forgejo/vendor/github.com/yuin/goldmark/text/reader.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

540 lines
11 KiB
Go

package text
import (
"io"
"regexp"
"unicode/utf8"
"github.com/yuin/goldmark/util"
)
const invalidValue = -1
// EOF indicates the end of file.
const EOF = byte(0xff)
// A Reader interface provides abstracted method for reading text.
type Reader interface {
io.RuneReader
// Source returns a source of the reader.
Source() []byte
// ResetPosition resets positions.
ResetPosition()
// Peek returns a byte at current position without advancing the internal pointer.
Peek() byte
// PeekLine returns the current line without advancing the internal pointer.
PeekLine() ([]byte, Segment)
// PrecendingCharacter returns a character just before current internal pointer.
PrecendingCharacter() rune
// Value returns a value of the given segment.
Value(Segment) []byte
// LineOffset returns a distance from the line head to current position.
LineOffset() int
// Position returns current line number and position.
Position() (int, Segment)
// SetPosition sets current line number and position.
SetPosition(int, Segment)
// SetPadding sets padding to the reader.
SetPadding(int)
// Advance advances the internal pointer.
Advance(int)
// AdvanceAndSetPadding advances the internal pointer and add padding to the
// reader.
AdvanceAndSetPadding(int, int)
// AdvanceLine advances the internal pointer to the next line head.
AdvanceLine()
// SkipSpaces skips space characters and returns a non-blank line.
// If it reaches EOF, returns false.
SkipSpaces() (Segment, int, bool)
// SkipSpaces skips blank lines and returns a non-blank line.
// If it reaches EOF, returns false.
SkipBlankLines() (Segment, int, bool)
// Match performs regular expression matching to current line.
Match(reg *regexp.Regexp) bool
// Match performs regular expression searching to current line.
FindSubMatch(reg *regexp.Regexp) [][]byte
}
type reader struct {
source []byte
sourceLength int
line int
peekedLine []byte
pos Segment
head int
lineOffset int
}
// NewReader return a new Reader that can read UTF-8 bytes .
func NewReader(source []byte) Reader {
r := &reader{
source: source,
sourceLength: len(source),
}
r.ResetPosition()
return r
}
func (r *reader) ResetPosition() {
r.line = -1
r.head = 0
r.lineOffset = -1
r.AdvanceLine()
}
func (r *reader) Source() []byte {
return r.source
}
func (r *reader) Value(seg Segment) []byte {
return seg.Value(r.source)
}
func (r *reader) Peek() byte {
if r.pos.Start >= 0 && r.pos.Start < r.sourceLength {
if r.pos.Padding != 0 {
return space[0]
}
return r.source[r.pos.Start]
}
return EOF
}
func (r *reader) PeekLine() ([]byte, Segment) {
if r.pos.Start >= 0 && r.pos.Start < r.sourceLength {
if r.peekedLine == nil {
r.peekedLine = r.pos.Value(r.Source())
}
return r.peekedLine, r.pos
}
return nil, r.pos
}
// io.RuneReader interface
func (r *reader) ReadRune() (rune, int, error) {
return readRuneReader(r)
}
func (r *reader) LineOffset() int {
if r.lineOffset < 0 {
v := 0
for i := r.head; i < r.pos.Start; i++ {
if r.source[i] == '\t' {
v += util.TabWidth(v)
} else {
v++
}
}
r.lineOffset = v - r.pos.Padding
}
return r.lineOffset
}
func (r *reader) PrecendingCharacter() rune {
if r.pos.Start <= 0 {
if r.pos.Padding != 0 {
return rune(' ')
}
return rune('\n')
}
i := r.pos.Start - 1
for ; i >= 0; i-- {
if utf8.RuneStart(r.source[i]) {
break
}
}
rn, _ := utf8.DecodeRune(r.source[i:])
