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); 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 id := ""
190 if p.flags&EXTENSION_HEADER_IDS != 0 {
191 j, k := 0, 0
192 for j = i; j < end - 1 && data[j] != '{' && data[j+1] != '#'; j++ {
193 }
194 for k = j + 1; k < end && data[k] != '}'; k++ {
195 }
196 if j < end && k < end {
197 id = string(data[j+2:k])
198 end = j
199 }
200 }
201 for end > 0 && data[end-1] == '#' {
202 end--
203 }
204 for end > 0 && data[end-1] == ' ' {
205 end--
206 }
207 if end > i {
208 work := func() bool {
209 p.inline(out, data[i:end])
210 return true
211 }
212 p.r.Header(out, work, level, id)
213 }
214 return skip
215}
216
217func (p *parser) isUnderlinedHeader(data []byte) int {
218 // test of level 1 header
219 if data[0] == '=' {
220 i := 1
221 for data[i] == '=' {
222 i++
223 }
224 for data[i] == ' ' {
225 i++
226 }
227 if data[i] == '\n' {
228 return 1
229 } else {
230 return 0
231 }
232 }
233
234 // test of level 2 header
235 if data[0] == '-' {
236 i := 1
237 for data[i] == '-' {
238 i++
239 }
240 for data[i] == ' ' {
241 i++
242 }
243 if data[i] == '\n' {
244 return 2
245 } else {
246 return 0
247 }
248 }
249
250 return 0
251}
252
253func (p *parser) html(out *bytes.Buffer, data []byte, doRender bool) int {
254 var i, j int
255
256 // identify the opening tag
257 if data[0] != '<' {
258 return 0
259 }
260 curtag, tagfound := p.htmlFindTag(data[1:])
261
262 // handle special cases
263 if !tagfound {
264 // check for an HTML comment
265 if size := p.htmlComment(out, data, doRender); size > 0 {
266 return size
267 }
268
269 // check for an <hr> tag
270 if size := p.htmlHr(out, data, doRender); size > 0 {
271 return size
272 }
273
274 // no special case recognized
275 return 0
276 }
277
278 // look for an unindented matching closing tag
279 // followed by a blank line
280 found := false
281 /*
282 closetag := []byte("\n</" + curtag + ">")
283 j = len(curtag) + 1
284 for !found {
285 // scan for a closing tag at the beginning of a line
286 if skip := bytes.Index(data[j:], closetag); skip >= 0 {
287 j += skip + len(closetag)
288 } else {
289 break
290 }
291
292 // see if it is the only thing on the line
293 if skip := p.isEmpty(data[j:]); skip > 0 {
294 // see if it is followed by a blank line/eof
295 j += skip
296 if j >= len(data) {
297 found = true
298 i = j
299 } else {
300 if skip := p.isEmpty(data[j:]); skip > 0 {
301 j += skip
302 found = true
303 i = j
304 }
305 }
306 }
307 }
308 */
309
310 // if not found, try a second pass looking for indented match
311 // but not if tag is "ins" or "del" (following original Markdown.pl)
312 if !found && curtag != "ins" && curtag != "del" {
313 i = 1
314 for i < len(data) {
315 i++
316 for i < len(data) && !(data[i-1] == '<' && data[i] == '/') {
317 i++
318 }
319
320 if i+2+len(curtag) >= len(data) {
321 break
322 }
323
324 j = p.htmlFindEnd(curtag, data[i-1:])
325
326 if j > 0 {
327 i += j - 1
328 found = true
329 break
330 }
331 }
332 }
333
334 if !found {
335 return 0
336 }
337
338 // the end of the block has been found
339 if doRender {
340 // trim newlines
341 end := i
342 for end > 0 && data[end-1] == '\n' {
343 end--
344 }
345 p.r.BlockHtml(out, data[:end])
346 }
347
348 return i
349}
350
351// HTML comment, lax form
352func (p *parser) htmlComment(out *bytes.Buffer, data []byte, doRender bool) int {
