path/filepath"
+	"testing"
+
+	bp "github.com/gohugoio/hugo/bufferpool"
+
+	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/transform"
+)
+
+const (
+	h5JsContentDoubleQuote      = "<!DOCTYPE html><html><head><script src=\"foobar.js\"></script><script src=\"/barfoo.js\"></script></head><body><nav><h1>title</h1></nav><article>content <a href=\"foobar\">foobar</a>. <a href=\"/foobar\">Follow up</a></article></body></html>"
+	h5JsContentSingleQuote      = "<!DOCTYPE html><html><head><script src='foobar.js'></script><script src='/barfoo.js'></script></head><body><nav><h1>title</h1></nav><article>content <a href='foobar'>foobar</a>. <a href='/foobar'>Follow up</a></article></body></html>"
+	h5JsContentAbsURL           = "<!DOCTYPE html><html><head><script src=\"http://user@host:10234/foobar.js\"></script></head><body><nav><h1>title</h1></nav><article>content <a href=\"https://host/foobar\">foobar</a>. Follow up</article></body></html>"
+	h5JsContentAbsURLSchemaless = "<!DOCTYPE html><html><head><script src=\"//host/foobar.js\"></script><script src='//host2/barfoo.js'></head><body><nav><h1>title</h1></nav><article>content <a href=\"//host/foobar\">foobar</a>. <a href='//host2/foobar'>Follow up</a></article></body></html>"
+	corectOutputSrcHrefDq       = "<!DOCTYPE html><html><head><script src=\"foobar.js\"></script><script src=\"http://base/barfoo.js\"></script></head><body><nav><h1>title</h1></nav><article>content <a href=\"foobar\">foobar</a>. <a href=\"http://base/foobar\">Follow up</a></article></body></html>"
+	corectOutputSrcHrefSq       = "<!DOCTYPE html><html><head><script src='foobar.js'></script><script src='http://base/barfoo.js'></script></head><body><nav><h1>title</h1></nav><article>content <a href='foobar'>foobar</a>. <a href='http://base/foobar'>Follow up</a></article></body></html>"
+
+	h5XMLXontentAbsURL        = "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?><feed xmlns=\"http://www.w3.org/2005/Atom\"><entry><content type=\"html\">&lt;p&gt;&lt;a href=&#34;/foobar&#34;&gt;foobar&lt;/a&gt;&lt;/p&gt; &lt;p&gt;A video: &lt;iframe src=&#39;/foo&#39;&gt;&lt;/iframe&gt;&lt;/p&gt;</content></entry></feed>"
+	correctOutputSrcHrefInXML = "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?><feed xmlns=\"http://www.w3.org/2005/Atom\"><entry><content type=\"html\">&lt;p&gt;&lt;a href=&#34;http://base/foobar&#34;&gt;foobar&lt;/a&gt;&lt;/p&gt; &lt;p&gt;A video: &lt;iframe src=&#39;http://base/foo&#39;&gt;&lt;/iframe&gt;&lt;/p&gt;</content></entry></feed>"
+	h5XMLContentGuarded       = "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\" ?><feed xmlns=\"http://www.w3.org/2005/Atom\"><entry><content type=\"html\">&lt;p&gt;&lt;a href=&#34;//foobar&#34;&gt;foobar&lt;/a&gt;&lt;/p&gt; &lt;p&gt;A video: &lt;iframe src=&#39;//foo&#39;&gt;&lt;/iframe&gt;&lt;/p&gt;</content></entry></feed>"
+)
+
+const (
+	// additional sanity tests for replacements testing
+	replace1 = "No replacements."
