blog/blog.go - tools - Git at Google

 // Copyright 2013 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Package blog implements a web server for articles written in present format.
 package blog // import "golang.org/x/tools/blog"

 import (
 	"bytes"
 	"encoding/json"
 	"encoding/xml"
 	"fmt"
 	"html/template"
 	"log"
 	"net/http"
 	"os"
 	"path/filepath"
 	"regexp"
 	"sort"
 	"strings"
 	"time"

 	"golang.org/x/tools/blog/atom"
 	"golang.org/x/tools/present"
 )

 var (
 	validJSONPFunc = regexp.MustCompile(`(?i)^[a-z_][a-z0-9_.]*$`)
 	// used to serve relative paths when ServeLocalLinks is enabled.
 	golangOrgAbsLinkReplacer = strings.NewReplacer(
 		`href="https://golang.org/pkg`, `href="/pkg`,
 		`href="https://golang.org/cmd`, `href="/cmd`,
 	)
 )

 // Config specifies Server configuration values.
 type Config struct {
 	ContentPath  string // Relative or absolute location of article files and related content.
 	TemplatePath string // Relative or absolute location of template files.

 	BaseURL       string        // Absolute base URL (for permalinks; no trailing slash).
 	BasePath      string        // Base URL path relative to server root (no trailing slash).
 	GodocURL      string        // The base URL of godoc (for menu bar; no trailing slash).
 	Hostname      string        // Server host name, used for rendering ATOM feeds.
 	AnalyticsHTML template.HTML // Optional analytics HTML to insert at the beginning of <head>.

 	HomeArticles int    // Articles to display on the home page.
 	FeedArticles int    // Articles to include in Atom and JSON feeds.
 	FeedTitle    string // The title of the Atom XML feed

 	PlayEnabled     bool
 	ServeLocalLinks bool // rewrite golang.org/{pkg,cmd} links to host-less, relative paths.
 }

 // Doc represents an article adorned with presentation data.
 type Doc struct {
 	*present.Doc
 	Permalink string        // Canonical URL for this document.
 	Path      string        // Path relative to server root (including base).
 	HTML      template.HTML // rendered article

 	Related      []*Doc
 	Newer, Older *Doc
 }

 // Server implements an http.Handler that serves blog articles.
 type Server struct {
 	cfg       Config
 	docs      []*Doc
 	redirects map[string]string
 	tags      []string
 	docPaths  map[string]*Doc // key is path without BasePath.
 	docTags   map[string][]*Doc
 	template  struct {
 		home, index, article, doc *template.Template
 	}
 	atomFeed []byte // pre-rendered Atom feed
 	jsonFeed []byte // pre-rendered JSON feed
 	content  http.Handler
 }

 // NewServer constructs a new Server using the specified config.
 func NewServer(cfg Config) (*Server, error) {
 	present.PlayEnabled = cfg.PlayEnabled

 	if notExist(cfg.TemplatePath) {
 		return nil, fmt.Errorf("template directory not found: %s", cfg.TemplatePath)
 	}
 	root := filepath.Join(cfg.TemplatePath, "root.tmpl")
 	parse := func(name string) (*template.Template, error) {
 		path := filepath.Join(cfg.TemplatePath, name)
 		if notExist(path) {
 			return nil, fmt.Errorf("template %s was not found in %s", name, cfg.TemplatePath)
 		}
 		t := template.New("").Funcs(funcMap)
 		return t.ParseFiles(root, path)
 	}

 	s := &Server{cfg: cfg}

 	// Parse templates.
 	var err error
 	s.template.home, err = parse("home.tmpl")
 	if err != nil {
 		return nil, err
 	}
 	s.template.index, err = parse("index.tmpl")
 	if err != nil {
 		return nil, err
 	}
 	s.template.article, err = parse("article.tmpl")
 	if err != nil {
 		return nil, err
 	}
 	p := present.Template().Funcs(funcMap)
 	s.template.doc, err = p.ParseFiles(filepath.Join(cfg.TemplatePath, "doc.tmpl"))
 	if err != nil {
 		return nil, err
 	}

