// 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] }