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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
import (
"golang.org/x/net/html/atom"
)
// A NodeType is the type of a Node.
type NodeType uint32
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". For element nodes, DataAtom
// is the atom for Data, or zero if Data is not a known tag name.
//
// 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, FirstChild, LastChild, PrevSibling, NextSibling *Node
Type NodeType
DataAtom atom.Atom
Data string
Namespace string
Attr []Attribute
}
// InsertBefore inserts newChild as a child of n, immediately before oldChild
// in the sequence of n's children. oldChild may be nil, in which case newChild
// is appended to the end of n's children.
//
// It will panic if newChild already has a parent or siblings.
func (n *Node) InsertBefore(newChild, oldChild *Node) {
if newChild.Parent != nil || newChild.PrevSibling != nil || newChild.NextSibling != nil {
panic("html: InsertBefore called for an attached child Node")
}
var prev, next *Node
if oldChild != nil {
prev, next = oldChild.PrevSibling, oldChild
} else {
prev = n.LastChild
}
if prev != nil {
prev.NextSibling = newChild
} else {
n.FirstChild = newChild
}
if next != nil {
next.PrevSibling = newChild
} else {
n.LastChild = newChild
}
newChild.Parent = n
newChild.PrevSibling = prev
newChild.NextSibling = next
}
// AppendChild adds a node c as a child of n.
//
// It will panic if c already has a parent or siblings.
func (n *Node) AppendChild(c *Node) {
if c.Parent != nil || c.PrevSibling != nil || c.NextSibling != nil {
panic("html: AppendChild called for an attached child Node")
}
last := n.LastChild
if last != nil {
last.NextSibling = c
} else {
n.FirstChild = c
}
n.LastChild = c
c.Parent = n
c.PrevSibling = last
}
// RemoveChild removes a node c that is a child of n. Afterwards, c will have
// no parent and no siblings.
//
// It will panic if c's parent is not n.
func (n *Node) RemoveChild(c *Node) {
if c.Parent != n {
panic("html: RemoveChild called for a non-child Node")
}
if n.FirstChild == c {
n.FirstChild = c.NextSibling
}
if c.NextSibling != nil {
c.NextSibling.PrevSibling = c.PrevSibling
}
if n.LastChild == c {
n.LastChild = c.PrevSibling
}
if c.PrevSibling != nil {
c.PrevSibling.NextSibling = c.NextSibling
}
c.Parent = nil
c.PrevSibling = nil
c.NextSibling = nil
}
// reparentChildren reparents all of src's child nodes to dst.
func reparentChildren(dst, src *Node) {
for {
child := src.FirstChild
if child == nil {
break
}
src.RemoveChild(child)
dst.AppendChild(child)
}
}
// clone returns a new node with the same type, data and attributes.
// The clone has no parent, no siblings and no children.
func (n *Node) clone() *Node {
m := &Node{
Type: n.Type,
DataAtom: n.DataAtom,
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 occurrence 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]
}
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