155 lines
3.7 KiB
Go
155 lines
3.7 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package html
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// A NodeType is the type of a Node.
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type NodeType int
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const (
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ErrorNode NodeType = iota
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TextNode
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DocumentNode
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ElementNode
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CommentNode
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DoctypeNode
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scopeMarkerNode
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)
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// Section 12.2.3.3 says "scope markers are inserted when entering applet
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// elements, buttons, object elements, marquees, table cells, and table
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// captions, and are used to prevent formatting from 'leaking'".
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var scopeMarker = Node{Type: scopeMarkerNode}
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// A Node consists of a NodeType and some Data (tag name for element nodes,
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// content for text) and are part of a tree of Nodes. Element nodes may also
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// have a Namespace and contain a slice of Attributes. Data is unescaped, so
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// that it looks like "a<b" rather than "a<b".
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//
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// An empty Namespace implies a "http://www.w3.org/1999/xhtml" namespace.
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// Similarly, "math" is short for "http://www.w3.org/1998/Math/MathML", and
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// "svg" is short for "http://www.w3.org/2000/svg".
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type Node struct {
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Parent *Node
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Child []*Node
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Type NodeType
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Data string
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Namespace string
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Attr []Attribute
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}
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// Add adds a node as a child of n.
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// It will panic if the child's parent is not nil.
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func (n *Node) Add(child *Node) {
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if child.Parent != nil {
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panic("html: Node.Add called for a child Node that already has a parent")
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}
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child.Parent = n
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n.Child = append(n.Child, child)
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}
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// Remove removes a node as a child of n.
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// It will panic if the child's parent is not n.
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func (n *Node) Remove(child *Node) {
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if child.Parent == n {
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child.Parent = nil
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for i, m := range n.Child {
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if m == child {
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copy(n.Child[i:], n.Child[i+1:])
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j := len(n.Child) - 1
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n.Child[j] = nil
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n.Child = n.Child[:j]
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return
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}
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}
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}
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panic("html: Node.Remove called for a non-child Node")
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}
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// reparentChildren reparents all of src's child nodes to dst.
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func reparentChildren(dst, src *Node) {
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for _, n := range src.Child {
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if n.Parent != src {
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panic("html: nodes have an inconsistent parent/child relationship")
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}
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n.Parent = dst
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}
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dst.Child = append(dst.Child, src.Child...)
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src.Child = nil
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}
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// clone returns a new node with the same type, data and attributes.
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// The clone has no parent and no children.
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func (n *Node) clone() *Node {
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m := &Node{
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Type: n.Type,
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Data: n.Data,
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Attr: make([]Attribute, len(n.Attr)),
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}
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copy(m.Attr, n.Attr)
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return m
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}
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// nodeStack is a stack of nodes.
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type nodeStack []*Node
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// pop pops the stack. It will panic if s is empty.
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func (s *nodeStack) pop() *Node {
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i := len(*s)
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n := (*s)[i-1]
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*s = (*s)[:i-1]
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return n
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}
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// top returns the most recently pushed node, or nil if s is empty.
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func (s *nodeStack) top() *Node {
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if i := len(*s); i > 0 {
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return (*s)[i-1]
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}
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return nil
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}
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// index returns the index of the top-most occurence of n in the stack, or -1
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// if n is not present.
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func (s *nodeStack) index(n *Node) int {
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for i := len(*s) - 1; i >= 0; i-- {
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if (*s)[i] == n {
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return i
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}
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}
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return -1
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}
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// insert inserts a node at the given index.
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func (s *nodeStack) insert(i int, n *Node) {
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(*s) = append(*s, nil)
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copy((*s)[i+1:], (*s)[i:])
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(*s)[i] = n
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}
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// remove removes a node from the stack. It is a no-op if n is not present.
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func (s *nodeStack) remove(n *Node) {
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i := s.index(n)
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if i == -1 {
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return
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}
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copy((*s)[i:], (*s)[i+1:])
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j := len(*s) - 1
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(*s)[j] = nil
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*s = (*s)[:j]
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}
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// TODO(nigeltao): forTag no longer used. Should it be deleted?
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// forTag returns the top-most element node with the given tag.
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func (s *nodeStack) forTag(tag string) *Node {
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for i := len(*s) - 1; i >= 0; i-- {
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n := (*s)[i]
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if n.Type == ElementNode && n.Data == tag {
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return n
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}
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}
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return nil
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}
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