Add support for sitemap indexes.

LICENSE

@@ -1,4 +1,4 @@
-Copyright © 2016 Janne Snabb snabb AT epipe.com
+Copyright © 2016-2017 Janne Snabb snabb AT epipe.com
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the

README.md

@@ -3,9 +3,11 @@ sitemap
 
 [![GoDoc](https://godoc.org/github.com/snabb/sitemap?status.svg)](https://godoc.org/github.com/snabb/sitemap)
 
-The Go package sitemap provides tools for creating an XML sitemap and
-writing it to an io.Writer (such as http.ResponseWriter). Please see
-http://www.sitemaps.org/ for description of sitemap contents.
+The Go package sitemap provides tools for creating XML sitemaps
+and sitemap indexes and writing them to an io.Writer (such as
+http.ResponseWriter).
+
+Please see http://www.sitemaps.org/ for description of sitemap contents.
 
 The package implements io.WriterTo and io.ReaderFrom interfaces.
 

sitemap.go

@@ -1,6 +1,8 @@
-// Package sitemap provides tools for creating an XML sitemap and writing it
-// to an io.Writer (such as http.ResponseWriter). Please see
-// http://www.sitemaps.org/ for description of sitemap contents.
+// Package sitemap provides tools for creating XML sitemaps
+// and sitemap indexes and writing them to io.Writer (such as
+// http.ResponseWriter).
+//
+// Please see http://www.sitemaps.org/ for description of sitemap contents.
 package sitemap
 
 import (
@@ -24,15 +26,20 @@ const (
 	Never   ChangeFreq = "never"
 )
 
-// Single URL entry in sitemap. LastMod is a pointer to time.Time because
-// omitempty does not work otherwise. Loc is the only mandatory item.
+// Single URL entry in sitemap or sitemap index. LastMod is a pointer
+// to time.Time because omitempty does not work otherwise. Loc is the
+// only mandatory item. ChangeFreq and Priority must be left empty when
+// using with a sitemap index.
 type URL struct {
 	Loc        string     `xml:"loc"`
 	LastMod    *time.Time `xml:"lastmod,omitempty"`
 	ChangeFreq ChangeFreq `xml:"changefreq,omitempty"`
 	Priority   float32    `xml:"priority,omitempty"`
 }
 
+// Sitemap represents a complete sitemap which can be marshaled to XML.
+// New instances must be created with New() in order to set the xmlns
+// attribute correctly.
 type Sitemap struct {
 	XMLName xml.Name `xml:"urlset"`
 	Xmlns   string   `xml:"xmlns,attr"`

sitemapindex.go

@@ -0,0 +1,59 @@
+package sitemap
+
+import (
+	"encoding/xml"
+	"github.com/snabb/diagio"
+	"io"
+)
+
+// SitemapIndex is like Sitemap except the elements are named differently
+// (and ChangeFreq and Priority may not be used).
+// New instances must be created with NewSitemapIndex() in order to set the
+// xmlns attribute correctly.
+type SitemapIndex struct {
+	XMLName xml.Name `xml:"sitemapindex"`
+	Xmlns   string   `xml:"xmlns,attr"`
+
+	URLs []*URL `xml:"sitemap"`
+}
+
+// New returns new SitemapIndex.
+func NewSitemapIndex() *SitemapIndex {
+	return &SitemapIndex{
+		Xmlns: "http://www.sitemaps.org/schemas/sitemap/0.9",
+		URLs:  make([]*URL, 0),
+	}
+}
+
+// Add adds an URL to a SitemapIndex.
+func (s *SitemapIndex) Add(u *URL) {
+	s.URLs = append(s.URLs, u)
+}
+
+// WriteTo writes XML encoded sitemap index to given io.Writer.
+// Implements io.WriterTo.
+func (s *SitemapIndex) WriteTo(w io.Writer) (n int64, err error) {
+	cw := diagio.NewCounterWriter(w)
+
+	_, err = cw.Write([]byte(xml.Header))
+	if err != nil {
+		return cw.Count(), err
+	}
+	en := xml.NewEncoder(cw)
+	en.Indent("", "  ")
+	err = en.Encode(s)
+	cw.Write([]byte{'\n'})
+	return cw.Count(), err
+}
+
+var _ io.WriterTo = (*Sitemap)(nil)
+
+// ReadFrom reads and parses an XML encoded sitemap index from io.Reader.
+// Implements io.ReaderFrom.
+func (s *SitemapIndex) ReadFrom(r io.Reader) (n int64, err error) {
+	de := xml.NewDecoder(r)
+	err = de.Decode(s)
+	return de.InputOffset(), err
+}
+
+var _ io.ReaderFrom = (*Sitemap)(nil)

sitemapindex_test.go

@@ -0,0 +1,25 @@
+package sitemap_test
+
+import (
+	"github.com/snabb/sitemap"
+	"os"
+	"time"
+)
+
+func ExampleSitemapIndex() {
+	smi := sitemap.NewSitemapIndex()
+	t := time.Unix(0, 0).UTC()
+	smi.Add(&sitemap.URL{
+		Loc:     "http://example.com/",
+		LastMod: &t,
+	})
+	smi.WriteTo(os.Stdout)
+	// Output:
+	// <?xml version="1.0" encoding="UTF-8"?>
+	// <sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+	//   <sitemap>
+	//     <loc>http://example.com/</loc>
+	//     <lastmod>1970-01-01T00:00:00Z</lastmod>
+	//   </sitemap>
+	// </sitemapindex>
+}