source: code/trunk/vendor/github.com/russross/blackfriday/v2/node.go@ 67

Last change on this file since 67 was 67, checked in by Izuru Yakumo, 23 months ago

Use vendored modules

Signed-off-by: Izuru Yakumo <yakumo.izuru@…>
File size: 8.6 KB
Line 
1package blackfriday
2
3import (
4 "bytes"
5 "fmt"
6)
7
8// NodeType specifies a type of a single node of a syntax tree. Usually one
9// node (and its type) corresponds to a single markdown feature, e.g. emphasis
10// or code block.
11type NodeType int
12
13// Constants for identifying different types of nodes. See NodeType.
14const (
15 Document NodeType = iota
16 BlockQuote
17 List
18 Item
19 Paragraph
20 Heading
21 HorizontalRule
22 Emph
23 Strong
24 Del
25 Link
26 Image
27 Text
28 HTMLBlock
29 CodeBlock
30 Softbreak
31 Hardbreak
32 Code
33 HTMLSpan
34 Table
35 TableCell
36 TableHead
37 TableBody
38 TableRow
39)
40
41var nodeTypeNames = []string{
42 Document: "Document",
43 BlockQuote: "BlockQuote",
44 List: "List",
45 Item: "Item",
46 Paragraph: "Paragraph",
47 Heading: "Heading",
48 HorizontalRule: "HorizontalRule",
49 Emph: "Emph",
50 Strong: "Strong",
51 Del: "Del",
52 Link: "Link",
53 Image: "Image",
54 Text: "Text",
55 HTMLBlock: "HTMLBlock",
56 CodeBlock: "CodeBlock",
57 Softbreak: "Softbreak",
58 Hardbreak: "Hardbreak",
59 Code: "Code",
60 HTMLSpan: "HTMLSpan",
61 Table: "Table",
62 TableCell: "TableCell",
63 TableHead: "TableHead",
64 TableBody: "TableBody",
65 TableRow: "TableRow",
66}
67
68func (t NodeType) String() string {
69 return nodeTypeNames[t]
70}
71
72// ListData contains fields relevant to a List and Item node type.
73type ListData struct {
74 ListFlags ListType
75 Tight bool // Skip <p>s around list item data if true
76 BulletChar byte // '*', '+' or '-' in bullet lists
77 Delimiter byte // '.' or ')' after the number in ordered lists
78 RefLink []byte // If not nil, turns this list item into a footnote item and triggers different rendering
79 IsFootnotesList bool // This is a list of footnotes
80}
81
82// LinkData contains fields relevant to a Link node type.
83type LinkData struct {
84 Destination []byte // Destination is what goes into a href
85 Title []byte // Title is the tooltip thing that goes in a title attribute
86 NoteID int // NoteID contains a serial number of a footnote, zero if it's not a footnote
87 Footnote *Node // If it's a footnote, this is a direct link to the footnote Node. Otherwise nil.
88}
89
90// CodeBlockData contains fields relevant to a CodeBlock node type.
91type CodeBlockData struct {
92 IsFenced bool // Specifies whether it's a fenced code block or an indented one
93 Info []byte // This holds the info string
94 FenceChar byte
95 FenceLength int
96 FenceOffset int
97}
98
99// TableCellData contains fields relevant to a TableCell node type.
100type TableCellData struct {
101 IsHeader bool // This tells if it's under the header row
102 Align CellAlignFlags // This holds the value for align attribute
103}
104
105// HeadingData contains fields relevant to a Heading node type.
106type HeadingData struct {
107 Level int // This holds the heading level number
108 HeadingID string // This might hold heading ID, if present
109 IsTitleblock bool // Specifies whether it's a title block
110}
111
112// Node is a single element in the abstract syntax tree of the parsed document.
113// It holds connections to the structurally neighboring nodes and, for certain
114// types of nodes, additional information that might be needed when rendering.
115type Node struct {
116 Type NodeType // Determines the type of the node
117 Parent *Node // Points to the parent
118 FirstChild *Node // Points to the first child, if any
119 LastChild *Node // Points to the last child, if any
120 Prev *Node // Previous sibling; nil if it's the first child
121 Next *Node // Next sibling; nil if it's the last child
122
123 Literal []byte // Text contents of the leaf nodes
124
125 HeadingData // Populated if Type is Heading
126 ListData // Populated if Type is List
127 CodeBlockData // Populated if Type is CodeBlock
128 LinkData // Populated if Type is Link
129 TableCellData // Populated if Type is TableCell
130
131 content []byte // Markdown content of the block nodes
132 open bool // Specifies an open block node that has not been finished to process yet
133}
134
135// NewNode allocates a node of a specified type.
136func NewNode(typ NodeType) *Node {
137 return &Node{
138 Type: typ,
139 open: true,
140 }
141}
142
143func (n *Node) String() string {
144 ellipsis := ""
145 snippet := n.Literal
146 if len(snippet) > 16 {
147 snippet = snippet[:16]
148 ellipsis = "..."
149 }
150 return fmt.Sprintf("%s: '%s%s'", n.Type, snippet, ellipsis)
151}
152
153// Unlink removes node 'n' from the tree.
154// It panics if the node is nil.
155func (n *Node) Unlink() {
156 if n.Prev != nil {
157 n.Prev.Next = n.Next
