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