gitea/vendor/github.com/yuin/goldmark/parser/link.go
zeripath 27757714d0 Change markdown rendering from blackfriday to goldmark (#9533)
* Move to goldmark

Markdown rendering moved from blackfriday to the goldmark.

Multiple subtle changes required to the goldmark extensions to keep
current rendering and defaults.

Can go further with goldmark linkify and have this work within markdown
rendering making the link processor unnecessary.

Need to think about how to go about allowing extensions - at present it
seems that these would be hard to do without recompilation.

* linter fixes

Co-authored-by: Lauris BH <lauris@nix.lv>
2019-12-31 03:53:28 +02:00

376 lines
8.3 KiB
Go

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
}
labelValue := block.Value(text.NewSegment(last.Segment.Start+1, segment.Start))
if util.IsBlank(labelValue) && !last.IsImage {
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 = ')'
}
line, _ := block.PeekLine()
pos := util.FindClosure(line[1:], opener, closer, false, true)
if pos < 0 {
return nil, false
}
pos += 2 // opener + closer
block.Advance(pos)
return line[1 : 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
}
}