 	// Load content.
 	content := filepath.Clean(cfg.ContentPath)
 	err = s.loadDocs(content)
 	if err != nil {
 		return nil, err
 	}

 	err = s.renderAtomFeed()
 	if err != nil {
 		return nil, err
 	}

 	err = s.renderJSONFeed()
 	if err != nil {
 		return nil, err
 	}

 	// Set up content file server.
 	s.content = http.StripPrefix(s.cfg.BasePath, http.FileServer(http.Dir(cfg.ContentPath)))

 	return s, nil
 }

 var funcMap = template.FuncMap{
 	"sectioned": sectioned,
 	"authors":   authors,
 }

 // sectioned returns true if the provided Doc contains more than one section.
 // This is used to control whether to display the table of contents and headings.
 func sectioned(d *present.Doc) bool {
 	return len(d.Sections) > 1
 }

 // authors returns a comma-separated list of author names.
 func authors(authors []present.Author) string {
 	var b bytes.Buffer
 	last := len(authors) - 1
 	for i, a := range authors {
 		if i > 0 {
 			if i == last {
 				if len(authors) > 2 {
 					b.WriteString(",")
 				}
 				b.WriteString(" and ")
 			} else {
 				b.WriteString(", ")
 			}
 		}
 		b.WriteString(authorName(a))
 	}
 	return b.String()
 }

 // authorName returns the first line of the Author text: the author's name.
 func authorName(a present.Author) string {
 	el := a.TextElem()
 	if len(el) == 0 {
 		return ""
 	}
 	text, ok := el[0].(present.Text)
 	if !ok || len(text.Lines) == 0 {
 		return ""
 	}
 	return text.Lines[0]
 }

 // loadDocs reads all content from the provided file system root, renders all
 // the articles it finds, adds them to the Server's docs field, computes the
 // denormalized docPaths, docTags, and tags fields, and populates the various
 // helper fields (Next, Previous, Related) for each Doc.
 func (s *Server) loadDocs(root string) error {
 	// Read content into docs field.
 	const ext = ".article"
 	fn := func(p string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}

 		if filepath.Ext(p) != ext {
 			return nil
 		}
 		f, err := os.Open(p)
 		if err != nil {
 			return err
 		}
 		defer f.Close()
 		d, err := present.Parse(f, p, 0)
 		if err != nil {
 			return err
 		}
 		var html bytes.Buffer
 		err = d.Render(&html, s.template.doc)
 		if err != nil {
 			return err
 		}
 		p = p[len(root) : len(p)-len(ext)] // trim root and extension
 		p = filepath.ToSlash(p)
 		s.docs = append(s.docs, &Doc{
 			Doc:       d,
 			Path:      s.cfg.BasePath + p,
 			Permalink: s.cfg.BaseURL + p,
 			HTML:      template.HTML(html.String()),
 		})
 		return nil
 	}
 	err := filepath.Walk(root, fn)
 	if err != nil {
 		return err
 	}
 	sort.Sort(docsByTime(s.docs))

 	// Pull out doc paths and tags and put in reverse-associating maps.
 	s.docPaths = make(map[string]*Doc)
 	s.docTags = make(map[string][]*Doc)
 	s.redirects = make(map[string]string)
 	for _, d := range s.docs {
 		s.docPaths[strings.TrimPrefix(d.Path, s.cfg.BasePath)] = d
 		for _, t := range d.Tags {
 			s.docTags[t] = append(s.docTags[t], d)
 		}
 	}
 	for _, d := range s.docs {
 		for _, old := range d.OldURL {
 			if !strings.HasPrefix(old, "/") {
 				old = "/" + old
 			}
 			if _, ok := s.docPaths[old]; ok {
 				return fmt.Errorf("redirect %s -> %s conflicts with document %s", old, d.Path, old)
 			}
 			if new, ok := s.redirects[old]; ok {
 				return fmt.Errorf("redirect %s -> %s conflicts with redirect %s -> %s", old, d.Path, old, new)
 			}
 			s.redirects[old] = d.Path
 		}
 	}

 	// Pull out unique sorted list of tags.
 	for t := range s.docTags {
 		s.tags = append(s.tags, t)
 	}
 	sort.Strings(s.tags)

