block.go (view raw)
1//
2// Blackfriday Markdown Processor
3// Available at http://github.com/russross/blackfriday
4//
5// Copyright © 2011 Russ Ross <russ@russross.com>.
6// Distributed under the Simplified BSD License.
7// See README.md for details.
8//
9
10//
11// Functions to parse block-level elements.
12//
13
14package blackfriday
15
16import (
17 "bytes"
18
19 "github.com/shurcooL/sanitized_anchor_name"
20)
21
22// Parse block-level data.
23// Note: this function and many that it calls assume that
24// the input buffer ends with a newline.
25func (p *parser) block(data []byte) {
26 if len(data) == 0 || data[len(data)-1] != '\n' {
27 panic("block input is missing terminating newline")
28 }
29
30 // this is called recursively: enforce a maximum depth
31 if p.nesting >= p.maxNesting {
32 return
33 }
34 p.nesting++
35
36 // parse out one block-level construct at a time
37 for len(data) > 0 {
38 // prefixed header:
39 //
40 // # Header 1
41 // ## Header 2
42 // ...
43 // ###### Header 6
44 if p.isPrefixHeader(data) {
45 data = data[p.prefixHeader(data):]
46 continue
47 }
48
49 // block of preformatted HTML:
50 //
51 // <div>
52 // ...
53 // </div>
54 if data[0] == '<' {
55 if i := p.html(data, true); i > 0 {
56 data = data[i:]
57 continue
58 }
59 }
60
61 // title block
62 //
63 // % stuff
64 // % more stuff
65 // % even more stuff
66 if p.flags&Titleblock != 0 {
67 if data[0] == '%' {
68 if i := p.titleBlock(data, true); i > 0 {
69 data = data[i:]
70 continue
71 }
72 }
73 }
74
75 // blank lines. note: returns the # of bytes to skip
76 if i := p.isEmpty(data); i > 0 {
77 data = data[i:]
78 continue
79 }
80
81 // indented code block:
82 //
83 // func max(a, b int) int {
84 // if a > b {
85 // return a
86 // }
87 // return b
88 // }
89 if p.codePrefix(data) > 0 {
90 data = data[p.code(data):]
91 continue
92 }
93
94 // fenced code block:
95 //
96 // ``` go
97 // func fact(n int) int {
98 // if n <= 1 {
99 // return n
100 // }
101 // return n * fact(n-1)
102 // }
103 // ```
104 if p.flags&FencedCode != 0 {
105 if i := p.fencedCode(data, true); i > 0 {
106 data = data[i:]
107 continue
108 }
109 }
110
111 // horizontal rule:
112 //
113 // ------
114 // or
115 // ******
116 // or
117 // ______
118 if p.isHRule(data) {
119 p.r.HRule()
120 var i int
121 for i = 0; data[i] != '\n'; i++ {
122 }
123 data = data[i:]
124 continue
125 }
126
127 // block quote:
128 //
129 // > A big quote I found somewhere
130 // > on the web
131 if p.quotePrefix(data) > 0 {
132 data = data[p.quote(data):]
133 continue
134 }
135
136 // table:
137 //
138 // Name | Age | Phone
139 // ------|-----|---------
140 // Bob | 31 | 555-1234
141 // Alice | 27 | 555-4321
142 if p.flags&Tables != 0 {
143 if i := p.table(data); i > 0 {
144 data = data[i:]
145 continue
146 }
147 }
148
149 // an itemized/unordered list:
150 //
151 // * Item 1
152 // * Item 2
153 //
154 // also works with + or -
155 if p.uliPrefix(data) > 0 {
156 data = data[p.list(data, 0):]
157 continue
158 }
159
160 // a numbered/ordered list:
161 //
162 // 1. Item 1
163 // 2. Item 2
164 if p.oliPrefix(data) > 0 {
165 data = data[p.list(data, ListTypeOrdered):]
166 continue
167 }
168
169 // definition lists:
170 //
171 // Term 1
172 // : Definition a
173 // : Definition b
174 //
175 // Term 2
176 // : Definition c
177 if p.flags&DefinitionLists != 0 {
178 if p.dliPrefix(data) > 0 {
179 data = data[p.list(data, ListTypeDefinition):]
180 continue
181 }
182 }
183
184 // anything else must look like a normal paragraph
185 // note: this finds underlined headers, too
186 data = data[p.paragraph(data):]
187 }
188
189 p.nesting--
190}
191
192func (p *parser) isPrefixHeader(data []byte) bool {