353 if data[0] != '<' || data[1] != '!' || data[2] != '-' || data[3] != '-' {
354 return 0
355 }
356
357 i := 5
358
359 // scan for an end-of-comment marker, across lines if necessary
360 for i < len(data) && !(data[i-2] == '-' && data[i-1] == '-' && data[i] == '>') {
361 i++
362 }
363 i++
364
365 // no end-of-comment marker
366 if i >= len(data) {
367 return 0
368 }
369
370 // needs to end with a blank line
371 if j := p.isEmpty(data[i:]); j > 0 {
372 size := i + j
373 if doRender {
374 // trim trailing newlines
375 end := size
376 for end > 0 && data[end-1] == '\n' {
377 end--
378 }
379 p.r.BlockHtml(out, data[:end])
380 }
381 return size
382 }
383
384 return 0
385}
386
387// HR, which is the only self-closing block tag considered
388func (p *parser) htmlHr(out *bytes.Buffer, data []byte, doRender bool) int {
389 if data[0] != '<' || (data[1] != 'h' && data[1] != 'H') || (data[2] != 'r' && data[2] != 'R') {
390 return 0
391 }
392 if data[3] != ' ' && data[3] != '/' && data[3] != '>' {
393 // not an <hr> tag after all; at least not a valid one
394 return 0
395 }
396
397 i := 3
398 for data[i] != '>' && data[i] != '\n' {
399 i++
400 }
401
402 if data[i] == '>' {
403 i++
404 if j := p.isEmpty(data[i:]); j > 0 {
405 size := i + j
406 if doRender {
407 // trim newlines
408 end := size
409 for end > 0 && data[end-1] == '\n' {
410 end--
411 }
412 p.r.BlockHtml(out, data[:end])
413 }
414 return size
415 }
416 }
417
418 return 0
419}
420
421func (p *parser) htmlFindTag(data []byte) (string, bool) {
422 i := 0
423 for isalnum(data[i]) {
424 i++
425 }
426 key := string(data[:i])
427 if blockTags[key] {
428 return key, true
429 }
430 return "", false
431}
432
433func (p *parser) htmlFindEnd(tag string, data []byte) int {
434 // assume data[0] == '<' && data[1] == '/' already tested
435
436 // check if tag is a match
437 closetag := []byte("</" + tag + ">")
438 if !bytes.HasPrefix(data, closetag) {
439 return 0
440 }
441 i := len(closetag)
442
443 // check that the rest of the line is blank
444 skip := 0
445 if skip = p.isEmpty(data[i:]); skip == 0 {
446 return 0
447 }
448 i += skip
449 skip = 0
450
451 if i >= len(data) {
452 return i
453 }
454
455 if p.flags&EXTENSION_LAX_HTML_BLOCKS != 0 {
456 return i
457 }
458 if skip = p.isEmpty(data[i:]); skip == 0 {
459 // following line must be blank
460 return 0
461 }
462
463 return i + skip
464}
465
466func (p *parser) isEmpty(data []byte) int {
467 // it is okay to call isEmpty on an empty buffer
468 if len(data) == 0 {
469 return 0
470 }
471
472 var i int
473 for i = 0; i < len(data) && data[i] != '\n'; i++ {
474 if data[i] != ' ' && data[i] != '\t' {
475 return 0
476 }
477 }
478 return i + 1
479}
480
481func (p *parser) isHRule(data []byte) bool {
482 i := 0
483
484 // skip up to three spaces
485 for i < 3 && data[i] == ' ' {
486 i++
487 }
488
489 // look at the hrule char
490 if data[i] != '*' && data[i] != '-' && data[i] != '_' {
491 return false
492 }
493 c := data[i]
494
495 // the whole line must be the char or whitespace
496 n := 0
497 for data[i] != '\n' {
498 switch {
499 case data[i] == c:
500 n++
501 case data[i] != ' ':
502 return false
503 }
504 i++
505 }
506
507 return n >= 3
508}
509
510func (p *parser) isFencedCode(data []byte, syntax **string, oldmarker string) (skip int, marker string) {
511 i, size := 0, 0
512 skip = 0
513
514 // skip up to three spaces
515 for i < 3 && data[i] == ' ' {