 	// Set up presentation-related fields, Newer, Older, and Related.
 	for _, doc := range s.docs {
 		// Newer, Older: docs adjacent to doc
 		for i := range s.docs {
 			if s.docs[i] != doc {
 				continue
 			}
 			if i > 0 {
 				doc.Newer = s.docs[i-1]
 			}
 			if i+1 < len(s.docs) {
 				doc.Older = s.docs[i+1]
 			}
 			break
 		}

 		// Related: all docs that share tags with doc.
 		related := make(map[*Doc]bool)
 		for _, t := range doc.Tags {
 			for _, d := range s.docTags[t] {
 				if d != doc {
 					related[d] = true
 				}
 			}
 		}
 		for d := range related {
 			doc.Related = append(doc.Related, d)
 		}
 		sort.Sort(docsByTime(doc.Related))
 	}

 	return nil
 }

 // renderAtomFeed generates an XML Atom feed and stores it in the Server's
 // atomFeed field.
 func (s *Server) renderAtomFeed() error {
 	var updated time.Time
 	if len(s.docs) > 0 {
 		updated = s.docs[0].Time
 	}
 	feed := atom.Feed{
 		Title:   s.cfg.FeedTitle,
 		ID:      "tag:" + s.cfg.Hostname + ",2013:" + s.cfg.Hostname,
 		Updated: atom.Time(updated),
 		Link: []atom.Link{{
 			Rel:  "self",
 			Href: s.cfg.BaseURL + "/feed.atom",
 		}},
 	}
 	for i, doc := range s.docs {
 		if i >= s.cfg.FeedArticles {
 			break
 		}

 		// Use original article path as ID in atom feed
 		// to avoid articles being treated as new when renamed.
 		idPath := doc.Path
 		if len(doc.OldURL) > 0 {
 			old := doc.OldURL[0]
 			if !strings.HasPrefix(old, "/") {
 				old = "/" + old
 			}
 			idPath = old
 		}

 		e := &atom.Entry{
 			Title: doc.Title,
 			ID:    feed.ID + idPath,
 			Link: []atom.Link{{
 				Rel:  "alternate",
 				Href: doc.Permalink,
 			}},
 			Published: atom.Time(doc.Time),
 			Updated:   atom.Time(doc.Time),
 			Summary: &atom.Text{
 				Type: "html",
 				Body: summary(doc),
 			},
 			Content: &atom.Text{
 				Type: "html",
 				Body: string(doc.HTML),
 			},
 			Author: &atom.Person{
 				Name: authors(doc.Authors),
 			},
 		}
 		feed.Entry = append(feed.Entry, e)
 	}
 	data, err := xml.Marshal(&feed)
 	if err != nil {
 		return err
 	}
 	s.atomFeed = data
 	return nil
 }

 type jsonItem struct {
 	Title   string
 	Link    string
 	Time    time.Time
 	Summary string
 	Content string
 	Author  string
 }

 // renderJSONFeed generates a JSON feed and stores it in the Server's jsonFeed
 // field.
 func (s *Server) renderJSONFeed() error {
 	var feed []jsonItem
 	for i, doc := range s.docs {
 		if i >= s.cfg.FeedArticles {
 			break
 		}
 		item := jsonItem{
 			Title:   doc.Title,
 			Link:    doc.Permalink,
 			Time:    doc.Time,
 			Summary: summary(doc),
 			Content: string(doc.HTML),
 			Author:  authors(doc.Authors),
 		}
 		feed = append(feed, item)
 	}
 	data, err := json.Marshal(feed)
 	if err != nil {
 		return err
 	}
 	s.jsonFeed = data
 	return nil
 }

 // summary returns the first paragraph of text from the provided Doc.
 func summary(d *Doc) string {
 	if len(d.Sections) == 0 {
 		return ""
 	}
 	for _, elem := range d.Sections[0].Elem {
 		text, ok := elem.(present.Text)
 		if !ok || text.Pre {
 			// skip everything but non-text elements
 			continue
 		}
 		var buf bytes.Buffer
 		for _, s := range text.Lines {
 			buf.WriteString(string(present.Style(s)))
 			buf.WriteByte('\n')
 		}
 		return buf.String()
 	}
 	return ""
 }

 // rootData encapsulates data destined for the root template.
 type rootData struct {
 	Doc           *Doc
 	BasePath      string
 	GodocURL      string
 	AnalyticsHTML template.HTML
 	Data          interface{}
 }

