1package parser
  2
  3import (
  4	"bytes"
  5
  6	"github.com/yuin/goldmark/ast"
  7	"github.com/yuin/goldmark/text"
  8	"github.com/yuin/goldmark/util"
  9)
 10
 11type fencedCodeBlockParser struct {
 12}
 13
 14var defaultFencedCodeBlockParser = &fencedCodeBlockParser{}
 15
 16// NewFencedCodeBlockParser returns a new BlockParser that
 17// parses fenced code blocks.
 18func NewFencedCodeBlockParser() BlockParser {
 19	return defaultFencedCodeBlockParser
 20}
 21
 22type fenceData struct {
 23	char   byte
 24	indent int
 25	length int
 26	node   ast.Node
 27}
 28
 29var fencedCodeBlockInfoKey = NewContextKey()
 30
 31func (b *fencedCodeBlockParser) Trigger() []byte {
 32	return []byte{'~', '`'}
 33}
 34
 35func (b *fencedCodeBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
 36	line, segment := reader.PeekLine()
 37	pos := pc.BlockIndent()
 38	findent := pos
 39	fenceChar := line[pos]
 40	i := pos
 41	for ; i < len(line) && line[i] == fenceChar; i++ {
 42	}
 43	oFenceLength := i - pos
 44	if oFenceLength < 3 {
 45		return nil, NoChildren
 46	}
 47	var info *ast.Text
 48	if i < len(line)-1 {
 49		rest := line[i:]
 50		left := util.TrimLeftSpaceLength(rest)
 51		right := util.TrimRightSpaceLength(rest)
 52		if left < len(rest)-right {
 53			infoStart, infoStop := segment.Start-segment.Padding+i+left, segment.Stop-right
 54			value := rest[left : len(rest)-right]
 55			if fenceChar == '`' && bytes.IndexByte(value, '`') > -1 {
 56				return nil, NoChildren
 57			} else if infoStart != infoStop {
 58				info = ast.NewTextSegment(text.NewSegment(infoStart, infoStop))
 59			}
 60		}
 61	}
 62	node := ast.NewFencedCodeBlock(info)
 63	pc.Set(fencedCodeBlockInfoKey, &fenceData{fenceChar, findent, oFenceLength, node})
 64	return node, NoChildren
 65
 66}
 67
 68func (b *fencedCodeBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
 69	line, segment := reader.PeekLine()
 70	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
 71
 72	w, pos := util.IndentWidth(line, reader.LineOffset())
 73	if w < 4 {
 74		i := pos
 75		for ; i < len(line) && line[i] == fdata.char; i++ {
 76		}
 77		length := i - pos
 78		if length >= fdata.length && util.IsBlank(line[i:]) {
 79			reader.AdvanceToEOL()
 80			return Close
 81		}
 82	}
 83	pos, padding := util.IndentPositionPadding(line, reader.LineOffset(), segment.Padding, fdata.indent)
 84	if pos < 0 {
 85		pos = max(0, util.FirstNonSpacePosition(line)) - segment.Padding
 86		padding = 0
 87	}
 88	seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
 89	// if code block line starts with a tab, keep a tab as it is.
 90	if padding != 0 {
 91		preserveLeadingTabInCodeBlock(&seg, reader, fdata.indent)
 92	}
 93	seg.ForceNewline = true // EOF as newline
 94	node.Lines().Append(seg)
 95	reader.AdvanceToEOL()
 96	return Continue | NoChildren
 97}
 98
 99func (b *fencedCodeBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
100	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
101	if fdata.node == node {
102		pc.Set(fencedCodeBlockInfoKey, nil)
103	}
104}
105
106func (b *fencedCodeBlockParser) CanInterruptParagraph() bool {
107	return true
108}
109
110func (b *fencedCodeBlockParser) CanAcceptIndentedLine() bool {
111	return false
112}