516 i++
517 }
518
519 // check for the marker characters: ~ or `
520 if data[i] != '~' && data[i] != '`' {
521 return
522 }
523
524 c := data[i]
525
526 // the whole line must be the same char or whitespace
527 for data[i] == c {
528 size++
529 i++
530 }
531
532 // the marker char must occur at least 3 times
533 if size < 3 {
534 return
535 }
536 marker = string(data[i-size : i])
537
538 // if this is the end marker, it must match the beginning marker
539 if oldmarker != "" && marker != oldmarker {
540 return
541 }
542
543 if syntax != nil {
544 syn := 0
545
546 for data[i] == ' ' {
547 i++
548 }
549
550 syntaxStart := i
551
552 if data[i] == '{' {
553 i++
554 syntaxStart++
555
556 for data[i] != '}' && data[i] != '\n' {
557 syn++
558 i++
559 }
560
561 if data[i] != '}' {
562 return
563 }
564
565 // strip all whitespace at the beginning and the end
566 // of the {} block
567 for syn > 0 && isspace(data[syntaxStart]) {
568 syntaxStart++
569 syn--
570 }
571
572 for syn > 0 && isspace(data[syntaxStart+syn-1]) {
573 syn--
574 }
575
576 i++
577 } else {
578 for !isspace(data[i]) {
579 syn++
580 i++
581 }
582 }
583
584 language := string(data[syntaxStart : syntaxStart+syn])
585 *syntax = &language
586 }
587
588 for data[i] == ' ' {
589 i++
590 }
591 if data[i] != '\n' {
592 return
593 }
594
595 skip = i + 1
596 return
597}
598
599func (p *parser) fencedCode(out *bytes.Buffer, data []byte) int {
600 var lang *string
601 beg, marker := p.isFencedCode(data, &lang, "")
602 if beg == 0 || beg >= len(data) {
603 return 0
604 }
605
606 var work bytes.Buffer
607
608 for {
609 // safe to assume beg < len(data)
610
611 // check for the end of the code block
612 fenceEnd, _ := p.isFencedCode(data[beg:], nil, marker)
613 if fenceEnd != 0 {
614 beg += fenceEnd
615 break
616 }
617
618 // copy the current line
619 end := beg
620 for data[end] != '\n' {
621 end++
622 }
623 end++
624
625 // did we reach the end of the buffer without a closing marker?
626 if end >= len(data) {
627 return 0
628 }
629
630 // verbatim copy to the working buffer
631 work.Write(data[beg:end])
632 beg = end
633 }
634
635 syntax := ""
636 if lang != nil {
637 syntax = *lang
638 }
639
640 p.r.BlockCode(out, work.Bytes(), syntax)
641
642 return beg
643}
644
645func (p *parser) table(out *bytes.Buffer, data []byte) int {
646 var header bytes.Buffer
647 i, columns := p.tableHeader(&header, data)
648 if i == 0 {
649 return 0
650 }
651
652 var body bytes.Buffer
653
654 for i < len(data) {
655 pipes, rowStart := 0, i
656 for ; data[i] != '\n'; i++ {
657 if data[i] == '|' {
658 pipes++
659 }
660 }
661
662 if pipes == 0 {
663 i = rowStart
664 break
665 }
666
667 // include the newline in data sent to tableRow
668 i++
669 p.tableRow(&body, data[rowStart:i], columns, false)
670 }
671
672 p.r.Table(out, header.Bytes(), body.Bytes(), columns)
673
674 return i
675}
676
677// check if the specified position is preceeded by an odd number of backslashes
678func isBackslashEscaped(data []byte, i int) bool {
679 backslashes := 0
680 for i-backslashes-1 >= 0 && data[i-backslashes-1] == '\\' {
681 backslashes++
682 }
683 return backslashes&1 == 1
684}
685
686func (p *parser) tableHeader(out *bytes.Buffer, data []byte) (size int, columns []int) {
687 i := 0
688 colCount := 1
689 for i = 0; data[i] != '\n'; i++ {
690 if data[i] == '|' && !isBackslashEscaped(data, i) {