 // ServeHTTP serves the front, index, and article pages
 // as well as the ATOM and JSON feeds.
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	var (
 		d = rootData{
 			BasePath:      s.cfg.BasePath,
 			GodocURL:      s.cfg.GodocURL,
 			AnalyticsHTML: s.cfg.AnalyticsHTML,
 		}
 		t *template.Template
 	)
 	switch p := strings.TrimPrefix(r.URL.Path, s.cfg.BasePath); p {
 	case "/":
 		d.Data = s.docs
 		if len(s.docs) > s.cfg.HomeArticles {
 			d.Data = s.docs[:s.cfg.HomeArticles]
 		}
 		t = s.template.home
 	case "/index":
 		d.Data = s.docs
 		t = s.template.index
 	case "/feed.atom", "/feeds/posts/default":
 		w.Header().Set("Content-type", "application/atom+xml; charset=utf-8")
 		w.Write(s.atomFeed)
 		return
 	case "/.json":
 		if p := r.FormValue("jsonp"); validJSONPFunc.MatchString(p) {
 			w.Header().Set("Content-type", "application/javascript; charset=utf-8")
 			fmt.Fprintf(w, "%v(%s)", p, s.jsonFeed)
 			return
 		}
 		w.Header().Set("Content-type", "application/json; charset=utf-8")
 		w.Write(s.jsonFeed)
 		return
 	default:
 		if redir, ok := s.redirects[p]; ok {
 			http.Redirect(w, r, redir, http.StatusMovedPermanently)
 			return
 		}
 		doc, ok := s.docPaths[p]
 		if !ok {
 			// Not a doc; try to just serve static content.
 			s.content.ServeHTTP(w, r)
 			return
 		}
 		d.Doc = doc
 		t = s.template.article
 	}
 	var err error
 	if s.cfg.ServeLocalLinks {
 		var buf bytes.Buffer
 		err = t.ExecuteTemplate(&buf, "root", d)
 		if err != nil {
 			log.Println(err)
 			return
 		}
 		_, err = golangOrgAbsLinkReplacer.WriteString(w, buf.String())
 	} else {
 		err = t.ExecuteTemplate(w, "root", d)
 	}
 	if err != nil {
 		log.Println(err)
 	}
 }

 // docsByTime implements sort.Interface, sorting Docs by their Time field.
 type docsByTime []*Doc

 func (s docsByTime) Len() int           { return len(s) }
 func (s docsByTime) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 func (s docsByTime) Less(i, j int) bool { return s[i].Time.After(s[j].Time) }

 // notExist reports whether the path exists or not.
 func notExist(path string) bool {
 	_, err := os.Stat(path)
 	return os.IsNotExist(err)
 }
	// Copyright 2013 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Package blog implements a web server for articles written in present format.
	package blog // import "golang.org/x/tools/blog"

	import (
	"bytes"
	"encoding/json"
	"encoding/xml"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"time"

	"golang.org/x/tools/blog/atom"
	"golang.org/x/tools/present"
	)

	var (
	validJSONPFunc = regexp.MustCompile(`(?i)^[a-z_][a-z0-9_.]*$`)
	// used to serve relative paths when ServeLocalLinks is enabled.
	golangOrgAbsLinkReplacer = strings.NewReplacer(
	`href="https://golang.org/pkg`, `href="/pkg`,
	`href="https://golang.org/cmd`, `href="/cmd`,
	)
	)

	// Config specifies Server configuration values.
	type Config struct {
	ContentPath string // Relative or absolute location of article files and related content.
	TemplatePath string // Relative or absolute location of template files.

	BaseURL string // Absolute base URL (for permalinks; no trailing slash).
	BasePath string // Base URL path relative to server root (no trailing slash).
	GodocURL string // The base URL of godoc (for menu bar; no trailing slash).
	Hostname string // Server host name, used for rendering ATOM feeds.
	AnalyticsHTML template.HTML // Optional analytics HTML to insert at the beginning of <head>.