193 if data[0] != '#' {
194 return false
195 }
196
197 if p.flags&SpaceHeaders != 0 {
198 level := 0
199 for level < 6 && data[level] == '#' {
200 level++
201 }
202 if data[level] != ' ' {
203 return false
204 }
205 }
206 return true
207}
208
209func (p *parser) prefixHeader(data []byte) int {
210 level := 0
211 for level < 6 && data[level] == '#' {
212 level++
213 }
214 i := skipChar(data, level, ' ')
215 end := skipUntilChar(data, i, '\n')
216 skip := end
217 id := ""
218 if p.flags&HeaderIDs != 0 {
219 j, k := 0, 0
220 // find start/end of header id
221 for j = i; j < end-1 && (data[j] != '{' || data[j+1] != '#'); j++ {
222 }
223 for k = j + 1; k < end && data[k] != '}'; k++ {
224 }
225 // extract header id iff found
226 if j < end && k < end {
227 id = string(data[j+2 : k])
228 end = j
229 skip = k + 1
230 for end > 0 && data[end-1] == ' ' {
231 end--
232 }
233 }
234 }
235 for end > 0 && data[end-1] == '#' {
236 if isBackslashEscaped(data, end-1) {
237 break
238 }
239 end--
240 }
241 for end > 0 && data[end-1] == ' ' {
242 end--
243 }
244 if end > i {
245 if id == "" && p.flags&AutoHeaderIDs != 0 {
246 id = sanitized_anchor_name.Create(string(data[i:end]))
247 }
248 p.r.BeginHeader(level, id)
249 header := p.r.CopyWrites(func() {
250 p.inline(data[i:end])
251 })
252 p.r.EndHeader(level, id, header)
253 }
254 return skip
255}
256
257func (p *parser) isUnderlinedHeader(data []byte) int {
258 // test of level 1 header
259 if data[0] == '=' {
260 i := skipChar(data, 1, '=')
261 i = skipChar(data, i, ' ')
262 if data[i] == '\n' {
263 return 1
264 } else {
265 return 0
266 }
267 }
268
269 // test of level 2 header
270 if data[0] == '-' {
271 i := skipChar(data, 1, '-')
272 i = skipChar(data, i, ' ')
273 if data[i] == '\n' {
274 return 2
275 } else {
276 return 0
277 }
278 }
279
280 return 0
281}
282
283func (p *parser) titleBlock(data []byte, doRender bool) int {
284 if data[0] != '%' {
285 return 0
286 }
287 splitData := bytes.Split(data, []byte("\n"))
288 var i int
289 for idx, b := range splitData {
290 if !bytes.HasPrefix(b, []byte("%")) {
291 i = idx // - 1
292 break
293 }
294 }
295
296 data = bytes.Join(splitData[0:i], []byte("\n"))
297 p.r.TitleBlock(data)
298
299 return len(data)
300}
301
302func (p *parser) html(data []byte, doRender bool) int {
303 var i, j int
304
305 // identify the opening tag
306 if data[0] != '<' {
307 return 0
308 }
309 curtag, tagfound := p.htmlFindTag(data[1:])
310
311 // handle special cases
312 if !tagfound {
313 // check for an HTML comment
314 if size := p.htmlComment(data, doRender); size > 0 {
315 return size
316 }
317
318 // check for an <hr> tag
319 if size := p.htmlHr(data, doRender); size > 0 {
320 return size
321 }
322
323 // no special case recognized
324 return 0
325 }
326
327 // look for an unindented matching closing tag
328 // followed by a blank line
329 found := false
330 /*
331 closetag := []byte("\n</" + curtag + ">")
332 j = len(curtag) + 1
333 for !found {
334 // scan for a closing tag at the beginning of a line
335 if skip := bytes.Index(data[j:], closetag); skip >= 0 {
336 j += skip + len(closetag)
337 } else {
338 break
339 }
340
341 // see if it is the only thing on the line
342 if skip := p.isEmpty(data[j:]); skip > 0 {
343 // see if it is followed by a blank line/eof
344 j += skip
345 if j >= len(data) {
346 found = true
347 i = j
348 } else {
349 if skip := p.isEmpty(data[j:]); skip > 0 {
350 j += skip
351 found = true
352 i = j
353 }
354 }
355 }
356 }
357 */
358
359 // if not found, try a second pass looking for indented match
360 // but not if tag is "ins" or "del" (following original Markdown.pl)
361 if !found && curtag != "ins" && curtag != "del" {
362 i = 1
