gotosocial/vendor/github.com/yuin/goldmark/parser/link.go
Autumn! eb08529f35
[chore/bugfix] Switch markdown from blackfriday to goldmark (#1267)
Co-authored-by: Autumn! <autumnull@posteo.net>
2022-12-16 12:20:22 +01:00

409 lines
9.1 KiB
Go

package parser
import (
"fmt"
"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 linkLabelStateLength(v *linkLabelState) int {
if v == nil || v.Last == nil || v.First == nil {
return 0
}
return v.Last.Segment.Stop - v.First.Segment.Start
}
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 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)
// CommonMark spec says:
// > A link label can have at most 999 characters inside the square brackets.
if linkLabelStateLength(tlist.(*linkLabelState)) > 998 {
ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
return nil
}
if !last.IsImage && 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)
// CommonMark spec says:
// > A link label can have at most 999 characters inside the square brackets.
if len(maybeReference) > 999 {
ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
return nil
}
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(n ast.Node) bool {
if n == nil {
return false
}
for c := n; c != nil; c = c.NextSibling() {
if _, ok := c.(*ast.Link); ok {
return true
}
if s.containsLink(c.FirstChild()) {
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
}
}
var linkFindClosureOptions text.FindClosureOptions = text.FindClosureOptions{
Nesting: false,
Newline: true,
Advance: true,
}
func (s *linkParser) parseReferenceLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) (*ast.Link, bool) {
_, orgpos := block.Position()
block.Advance(1) // skip '['
segments, found := block.FindClosure('[', ']', linkFindClosureOptions)
if !found {
return nil, false
}
var maybeReference []byte
if segments.Len() == 1 { // avoid allocate a new byte slice
maybeReference = block.Value(segments.At(0))
} else {
maybeReference = []byte{}
for i := 0; i < segments.Len(); i++ {
s := segments.At(i)
maybeReference = append(maybeReference, block.Value(s)...)
}
}
if util.IsBlank(maybeReference) { // collapsed reference link
s := text.NewSegment(last.Segment.Stop, orgpos.Start-1)
maybeReference = block.Value(s)
}
// CommonMark spec says:
// > A link label can have at most 999 characters inside the square brackets.
if len(maybeReference) > 999 {
return nil, true
}
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()
if block.Peek() == '<' {
i := 1
for i < len(line) {
c := line[i]
if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
i += 2
continue
} else if c == '>' {
block.Advance(i + 1)
return line[1:i], true
}
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]) {
i += 2
continue
} else if c == '(' {
opened++
} else if c == ')' {
opened--
if opened < 0 {
break
}
} else if util.IsSpace(c) {
break
}
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 = ')'
}
block.Advance(1)
segments, found := block.FindClosure(opener, closer, linkFindClosureOptions)
if found {
if segments.Len() == 1 {
return block.Value(segments.At(0)), true
}
var title []byte
for i := 0; i < segments.Len(); i++ {
s := segments.At(i)
title = append(title, block.Value(s)...)
}
return title, true
}
return nil, false
}
func (s *linkParser) CloseBlock(parent ast.Node, block text.Reader, pc Context) {
pc.Set(linkBottom, nil)
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
}
}