	HomeArticles int // Articles to display on the home page.
	FeedArticles int // Articles to include in Atom and JSON feeds.
	FeedTitle string // The title of the Atom XML feed

	PlayEnabled bool
	ServeLocalLinks bool // rewrite golang.org/{pkg,cmd} links to host-less, relative paths.
	}

	// Doc represents an article adorned with presentation data.
	type Doc struct {
	*present.Doc
	Permalink string // Canonical URL for this document.
	Path string // Path relative to server root (including base).
	HTML template.HTML // rendered article

	Related []*Doc
	Newer, Older *Doc
	}

	// Server implements an http.Handler that serves blog articles.
	type Server struct {
	cfg Config
	docs []*Doc
	redirects map[string]string
	tags []string
	docPaths map[string]*Doc // key is path without BasePath.
	docTags map[string][]*Doc
	template struct {
	home, index, article, doc *template.Template
	}
	atomFeed []byte // pre-rendered Atom feed
	jsonFeed []byte // pre-rendered JSON feed
	content http.Handler
	}

	// NewServer constructs a new Server using the specified config.
	func NewServer(cfg Config) (*Server, error) {
	present.PlayEnabled = cfg.PlayEnabled

	if notExist(cfg.TemplatePath) {
	return nil, fmt.Errorf("template directory not found: %s", cfg.TemplatePath)
	}
	root := filepath.Join(cfg.TemplatePath, "root.tmpl")
	parse := func(name string) (*template.Template, error) {
	path := filepath.Join(cfg.TemplatePath, name)
	if notExist(path) {
	return nil, fmt.Errorf("template %s was not found in %s", name, cfg.TemplatePath)
	}
	t := template.New("").Funcs(funcMap)
	return t.ParseFiles(root, path)
	}

	s := &Server{cfg: cfg}

	// Parse templates.
	var err error
	s.template.home, err = parse("home.tmpl")
	if err != nil {
	return nil, err
	}
	s.template.index, err = parse("index.tmpl")
	if err != nil {
	return nil, err
	}
	s.template.article, err = parse("article.tmpl")
	if err != nil {
	return nil, err
	}
	p := present.Template().Funcs(funcMap)
	s.template.doc, err = p.ParseFiles(filepath.Join(cfg.TemplatePath, "doc.tmpl"))
	if err != nil {
	return nil, err
	}

	// Load content.
	content := filepath.Clean(cfg.ContentPath)
	err = s.loadDocs(content)
	if err != nil {
	return nil, err
	}

	err = s.renderAtomFeed()
	if err != nil {
	return nil, err
	}

	err = s.renderJSONFeed()
	if err != nil {
	return nil, err
	}

	// Set up content file server.
	s.content = http.StripPrefix(s.cfg.BasePath, http.FileServer(http.Dir(cfg.ContentPath)))

	return s, nil
	}

	var funcMap = template.FuncMap{
	"sectioned": sectioned,
	"authors": authors,
	}

	// sectioned returns true if the provided Doc contains more than one section.
	// This is used to control whether to display the table of contents and headings.
	func sectioned(d *present.Doc) bool {
	return len(d.Sections) > 1
	}

	// authors returns a comma-separated list of author names.
	func authors(authors []present.Author) string {
	var b bytes.Buffer
	last := len(authors) - 1
	for i, a := range authors {
	if i > 0 {
	if i == last {
	if len(authors) > 2 {
	b.WriteString(",")
	}
	b.WriteString(" and ")
	} else {
	b.WriteString(", ")
	}
	}
	b.WriteString(authorName(a))
	}
	return b.String()
	}

	// authorName returns the first line of the Author text: the author's name.
	func authorName(a present.Author) string {
	el := a.TextElem()
	if len(el) == 0 {
	return ""
	}
	text, ok := el[0].(present.Text)
	if !ok \|\| len(text.Lines) == 0 {
	return ""
	}
	return text.Lines[0]
	}

