hswg: add .Attr, .AttrList, contains

Trying to figure out a sensible way of handle tags.

hswg/main.go

@@ -16,6 +16,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"sort"
+	"strings"
 	"syscall"
 	"time"
 
@@ -40,6 +41,21 @@ type Metadata struct {
 // be linked anywhere else.
 func (m *Metadata) IsDraft() bool { return m.Attributes.Has("draft") }
 
+// Attr is a shortcut for retrieving document attributes by name.
+func (m *Metadata) Attr(name string) string {
+	return m.Attributes.GetAsStringWithDefault(name, "")
+}
+
+// AttrList is similar to Attr, but splits the result at commas,
+// and trims whitespace around array elements.
+func (m *Metadata) AttrList(name string) []string {
+	res := strings.Split(m.Attr(name), ",")
+	for i := range res {
+		res[i] = strings.TrimSpace(res[i])
+	}
+	return res
+}
+
 // Render converts an io.Reader with an AsciiDoc document to HTML. So long as
 // the file could be read at all, it will always return a non-empty document.
 func Render(r io.Reader, config configuration.Configuration) (
@@ -398,6 +414,17 @@ func watchDirectory(dirname string) (<-chan *watchEvent, error) {
 	return ch, nil
 }
 
+var funcs = template.FuncMap{
+	"contains": func(needle string, haystack []string) bool {
+		for _, el := range haystack {
+			if el == needle {
+				return true
+			}
+		}
+		return false
+	},
+}
+
 func singleFile() {
 	html, meta, err := Render(os.Stdin, configuration.NewConfiguration())
 	if err != nil {
@@ -426,7 +453,7 @@ func main() {
 	if err != nil {
 		log.Fatalln(err)
 	}
-	tmplEntry, err := template.New("entry").Parse(string(header))
+	tmplEntry, err := template.New("entry").Funcs(funcs).Parse(string(header))
 	if err != nil {
 		log.Fatalln(err)
 	}
@@ -436,7 +463,7 @@ func main() {
 	if err != nil {
 		log.Fatalln(err)
 	}
-	tmplIndex, err := template.New("index").Parse(string(index))
+	tmplIndex, err := template.New("index").Funcs(funcs).Parse(string(index))
 	if err != nil {
 		log.Fatalln(err)
 	}