Add sort.Interface implementation for Feed (#141)

Order Feed.Items by oldest to newest publish time.

feed.go

@@ -10,6 +10,8 @@ import (
 // Feed is the universal Feed type that atom.Feed
 // and rss.Feed gets translated to. It represents
 // a web feed.
+// Sorting with sort.Sort will order the Items by
+// oldest to newest publish time.
 type Feed struct {
  Title string `json:"title,omitempty"`
  Description string `json:"description,omitempty"`
@@ -82,3 +84,21 @@ type Enclosure struct {
  Length string `json:"length,omitempty"`
  Type string `json:"type,omitempty"`
 }
+
+// Len returns the length of Items.
+func (f Feed) Len() int {
+ return len(f.Items)
+}
+
+// Less compares PublishedParsed of Items[i], Items[k]
+// and returns true if Items[i] is less than Items[k].
+func (f Feed) Less(i, k int) bool {
+ return f.Items[i].PublishedParsed.Before(
+ *f.Items[k].PublishedParsed,
+ )
+}
+
+// Swap swaps Items[i] and Items[k].
+func (f Feed) Swap(i, k int) {
+ f.Items[i], f.Items[k] = f.Items[k], f.Items[i]
+}

feed_test.go

@@ -0,0 +1,50 @@
+package gofeed_test
+
+import (
+ "sort"
+ "testing"
+ "time"
+
+ "github.com/mmcdole/gofeed"
+)
+
+func TestFeedSort(t *testing.T) {
+ oldestItem := &gofeed.Item{
+ PublishedParsed: &[]time.Time{time.Unix(0, 0)}[0],
+ }
+ inbetweenItem := &gofeed.Item{
+ PublishedParsed: &[]time.Time{time.Unix(1, 0)}[0],
+ }
+ newestItem := &gofeed.Item{
+ PublishedParsed: &[]time.Time{time.Unix(2, 0)}[0],
+ }
+
+ feed := gofeed.Feed{
+ Items: []*gofeed.Item{
+ newestItem,
+ oldestItem,
+ inbetweenItem,
+ },
+ }
+ expected := gofeed.Feed{
+ Items: []*gofeed.Item{
+ oldestItem,
+ inbetweenItem,
+ newestItem,
+ },
+ }
+
+ sort.Sort(feed)
+
+ for i, item := range feed.Items {
+ if !item.PublishedParsed.Equal(
+ *expected.Items[i].PublishedParsed,
+ ) {
+ t.Errorf(
+ "Item PublishedParsed = %s; want %s",
+ item.PublishedParsed,
+ expected.Items[i].PublishedParsed,
+ )
+ }
+ }
+}