363 for i < len(data) {
364 i++
365 for i < len(data) && !(data[i-1] == '<' && data[i] == '/') {
366 i++
367 }
368
369 if i+2+len(curtag) >= len(data) {
370 break
371 }
372
373 j = p.htmlFindEnd(curtag, data[i-1:])
374
375 if j > 0 {
376 i += j - 1
377 found = true
378 break
379 }
380 }
381 }
382
383 if !found {
384 return 0
385 }
386
387 // the end of the block has been found
388 if doRender {
389 // trim newlines
390 end := i
391 for end > 0 && data[end-1] == '\n' {
392 end--
393 }
394 p.r.BlockHtml(data[:end])
395 }
396
397 return i
398}
399
400// HTML comment, lax form
401func (p *parser) htmlComment(data []byte, doRender bool) int {
402 i := p.inlineHtmlComment(data)
403 // needs to end with a blank line
404 if j := p.isEmpty(data[i:]); j > 0 {
405 size := i + j
406 if doRender {
407 // trim trailing newlines
408 end := size
409 for end > 0 && data[end-1] == '\n' {
410 end--
411 }
412 p.r.BlockHtml(data[:end])
413 }
414 return size
415 }
416 return 0
417}
418
419// HR, which is the only self-closing block tag considered
420func (p *parser) htmlHr(data []byte, doRender bool) int {
421 if data[0] != '<' || (data[1] != 'h' && data[1] != 'H') || (data[2] != 'r' && data[2] != 'R') {
422 return 0
423 }
424 if data[3] != ' ' && data[3] != '/' && data[3] != '>' {
425 // not an <hr> tag after all; at least not a valid one
426 return 0
427 }
428
429 i := 3
430 for data[i] != '>' && data[i] != '\n' {
431 i++
432 }
433
434 if data[i] == '>' {
435 i++
436 if j := p.isEmpty(data[i:]); j > 0 {
437 size := i + j
438 if doRender {
439 // trim newlines
440 end := size
441 for end > 0 && data[end-1] == '\n' {
442 end--
443 }
444 p.r.BlockHtml(data[:end])
445 }
446 return size
447 }
448 }
449
450 return 0
451}
452
453func (p *parser) htmlFindTag(data []byte) (string, bool) {
454 i := 0
455 for isalnum(data[i]) {
456 i++
457 }
458 key := string(data[:i])
459 if _, ok := blockTags[key]; ok {
460 return key, true
461 }
462 return "", false
463}
464
465func (p *parser) htmlFindEnd(tag string, data []byte) int {
466 // assume data[0] == '<' && data[1] == '/' already tested
467
468 // check if tag is a match
469 closetag := []byte("</" + tag + ">")
470 if !bytes.HasPrefix(data, closetag) {
471 return 0
472 }
473 i := len(closetag)
474
475 // check that the rest of the line is blank
476 skip := 0
477 if skip = p.isEmpty(data[i:]); skip == 0 {
478 return 0
479 }
480 i += skip
481 skip = 0
482
483 if i >= len(data) {
484 return i
485 }
486
487 if p.flags&LaxHTMLBlocks != 0 {
488 return i
489 }
490 if skip = p.isEmpty(data[i:]); skip == 0 {
491 // following line must be blank
492 return 0
493 }
494
495 return i + skip
496}
497
498func (p *parser) isEmpty(data []byte) int {
499 // it is okay to call isEmpty on an empty buffer
500 if len(data) == 0 {
501 return 0
502 }
503
504 var i int
505 for i = 0; i < len(data) && data[i] != '\n'; i++ {
506 if data[i] != ' ' && data[i] != '\t' {
507 return 0
508 }
509 }
510 return i + 1
511}
512
513func (p *parser) isHRule(data []byte) bool {
514 i := 0
515
516 // skip up to three spaces
517 for i < 3 && data[i] == ' ' {
518 i++
519 }
520
521 // look at the hrule char
522 if data[i] != '*' && data[i] != '-' && data[i] != '_' {
523 return false
524 }
525 c := data[i]
526
527 // the whole line must be the char or whitespace
528 n := 0
529 for data[i] != '\n' {
530 switch {
531 case data[i] == c:
532 n++
533 case data[i] != ' ':
534 return false
535 }
536 i++
537 }
538
539 return n >= 3
540}
541
542func (p *parser) isFencedCode(data []byte, syntax **string, oldmarker string) (skip int, marker string) {
543 i, size := 0, 0
544 skip = 0
545
546 // skip up to three spaces
547 for i < len(data) && i < 3 && data[i] == ' ' {