691 colCount++
692 }
693 }
694
695 // doesn't look like a table header
696 if colCount == 1 {
697 return
698 }
699
700 // include the newline in the data sent to tableRow
701 header := data[:i+1]
702
703 // column count ignores pipes at beginning or end of line
704 if data[0] == '|' {
705 colCount--
706 }
707 if i > 2 && data[i-1] == '|' && !isBackslashEscaped(data, i-1) {
708 colCount--
709 }
710
711 columns = make([]int, colCount)
712
713 // move on to the header underline
714 i++
715 if i >= len(data) {
716 return
717 }
718
719 if data[i] == '|' && !isBackslashEscaped(data, i) {
720 i++
721 }
722 for data[i] == ' ' {
723 i++
724 }
725
726 // each column header is of form: / *:?-+:? *|/ with # dashes + # colons >= 3
727 // and trailing | optional on last column
728 col := 0
729 for data[i] != '\n' {
730 dashes := 0
731
732 if data[i] == ':' {
733 i++
734 columns[col] |= TABLE_ALIGNMENT_LEFT
735 dashes++
736 }
737 for data[i] == '-' {
738 i++
739 dashes++
740 }
741 if data[i] == ':' {
742 i++
743 columns[col] |= TABLE_ALIGNMENT_RIGHT
744 dashes++
745 }
746 for data[i] == ' ' {
747 i++
748 }
749
750 // end of column test is messy
751 switch {
752 case dashes < 3:
753 // not a valid column
754 return
755
756 case data[i] == '|' && !isBackslashEscaped(data, i):
757 // marker found, now skip past trailing whitespace
758 col++
759 i++
760 for data[i] == ' ' {
761 i++
762 }
763
764 // trailing junk found after last column
765 if col >= colCount && data[i] != '\n' {
766 return
767 }
768
769 case (data[i] != '|' || isBackslashEscaped(data, i)) && col+1 < colCount:
770 // something else found where marker was required
771 return
772
773 case data[i] == '\n':
774 // marker is optional for the last column
775 col++
776
777 default:
778 // trailing junk found after last column
779 return
780 }
781 }
782 if col != colCount {
783 return
784 }
785
786 p.tableRow(out, header, columns, true)
787 size = i + 1
788 return
789}
790
791func (p *parser) tableRow(out *bytes.Buffer, data []byte, columns []int, header bool) {
792 i, col := 0, 0
793 var rowWork bytes.Buffer
794
795 if data[i] == '|' && !isBackslashEscaped(data, i) {
796 i++
797 }
798
799 for col = 0; col < len(columns) && i < len(data); col++ {
800 for data[i] == ' ' {
801 i++
802 }
803
804 cellStart := i
805
806 for (data[i] != '|' || isBackslashEscaped(data, i)) && data[i] != '\n' {
807 i++
808 }
809
810 cellEnd := i
811
812 // skip the end-of-cell marker, possibly taking us past end of buffer
813 i++
814
815 for cellEnd > cellStart && data[cellEnd-1] == ' ' {
816 cellEnd--
817 }
818
819 var cellWork bytes.Buffer
820 p.inline(&cellWork, data[cellStart:cellEnd])
821
822 if header {
823 p.r.TableHeaderCell(&rowWork, cellWork.Bytes(), columns[col])
824 } else {
825 p.r.TableCell(&rowWork, cellWork.Bytes(), columns[col])
826 }
827 }
828
829 // pad it out with empty columns to get the right number
830 for ; col < len(columns); col++ {
831 if header {
832 p.r.TableHeaderCell(&rowWork, nil, columns[col])
833 } else {
834 p.r.TableCell(&rowWork, nil, columns[col])
835 }
836 }
837
838 // silently ignore rows with too many cells
839
840 p.r.TableRow(out, rowWork.Bytes())
841}
842
843// returns blockquote prefix length
844func (p *parser) quotePrefix(data []byte) int {
845 i := 0
846 for i < 3 && data[i] == ' ' {
847 i++
848 }
849 if data[i] == '>' {
850 if data[i+1] == ' ' {
