mfer/vendor/github.com/russross/blackfriday/v2/node.go

355 lines
8.5 KiB
Go

package blackfriday
import (
"bytes"
"fmt"
)
// NodeType specifies a type of a single node of a syntax tree. Usually one
// node (and its type) corresponds to a single markdown feature, e.g. emphasis
// or code block.
type NodeType int
// Constants for identifying different types of nodes. See NodeType.
const (
Document NodeType = iota
BlockQuote
List
Item
Paragraph
Heading
HorizontalRule
Emph
Strong
Del
Link
Image
Text
HTMLBlock
CodeBlock
Softbreak
Hardbreak
Code
HTMLSpan
Table
TableCell
TableHead
TableBody
TableRow
)
var nodeTypeNames = []string{
Document: "Document",
BlockQuote: "BlockQuote",
List: "List",
Item: "Item",
Paragraph: "Paragraph",
Heading: "Heading",
HorizontalRule: "HorizontalRule",
Emph: "Emph",
Strong: "Strong",
Del: "Del",
Link: "Link",
Image: "Image",
Text: "Text",
HTMLBlock: "HTMLBlock",
CodeBlock: "CodeBlock",
Softbreak: "Softbreak",
Hardbreak: "Hardbreak",
Code: "Code",
HTMLSpan: "HTMLSpan",
Table: "Table",
TableCell: "TableCell",
TableHead: "TableHead",
TableBody: "TableBody",
TableRow: "TableRow",
}
func (t NodeType) String() string {
return nodeTypeNames[t]
}
// ListData contains fields relevant to a List and Item node type.
type ListData struct {
ListFlags ListType
Tight bool // Skip <p>s around list item data if true
BulletChar byte // '*', '+' or '-' in bullet lists
Delimiter byte // '.' or ')' after the number in ordered lists
RefLink []byte // If not nil, turns this list item into a footnote item and triggers different rendering
IsFootnotesList bool // This is a list of footnotes
}
// LinkData contains fields relevant to a Link node type.
type LinkData struct {
Destination []byte // Destination is what goes into a href
Title []byte // Title is the tooltip thing that goes in a title attribute
NoteID int // NoteID contains a serial number of a footnote, zero if it's not a footnote
Footnote *Node // If it's a footnote, this is a direct link to the footnote Node. Otherwise nil.
}
// CodeBlockData contains fields relevant to a CodeBlock node type.
type CodeBlockData struct {
IsFenced bool // Specifies whether it's a fenced code block or an indented one
Info []byte // This holds the info string
FenceChar byte
FenceLength int
FenceOffset int
}
// TableCellData contains fields relevant to a TableCell node type.
type TableCellData struct {
IsHeader bool // This tells if it's under the header row
Align CellAlignFlags // This holds the value for align attribute
}
// HeadingData contains fields relevant to a Heading node type.
type HeadingData struct {
Level int // This holds the heading level number
HeadingID string // This might hold heading ID, if present
IsTitleblock bool // Specifies whether it's a title block
}
// Node is a single element in the abstract syntax tree of the parsed document.
// It holds connections to the structurally neighboring nodes and, for certain
// types of nodes, additional information that might be needed when rendering.
type Node struct {
Type NodeType // Determines the type of the node
Parent *Node // Points to the parent
FirstChild *Node // Points to the first child, if any
LastChild *Node // Points to the last child, if any
Prev *Node // Previous sibling; nil if it's the first child
Next *Node // Next sibling; nil if it's the last child
Literal []byte // Text contents of the leaf nodes
HeadingData // Populated if Type is Heading
ListData // Populated if Type is List
CodeBlockData // Populated if Type is CodeBlock
LinkData // Populated if Type is Link
TableCellData // Populated if Type is TableCell
content []byte // Markdown content of the block nodes
open bool // Specifies an open block node that has not been finished to process yet
}
// NewNode allocates a node of a specified type.
func NewNode(typ NodeType) *Node {
return &Node{
Type: typ,
open: true,
}
}
func (n *Node) String() string {
ellipsis := ""
snippet := n.Literal
if len(snippet) > 16 {
snippet = snippet[:16]
ellipsis = "..."
}
return fmt.Sprintf("%s: '%s%s'", n.Type, snippet, ellipsis)
}
// Unlink removes node 'n' from the tree.