548 i++
549 }
550 if i >= len(data) {
551 return
552 }
553
554 // check for the marker characters: ~ or `
555 if data[i] != '~' && data[i] != '`' {
556 return
557 }
558
559 c := data[i]
560
561 // the whole line must be the same char or whitespace
562 for i < len(data) && data[i] == c {
563 size++
564 i++
565 }
566
567 if i >= len(data) {
568 return
569 }
570
571 // the marker char must occur at least 3 times
572 if size < 3 {
573 return
574 }
575 marker = string(data[i-size : i])
576
577 // if this is the end marker, it must match the beginning marker
578 if oldmarker != "" && marker != oldmarker {
579 return
580 }
581
582 if syntax != nil {
583 syn := 0
584 i = skipChar(data, i, ' ')
585
586 if i >= len(data) {
587 return
588 }
589
590 syntaxStart := i
591
592 if data[i] == '{' {
593 i++
594 syntaxStart++
595
596 for i < len(data) && data[i] != '}' && data[i] != '\n' {
597 syn++
598 i++
599 }
600
601 if i >= len(data) || data[i] != '}' {
602 return
603 }
604
605 // strip all whitespace at the beginning and the end
606 // of the {} block
607 for syn > 0 && isspace(data[syntaxStart]) {
608 syntaxStart++
609 syn--
610 }
611
612 for syn > 0 && isspace(data[syntaxStart+syn-1]) {
613 syn--
614 }
615
616 i++
617 } else {
618 for i < len(data) && !isspace(data[i]) {
619 syn++
620 i++
621 }
622 }
623
624 language := string(data[syntaxStart : syntaxStart+syn])
625 *syntax = &language
626 }
627
628 i = skipChar(data, i, ' ')
629 if i >= len(data) || data[i] != '\n' {
630 return
631 }
632
633 skip = i + 1
634 return
635}
636
637func (p *parser) fencedCode(data []byte, doRender bool) int {
638 var lang *string
639 beg, marker := p.isFencedCode(data, &lang, "")
640 if beg == 0 || beg >= len(data) {
641 return 0
642 }
643
644 var work bytes.Buffer
645
646 for {
647 // safe to assume beg < len(data)
648
649 // check for the end of the code block
650 fenceEnd, _ := p.isFencedCode(data[beg:], nil, marker)
651 if fenceEnd != 0 {
652 beg += fenceEnd
653 break
654 }
655
656 // copy the current line
657 end := skipUntilChar(data, beg, '\n') + 1
658
659 // did we reach the end of the buffer without a closing marker?
660 if end >= len(data) {
661 return 0
662 }
663
664 // verbatim copy to the working buffer
665 if doRender {
666 work.Write(data[beg:end])
667 }
668 beg = end
669 }
670
671 syntax := ""
672 if lang != nil {
673 syntax = *lang
674 }
675
676 if doRender {
677 p.r.BlockCode(work.Bytes(), syntax)
678 }
679
680 return beg
681}
682
683func (p *parser) table(data []byte) int {
684 var header bytes.Buffer
685 i, columns := p.tableHeader(&header, data)
686 if i == 0 {
687 return 0
688 }
689
690 var body bytes.Buffer
691
692 for i < len(data) {
693 pipes, rowStart := 0, i
694 for ; data[i] != '\n'; i++ {
695 if data[i] == '|' {
696 pipes++
697 }
698 }
699
700 if pipes == 0 {
701 i = rowStart
702 break
703 }
704
705 // include the newline in data sent to tableRow
706 i++
707 p.tableRow(&body, data[rowStart:i], columns, false)
708 }
709
710 p.r.Table(header.Bytes(), body.Bytes(), columns)
711
712 return i
713}
714
715// check if the specified position is preceded by an odd number of backslashes
716func isBackslashEscaped(data []byte, i int) bool {
717 backslashes := 0
718 for i-backslashes-1 >= 0 && data[i-backslashes-1] == '\\' {
719 backslashes++
720 }
721 return backslashes&1 == 1
722}
723
724func (p *parser) tableHeader(out *bytes.Buffer, data []byte) (size int, columns []int) {
725 i := 0
726 colCount := 1
727 for i = 0; data[i] != '\n'; i++ {
728 if data[i] == '|' && !isBackslashEscaped(data, i) {
729 colCount++
730 }
731 }
732
733 // doesn't look like a table header
734 if colCount == 1 {
735 return
736 }
737
