1package parser
  2
  3import (
  4	"github.com/yuin/goldmark/ast"
  5	"github.com/yuin/goldmark/text"
  6	"github.com/yuin/goldmark/util"
  7)
  8
  9type linkReferenceParagraphTransformer struct {
 10}
 11
 12// LinkReferenceParagraphTransformer is a ParagraphTransformer implementation
 13// that parses and extracts link reference from paragraphs.
 14var LinkReferenceParagraphTransformer = &linkReferenceParagraphTransformer{}
 15
 16func (p *linkReferenceParagraphTransformer) Transform(node *ast.Paragraph, reader text.Reader, pc Context) {
 17	lines := node.Lines()
 18	block := text.NewBlockReader(reader.Source(), lines)
 19	removes := [][2]int{}
 20	for {
 21		ref, start, end := parseLinkReferenceDefinition(block, pc)
 22		if start > -1 {
 23			if start == 0 {
 24				ref.SetBlankPreviousLines(node.HasBlankPreviousLines())
 25			}
 26			node.Parent().InsertBefore(node.Parent(), node, ref)
 27			for i := start + 1; i < end; i++ {
 28				ref.Lines().Append(lines.At(i))
 29			}
 30			seg := ref.Lines().At(ref.Lines().Len() - 1)
 31			ref.Lines().Set(ref.Lines().Len()-1, seg.TrimRightSpace(reader.Source()))
 32			if start == end {
 33				end++
 34			}
 35			removes = append(removes, [2]int{start, end})
 36			continue
 37		}
 38		break
 39	}
 40
 41	offset := 0
 42	for _, remove := range removes {
 43		if lines.Len() == 0 {
 44			break
 45		}
 46		s := lines.Sliced(remove[1]-offset, lines.Len())
 47		lines.SetSliced(0, remove[0]-offset)
 48		lines.AppendAll(s)
 49		offset = remove[1]
 50	}
 51
 52	if lines.Len() == 0 {
 53		node.Parent().RemoveChild(node.Parent(), node)
 54		return
 55	}
 56
 57	node.SetLines(lines)
 58}
 59
 60func parseLinkReferenceDefinition(block text.Reader, pc Context) (ast.Node, int, int) {
 61	block.SkipSpaces()
 62	line, _ := block.PeekLine()
 63	if line == nil {
 64		return nil, -1, -1
 65	}
 66	startLine, _ := block.Position()
 67	width, pos := util.IndentWidth(line, 0)
 68	if width > 3 {
 69		return nil, -1, -1
 70	}
 71	if width != 0 {
 72		pos++
 73	}
 74	if line[pos] != '[' {
 75		return nil, -1, -1
 76	}
 77	_, startPos := block.Position()
 78	block.Advance(pos + 1)
 79	segments, found := block.FindClosure('[', ']', linkFindClosureOptions)
 80	if !found {
 81		return nil, -1, -1
 82	}
 83	var label []byte
 84	if segments.Len() == 1 {
 85		label = block.Value(segments.At(0))
 86	} else {
 87		for i := range segments.Len() {
 88			s := segments.At(i)
 89			label = append(label, block.Value(s)...)
 90		}
 91	}
 92	if util.IsBlank(label) {
 93		return nil, -1, -1
 94	}
 95	if block.Peek() != ':' {
 96		return nil, -1, -1
 97	}
 98	block.Advance(1)
 99	block.SkipSpaces()
100	destination, ok := parseLinkDestination(block)
101	if !ok {
102		return nil, -1, -1
103	}
104	line, _ = block.PeekLine()
105	isNewLine := line == nil || util.IsBlank(line)
106
107	endLine, _ := block.Position()
108	_, spaces, _ := block.SkipSpaces()
109	opener := block.Peek()
110	if opener != '"' && opener != '\'' && opener != '(' {
111		if !isNewLine {
112			return nil, -1, -1
113		}
114		ref := ast.NewLinkReferenceDefinition(label, destination, nil)
115		ref.Lines().Append(startPos)
116		pc.AddReference(newASTReference(ref))
117		return ref, startLine, endLine + 1
118	}
119	if spaces == 0 {
120		return nil, -1, -1
121	}
122	block.Advance(1)
123	closer := opener
124	if opener == '(' {
125		closer = ')'
126	}
127	segments, found = block.FindClosure(opener, closer, linkFindClosureOptions)
128	if !found {
129		if !isNewLine {
130			return nil, -1, -1
131		}
132		ref := ast.NewLinkReferenceDefinition(label, destination, nil)
133		ref.Lines().Append(startPos)
134		pc.AddReference(newASTReference(ref))
135		block.AdvanceLine()
136		return ref, startLine, endLine + 1
137	}
138	var title []byte
139	if segments.Len() == 1 {
140		title = block.Value(segments.At(0))
141	} else {
142		for i := range segments.Len() {
143			s := segments.At(i)
144			title = append(title, block.Value(s)...)
145		}
146	}
147
148	line, _ = block.PeekLine()
149	if line != nil && !util.IsBlank(line) {
150		if !isNewLine {
151			return nil, -1, -1
152		}
153		ref := ast.NewLinkReferenceDefinition(label, destination, title)
154		ref.Lines().Append(startPos)
155		pc.AddReference(newASTReference(ref))
156		return ref, startLine, endLine
157	}
158
159	endLine, _ = block.Position()
160	ref := ast.NewLinkReferenceDefinition(label, destination, title)
161	ref.Lines().Append(startPos)
162	pc.AddReference(newASTReference(ref))
163	return ref, startLine, endLine + 1
164}