158 } else if n.Parent != nil {
159 n.Parent.FirstChild = n.Next
160 }
161 if n.Next != nil {
162 n.Next.Prev = n.Prev
163 } else if n.Parent != nil {
164 n.Parent.LastChild = n.Prev
165 }
166 n.Parent = nil
167 n.Next = nil
168 n.Prev = nil
169}
170
171// AppendChild adds a node 'child' as a child of 'n'.
172// It panics if either node is nil.
173func (n *Node) AppendChild(child *Node) {
174 child.Unlink()
175 child.Parent = n
176 if n.LastChild != nil {
177 n.LastChild.Next = child
178 child.Prev = n.LastChild
179 n.LastChild = child
180 } else {
181 n.FirstChild = child
182 n.LastChild = child
183 }
184}
185
186// InsertBefore inserts 'sibling' immediately before 'n'.
187// It panics if either node is nil.
188func (n *Node) InsertBefore(sibling *Node) {
189 sibling.Unlink()
190 sibling.Prev = n.Prev
191 if sibling.Prev != nil {
192 sibling.Prev.Next = sibling
193 }
194 sibling.Next = n
195 n.Prev = sibling
196 sibling.Parent = n.Parent
197 if sibling.Prev == nil {
198 sibling.Parent.FirstChild = sibling
199 }
200}
201
202// IsContainer returns true if 'n' can contain children.
203func (n *Node) IsContainer() bool {
204 switch n.Type {
205 case Document:
206 fallthrough
207 case BlockQuote:
208 fallthrough
209 case List:
210 fallthrough
211 case Item:
212 fallthrough
213 case Paragraph:
214 fallthrough
215 case Heading:
216 fallthrough
217 case Emph:
218 fallthrough
219 case Strong:
220 fallthrough
221 case Del:
222 fallthrough
223 case Link:
224 fallthrough
225 case Image:
226 fallthrough
227 case Table:
228 fallthrough
229 case TableHead:
230 fallthrough
231 case TableBody:
232 fallthrough
233 case TableRow:
234 fallthrough
235 case TableCell:
236 return true
237 default:
238 return false
239 }
240}
241
242// IsLeaf returns true if 'n' is a leaf node.
243func (n *Node) IsLeaf() bool {
244 return !n.IsContainer()
245}
246
247func (n *Node) canContain(t NodeType) bool {
248 if n.Type == List {
249 return t == Item
250 }
251 if n.Type == Document || n.Type == BlockQuote || n.Type == Item {
252 return t != Item
253 }
254 if n.Type == Table {
255 return t == TableHead || t == TableBody
256 }
257 if n.Type == TableHead || n.Type == TableBody {
258 return t == TableRow
259 }
260 if n.Type == TableRow {
261 return t == TableCell
262 }
263 return false
264}
265
266// WalkStatus allows NodeVisitor to have some control over the tree traversal.
267// It is returned from NodeVisitor and different values allow Node.Walk to
268// decide which node to go to next.
269type WalkStatus int
270
271const (
272 // GoToNext is the default traversal of every node.
273 GoToNext WalkStatus = iota
274 // SkipChildren tells walker to skip all children of current node.
275 SkipChildren
276 // Terminate tells walker to terminate the traversal.
277 Terminate
278)
279
280// NodeVisitor is a callback to be called when traversing the syntax tree.
281// Called twice for every node: once with entering=true when the branch is
282// first visited, then with entering=false after all the children are done.
283type NodeVisitor func(node *Node, entering bool) WalkStatus
284
285// Walk is a convenience method that instantiates a walker and starts a
286// traversal of subtree rooted at n.
287func (n *Node) Walk(visitor NodeVisitor) {
288 w := newNodeWalker(n)
289 for w.current != nil {
290 status := visitor(w.current, w.entering)
291 switch status {
292 case GoToNext:
293 w.next()
294 case SkipChildren:
295 w.entering = false
296 w.next()
297 case Terminate:
298 return
299 }
300 }
301}
302
303type nodeWalker struct {
304 current *Node
305 root *Node
306 entering bool
307}
308
309func newNodeWalker(root *Node) *nodeWalker {
310 return &nodeWalker{
311 current: root,
312 root: root,
313 entering: true,
314 }
315}
316
317func (nw *nodeWalker) next() {
318 if (!nw.current.IsContainer() || !nw.entering) && nw.current == nw.root {
319 nw.current = nil
320 return
321 }
322 if nw.entering && nw.current.IsContainer() {
323 if nw.current.FirstChild != nil {
324 nw.current = nw.current.FirstChild
325 nw.entering = true
326 } else {
327 nw.entering = false
328 }
329 } else if nw.current.Next == nil {
330 nw.current = nw.current.Parent
331 nw.entering = false
332 } else {
333 nw.current = nw.current.Next
334 nw.entering = true
335 }
336}
337
338func dump(ast *Node) {
339 fmt.Println(dumpString(ast))
340}
341
342func dumpR(ast *Node, depth int) string {
343 if ast == nil {
344 return ""
345 }
346 indent := bytes.Repeat([]byte("\t"), depth)
347 content := ast.Literal
348 if content == nil {
349 content = ast.content
350 }
351 result := fmt.Sprintf("%s%s(%q)\n", indent, ast.Type, content)
352 for n := ast.FirstChild; n != nil; n = n.Next {
353 result += dumpR(n, depth+1)
354 }
355 return result
356}
357
358func dumpString(ast *Node) string {
359 return dumpR(ast, 0)
360}
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