738 // include the newline in the data sent to tableRow
739 header := data[:i+1]
740
741 // column count ignores pipes at beginning or end of line
742 if data[0] == '|' {
743 colCount--
744 }
745 if i > 2 && data[i-1] == '|' && !isBackslashEscaped(data, i-1) {
746 colCount--
747 }
748
749 columns = make([]int, colCount)
750
751 // move on to the header underline
752 i++
753 if i >= len(data) {
754 return
755 }
756
757 if data[i] == '|' && !isBackslashEscaped(data, i) {
758 i++
759 }
760 i = skipChar(data, i, ' ')
761
762 // each column header is of form: / *:?-+:? *|/ with # dashes + # colons >= 3
763 // and trailing | optional on last column
764 col := 0
765 for data[i] != '\n' {
766 dashes := 0
767
768 if data[i] == ':' {
769 i++
770 columns[col] |= TableAlignmentLeft
771 dashes++
772 }
773 for data[i] == '-' {
774 i++
775 dashes++
776 }
777 if data[i] == ':' {
778 i++
779 columns[col] |= TableAlignmentRight
780 dashes++
781 }
782 for data[i] == ' ' {
783 i++
784 }
785
786 // end of column test is messy
787 switch {
788 case dashes < 3:
789 // not a valid column
790 return
791
792 case data[i] == '|' && !isBackslashEscaped(data, i):
793 // marker found, now skip past trailing whitespace
794 col++
795 i++
796 for data[i] == ' ' {
797 i++
798 }
799
800 // trailing junk found after last column
801 if col >= colCount && data[i] != '\n' {
802 return
803 }
804
805 case (data[i] != '|' || isBackslashEscaped(data, i)) && col+1 < colCount:
806 // something else found where marker was required
807 return
808
809 case data[i] == '\n':
810 // marker is optional for the last column
811 col++
812
813 default:
814 // trailing junk found after last column
815 return
816 }
817 }
818 if col != colCount {
819 return
820 }
821
822 p.tableRow(out, header, columns, true)
823 size = i + 1
824 return
825}
826
827func (p *parser) tableRow(out *bytes.Buffer, data []byte, columns []int, header bool) {
828 i, col := 0, 0
829 var rowWork bytes.Buffer
830
831 if data[i] == '|' && !isBackslashEscaped(data, i) {
832 i++
833 }
834
835 for col = 0; col < len(columns) && i < len(data); col++ {
836 for data[i] == ' ' {
837 i++
838 }
839
840 cellStart := i
841
842 for (data[i] != '|' || isBackslashEscaped(data, i)) && data[i] != '\n' {
843 i++
844 }
845
846 cellEnd := i
847
848 // skip the end-of-cell marker, possibly taking us past end of buffer
849 i++
850
851 for cellEnd > cellStart && data[cellEnd-1] == ' ' {
852 cellEnd--
853 }
854
855 cellWork := p.r.CaptureWrites(func() {
856 p.inline(data[cellStart:cellEnd])
857 })
858
859 if header {
860 p.r.TableHeaderCell(&rowWork, cellWork, columns[col])
861 } else {
862 p.r.TableCell(&rowWork, cellWork, columns[col])
863 }
864 }
865
866 // pad it out with empty columns to get the right number
867 for ; col < len(columns); col++ {
868 if header {
869 p.r.TableHeaderCell(&rowWork, nil, columns[col])
870 } else {
871 p.r.TableCell(&rowWork, nil, columns[col])
872 }
873 }
874
875 // silently ignore rows with too many cells
876
877 p.r.TableRow(rowWork.Bytes())
878}
879
880// returns blockquote prefix length
881func (p *parser) quotePrefix(data []byte) int {
882 i := 0
883 for i < 3 && data[i] == ' ' {
884 i++
885 }
886 if data[i] == '>' {
887 if data[i+1] == ' ' {
888 return i + 2
889 }
890 return i + 1
891 }
892 return 0
893}
894
895// blockquote ends with at least one blank line
896// followed by something without a blockquote prefix
897func (p *parser) terminateBlockquote(data []byte, beg, end int) bool {
898 if p.isEmpty(data[beg:]) <= 0 {
899 return false
900 }
901 if end >= len(data) {
902 return true
903 }
904 return p.quotePrefix(data[end:]) == 0 && p.isEmpty(data[end:]) == 0
905}
906
907// parse a blockquote fragment
