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388 lines
8.5 KiB
388 lines
8.5 KiB
package parser
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import (
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"fmt"
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"regexp"
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"strings"
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"github.com/yuin/goldmark/ast"
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"github.com/yuin/goldmark/text"
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"github.com/yuin/goldmark/util"
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)
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var linkLabelStateKey = NewContextKey()
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type linkLabelState struct {
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ast.BaseInline
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Segment text.Segment
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IsImage bool
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Prev *linkLabelState
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Next *linkLabelState
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First *linkLabelState
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Last *linkLabelState
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}
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func newLinkLabelState(segment text.Segment, isImage bool) *linkLabelState {
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return &linkLabelState{
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Segment: segment,
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IsImage: isImage,
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}
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}
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func (s *linkLabelState) Text(source []byte) []byte {
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return s.Segment.Value(source)
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}
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func (s *linkLabelState) Dump(source []byte, level int) {
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fmt.Printf("%slinkLabelState: \"%s\"\n", strings.Repeat(" ", level), s.Text(source))
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}
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var kindLinkLabelState = ast.NewNodeKind("LinkLabelState")
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func (s *linkLabelState) Kind() ast.NodeKind {
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return kindLinkLabelState
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}
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func pushLinkLabelState(pc Context, v *linkLabelState) {
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tlist := pc.Get(linkLabelStateKey)
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var list *linkLabelState
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if tlist == nil {
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list = v
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v.First = v
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v.Last = v
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pc.Set(linkLabelStateKey, list)
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} else {
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list = tlist.(*linkLabelState)
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l := list.Last
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list.Last = v
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l.Next = v
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v.Prev = l
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}
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}
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func removeLinkLabelState(pc Context, d *linkLabelState) {
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tlist := pc.Get(linkLabelStateKey)
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var list *linkLabelState
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if tlist == nil {
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return
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}
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list = tlist.(*linkLabelState)
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if d.Prev == nil {
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list = d.Next
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if list != nil {
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list.First = d
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list.Last = d.Last
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list.Prev = nil
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pc.Set(linkLabelStateKey, list)
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} else {
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pc.Set(linkLabelStateKey, nil)
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}
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} else {
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d.Prev.Next = d.Next
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if d.Next != nil {
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d.Next.Prev = d.Prev
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}
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}
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if list != nil && d.Next == nil {
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list.Last = d.Prev
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}
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d.Next = nil
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d.Prev = nil
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d.First = nil
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d.Last = nil
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}
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type linkParser struct {
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}
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var defaultLinkParser = &linkParser{}
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// NewLinkParser return a new InlineParser that parses links.
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func NewLinkParser() InlineParser {
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return defaultLinkParser
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}
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func (s *linkParser) Trigger() []byte {
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return []byte{'!', '[', ']'}
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}
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var linkDestinationRegexp = regexp.MustCompile(`\s*([^\s].+)`)
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var linkTitleRegexp = regexp.MustCompile(`\s+(\)|["'\(].+)`)
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var linkBottom = NewContextKey()
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func (s *linkParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
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line, segment := block.PeekLine()
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if line[0] == '!' {
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if len(line) > 1 && line[1] == '[' {
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block.Advance(1)
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pc.Set(linkBottom, pc.LastDelimiter())
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return processLinkLabelOpen(block, segment.Start+1, true, pc)
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}
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return nil
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}
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if line[0] == '[' {
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pc.Set(linkBottom, pc.LastDelimiter())
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return processLinkLabelOpen(block, segment.Start, false, pc)
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}
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// line[0] == ']'
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tlist := pc.Get(linkLabelStateKey)
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if tlist == nil {
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return nil
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}
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last := tlist.(*linkLabelState).Last
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if last == nil {
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return nil
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}
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block.Advance(1)
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removeLinkLabelState(pc, last)
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if s.containsLink(last) { // a link in a link text is not allowed
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ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
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return nil
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}
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c := block.Peek()
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l, pos := block.Position()
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var link *ast.Link
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var hasValue bool
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if c == '(' { // normal link
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link = s.parseLink(parent, last, block, pc)
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} else if c == '[' { // reference link
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link, hasValue = s.parseReferenceLink(parent, last, block, pc)
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if link == nil && hasValue {
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ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
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return nil
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}
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}
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if link == nil {
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// maybe shortcut reference link
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block.SetPosition(l, pos)
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ssegment := text.NewSegment(last.Segment.Stop, segment.Start)
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maybeReference := block.Value(ssegment)
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ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
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if !ok {
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ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
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return nil
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}
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link = ast.NewLink()
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s.processLinkLabel(parent, link, last, pc)
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link.Title = ref.Title()
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link.Destination = ref.Destination()
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}
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if last.IsImage {
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last.Parent().RemoveChild(last.Parent(), last)
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return ast.NewImage(link)
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}
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last.Parent().RemoveChild(last.Parent(), last)
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return link
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}
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func (s *linkParser) containsLink(last *linkLabelState) bool {
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if last.IsImage {
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return false
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}
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var c ast.Node
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for c = last; c != nil; c = c.NextSibling() {
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if _, ok := c.(*ast.Link); ok {
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return true
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}
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}
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return false
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}
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func processLinkLabelOpen(block text.Reader, pos int, isImage bool, pc Context) *linkLabelState {