+	replace2 = "ᚠᛇᚻ ᛒᛦᚦ ᚠᚱᚩᚠᚢᚱ\nᚠᛁᚱᚪ ᚷᛖᚻᚹᛦᛚᚳᚢᛗ"
+	replace3 = `End of file: src="/`
+	replace4 = `End of file: srcset="/`
+	replace5 = `Srcsett with no closing quote: srcset="/img/small.jpg do be do be do.`
+
+	// Issue: 816, schemaless links combined with others
+	replaceSchemalessHTML        = `Pre. src='//schemaless' src='/normal'  <a href="//schemaless">Schemaless</a>. <a href="/normal">normal</a>. Post.`
+	replaceSchemalessHTMLCorrect = `Pre. src='//schemaless' src='http://base/normal'  <a href="//schemaless">Schemaless</a>. <a href="http://base/normal">normal</a>. Post.`
+	replaceSchemalessXML         = `Pre. src=&#39;//schemaless&#39; src=&#39;/normal&#39;  <a href=&#39;//schemaless&#39;>Schemaless</a>. <a href=&#39;/normal&#39;>normal</a>. Post.`
+	replaceSchemalessXMLCorrect  = `Pre. src=&#39;//schemaless&#39; src=&#39;http://base/normal&#39;  <a href=&#39;//schemaless&#39;>Schemaless</a>. <a href=&#39;http://base/normal&#39;>normal</a>. Post.`
+)
+
+const (
+	// srcset=
+	srcsetBasic                 = `Pre. <img srcset="/img/small.jpg 200w, /img/medium.jpg 300w, /img/big.jpg 700w" alt="text" src="/img/foo.jpg">`
+	srcsetBasicCorrect          = `Pre. <img srcset="http://base/img/small.jpg 200w, http://base/img/medium.jpg 300w, http://base/img/big.jpg 700w" alt="text" src="http://base/img/foo.jpg">`
+	srcsetSingleQuote           = `Pre. <img srcset='/img/small.jpg 200w, /img/big.jpg 700w' alt="text" src="/img/foo.jpg"> POST.`
+	srcsetSingleQuoteCorrect    = `Pre. <img srcset='http://base/img/small.jpg 200w, http://base/img/big.jpg 700w' alt="text" src="http://base/img/foo.jpg"> POST.`
+	srcsetXMLBasic              = `Pre. <img srcset=&#34;/img/small.jpg 200w, /img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;/img/foo.jpg&#34;>`
+	srcsetXMLBasicCorrect       = `Pre. <img srcset=&#34;http://base/img/small.jpg 200w, http://base/img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;http://base/img/foo.jpg&#34;>`
+	srcsetXMLSingleQuote        = `Pre. <img srcset=&#34;/img/small.jpg 200w, /img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;/img/foo.jpg&#34;>`
+	srcsetXMLSingleQuoteCorrect = `Pre. <img srcset=&#34;http://base/img/small.jpg 200w, http://base/img/big.jpg 700w&#34; alt=&#34;text&#34; src=&#34;http://base/img/foo.jpg&#34;>`
+	srcsetVariations            = `Pre. 
+Missing start quote: <img srcset=/img/small.jpg 200w, /img/big.jpg 700w" alt="text"> src='/img/foo.jpg'> FOO. 
+<img srcset='/img.jpg'> 
+schemaless: <img srcset='//img.jpg' src='//basic.jpg'>
+schemaless2: <img srcset="//img.jpg" src="//basic.jpg2> POST
+`
+)
+
+const (
+	srcsetVariationsCorrect = `Pre. 
+Missing start quote: <img srcset=/img/small.jpg 200w, /img/big.jpg 700w" alt="text"> src='http://base/img/foo.jpg'> FOO. 
+<img srcset='http://base/img.jpg'> 
+schemaless: <img srcset='//img.jpg' src='//basic.jpg'>
+schemaless2: <img srcset="//img.jpg" src="//basic.jpg2> POST
+`
+	srcsetXMLVariations = `Pre. 
+Missing start quote: &lt;img srcset=/img/small.jpg 200w /img/big.jpg 700w&quot; alt=&quot;text&quot;&gt; src=&#39;/img/foo.jpg&#39;&gt; FOO. 
+&lt;img srcset=&#39;/img.jpg&#39;&gt; 
+schemaless: &lt;img srcset=&#39;//img.jpg&#39; src=&#39;//basic.jpg&#39;&gt;
+schemaless2: &lt;img srcset=&quot;//img.jpg&quot; src=&quot;//basic.jpg2&gt; POST
+`
+	srcsetXMLVariationsCorrect = `Pre. 
+Missing start quote: &lt;img srcset=/img/small.jpg 200w /img/big.jpg 700w&quot; alt=&quot;text&quot;&gt; src=&#39;http://base/img/foo.jpg&#39;&gt; FOO. 