908func (p *parser) quote(data []byte) int {
909 var raw bytes.Buffer
910 beg, end := 0, 0
911 for beg < len(data) {
912 end = beg
913 // Step over whole lines, collecting them. While doing that, check for
914 // fenced code and if one's found, incorporate it altogether,
915 // irregardless of any contents inside it
916 for data[end] != '\n' {
917 if p.flags&FencedCode != 0 {
918 if i := p.fencedCode(data[end:], false); i > 0 {
919 // -1 to compensate for the extra end++ after the loop:
920 end += i - 1
921 break
922 }
923 }
924 end++
925 }
926 end++
927
928 if pre := p.quotePrefix(data[beg:]); pre > 0 {
929 // skip the prefix
930 beg += pre
931 } else if p.terminateBlockquote(data, beg, end) {
932 break
933 }
934
935 // this line is part of the blockquote
936 raw.Write(data[beg:end])
937 beg = end
938 }
939
940 p.r.BlockQuote(p.r.CaptureWrites(func() {
941 p.block(raw.Bytes())
942 }))
943 return end
944}
945
946// returns prefix length for block code
947func (p *parser) codePrefix(data []byte) int {
948 if data[0] == ' ' && data[1] == ' ' && data[2] == ' ' && data[3] == ' ' {
949 return 4
950 }
951 return 0
952}
953
954func (p *parser) code(data []byte) int {
955 var work bytes.Buffer
956
957 i := 0
958 for i < len(data) {
959 beg := i
960 for data[i] != '\n' {
961 i++
962 }
963 i++
964
965 blankline := p.isEmpty(data[beg:i]) > 0
966 if pre := p.codePrefix(data[beg:i]); pre > 0 {
967 beg += pre
968 } else if !blankline {
969 // non-empty, non-prefixed line breaks the pre
970 i = beg
971 break
972 }
973
974 // verbatim copy to the working buffeu
975 if blankline {
976 work.WriteByte('\n')
977 } else {
978 work.Write(data[beg:i])
979 }
980 }
981
982 // trim all the \n off the end of work
983 workbytes := work.Bytes()
984 eol := len(workbytes)
985 for eol > 0 && workbytes[eol-1] == '\n' {
986 eol--
987 }
988 if eol != len(workbytes) {
989 work.Truncate(eol)
990 }
991
992 work.WriteByte('\n')
993
994 p.r.BlockCode(work.Bytes(), "")
995
996 return i
997}
998
999// returns unordered list item prefix
1000func (p *parser) uliPrefix(data []byte) int {
1001 i := 0
1002
1003 // start with up to 3 spaces
1004 for i < 3 && data[i] == ' ' {
1005 i++
1006 }
1007
1008 // need a *, +, or - followed by a space
1009 if (data[i] != '*' && data[i] != '+' && data[i] != '-') ||
1010 data[i+1] != ' ' {
1011 return 0
1012 }
1013 return i + 2
1014}
1015
1016// returns ordered list item prefix
1017func (p *parser) oliPrefix(data []byte) int {
1018 i := 0
1019
1020 // start with up to 3 spaces
1021 for i < 3 && data[i] == ' ' {
1022 i++
1023 }
1024
1025 // count the digits
1026 start := i
1027 for data[i] >= '0' && data[i] <= '9' {
1028 i++
1029 }
1030
1031 // we need >= 1 digits followed by a dot and a space
1032 if start == i || data[i] != '.' || data[i+1] != ' ' {
1033 return 0
1034 }
1035 return i + 2
1036}
1037
1038// returns definition list item prefix
1039func (p *parser) dliPrefix(data []byte) int {
1040 i := 0
1041
1042 // need a : followed by a spaces
1043 if data[i] != ':' || data[i+1] != ' ' {
1044 return 0
1045 }
1046 for data[i] == ' ' {
1047 i++
1048 }
1049 return i + 2
1050}
1051
1052// parse ordered or unordered list block
1053func (p *parser) list(data []byte, flags ListType) int {
1054 i := 0
1055 flags |= ListItemBeginningOfList
1056 p.r.BeginList(flags)
1057
1058 for i < len(data) {
1059 skip := p.listItem(data[i:], &flags)
1060 i += skip
1061 if skip == 0 || flags&ListItemEndOfList != 0 {
1062 break
1063 }
1064 flags &= ^ListItemBeginningOfList
1065 }
1066
1067 p.r.EndList(flags)
1068 return i
1069}
1070
1071// Parse a single list item.
1072// Assumes initial prefix is already removed if this is a sublist.