	// loadDocs reads all content from the provided file system root, renders all
	// the articles it finds, adds them to the Server's docs field, computes the
	// denormalized docPaths, docTags, and tags fields, and populates the various
	// helper fields (Next, Previous, Related) for each Doc.
	func (s *Server) loadDocs(root string) error {
	// Read content into docs field.
	const ext = ".article"
	fn := func(p string, info os.FileInfo, err error) error {
	if err != nil {
	return err
	}

	if filepath.Ext(p) != ext {
	return nil
	}
	f, err := os.Open(p)
	if err != nil {
	return err
	}
	defer f.Close()
	d, err := present.Parse(f, p, 0)
	if err != nil {
	return err
	}
	var html bytes.Buffer
	err = d.Render(&html, s.template.doc)
	if err != nil {
	return err
	}
	p = p[len(root) : len(p)-len(ext)] // trim root and extension
	p = filepath.ToSlash(p)
	s.docs = append(s.docs, &Doc{
	Doc: d,
	Path: s.cfg.BasePath + p,
	Permalink: s.cfg.BaseURL + p,
	HTML: template.HTML(html.String()),
	})
	return nil
	}
	err := filepath.Walk(root, fn)
	if err != nil {
	return err
	}
	sort.Sort(docsByTime(s.docs))

	// Pull out doc paths and tags and put in reverse-associating maps.
	s.docPaths = make(map[string]*Doc)
	s.docTags = make(map[string][]*Doc)
	s.redirects = make(map[string]string)
	for _, d := range s.docs {
	s.docPaths[strings.TrimPrefix(d.Path, s.cfg.BasePath)] = d
	for _, t := range d.Tags {
	s.docTags[t] = append(s.docTags[t], d)
	}
	}
	for _, d := range s.docs {
	for _, old := range d.OldURL {
	if !strings.HasPrefix(old, "/") {
	old = "/" + old
	}
	if _, ok := s.docPaths[old]; ok {
	return fmt.Errorf("redirect %s -> %s conflicts with document %s", old, d.Path, old)
	}
	if new, ok := s.redirects[old]; ok {
	return fmt.Errorf("redirect %s -> %s conflicts with redirect %s -> %s", old, d.Path, old, new)
	}
	s.redirects[old] = d.Path
	}
	}

	// Pull out unique sorted list of tags.
	for t := range s.docTags {
	s.tags = append(s.tags, t)
	}
	sort.Strings(s.tags)

	// Set up presentation-related fields, Newer, Older, and Related.
	for _, doc := range s.docs {
	// Newer, Older: docs adjacent to doc
	for i := range s.docs {
	if s.docs[i] != doc {
	continue
	}
	if i > 0 {
	doc.Newer = s.docs[i-1]
	}
	if i+1 < len(s.docs) {
	doc.Older = s.docs[i+1]
	}
	break
	}

	// Related: all docs that share tags with doc.
	related := make(map[*Doc]bool)
	for _, t := range doc.Tags {
	for _, d := range s.docTags[t] {
	if d != doc {
	related[d] = true
	}
	}
	}
	for d := range related {
	doc.Related = append(doc.Related, d)
	}
	sort.Sort(docsByTime(doc.Related))
	}

	return nil
	}

	// renderAtomFeed generates an XML Atom feed and stores it in the Server's
	// atomFeed field.
	func (s *Server) renderAtomFeed() error {
	var updated time.Time
	if len(s.docs) > 0 {
	updated = s.docs[0].Time
	}
	feed := atom.Feed{
	Title: s.cfg.FeedTitle,
	ID: "tag:" + s.cfg.Hostname + ",2013:" + s.cfg.Hostname,
	Updated: atom.Time(updated),
	Link: []atom.Link{{
	Rel: "self",
	Href: s.cfg.BaseURL + "/feed.atom",
	}},
	}
	for i, doc := range s.docs {
	if i >= s.cfg.FeedArticles {
	break
	}

	// Use original article path as ID in atom feed
	// to avoid articles being treated as new when renamed.
	idPath := doc.Path
	if len(doc.OldURL) > 0 {
	old := doc.OldURL[0]
	if !strings.HasPrefix(old, "/") {
	old = "/" + old
	}
	idPath = old
	}

	e := &atom.Entry{
	Title: doc.Title,
	ID: feed.ID + idPath,
	Link: []atom.Link{{
	Rel: "alternate",
	Href: doc.Permalink,
	}},
	Published: atom.Time(doc.Time),
	Updated: atom.Time(doc.Time),
	Summary: &atom.Text{
	Type: "html",
	Body: summary(doc),
	},
	Content: &atom.Text{
	Type: "html",
	Body: string(doc.HTML),
	},
	Author: &atom.Person{
	Name: authors(doc.Authors),
	},
	}
	feed.Entry = append(feed.Entry, e)
	}
	data, err := xml.Marshal(&feed)
	if err != nil {
	return err
	}
	s.atomFeed = data
	return nil
	}

	type jsonItem struct {
	Title string
	Link string
	Time time.Time
	Summary string
	Content string
	Author string
	}