851 return i + 2
852 }
853 return i + 1
854 }
855 return 0
856}
857
858// parse a blockquote fragment
859func (p *parser) quote(out *bytes.Buffer, data []byte) int {
860 var raw bytes.Buffer
861 beg, end := 0, 0
862 for beg < len(data) {
863 end = beg
864 for data[end] != '\n' {
865 end++
866 }
867 end++
868
869 if pre := p.quotePrefix(data[beg:]); pre > 0 {
870 // skip the prefix
871 beg += pre
872 } else if p.isEmpty(data[beg:]) > 0 &&
873 (end >= len(data) ||
874 (p.quotePrefix(data[end:]) == 0 && p.isEmpty(data[end:]) == 0)) {
875 // blockquote ends with at least one blank line
876 // followed by something without a blockquote prefix
877 break
878 }
879
880 // this line is part of the blockquote
881 raw.Write(data[beg:end])
882 beg = end
883 }
884
885 var cooked bytes.Buffer
886 p.block(&cooked, raw.Bytes())
887 p.r.BlockQuote(out, cooked.Bytes())
888 return end
889}
890
891// returns prefix length for block code
892func (p *parser) codePrefix(data []byte) int {
893 if data[0] == ' ' && data[1] == ' ' && data[2] == ' ' && data[3] == ' ' {
894 return 4
895 }
896 return 0
897}
898
899func (p *parser) code(out *bytes.Buffer, data []byte) int {
900 var work bytes.Buffer
901
902 i := 0
903 for i < len(data) {
904 beg := i
905 for data[i] != '\n' {
906 i++
907 }
908 i++
909
910 blankline := p.isEmpty(data[beg:i]) > 0
911 if pre := p.codePrefix(data[beg:i]); pre > 0 {
912 beg += pre
913 } else if !blankline {
914 // non-empty, non-prefixed line breaks the pre
915 i = beg
916 break
917 }
918
919 // verbatim copy to the working buffeu
920 if blankline {
921 work.WriteByte('\n')
922 } else {
923 work.Write(data[beg:i])
924 }
925 }
926
927 // trim all the \n off the end of work
928 workbytes := work.Bytes()
929 eol := len(workbytes)
930 for eol > 0 && workbytes[eol-1] == '\n' {
931 eol--
932 }
933 if eol != len(workbytes) {
934 work.Truncate(eol)
935 }
936
937 work.WriteByte('\n')
938
939 p.r.BlockCode(out, work.Bytes(), "")
940
941 return i
942}
943
944// returns unordered list item prefix
945func (p *parser) uliPrefix(data []byte) int {
946 i := 0
947
948 // start with up to 3 spaces
949 for i < 3 && data[i] == ' ' {
950 i++
951 }
952
953 // need a *, +, or - followed by a space
954 if (data[i] != '*' && data[i] != '+' && data[i] != '-') ||
955 data[i+1] != ' ' {
956 return 0
957 }
958 return i + 2
959}
960
961// returns ordered list item prefix
962func (p *parser) oliPrefix(data []byte) int {
963 i := 0
964
965 // start with up to 3 spaces
966 for i < 3 && data[i] == ' ' {
967 i++
968 }
969
970 // count the digits
971 start := i
972 for data[i] >= '0' && data[i] <= '9' {
973 i++
974 }
975
976 // we need >= 1 digits followed by a dot and a space
977 if start == i || data[i] != '.' || data[i+1] != ' ' {
978 return 0
979 }
980 return i + 2
981}
982
983// parse ordered or unordered list block
984func (p *parser) list(out *bytes.Buffer, data []byte, flags int) int {
985 i := 0
986 flags |= LIST_ITEM_BEGINNING_OF_LIST
987 work := func() bool {
988 for i < len(data) {
989 skip := p.listItem(out, data[i:], &flags)
990 i += skip
991
992 if skip == 0 || flags&LIST_ITEM_END_OF_LIST != 0 {
993 break
994 }
995 flags &= ^LIST_ITEM_BEGINNING_OF_LIST
996 }
997 return true
998 }
999
1000 p.r.List(out, work, flags)
1001 return i
1002}
1003
1004// Parse a single list item.
1005// Assumes initial prefix is already removed if this is a sublist.
