blackfriday/v2/node.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
        }
}

// IsContainer returns true if 'n' can contain children.
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
        }
}

// IsLeaf returns true if 'n' is a leaf node.
func (n *Node) IsLeaf() bool {
        return !n.IsContainer()
}

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)
}
Revision:	1.1
Committed:	Mon Sep 30 00:42:06 2024 UTC (6 weeks, 4 days ago) by yakumo_izuru
Branch:	MAIN
CVS Tags:	HEAD
Log Message:	Mirrored from https://git.chaotic.ninja/git/yakumo_izuru/aya
#	User	Rev	Content
1	yakumo_izuru	1.1	package blackfriday
2
3			import (
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.
11			type NodeType int
12
13			// Constants for identifying different types of nodes. See NodeType.
14			const (
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
41			var 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
68			func (t NodeType) String() string {
69			return nodeTypeNames[t]
70			}
71
72			// ListData contains fields relevant to a List and Item node type.
73			type 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.
83			type 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.
91			type 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.
100			type 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.
106			type 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.
115			type 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.
136			func NewNode(typ NodeType) *Node {
137			return &Node{
138			Type: typ,
139			open: true,
140			}
141			}
142
143			func (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.
155			func (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.
173			func (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.
188			func (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.
203			func (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.
243			func (n *Node) IsLeaf() bool {
244			return !n.IsContainer()
245			}
246
247			func (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.
269			type WalkStatus int
270
271			const (
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.
283			type 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.
287			func (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
303			type nodeWalker struct {
304			current *Node
305			root *Node
306			entering bool
307			}
308
309			func newNodeWalker(root Node) nodeWalker {
310			return &nodeWalker{
311			current: root,
312			root: root,
313			entering: true,
314			}
315			}
316
317			func (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
338			func dump(ast *Node) {
339			fmt.Println(dumpString(ast))
340			}
341
342			func 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
358			func dumpString(ast *Node) string {
359			return dumpR(ast, 0)
360			}