// It panics if the node is nil.
func (n *Node) Unlink() {
if n.Prev != nil {
n.Prev.Next = n.Next
} else if n.Parent != nil {
n.Parent.FirstChild = n.Next
}
if n.Next != nil {
n.Next.Prev = n.Prev
} else if n.Parent != nil {
n.Parent.LastChild = n.Prev
}
n.Parent = nil
n.Next = nil
n.Prev = nil
}
// AppendChild adds a node 'child' as a child of 'n'.
// It panics if either node is nil.
func (n *Node) AppendChild(child *Node) {
child.Unlink()
child.Parent = n
if n.LastChild != nil {
n.LastChild.Next = child
child.Prev = n.LastChild
n.LastChild = child
} else {
n.FirstChild = child
n.LastChild = child
}
}
// InsertBefore inserts 'sibling' immediately before 'n'.
// It panics if either node is nil.
func (n *Node) InsertBefore(sibling *Node) {
sibling.Unlink()
sibling.Prev = n.Prev
if sibling.Prev != nil {
sibling.Prev.Next = sibling
}
sibling.Next = n
n.Prev = sibling
sibling.Parent = n.Parent
if sibling.Prev == nil {
sibling.Parent.FirstChild = sibling
}
}
func (n *Node) isContainer() bool {
switch n.Type {
case Document:
fallthrough
case BlockQuote:
fallthrough
case List:
fallthrough
case Item:
fallthrough
case Paragraph:
fallthrough
case Heading:
fallthrough
case Emph:
fallthrough
case Strong:
fallthrough
case Del:
fallthrough
case Link:
fallthrough
case Image:
fallthrough
case Table:
fallthrough
case TableHead:
fallthrough
case TableBody:
fallthrough
case TableRow:
fallthrough
case TableCell:
return true
default:
return false
}
}
func (n *Node) canContain(t NodeType) bool {
if n.Type == List {
return t == Item
}
if n.Type == Document || n.Type == BlockQuote || n.Type == Item {
return t != Item
}
if n.Type == Table {
return t == TableHead || t == TableBody
}
if n.Type == TableHead || n.Type == TableBody {
return t == TableRow
}
if n.Type == TableRow {
return t == TableCell
}
return false
}
// WalkStatus allows NodeVisitor to have some control over the tree traversal.
// It is returned from NodeVisitor and different values allow Node.Walk to
// decide which node to go to next.
type WalkStatus int
const (
// GoToNext is the default traversal of every node.
GoToNext WalkStatus = iota
// SkipChildren tells walker to skip all children of current node.
SkipChildren
// Terminate tells walker to terminate the traversal.
Terminate
)
// NodeVisitor is a callback to be called when traversing the syntax tree.
// Called twice for every node: once with entering=true when the branch is
// first visited, then with entering=false after all the children are done.
type NodeVisitor func(node *Node, entering bool) WalkStatus
// Walk is a convenience method that instantiates a walker and starts a
// traversal of subtree rooted at n.
func (n *Node) Walk(visitor NodeVisitor) {
w := newNodeWalker(n)
for w.current != nil {
status := visitor(w.current, w.entering)
switch status {
case GoToNext:
w.next()
case SkipChildren:
w.entering = false
w.next()
case Terminate:
return
}
}
}
type nodeWalker struct {
current *Node
root *Node
entering bool
}
func newNodeWalker(root *Node) *nodeWalker {
return &nodeWalker{
current: root,
root: root,
entering: true,
}
}
func (nw *nodeWalker) next() {
if (!nw.current.isContainer() || !nw.entering) && nw.current == nw.root {
nw.current = nil
return
}
if nw.entering && nw.current.isContainer() {
if nw.current.FirstChild != nil {
nw.current = nw.current.FirstChild
nw.entering = true
} else {
nw.entering = false
}
} else if nw.current.Next == nil {
nw.current = nw.current.Parent
nw.entering = false
} else {
nw.current = nw.current.Next
nw.entering = true
}
}
func dump(ast *Node) {
fmt.Println(dumpString(ast))
}
func dumpR(ast *Node, depth int) string {
if ast == nil {
return ""
}
indent := bytes.Repeat([]byte("\t"), depth)
content := ast.Literal
if content == nil {
content = ast.content
}
result := fmt.Sprintf("%s%s(%q)\n", indent, ast.Type, content)
for n := ast.FirstChild; n != nil; n = n.Next {
result += dumpR(n, depth+1)
}
return result
}
func dumpString(ast *Node) string {
return dumpR(ast, 0)
}