1073func (p *parser) listItem(data []byte, flags *ListType) int {
1074 // keep track of the indentation of the first line
1075 itemIndent := 0
1076 for itemIndent < 3 && data[itemIndent] == ' ' {
1077 itemIndent++
1078 }
1079
1080 i := p.uliPrefix(data)
1081 if i == 0 {
1082 i = p.oliPrefix(data)
1083 }
1084 if i == 0 {
1085 i = p.dliPrefix(data)
1086 // reset definition term flag
1087 if i > 0 {
1088 *flags &= ^ListTypeTerm
1089 }
1090 }
1091 if i == 0 {
1092 // if in defnition list, set term flag and continue
1093 if *flags&ListTypeDefinition != 0 {
1094 *flags |= ListTypeTerm
1095 } else {
1096 return 0
1097 }
1098 }
1099
1100 // skip leading whitespace on first line
1101 for data[i] == ' ' {
1102 i++
1103 }
1104
1105 // find the end of the line
1106 line := i
1107 for i > 0 && data[i-1] != '\n' {
1108 i++
1109 }
1110
1111 // get working buffer
1112 var raw bytes.Buffer
1113
1114 // put the first line into the working buffer
1115 raw.Write(data[line:i])
1116 line = i
1117
1118 // process the following lines
1119 containsBlankLine := false
1120 sublist := 0
1121
1122gatherlines:
1123 for line < len(data) {
1124 i++
1125
1126 // find the end of this line
1127 for data[i-1] != '\n' {
1128 i++
1129 }
1130
1131 // if it is an empty line, guess that it is part of this item
1132 // and move on to the next line
1133 if p.isEmpty(data[line:i]) > 0 {
1134 containsBlankLine = true
1135 line = i
1136 continue
1137 }
1138
1139 // calculate the indentation
1140 indent := 0
1141 for indent < 4 && line+indent < i && data[line+indent] == ' ' {
1142 indent++
1143 }
1144
1145 chunk := data[line+indent : i]
1146
1147 // evaluate how this line fits in
1148 switch {
1149 // is this a nested list item?
1150 case (p.uliPrefix(chunk) > 0 && !p.isHRule(chunk)) ||
1151 p.oliPrefix(chunk) > 0 ||
1152 p.dliPrefix(chunk) > 0:
1153
1154 if containsBlankLine {
1155 *flags |= ListItemContainsBlock
1156 }
1157
1158 // to be a nested list, it must be indented more
1159 // if not, it is the next item in the same list
1160 if indent <= itemIndent {
1161 break gatherlines
1162 }
1163
1164 // is this the first item in the nested list?
1165 if sublist == 0 {
1166 sublist = raw.Len()
1167 }
1168
1169 // is this a nested prefix header?
1170 case p.isPrefixHeader(chunk):
1171 // if the header is not indented, it is not nested in the list
1172 // and thus ends the list
1173 if containsBlankLine && indent < 4 {
1174 *flags |= ListItemEndOfList
1175 break gatherlines
1176 }
1177 *flags |= ListItemContainsBlock
1178
1179 // anything following an empty line is only part
1180 // of this item if it is indented 4 spaces
1181 // (regardless of the indentation of the beginning of the item)
1182 case containsBlankLine && indent < 4:
1183 if *flags&ListTypeDefinition != 0 && i < len(data)-1 {
1184 // is the next item still a part of this list?
1185 next := i
1186 for data[next] != '\n' {
1187 next++
1188 }
1189 for next < len(data)-1 && data[next] == '\n' {
1190 next++
1191 }
1192 if i < len(data)-1 && data[i] != ':' && data[next] != ':' {
1193 *flags |= ListItemEndOfList
1194 }
1195 } else {
1196 *flags |= ListItemEndOfList
1197 }
1198 break gatherlines
1199
1200 // a blank line means this should be parsed as a block
1201 case containsBlankLine:
1202 raw.WriteByte('\n')
1203 *flags |= ListItemContainsBlock
1204 }
1205
1206 // if this line was preceeded by one or more blanks,
1207 // re-introduce the blank into the buffer
1208 if containsBlankLine {
1209 containsBlankLine = false
1210 raw.WriteByte('\n')
1211
1212 }
1213
1214 // add the line into the working buffer without prefix
1215 raw.Write(data[line+indent : i])
1216
1217 line = i
1218 }
1219
1220 rawBytes := raw.Bytes()
1221
1222 // render the contents of the list item
1223 var cooked bytes.Buffer
1224 if *flags&ListItemContainsBlock != 0 && *flags&ListTypeTerm == 0 {
1225 // intermediate render of block item, except for definition term
1226 if sublist > 0 {
1227 cooked.Write(p.r.CaptureWrites(func() {
1228 p.block(rawBytes[:sublist])
1229 p.block(rawBytes[sublist:])
1230 }))
1231 } else {
1232 cooked.Write(p.r.CaptureWrites(func() {
1233 p.block(rawBytes)
1234 }))
1235 }
