1 files changed, 293 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/html/render.go b/vendor/golang.org/x/net/html/render.go
new file mode 100644
index 0000000..e8c1233
--- /dev/null
+++ b/vendor/golang.org/x/net/html/render.go
@@ -0,0 +1,293 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package html
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+)
+
+type writer interface {
+	io.Writer
+	io.ByteWriter
+	WriteString(string) (int, error)
+}
+
+// Render renders the parse tree n to the given writer.
+//
+// Rendering is done on a 'best effort' basis: calling Parse on the output of
+// Render will always result in something similar to the original tree, but it
+// is not necessarily an exact clone unless the original tree was 'well-formed'.
+// 'Well-formed' is not easily specified; the HTML5 specification is
+// complicated.
+//
+// Calling Parse on arbitrary input typically results in a 'well-formed' parse
+// tree. However, it is possible for Parse to yield a 'badly-formed' parse tree.
+// For example, in a 'well-formed' parse tree, no <a> element is a child of
+// another <a> element: parsing "<a><a>" results in two sibling elements.
+// Similarly, in a 'well-formed' parse tree, no <a> element is a child of a
+// <table> element: parsing "<p><table><a>" results in a <p> with two sibling
+// children; the <a> is reparented to the <table>'s parent. However, calling
+// Parse on "<a><table><a>" does not return an error, but the result has an <a>
+// element with an <a> child, and is therefore not 'well-formed'.
+//
+// Programmatically constructed trees are typically also 'well-formed', but it
+// is possible to construct a tree that looks innocuous but, when rendered and
+// re-parsed, results in a different tree. A simple example is that a solitary
+// text node would become a tree containing <html>, <head> and <body> elements.
+// Another example is that the programmatic equivalent of "a<head>b</head>c"
+// becomes "<html><head><head/><body>abc</body></html>".
+func Render(w io.Writer, n *Node) error {
+	if x, ok := w.(writer); ok {
+		return render(x, n)
+	}
+	buf := bufio.NewWriter(w)
+	if err := render(buf, n); err != nil {
+		return err
+	}
+	return buf.Flush()
+}
+
+// plaintextAbort is returned from render1 when a <plaintext> element
+// has been rendered. No more end tags should be rendered after that.
+var plaintextAbort = errors.New("html: internal error (plaintext abort)")
+
+func render(w writer, n *Node) error {
+	err := render1(w, n)
+	if err == plaintextAbort {
+		err = nil
+	}
+	return err
+}
+
+func render1(w writer, n *Node) error {
+	// Render non-element nodes; these are the easy cases.
+	switch n.Type {
+	case ErrorNode:
+		return errors.New("html: cannot render an ErrorNode node")
+	case TextNode:
+		return escape(w, n.Data)
+	case DocumentNode:
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			if err := render1(w, c); err != nil {
+				return err
+			}
+		}
+		return nil
+	case ElementNode:
+		// No-op.
+	case CommentNode:
+		if _, err := w.WriteString("<!--"); err != nil {
+			return err
+		}
+		if err := escapeComment(w, n.Data); err != nil {
+			return err
+		}
+		if _, err := w.WriteString("-->"); err != nil {
+			return err
+		}
+		return nil
+	case DoctypeNode:
+		if _, err := w.WriteString("<!DOCTYPE "); err != nil {
+			return err
+		}
+		if err := escape(w, n.Data); err != nil {
+			return err
+		}
+		if n.Attr != nil {
+			var p, s string
+			for _, a := range n.Attr {
+				switch a.Key {
+				case "public":
+					p = a.Val
+				case "system":
+					s = a.Val
+				}
+			}
+			if p != "" {
+				if _, err := w.WriteString(" PUBLIC "); err != nil {
+					return err
+				}
+				if err := writeQuoted(w, p); err != nil {
+					return err
+				}
+				if s != "" {
+					if err := w.WriteByte(' '); err != nil {
+						return err
+					}
+					if err := writeQuoted(w, s); err != nil {
+						return err
+					}
+				}
+			} else if s != "" {
+				if _, err := w.WriteString(" SYSTEM "); err != nil {
+					return err
+				}
+				if err := writeQuoted(w, s); err != nil {
+					return err
+				}
+			}
+		}
+		return w.WriteByte('>')
+	case RawNode:
+		_, err := w.WriteString(n.Data)
+		return err
+	default:
+		return errors.New("html: unknown node type")
+	}
+
+	// Render the <xxx> opening tag.
