Implement parsing of Gemini text responses

server.go

@@ -384,11 +384,12 @@ type File interface {
 type Dir string
 
 func (d Dir) Open(name string) (File, error) {
-	path := path.Join(string(d), name)
-	f, err := os.OpenFile(path, os.O_RDONLY, 0644)
+	p := path.Join(string(d), name)
+	f, err := os.OpenFile(p, os.O_RDONLY, 0644)
 	if err != nil {
 		return nil, err
 	}
+
 	if stat, err := f.Stat(); err == nil {
 		if !stat.Mode().IsRegular() {
 			return nil, ErrNotAFile
@@ -569,8 +570,6 @@ func (mux *ServeMux) shouldRedirectRLocked(host, path string) bool {
 // to the canonical path. If the host contains a port, it is ignored
 // when matching handlers.
 //
-// The path and host are used unchanged for CONNECT requests.
-//
 // Handler also returns the registered pattern that matches the
 // request or, in the case of internally-generated redirects,
 // the pattern that will match after following the redirect.
@@ -605,7 +604,7 @@ func (mux *ServeMux) Handler(r *Request) (h Handler, pattern string) {
 }
 
 // handler is the main implementation of Handler.
-// The path is known to be in canonical form, except for CONNECT methods.
+// The path is known to be in canonical form.
 func (mux *ServeMux) handler(host, path string) (h Handler, pattern string) {
 	mux.mu.RLock()
 	defer mux.mu.RUnlock()

text.go

@@ -0,0 +1,119 @@
+package gmi
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strings"
+)
+
+// Line represents a line of a Gemini text response.
+type Line interface {
+	String() string
+}
+
+// A link line.
+type LineLink struct {
+	URL  string
+	Name string
+}
+type LinePreformattingToggle string // A preformatting toggle line.
+type LinePreformattedText string    // A preformatted text line.
+type LineHeading1 string            // A first-level heading line.
+type LineHeading2 string            // A second-level heading line.
+type LineHeading3 string            // A third-level heading line.
+type LineListItem string            // An unordered list item line.
+type LineQuote string               // A quote line.
+type LineText string                // A text line.
+
+func (l LineLink) String() string {
+	if l.Name != "" {
+		return fmt.Sprintf("=> %s %s", l.URL, l.Name)
+	}
+	return fmt.Sprintf("=> %s", l.URL)
+}
+func (l LinePreformattingToggle) String() string {
+	return fmt.Sprintf("```%s", string(l))
+}
+func (l LinePreformattedText) String() string {
+	return string(l)
+}
+func (l LineHeading1) String() string {
+	return fmt.Sprintf("# %s", string(l))
+}
+func (l LineHeading2) String() string {
+	return fmt.Sprintf("## %s", string(l))
+}
+func (l LineHeading3) String() string {
+	return fmt.Sprintf("### %s", string(l))
+}
+func (l LineListItem) String() string {
+	return fmt.Sprintf("* %s", string(l))
+}
+func (l LineQuote) String() string {
+	return fmt.Sprintf("> %s", string(l))
+}
+func (l LineText) String() string {
+	return string(l)
+}
+
+// Text represents a Gemini text response.
+type Text []Line
+
+// Parse parses Gemini text from the provided io.Reader.
+func Parse(r io.Reader) Text {
+	const spacetab = " \t"
+	var t Text
+	var pre bool
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(line, "```") {
+			pre = !pre
+			line = line[3:]
+			t = append(t, LinePreformattingToggle(line))
+		} else if pre {
+			t = append(t, LinePreformattedText(line))
+		} else if strings.HasPrefix(line, "=>") {
+			line = line[2:]
+			line = strings.TrimLeft(line, spacetab)
+			split := strings.IndexAny(line, spacetab)
+			url := line[:split]
+			name := line[split:]
+			name = strings.TrimLeft(name, spacetab)
+			t = append(t, LineLink{url, name})
+		} else if strings.HasPrefix(line, "*") {
+			line = line[1:]
+			line = strings.TrimLeft(line, spacetab)
+			t = append(t, LineListItem(line))
+		} else if strings.HasPrefix(line, "###") {
+			line = line[3:]
+			line = strings.TrimLeft(line, spacetab)
+			t = append(t, LineHeading3(line))
+		} else if strings.HasPrefix(line, "##") {
+			line = line[2:]
+			line = strings.TrimLeft(line, spacetab)
+			t = append(t, LineHeading2(line))
+		} else if strings.HasPrefix(line, "#") {
+			line = line[1:]
+			line = strings.TrimLeft(line, spacetab)
+			t = append(t, LineHeading1(line))
+		} else if strings.HasPrefix(line, ">") {
+			line = line[1:]
+			line = strings.TrimLeft(line, spacetab)
+			t = append(t, LineQuote(line))
+		} else {
+			t = append(t, LineText(line))
+		}
+	}
+	return t
+}
+
+// String writes the Gemini text response to a string, and returns it.
+func (t Text) String() string {
+	var b strings.Builder
+	for _, l := range t {
+		b.WriteString(l.String())
+	}
+	return b.String()
+}