Use a Renderer interface instead of rendering fragments

elements.go

@@ -0,0 +1,171 @@
+package gold
+
+import (
+	"html"
+	"io"
+	"strings"
+
+	bf "gopkg.in/russross/blackfriday.v2"
+)
+
+type ElementRenderer interface {
+	Render(w io.Writer, node *bf.Node, tr *TermRenderer) error
+}
+
+type Element struct {
+	Pre      string
+	Post     string
+	Renderer ElementRenderer
+}
+
+func (tr *TermRenderer) NewElement(node *bf.Node) Element {
+	switch node.Type {
+	case bf.Document:
+		return Element{
+			Renderer: &BaseElement{
+				Style: Document,
+			},
+		}
+	case bf.BlockQuote:
+		return Element{
+			Pre:  "\n",
+			Post: "\n",
+			Renderer: &BaseElement{
+				Token: string(node.Literal),
+				Style: BlockQuote,
+			},
+		}
+	case bf.List:
+		return Element{
+			Renderer: &ListElement{},
+		}
+	case bf.Item:
+		return Element{
+			Renderer: &ItemElement{},
+		}
+	case bf.Paragraph:
+		return Element{
+			Post:     "\n",
+			Renderer: &ParagraphElement{},
+		}
+	case bf.Heading:
+		return Element{
+			Post:     "\n",
+			Renderer: &HeadingElement{},
+		}
+	case bf.HorizontalRule:
+		return Element{
+			Pre:  "\n",
+			Post: "\n",
+			Renderer: &BaseElement{
+				Token: "---",
+				Style: HorizontalRule,
+			},
+		}
+	case bf.Emph:
+		return Element{
+			Renderer: &BaseElement{
+				Token: string(node.FirstChild.Literal),
+				Style: Emph,
+			},
+		}
+	case bf.Strong:
+		return Element{
+			Renderer: &BaseElement{
+				Token: string(node.FirstChild.Literal),
+				Style: Strong,
+			},
+		}
+	case bf.Del:
+		return Element{
+			Renderer: &BaseElement{
+				Token: string(node.Literal),
+				Style: Del,
+			},
+		}
+	case bf.Link:
+		return Element{
+			Renderer: &LinkElement{},
+		}
+	case bf.Image:
+		return Element{
+			Renderer: &ImageElement{},
+		}
+	case bf.Text:
+		return Element{
+			Renderer: &BaseElement{
+				Token: html.UnescapeString(stripper.Sanitize(string(node.Literal))),
+				Style: Text,
+			},
+		}
+	case bf.HTMLBlock:
+		return Element{
+			Renderer: &BaseElement{
+				Token: html.UnescapeString(strings.TrimSpace(stripper.Sanitize(string(node.Literal)))) + "\n",
+				Style: HTMLBlock,
+			},
+		}
+	case bf.CodeBlock:
+		return Element{
+			Pre:  "\n",
+			Post: "\n",
+			Renderer: &CodeBlockElement{
+				Code:     string(node.Literal),
+				Language: string(node.CodeBlockData.Info),
+			},
+		}
+	case bf.Softbreak:
+		return Element{
+			Post: "\n",
+			Renderer: &BaseElement{
+				Token: string(node.Literal),
+				Style: Softbreak,
+			},
+		}
+	case bf.Hardbreak:
+		return Element{
+			Post: "\n",
+			Renderer: &BaseElement{
+				Token: string(node.Literal),
+				Style: Hardbreak,
+			},
+		}
+	case bf.Code:
+		return Element{
+			Renderer: &BaseElement{
+				Token: string(node.Literal),
+				Style: Code,
+			},
+		}
+	case bf.HTMLSpan:
+		return Element{
+			Renderer: &BaseElement{
+				Token: html.UnescapeString(strings.TrimSpace(stripper.Sanitize(string(node.Literal)))) + "\n",
+				Style: HTMLSpan,
+			},
+		}
+	case bf.Table:
+		return Element{
+			Pre:  "\n",
+			Post: "\n",
+		}
+	case bf.TableCell:
+		return Element{}
+	case bf.TableHead:
+		return Element{}
+	case bf.TableBody:
+		return Element{}
+	case bf.TableRow:
+		return Element{
+			Pre:  "\n",
+			Post: "\n",
+		}
+
+	default:
+		return Element{
+			Renderer: &BaseElement{
+				Token: string(node.Literal),
+			},
+		}
+	}
+}