+	if err := w.WriteByte('<'); err != nil {
+		return err
+	}
+	if _, err := w.WriteString(n.Data); err != nil {
+		return err
+	}
+	for _, a := range n.Attr {
+		if err := w.WriteByte(' '); err != nil {
+			return err
+		}
+		if a.Namespace != "" {
+			if _, err := w.WriteString(a.Namespace); err != nil {
+				return err
+			}
+			if err := w.WriteByte(':'); err != nil {
+				return err
+			}
+		}
+		if _, err := w.WriteString(a.Key); err != nil {
+			return err
+		}
+		if _, err := w.WriteString(`="`); err != nil {
+			return err
+		}
+		if err := escape(w, a.Val); err != nil {
+			return err
+		}
+		if err := w.WriteByte('"'); err != nil {
+			return err
+		}
+	}
+	if voidElements[n.Data] {
+		if n.FirstChild != nil {
+			return fmt.Errorf("html: void element <%s> has child nodes", n.Data)
+		}
+		_, err := w.WriteString("/>")
+		return err
+	}
+	if err := w.WriteByte('>'); err != nil {
+		return err
+	}
+
+	// Add initial newline where there is danger of a newline beging ignored.
+	if c := n.FirstChild; c != nil && c.Type == TextNode && strings.HasPrefix(c.Data, "\n") {
+		switch n.Data {
+		case "pre", "listing", "textarea":
+			if err := w.WriteByte('\n'); err != nil {
+				return err
+			}
+		}
+	}
+
+	// Render any child nodes
+	if childTextNodesAreLiteral(n) {
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			if c.Type == TextNode {
+				if _, err := w.WriteString(c.Data); err != nil {
+					return err
+				}
+			} else {
+				if err := render1(w, c); err != nil {
+					return err
+				}
+			}
+		}
+		if n.Data == "plaintext" {
+			// Don't render anything else. <plaintext> must be the
+			// last element in the file, with no closing tag.
+			return plaintextAbort
+		}
+	} else {
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			if err := render1(w, c); err != nil {
+				return err
+			}
+		}
+	}
+
+	// Render the </xxx> closing tag.
+	if _, err := w.WriteString("</"); err != nil {
+		return err
+	}
+	if _, err := w.WriteString(n.Data); err != nil {
+		return err
+	}
+	return w.WriteByte('>')
+}
+
+func childTextNodesAreLiteral(n *Node) bool {
+	// Per WHATWG HTML 13.3, if the parent of the current node is a style,
+	// script, xmp, iframe, noembed, noframes, or plaintext element, and the
+	// current node is a text node, append the value of the node's data
+	// literally. The specification is not explicit about it, but we only
+	// enforce this if we are in the HTML namespace (i.e. when the namespace is
+	// "").
+	// NOTE: we also always include noscript elements, although the
+	// specification states that they should only be rendered as such if
+	// scripting is enabled for the node (which is not something we track).
+	if n.Namespace != "" {
+		return false
+	}
+	switch n.Data {
+	case "iframe", "noembed", "noframes", "noscript", "plaintext", "script", "style", "xmp":
+		return true
+	default:
+		return false
+	}
+}
+
+// writeQuoted writes s to w surrounded by quotes. Normally it will use double
+// quotes, but if s contains a double quote, it will use single quotes.
+// It is used for writing the identifiers in a doctype declaration.
+// In valid HTML, they can't contain both types of quotes.
+func writeQuoted(w writer, s string) error {
+	var q byte = '"'
+	if strings.Contains(s, `"`) {
+		q = '\''
+	}
+	if err := w.WriteByte(q); err != nil {
+		return err
+	}
+	if _, err := w.WriteString(s); err != nil {
+		return err
+	}
+	if err := w.WriteByte(q); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Section 12.1.2, "Elements", gives this list of void elements. Void elements
+// are those that can't have any contents.
+var voidElements = map[string]bool{
+	"area":   true,
+	"base":   true,
+	"br":     true,
+	"col":    true,
+	"embed":  true,
+	"hr":     true,
+	"img":    true,
+	"input":  true,
+	"keygen": true, // "keygen" has been removed from the spec, but are kept here for backwards compatibility.
+	"link":   true,
+	"meta":   true,
+	"param":  true,
+	"source": true,
+	"track":  true,
+	"wbr":    true,
+}