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

544 lines
11 KiB
Go
Vendored

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.segments.Len() < 1 {
return rune('\n')
}
firstSegment := r.segments.At(0)
if r.line == 0 && r.pos.Start <= firstSegment.Start {
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
}