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// 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
// A NodeType is the type of a Node.
type NodeType int
const (
ErrorNode NodeType = iota
TextNode
DocumentNode
ElementNode
CommentNode
DoctypeNode
scopeMarkerNode
)
// Section 12.2.3.3 says "scope markers are inserted when entering applet
// elements, buttons, object elements, marquees, table cells, and table
// captions, and are used to prevent formatting from 'leaking'".
var scopeMarker = Node{Type: scopeMarkerNode}
// A Node consists of a NodeType and some Data (tag name for element nodes,
// content for text) and are part of a tree of Nodes. Element nodes may also
// have a Namespace and contain a slice of Attributes. Data is unescaped, so
// that it looks like "a<b" rather than "a<b".
//
// An empty Namespace implies a "http://www.w3.org/1999/xhtml" namespace.
// Similarly, "math" is short for "http://www.w3.org/1998/Math/MathML", and
// "svg" is short for "http://www.w3.org/2000/svg".
type Node struct {
Parent *Node
Child []*Node
Type NodeType
Data string
Namespace string
Attr []Attribute
}
// Add adds a node as a child of n.
// It will panic if the child's parent is not nil.
func (n *Node) Add(child *Node) {
if child.Parent != nil {
panic("html: Node.Add called for a child Node that already has a parent")
}
child.Parent = n
n.Child = append(n.Child, child)
}
// Remove removes a node as a child of n.
// It will panic if the child's parent is not n.
func (n *Node) Remove(child *Node) {
if child.Parent == n {
child.Parent = nil
for i, m := range n.Child {
if m == child {
copy(n.Child[i:], n.Child[i+1:])
j := len(n.Child) - 1
n.Child[j] = nil
n.Child = n.Child[:j]
return
}
}
}
panic("html: Node.Remove called for a non-child Node")
}
// reparentChildren reparents all of src's child nodes to dst.
func reparentChildren(dst, src *Node) {
for _, n := range src.Child {
if n.Parent != src {
panic("html: nodes have an inconsistent parent/child relationship")
}
n.Parent = dst
}
dst.Child = append(dst.Child, src.Child...)
src.Child = nil
}
// clone returns a new node with the same type, data and attributes.
// The clone has no parent and no children.
func (n *Node) clone() *Node {
m := &Node{
Type: n.Type,
Data: n.Data,
Attr: make([]Attribute, len(n.Attr)),
}
copy(m.Attr, n.Attr)
return m
}
// nodeStack is a stack of nodes.
type nodeStack []*Node
// pop pops the stack. It will panic if s is empty.
func (s *nodeStack) pop() *Node {
i := len(*s)
n := (*s)[i-1]
*s = (*s)[:i-1]
return n
}
// top returns the most recently pushed node, or nil if s is empty.
func (s *nodeStack) top() *Node {
if i := len(*s); i > 0 {
return (*s)[i-1]
}
return nil
}
// index returns the index of the top-most occurence of n in the stack, or -1
// if n is not present.
func (s *nodeStack) index(n *Node) int {
for i := len(*s) - 1; i >= 0; i-- {
if (*s)[i] == n {
return i
}
}
return -1
}
// insert inserts a node at the given index.
func (s *nodeStack) insert(i int, n *Node) {
(*s) = append(*s, nil)
copy((*s)[i+1:], (*s)[i:])
(*s)[i] = n
}
// remove removes a node from the stack. It is a no-op if n is not present.
func (s *nodeStack) remove(n *Node) {
i := s.index(n)
if i == -1 {
return
}
copy((*s)[i:], (*s)[i+1:])
j := len(*s) - 1
(*s)[j] = nil
*s = (*s)[:j]
}
// TODO(nigeltao): forTag no longer used. Should it be deleted?
// forTag returns the top-most element node with the given tag.
func (s *nodeStack) forTag(tag string) *Node {
for i := len(*s) - 1; i >= 0; i-- {
n := (*s)[i]
if n.Type == ElementNode && n.Data == tag {
return n
}
}
return nil
}
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