return rn
}
func (r *reader) Advance(n int) {
r.lineOffset = -1
if n < len(r.peekedLine) && r.pos.Padding == 0 {
r.pos.Start += n
r.peekedLine = nil
return
}
r.peekedLine = nil
l := r.sourceLength
for ; n > 0 && r.pos.Start < l; n-- {
if r.pos.Padding != 0 {
r.pos.Padding--
continue
}
if r.source[r.pos.Start] == '\n' {
r.AdvanceLine()
continue
}
r.pos.Start++
}
}
func (r *reader) AdvanceAndSetPadding(n, padding int) {
r.Advance(n)
if padding > r.pos.Padding {
r.SetPadding(padding)
}
}
func (r *reader) AdvanceLine() {
r.lineOffset = -1
r.peekedLine = nil
r.pos.Start = r.pos.Stop
r.head = r.pos.Start
if r.pos.Start < 0 {
return
}
r.pos.Stop = r.sourceLength
for i := r.pos.Start; i < r.sourceLength; i++ {
c := r.source[i]
if c == '\n' {
r.pos.Stop = i + 1
break
}
}
r.line++
r.pos.Padding = 0
}
func (r *reader) Position() (int, Segment) {
return r.line, r.pos
}
func (r *reader) SetPosition(line int, pos Segment) {
r.lineOffset = -1
r.line = line
r.pos = pos
}
func (r *reader) SetPadding(v int) {
r.pos.Padding = v
}
func (r *reader) SkipSpaces() (Segment, int, bool) {
return skipSpacesReader(r)
}
func (r *reader) SkipBlankLines() (Segment, int, bool) {
return skipBlankLinesReader(r)
}
func (r *reader) Match(reg *regexp.Regexp) bool {
return matchReader(r, reg)
}
func (r *reader) FindSubMatch(reg *regexp.Regexp) [][]byte {
return findSubMatchReader(r, reg)
}
// A BlockReader interface is a reader that is optimized for Blocks.
type BlockReader interface {
Reader
// Reset resets current state and sets new segments to the reader.
Reset(segment *Segments)
}
type blockReader struct {
source []byte
segments *Segments
segmentsLength int
line int
pos Segment
head int
last int
lineOffset int
}
// NewBlockReader returns a new BlockReader.
func NewBlockReader(source []byte, segments *Segments) BlockReader {
r := &blockReader{
source: source,
}
if segments != nil {
r.Reset(segments)
}
return r
}
func (r *blockReader) ResetPosition() {
r.line = -1
r.head = 0
r.last = 0
r.lineOffset = -1
r.pos.Start = -1
r.pos.Stop = -1
r.pos.Padding = 0
if r.segmentsLength > 0 {
last := r.segments.At(r.segmentsLength - 1)
r.last = last.Stop
}
r.AdvanceLine()
}
func (r *blockReader) Reset(segments *Segments) {
r.segments = segments
r.segmentsLength = segments.Len()
r.ResetPosition()
}
func (r *blockReader) Source() []byte {
return r.source
}
func (r *blockReader) Value(seg Segment) []byte {
line := r.segmentsLength - 1
ret := make([]byte, 0, seg.Stop-seg.Start+1)
for ; line >= 0; line-- {
if seg.Start >= r.segments.At(line).Start {
break
}
}
i := seg.Start
for ; line < r.segmentsLength; line++ {
s := r.segments.At(line)
if i < 0 {
i = s.Start
}
ret = s.ConcatPadding(ret)
for ; i < seg.Stop && i < s.Stop; i++ {
ret = append(ret, r.source[i])
}
i = -1
if s.Stop > seg.Stop {
break
}
}
return ret
}
// io.RuneReader interface
func (r *blockReader) ReadRune() (rune, int, error) {
return readRuneReader(r)
}
func (r *blockReader) PrecendingCharacter() rune {
if r.pos.Padding != 0 {
return rune(' ')
}
if r.pos.Start <= 0 {
return rune('\n')
}
l := len(r.source)
i := r.pos.Start - 1
for ; i < l && i >= 0; i-- {
if utf8.RuneStart(r.source[i]) {
break
}
}
if i < 0 || i >= l {
return rune('\n')
}
rn, _ := utf8.DecodeRune(r.source[i:])
return rn
}
func (r *blockReader) LineOffset() int {
if r.lineOffset < 0 {
v := 0
for i := r.head; i < r.pos.Start; i++ {
if r.source[i] == '\t' {
