forgejo/vendor/github.com/yuin/goldmark/parser/link.go
2020-02-28 13:06:10 +00:00

388 lines
8.5 KiB
Go
Vendored

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