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start := pos
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if isImage {
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start--
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}
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state := newLinkLabelState(text.NewSegment(start, pos+1), isImage)
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pushLinkLabelState(pc, state)
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block.Advance(1)
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return state
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}
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func (s *linkParser) processLinkLabel(parent ast.Node, link *ast.Link, last *linkLabelState, pc Context) {
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var bottom ast.Node
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if v := pc.Get(linkBottom); v != nil {
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bottom = v.(ast.Node)
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}
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pc.Set(linkBottom, nil)
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ProcessDelimiters(bottom, pc)
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for c := last.NextSibling(); c != nil; {
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next := c.NextSibling()
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parent.RemoveChild(parent, c)
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link.AppendChild(link, c)
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c = next
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}
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}
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func (s *linkParser) parseReferenceLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) (*ast.Link, bool) {
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_, orgpos := block.Position()
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block.Advance(1) // skip '['
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line, segment := block.PeekLine()
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endIndex := util.FindClosure(line, '[', ']', false, true)
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if endIndex < 0 {
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return nil, false
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}
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block.Advance(endIndex + 1)
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ssegment := segment.WithStop(segment.Start + endIndex)
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maybeReference := block.Value(ssegment)
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if util.IsBlank(maybeReference) { // collapsed reference link
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ssegment = text.NewSegment(last.Segment.Stop, orgpos.Start-1)
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maybeReference = block.Value(ssegment)
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}
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ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
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if !ok {
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return nil, true
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}
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link := ast.NewLink()
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s.processLinkLabel(parent, link, last, pc)
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link.Title = ref.Title()
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link.Destination = ref.Destination()
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return link, true
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}
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func (s *linkParser) parseLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) *ast.Link {
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block.Advance(1) // skip '('
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block.SkipSpaces()
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var title []byte
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var destination []byte
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var ok bool
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if block.Peek() == ')' { // empty link like '[link]()'
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block.Advance(1)
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} else {
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destination, ok = parseLinkDestination(block)
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if !ok {
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return nil
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}
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block.SkipSpaces()
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if block.Peek() == ')' {
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block.Advance(1)
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} else {
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title, ok = parseLinkTitle(block)
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if !ok {
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return nil
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}
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block.SkipSpaces()
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if block.Peek() == ')' {
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block.Advance(1)
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} else {
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return nil
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}
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}
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}
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link := ast.NewLink()
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s.processLinkLabel(parent, link, last, pc)
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link.Destination = destination
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link.Title = title
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return link
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}
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func parseLinkDestination(block text.Reader) ([]byte, bool) {
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block.SkipSpaces()
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line, _ := block.PeekLine()
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buf := []byte{}
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if block.Peek() == '<' {
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i := 1
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for i < len(line) {
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c := line[i]
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if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
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buf = append(buf, '\\', line[i+1])
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i += 2
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continue
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} else if c == '>' {
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block.Advance(i + 1)
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return line[1:i], true
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}
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buf = append(buf, c)
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i++
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}
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return nil, false
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}
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opened := 0
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i := 0
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for i < len(line) {
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c := line[i]
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if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
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buf = append(buf, '\\', line[i+1])
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i += 2
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continue
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} else if c == '(' {
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opened++
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} else if c == ')' {
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opened--
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if opened < 0 {
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break
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}
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} else if util.IsSpace(c) {
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break
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}
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buf = append(buf, c)
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i++
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}
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block.Advance(i)
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return line[:i], len(line[:i]) != 0
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}
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func parseLinkTitle(block text.Reader) ([]byte, bool) {
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block.SkipSpaces()
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opener := block.Peek()
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if opener != '"' && opener != '\'' && opener != '(' {
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return nil, false
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}
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closer := opener
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if opener == '(' {
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closer = ')'
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}
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savedLine, savedPosition := block.Position()
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var title []byte
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for i := 0; ; i++ {
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line, _ := block.PeekLine()
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if line == nil {
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block.SetPosition(savedLine, savedPosition)
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return nil, false
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}
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offset := 0
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if i == 0 {
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offset = 1
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}
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pos := util.FindClosure(line[offset:], opener, closer, false, true)
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if pos < 0 {
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title = append(title, line[offset:]...)
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block.AdvanceLine()
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continue
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}
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pos += offset + 1 // 1: closer
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block.Advance(pos)
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if i == 0 { // avoid allocating new slice
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return line[offset : pos-1], true
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}
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return append(title, line[offset:pos-1]...), true
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}
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}
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func (s *linkParser) CloseBlock(parent ast.Node, block text.Reader, pc Context) {
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tlist := pc.Get(linkLabelStateKey)
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if tlist == nil {
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return
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}
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for s := tlist.(*linkLabelState); s != nil; {
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next := s.Next
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removeLinkLabelState(pc, s)
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s.Parent().ReplaceChild(s.Parent(), s, ast.NewTextSegment(s.Segment))
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s = next
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}
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}
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