v += util.TabWidth(v)
} else {
v++
}
}
r.lineOffset = v - r.pos.Padding
}
return r.lineOffset
}
func (r *blockReader) Peek() byte {
if r.line < r.segmentsLength && r.pos.Start >= 0 && r.pos.Start < r.last {
if r.pos.Padding != 0 {
return space[0]
}
return r.source[r.pos.Start]
}
return EOF
}
func (r *blockReader) PeekLine() ([]byte, Segment) {
if r.line < r.segmentsLength && r.pos.Start >= 0 && r.pos.Start < r.last {
return r.pos.Value(r.source), r.pos
}
return nil, r.pos
}
func (r *blockReader) Advance(n int) {
r.lineOffset = -1
if n < r.pos.Stop-r.pos.Start && r.pos.Padding == 0 {
r.pos.Start += n
return
}
for ; n > 0; n-- {
if r.pos.Padding != 0 {
r.pos.Padding--
continue
}
if r.pos.Start >= r.pos.Stop-1 && r.pos.Stop < r.last {
r.AdvanceLine()
continue
}
r.pos.Start++
}
}
func (r *blockReader) AdvanceAndSetPadding(n, padding int) {
r.Advance(n)
if padding > r.pos.Padding {
r.SetPadding(padding)
}
}
func (r *blockReader) AdvanceLine() {
r.SetPosition(r.line+1, NewSegment(invalidValue, invalidValue))
r.head = r.pos.Start
}
func (r *blockReader) Position() (int, Segment) {
return r.line, r.pos
}
func (r *blockReader) SetPosition(line int, pos Segment) {
r.lineOffset = -1
r.line = line
if pos.Start == invalidValue {
if r.line < r.segmentsLength {
s := r.segments.At(line)
r.head = s.Start
r.pos = s
}
} else {
r.pos = pos
if r.line < r.segmentsLength {
s := r.segments.At(line)
r.head = s.Start
}
}
}
func (r *blockReader) SetPadding(v int) {
r.lineOffset = -1
r.pos.Padding = v
}
func (r *blockReader) SkipSpaces() (Segment, int, bool) {
return skipSpacesReader(r)
}
func (r *blockReader) SkipBlankLines() (Segment, int, bool) {
return skipBlankLinesReader(r)
}
func (r *blockReader) Match(reg *regexp.Regexp) bool {
return matchReader(r, reg)
}
func (r *blockReader) FindSubMatch(reg *regexp.Regexp) [][]byte {
return findSubMatchReader(r, reg)
}
func skipBlankLinesReader(r Reader) (Segment, int, bool) {
lines := 0
for {
line, seg := r.PeekLine()
if line == nil {
return seg, lines, false
}
if util.IsBlank(line) {
lines++
r.AdvanceLine()
} else {
return seg, lines, true
}
}
}
func skipSpacesReader(r Reader) (Segment, int, bool) {
chars := 0
for {
line, segment := r.PeekLine()
if line == nil {
return segment, chars, false
}
for i, c := range line {
if util.IsSpace(c) {
chars++
r.Advance(1)
continue
}
return segment.WithStart(segment.Start + i + 1), chars, true
}
}
}
func matchReader(r Reader, reg *regexp.Regexp) bool {
oldline, oldseg := r.Position()
match := reg.FindReaderSubmatchIndex(r)
r.SetPosition(oldline, oldseg)
if match == nil {
return false
}
r.Advance(match[1] - match[0])
return true
}
func findSubMatchReader(r Reader, reg *regexp.Regexp) [][]byte {
oldline, oldseg := r.Position()
match := reg.FindReaderSubmatchIndex(r)
r.SetPosition(oldline, oldseg)
if match == nil {
return nil
}
runes := make([]rune, 0, match[1]-match[0])
for i := 0; i < match[1]; {
r, size, _ := readRuneReader(r)
i += size
runes = append(runes, r)
}
result := [][]byte{}
for i := 0; i < len(match); i += 2 {
result = append(result, []byte(string(runes[match[i]:match[i+1]])))
}
r.SetPosition(oldline, oldseg)
r.Advance(match[1] - match[0])
return result
}
func readRuneReader(r Reader) (rune, int, error) {
line, _ := r.PeekLine()
if line == nil {
return 0, 0, io.EOF
}
rn, size := utf8.DecodeRune(line)
if rn == utf8.RuneError {
return 0, 0, io.EOF
}
r.Advance(size)
return rn, size, nil
}