Use a Renderer interface instead of rendering fragments

baselement.go

@@ -0,0 +1,72 @@
+package gold
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+
+	"github.com/logrusorgru/aurora"
+	bf "gopkg.in/russross/blackfriday.v2"
+)
+
+type BaseElement struct {
+	Token string
+	Pre   string
+	Post  string
+	Style StyleType
+}
+
+func (e *BaseElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error {
+	if e.Pre != "" {
+		fmt.Fprintf(w, "%s", e.Pre)
+	}
+	defer func() {
+		if e.Post != "" {
+			fmt.Fprintf(w, "%s", e.Post)
+		}
+	}()
+
+	rules := tr.style[e.Style]
+	if rules == nil {
+		fmt.Fprintf(w, "%s", e.Token)
+		return nil
+	}
+
+	out := aurora.Reset(e.Token)
+	if rules.Color != "" {
+		i, err := strconv.Atoi(rules.Color)
+		if err == nil && i >= 0 && i <= 255 {
+			out = out.Index(uint8(i))
+		}
+	}
+	if rules.BackgroundColor != "" {
+		i, err := strconv.Atoi(rules.BackgroundColor)
+		if err == nil && i >= 0 && i <= 255 {
+			out = out.Index(uint8(i))
+		}
+	}
+	if rules.Underline {
+		out = out.Underline()
+	}
+	if rules.Bold {
+		out = out.Bold()
+	}
+	if rules.Italic {
+		out = out.Italic()
+	}
+	if rules.CrossedOut {
+		out = out.CrossedOut()
+	}
+	if rules.Overlined {
+		out = out.Overlined()
+	}
+	if rules.Inverse {
+		out = out.Reverse()
+	}
+	if rules.Blink {
+		out = out.Blink()
+	}
+
+	w.Write([]byte(aurora.Sprintf("%s", out)))
+	return nil
+}