1236 } else {
1237 // intermediate render of inline item
1238 if sublist > 0 {
1239 cooked.Write(p.r.CaptureWrites(func() {
1240 p.inline(rawBytes[:sublist])
1241 p.block(rawBytes[sublist:])
1242 }))
1243 } else {
1244 cooked.Write(p.r.CaptureWrites(func() {
1245 p.inline(rawBytes)
1246 }))
1247 }
1248 }
1249
1250 // render the actual list item
1251 cookedBytes := cooked.Bytes()
1252 parsedEnd := len(cookedBytes)
1253
1254 // strip trailing newlines
1255 for parsedEnd > 0 && cookedBytes[parsedEnd-1] == '\n' {
1256 parsedEnd--
1257 }
1258 p.r.ListItem(cookedBytes[:parsedEnd], *flags)
1259
1260 return line
1261}
1262
1263// render a single paragraph that has already been parsed out
1264func (p *parser) renderParagraph(data []byte) {
1265 if len(data) == 0 {
1266 return
1267 }
1268
1269 // trim leading spaces
1270 beg := 0
1271 for data[beg] == ' ' {
1272 beg++
1273 }
1274
1275 // trim trailing newline
1276 end := len(data) - 1
1277
1278 // trim trailing spaces
1279 for end > beg && data[end-1] == ' ' {
1280 end--
1281 }
1282
1283 p.r.BeginParagraph()
1284 p.inline(data[beg:end])
1285 p.r.EndParagraph()
1286}
1287
1288func (p *parser) paragraph(data []byte) int {
1289 // prev: index of 1st char of previous line
1290 // line: index of 1st char of current line
1291 // i: index of cursor/end of current line
1292 var prev, line, i int
1293
1294 // keep going until we find something to mark the end of the paragraph
1295 for i < len(data) {
1296 // mark the beginning of the current line
1297 prev = line
1298 current := data[i:]
1299 line = i
1300
1301 // did we find a blank line marking the end of the paragraph?
1302 if n := p.isEmpty(current); n > 0 {
1303 // did this blank line followed by a definition list item?
1304 if p.flags&DefinitionLists != 0 {
1305 if i < len(data)-1 && data[i+1] == ':' {
1306 return p.list(data[prev:], ListTypeDefinition)
1307 }
1308 }
1309
1310 p.renderParagraph(data[:i])
1311 return i + n
1312 }
1313
1314 // an underline under some text marks a header, so our paragraph ended on prev line
1315 if i > 0 {
1316 if level := p.isUnderlinedHeader(current); level > 0 {
1317 // render the paragraph
1318 p.renderParagraph(data[:prev])
1319
1320 // ignore leading and trailing whitespace
1321 eol := i - 1
1322 for prev < eol && data[prev] == ' ' {
1323 prev++
1324 }
1325 for eol > prev && data[eol-1] == ' ' {
1326 eol--
1327 }
1328
1329 id := ""
1330 if p.flags&AutoHeaderIDs != 0 {
1331 id = sanitized_anchor_name.Create(string(data[prev:eol]))
1332 }
1333
1334 p.r.BeginHeader(level, id)
1335 header := p.r.CopyWrites(func() {
1336 p.inline(data[prev:eol])
1337 })
1338 p.r.EndHeader(level, id, header)
1339
1340 // find the end of the underline
1341 for data[i] != '\n' {
1342 i++
1343 }
1344 return i
1345 }
1346 }
1347
1348 // if the next line starts a block of HTML, then the paragraph ends here
1349 if p.flags&LaxHTMLBlocks != 0 {
1350 if data[i] == '<' && p.html(current, false) > 0 {
1351 // rewind to before the HTML block
1352 p.renderParagraph(data[:i])
1353 return i
1354 }
1355 }
1356
1357 // if there's a prefixed header or a horizontal rule after this, paragraph is over
1358 if p.isPrefixHeader(current) || p.isHRule(current) {
1359 p.renderParagraph(data[:i])
1360 return i
1361 }
1362
1363 // if there's a fenced code block, paragraph is over
1364 if p.flags&FencedCode != 0 {
1365 if p.fencedCode(current, false) > 0 {
1366 p.renderParagraph(data[:i])
1367 return i
1368 }
1369 }
1370
1371 // if there's a definition list item, prev line is a definition term
1372 if p.flags&DefinitionLists != 0 {
1373 if p.dliPrefix(current) != 0 {
1374 return p.list(data[prev:], ListTypeDefinition)
1375 }
1376 }
1377
1378 // if there's a list after this, paragraph is over
1379 if p.flags&NoEmptyLineBeforeBlock != 0 {
1380 if p.uliPrefix(current) != 0 ||
1381 p.oliPrefix(current) != 0 ||
1382 p.quotePrefix(current) != 0 ||
1383 p.codePrefix(current) != 0 {
1384 p.renderParagraph(data[:i])
1385 return i
1386 }
1387 }
1388
1389 // otherwise, scan to the beginning of the next line
1390 for data[i] != '\n' {
1391 i++
1392 }
1393 i++
1394 }
1395
1396 p.renderParagraph(data[:i])
1397 return i
1398}