1006func (p *parser) listItem(out *bytes.Buffer, data []byte, flags *int) int {
1007 // keep track of the indentation of the first line
1008 itemIndent := 0
1009 for itemIndent < 3 && data[itemIndent] == ' ' {
1010 itemIndent++
1011 }
1012
1013 i := p.uliPrefix(data)
1014 if i == 0 {
1015 i = p.oliPrefix(data)
1016 }
1017 if i == 0 {
1018 return 0
1019 }
1020
1021 // skip leading whitespace on first line
1022 for data[i] == ' ' {
1023 i++
1024 }
1025
1026 // find the end of the line
1027 line := i
1028 for data[i-1] != '\n' {
1029 i++
1030 }
1031
1032 // get working buffer
1033 var raw bytes.Buffer
1034
1035 // put the first line into the working buffer
1036 raw.Write(data[line:i])
1037 line = i
1038
1039 // process the following lines
1040 containsBlankLine := false
1041 sublist := 0
1042
1043gatherlines:
1044 for line < len(data) {
1045 i++
1046
1047 // find the end of this line
1048 for data[i-1] != '\n' {
1049 i++
1050 }
1051
1052 // if it is an empty line, guess that it is part of this item
1053 // and move on to the next line
1054 if p.isEmpty(data[line:i]) > 0 {
1055 containsBlankLine = true
1056 line = i
1057 continue
1058 }
1059
1060 // calculate the indentation
1061 indent := 0
1062 for indent < 4 && line+indent < i && data[line+indent] == ' ' {
1063 indent++
1064 }
1065
1066 chunk := data[line+indent : i]
1067
1068 // evaluate how this line fits in
1069 switch {
1070 // is this a nested list item?
1071 case (p.uliPrefix(chunk) > 0 && !p.isHRule(chunk)) ||
1072 p.oliPrefix(chunk) > 0:
1073
1074 if containsBlankLine {
1075 *flags |= LIST_ITEM_CONTAINS_BLOCK
1076 }
1077
1078 // to be a nested list, it must be indented more
1079 // if not, it is the next item in the same list
1080 if indent <= itemIndent {
1081 break gatherlines
1082 }
1083
1084 // is this the first item in the the nested list?
1085 if sublist == 0 {
1086 sublist = raw.Len()
1087 }
1088
1089 // is this a nested prefix header?
1090 case p.isPrefixHeader(chunk):
1091 // if the header is not indented, it is not nested in the list
1092 // and thus ends the list
1093 if containsBlankLine && indent < 4 {
1094 *flags |= LIST_ITEM_END_OF_LIST
1095 break gatherlines
1096 }
1097 *flags |= LIST_ITEM_CONTAINS_BLOCK
1098
1099 // anything following an empty line is only part
1100 // of this item if it is indented 4 spaces
1101 // (regardless of the indentation of the beginning of the item)
1102 case containsBlankLine && indent < 4:
1103 *flags |= LIST_ITEM_END_OF_LIST
1104 break gatherlines
1105
1106 // a blank line means this should be parsed as a block
1107 case containsBlankLine:
1108 raw.WriteByte('\n')
1109 *flags |= LIST_ITEM_CONTAINS_BLOCK
1110 }
1111
1112 // if this line was preceeded by one or more blanks,
1113 // re-introduce the blank into the buffer
1114 if containsBlankLine {
1115 containsBlankLine = false
1116 raw.WriteByte('\n')
1117 }
1118
1119 // add the line into the working buffer without prefix
1120 raw.Write(data[line+indent : i])
1121
1122 line = i
1123 }
1124
1125 rawBytes := raw.Bytes()
1126
1127 // render the contents of the list item
1128 var cooked bytes.Buffer
1129 if *flags&LIST_ITEM_CONTAINS_BLOCK != 0 {
1130 // intermediate render of block li
1131 if sublist > 0 {
1132 p.block(&cooked, rawBytes[:sublist])
1133 p.block(&cooked, rawBytes[sublist:])
1134 } else {
1135 p.block(&cooked, rawBytes)
1136 }
1137 } else {
1138 // intermediate render of inline li
1139 if sublist > 0 {
1140 p.inline(&cooked, rawBytes[:sublist])