+&lt;img srcset=&#39;http://base/img.jpg&#39;&gt; 
+schemaless: &lt;img srcset=&#39;//img.jpg&#39; src=&#39;//basic.jpg&#39;&gt;
+schemaless2: &lt;img srcset=&quot;//img.jpg&quot; src=&quot;//basic.jpg2&gt; POST
+`
+
+	relPathVariations        = `PRE. a href="/img/small.jpg" POST.`
+	relPathVariationsCorrect = `PRE. a href="../../img/small.jpg" POST.`
+
+	testBaseURL = "http://base/"
+)
+
+var (
+	absURLlBenchTests = []test{
+		{h5JsContentDoubleQuote, corectOutputSrcHrefDq},
+		{h5JsContentSingleQuote, corectOutputSrcHrefSq},
+		{h5JsContentAbsURL, h5JsContentAbsURL},
+		{h5JsContentAbsURLSchemaless, h5JsContentAbsURLSchemaless},
+	}
+
+	xmlAbsURLBenchTests = []test{
+		{h5XMLXontentAbsURL, correctOutputSrcHrefInXML},
+		{h5XMLContentGuarded, h5XMLContentGuarded},
+	}
+
+	sanityTests    = []test{{replace1, replace1}, {replace2, replace2}, {replace3, replace3}, {replace3, replace3}, {replace5, replace5}}
+	extraTestsHTML = []test{{replaceSchemalessHTML, replaceSchemalessHTMLCorrect}}
+	absURLTests    = append(absURLlBenchTests, append(sanityTests, extraTestsHTML...)...)
+	extraTestsXML  = []test{{replaceSchemalessXML, replaceSchemalessXMLCorrect}}
+	xmlAbsURLTests = append(xmlAbsURLBenchTests, append(sanityTests, extraTestsXML...)...)
+	srcsetTests    = []test{{srcsetBasic, srcsetBasicCorrect}, {srcsetSingleQuote, srcsetSingleQuoteCorrect}, {srcsetVariations, srcsetVariationsCorrect}}
+	srcsetXMLTests = []test{
+		{srcsetXMLBasic, srcsetXMLBasicCorrect},
+		{srcsetXMLSingleQuote, srcsetXMLSingleQuoteCorrect},
+		{srcsetXMLVariations, srcsetXMLVariationsCorrect}}
+
+	relurlTests = []test{{relPathVariations, relPathVariationsCorrect}}
+)
+
+func BenchmarkAbsURL(b *testing.B) {
+	tr := transform.New(NewAbsURLTransformer(testBaseURL))
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		apply(b.Errorf, tr, absURLlBenchTests)
+	}
+}
+
+func BenchmarkAbsURLSrcset(b *testing.B) {
+	tr := transform.New(NewAbsURLTransformer(testBaseURL))
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		apply(b.Errorf, tr, srcsetTests)
+	}
+}
+
+func BenchmarkXMLAbsURLSrcset(b *testing.B) {
+	tr := transform.New(NewAbsURLInXMLTransformer(testBaseURL))
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		apply(b.Errorf, tr, srcsetXMLTests)
+	}
+}
+
+func TestAbsURL(t *testing.T) {
+	tr := transform.New(NewAbsURLTransformer(testBaseURL))
+
+	apply(t.Errorf, tr, absURLTests)
+
+}
+
+func TestRelativeURL(t *testing.T) {
+	tr := transform.New(NewAbsURLTransformer(helpers.GetDottedRelativePath(filepath.FromSlash("/post/sub/"))))
+
+	applyWithPath(t.Errorf, tr, relurlTests)
+
+}
+
+func TestAbsURLSrcSet(t *testing.T) {
+	tr := transform.New(NewAbsURLTransformer(testBaseURL))
+
+	apply(t.Errorf, tr, srcsetTests)
+}
+
+func TestAbsXMLURLSrcSet(t *testing.T) {
+	tr := transform.New(NewAbsURLInXMLTransformer(testBaseURL))
+
+	apply(t.Errorf, tr, srcsetXMLTests)
+}
+
+func BenchmarkXMLAbsURL(b *testing.B) {
+	tr := transform.New(NewAbsURLInXMLTransformer(""))
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		apply(b.Errorf, tr, xmlAbsURLBenchTests)
+	}
+}
+
+func TestXMLAbsURL(t *testing.T) {
+	tr := transform.New(NewAbsURLInXMLTransformer(testBaseURL))
+	apply(t.Errorf, tr, xmlAbsURLTests)
+}
+
+func apply(ef errorf, tr transform.Chain, tests []test) {
+	applyWithPath(ef, tr, tests)
+}
+
+func applyWithPath(ef errorf, tr transform.Chain, tests []test) {
+	out := bp.GetBuffer()
+	defer bp.PutBuffer(out)
+
+	in := bp.GetBuffer()
+	defer bp.PutBuffer(in)
+
+	for _, test := range tests {
+		var err error
+		in.WriteString(test.content)
+		err = tr.Apply(out, in)
+		if err != nil {
+			ef("Unexpected error: %s", err)
+		}
+		if test.expected != out.String() {
+			ef("Expected:\n%s\nGot:\n%s", test.expected, out.String())
+		}
+		out.Reset()
+		in.Reset()
+	}
+}
+
+type test struct {
+	content  string
+	expected string
+}
+
+type errorf func(string, ...interface{})