From dd5c583e8b48b2f12e7d0875fff1f8580e0a956a Mon Sep 17 00:00:00 2001
From: Přemysl Eric Janouch <p@janouch.name>
Date: Tue, 22 Jun 2021 01:29:21 +0200
Subject: hswg: store backlinks in a map

---
 hswg/main.go | 41 ++++++++++++++++++-----------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/hswg/main.go b/hswg/main.go
index caae1f1..5076bd1 100644
--- a/hswg/main.go
+++ b/hswg/main.go
@@ -134,12 +134,12 @@ func Render(r io.Reader, config configuration.Configuration) (
 
 // Entry contains all context information about a single page.
 type Entry struct {
-	Metadata                      // metadata
-	PathSource      string        // path to source AsciiDoc
-	PathDestination string        // path to destination HTML
-	mtime           time.Time     // modification time
-	Content         template.HTML // inner document with expanded LinkWords
-	backlinks       []string      // what documents link back here
+	Metadata                        // metadata
+	PathSource      string          // path to source AsciiDoc
+	PathDestination string          // path to destination HTML
+	mtime           time.Time       // modification time
+	Content         template.HTML   // inner document with expanded LinkWords
+	backlinks       map[string]bool // what documents link back here
 	Backlinks       []template.HTML
 }
 
@@ -180,7 +180,7 @@ func expand(m *map[string]*Entry, name string, chunk []byte) []byte {
 	return linkWordRE.ReplaceAllFunc(chunk, func(match []byte) []byte {
 		if link, ok := (*m)[string(match)]; ok && string(match) != name &&
 			!link.IsDraft() {
-			link.backlinks = append(link.backlinks, name)
+			link.backlinks[name] = true
 			return []byte(makeLink(m, string(match)))
 		}
 		return match
@@ -234,6 +234,7 @@ func main() {
 			entries[name] = &Entry{
 				PathSource:      path,
 				PathDestination: resultPath(path),
+				backlinks:       map[string]bool{},
 			}
 		}
 	}
@@ -276,28 +277,22 @@ func main() {
 		e.Content = template.HTML(expanded.String())
 	}
 
-	for _, e := range entries {
-		sort.Strings(e.backlinks)
-
-		last, uniq := "", []string{}
-		for _, name := range e.backlinks {
-			if name != last {
-				uniq = append(uniq, name)
-			}
-			last = name
-		}
-		e.backlinks = uniq
-	}
-
 	for _, e := range entries {
 		f, err := os.Create(e.PathDestination)
 		if err != nil {
 			log.Fatalln(err)
 		}
-		for _, name := range e.backlinks {
-			e.Backlinks = append(e.Backlinks,
-				template.HTML(makeLink(&entries, name)))
+
+		backlinks := []string{}
+		for name := range e.backlinks {
+			backlinks = append(backlinks, name)
+		}
+		sort.Strings(backlinks)
+		for _, name := range backlinks {
+			e.Backlinks =
+				append(e.Backlinks, template.HTML(makeLink(&entries, name)))
 		}
+
 		if err = t.Execute(f, e); err != nil {
 			log.Fatalln(err)
 		}
-- 
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