hswg: merge in hasp as a mode

No need to have the two-line header processor in two places.

hswg/main.go

@@ -4,6 +4,7 @@ package main
 
 import (
 	"bytes"
+	"encoding/xml"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -67,6 +68,41 @@ func ConvertTitles(w *io.PipeWriter, input []byte) {
 	writeLine(w, last, nil)
 }
 
+// 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(doc io.Reader, config configuration.Configuration) (
+	html *bytes.Buffer, meta types.Metadata, err error) {
+	html = bytes.NewBuffer(nil)
+
+	var input []byte
+	if input, err = ioutil.ReadAll(doc); err != nil {
+		return
+	}
+
+	pr, pw := io.Pipe()
+	go func() {
+		defer pw.Close()
+		ConvertTitles(pw, input)
+	}()
+
+	// io.Copy(os.Stdout, pr)
+	// return
+
+	meta, err = libasciidoc.ConvertToHTML(pr, html, config)
+	if err != nil {
+		// Fallback: output all the text sanitized for direct inclusion.
+		html.Reset()
+
+		_, _ = html.WriteString("<pre>")
+		for _, line := range bytes.Split(input, []byte{'\n'}) {
+			_ = xml.EscapeText(html, line)
+			_, _ = html.WriteString("\n")
+		}
+		_, _ = html.WriteString("</pre>")
+	}
+	return
+}
+
 // entry contains all context information about a single page.
 type entry struct {
 	path      string         // path
@@ -106,7 +142,23 @@ func expand(m *map[string]*entry, name string, chunk []byte) []byte {
 	})
 }
 
+func singleFile() {
+	html, meta, err := Render(os.Stdin, configuration.NewConfiguration())
+	if err != nil {
+		log.Println(err)
+	} else if meta.Title != "" {
+		_, _ = os.Stdout.WriteString("<h1>")
+		_ = xml.EscapeText(os.Stdout, []byte(meta.Title))
+		_, _ = os.Stdout.WriteString("</h1>\n")
+	}
+	_, _ = io.Copy(os.Stdout, html)
+}
+
 func main() {
+	if len(os.Args) < 2 {
+		singleFile()
+		return
+	}
 	if len(os.Args) < 3 {
 		log.Fatalf("usage: %s TEMPLATE GLOB...\n", os.Args[0])
 	}
@@ -146,32 +198,17 @@ func main() {
 			e.mtime = i.ModTime()
 		}
 
-		input, err := ioutil.ReadAll(f)
-		if err != nil {
-			log.Fatalln(err)
-		}
-
-		pr, pw := io.Pipe()
-		go func() {
-			defer pw.Close()
-			ConvertTitles(pw, input)
-		}()
-
-		config := configuration.NewConfiguration(
-			configuration.WithHeaderFooter(false),
+		var html *bytes.Buffer
+		if html, e.metadata, err = Render(f, configuration.NewConfiguration(
 			configuration.WithFilename(e.path),
 			configuration.WithLastUpdated(e.mtime),
-		)
-
-		buf := bytes.NewBuffer(nil)
-		e.metadata, err = libasciidoc.ConvertToHTML(pr, buf, config)
-		if err != nil {
+		)); err != nil {
 			log.Fatalln(err)
 		}
 
 		// Expand LinkWords anywhere between <tags>.
 		// We want something like the inverse of Regexp.ReplaceAllStringFunc.
-		raw, last, expanded := buf.Bytes(), 0, bytes.NewBuffer(nil)
+		raw, last, expanded := html.Bytes(), 0, bytes.NewBuffer(nil)
 		for _, where := range tagRE.FindAllIndex(raw, -1) {
 			_, _ = expanded.Write(expand(&entries, name, raw[last:where[0]]))
 			_, _ = expanded.Write(raw[where[0]:where[1]])