1141 p.block(&cooked, rawBytes[sublist:])
1142 } else {
1143 p.inline(&cooked, rawBytes)
1144 }
1145 }
1146
1147 // render the actual list item
1148 cookedBytes := cooked.Bytes()
1149 parsedEnd := len(cookedBytes)
1150
1151 // strip trailing newlines
1152 for parsedEnd > 0 && cookedBytes[parsedEnd-1] == '\n' {
1153 parsedEnd--
1154 }
1155 p.r.ListItem(out, cookedBytes[:parsedEnd], *flags)
1156
1157 return line
1158}
1159
1160// render a single paragraph that has already been parsed out
1161func (p *parser) renderParagraph(out *bytes.Buffer, data []byte) {
1162 if len(data) == 0 {
1163 return
1164 }
1165
1166 // trim leading spaces
1167 beg := 0
1168 for data[beg] == ' ' {
1169 beg++
1170 }
1171
1172 // trim trailing newline
1173 end := len(data) - 1
1174
1175 // trim trailing spaces
1176 for end > beg && data[end-1] == ' ' {
1177 end--
1178 }
1179
1180 work := func() bool {
1181 p.inline(out, data[beg:end])
1182 return true
1183 }
1184 p.r.Paragraph(out, work)
1185}
1186
1187func (p *parser) paragraph(out *bytes.Buffer, data []byte) int {
1188 // prev: index of 1st char of previous line
1189 // line: index of 1st char of current line
1190 // i: index of cursor/end of current line
1191 var prev, line, i int
1192
1193 // keep going until we find something to mark the end of the paragraph
1194 for i < len(data) {
1195 // mark the beginning of the current line
1196 prev = line
1197 current := data[i:]
1198 line = i
1199
1200 // did we find a blank line marking the end of the paragraph?
1201 if n := p.isEmpty(current); n > 0 {
1202 p.renderParagraph(out, data[:i])
1203 return i + n
1204 }
1205
1206 // an underline under some text marks a header, so our paragraph ended on prev line
1207 if i > 0 {
1208 if level := p.isUnderlinedHeader(current); level > 0 {
1209 // render the paragraph
1210 p.renderParagraph(out, data[:prev])
1211
1212 // ignore leading and trailing whitespace
1213 eol := i - 1
1214 for prev < eol && data[prev] == ' ' {
1215 prev++
1216 }
1217 for eol > prev && data[eol-1] == ' ' {
1218 eol--
1219 }
1220
1221 // render the header
1222 // this ugly double closure avoids forcing variables onto the heap
1223 work := func(o *bytes.Buffer, pp *parser, d []byte) func() bool {
1224 return func() bool {
1225 pp.inline(o, d)
1226 return true
1227 }
1228 }(out, p, data[prev:eol])
1229 p.r.Header(out, work, level, "")
1230
1231 // find the end of the underline
1232 for data[i] != '\n' {
1233 i++
1234 }
1235 return i
1236 }
1237 }
1238
1239 // if the next line starts a block of HTML, then the paragraph ends here
1240 if p.flags&EXTENSION_LAX_HTML_BLOCKS != 0 {
1241 if data[i] == '<' && p.html(out, current, false) > 0 {
1242 // rewind to before the HTML block
1243 p.renderParagraph(out, data[:i])
1244 return i
1245 }
1246 }
1247
1248 // if there's a prefixed header or a horizontal rule after this, paragraph is over
1249 if p.isPrefixHeader(current) || p.isHRule(current) {
1250 p.renderParagraph(out, data[:i])
1251 return i
1252 }
1253
1254 // if there's a list after this, paragraph is over
1255 if p.flags&EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK != 0 {
1256 if p.uliPrefix(current) != 0 ||
1257 p.oliPrefix(current) != 0 ||
1258 p.quotePrefix(current) != 0 ||
1259 p.codePrefix(current) != 0 {
1260 p.renderParagraph(out, data[:i])
1261 return i
1262 }
1263 }
1264
1265 // otherwise, scan to the beginning of the next line
1266 for data[i] != '\n' {
1267 i++
1268 }
1269 i++
1270 }
1271
1272 p.renderParagraph(out, data[:i])
1273 return i
1274}