	// renderJSONFeed generates a JSON feed and stores it in the Server's jsonFeed
	// field.
	func (s *Server) renderJSONFeed() error {
	var feed []jsonItem
	for i, doc := range s.docs {
	if i >= s.cfg.FeedArticles {
	break
	}
	item := jsonItem{
	Title: doc.Title,
	Link: doc.Permalink,
	Time: doc.Time,
	Summary: summary(doc),
	Content: string(doc.HTML),
	Author: authors(doc.Authors),
	}
	feed = append(feed, item)
	}
	data, err := json.Marshal(feed)
	if err != nil {
	return err
	}
	s.jsonFeed = data
	return nil
	}

	// summary returns the first paragraph of text from the provided Doc.
	func summary(d *Doc) string {
	if len(d.Sections) == 0 {
	return ""
	}
	for _, elem := range d.Sections[0].Elem {
	text, ok := elem.(present.Text)
	if !ok \|\| text.Pre {
	// skip everything but non-text elements
	continue
	}
	var buf bytes.Buffer
	for _, s := range text.Lines {
	buf.WriteString(string(present.Style(s)))
	buf.WriteByte('\n')
	}
	return buf.String()
	}
	return ""
	}

	// rootData encapsulates data destined for the root template.
	type rootData struct {
	Doc *Doc
	BasePath string
	GodocURL string
	AnalyticsHTML template.HTML
	Data interface{}
	}

	// ServeHTTP serves the front, index, and article pages
	// as well as the ATOM and JSON feeds.
	func (s Server) ServeHTTP(w http.ResponseWriter, r http.Request) {
	var (
	d = rootData{
	BasePath: s.cfg.BasePath,
	GodocURL: s.cfg.GodocURL,
	AnalyticsHTML: s.cfg.AnalyticsHTML,
	}
	t *template.Template
	)
	switch p := strings.TrimPrefix(r.URL.Path, s.cfg.BasePath); p {
	case "/":
	d.Data = s.docs
	if len(s.docs) > s.cfg.HomeArticles {
	d.Data = s.docs[:s.cfg.HomeArticles]
	}
	t = s.template.home
	case "/index":
	d.Data = s.docs
	t = s.template.index
	case "/feed.atom", "/feeds/posts/default":
	w.Header().Set("Content-type", "application/atom+xml; charset=utf-8")
	w.Write(s.atomFeed)
	return
	case "/.json":
	if p := r.FormValue("jsonp"); validJSONPFunc.MatchString(p) {
	w.Header().Set("Content-type", "application/javascript; charset=utf-8")
	fmt.Fprintf(w, "%v(%s)", p, s.jsonFeed)
	return
	}
	w.Header().Set("Content-type", "application/json; charset=utf-8")
	w.Write(s.jsonFeed)
	return
	default:
	if redir, ok := s.redirects[p]; ok {
	http.Redirect(w, r, redir, http.StatusMovedPermanently)
	return
	}
	doc, ok := s.docPaths[p]
	if !ok {
	// Not a doc; try to just serve static content.
	s.content.ServeHTTP(w, r)
	return
	}
	d.Doc = doc
	t = s.template.article
	}
	var err error
	if s.cfg.ServeLocalLinks {
	var buf bytes.Buffer
	err = t.ExecuteTemplate(&buf, "root", d)
	if err != nil {
	log.Println(err)
	return
	}
	_, err = golangOrgAbsLinkReplacer.WriteString(w, buf.String())
	} else {
	err = t.ExecuteTemplate(w, "root", d)
	}
	if err != nil {
	log.Println(err)
	}
	}

	// docsByTime implements sort.Interface, sorting Docs by their Time field.
	type docsByTime []*Doc

	func (s docsByTime) Len() int { return len(s) }
	func (s docsByTime) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
	func (s docsByTime) Less(i, j int) bool { return s[i].Time.After(s[j].Time) }

	// notExist reports whether the path exists or not.
	func notExist(path string) bool {
	_, err := os.Stat(path)
	return os.IsNotExist(err)
	}