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 skip = k + 1
200 }
201 }
202 for end > 0 && data[end-1] == '#' {
203 end--
204 }
205 for end > 0 && data[end-1] == ' ' {
206 end--
207 }
208 if end > i {
209 work := func() bool {
210 p.inline(out, data[i:end])
211 return true
212 }
213 p.r.Header(out, work, level, id)
214 }
215 return skip
216}
217
218func (p *parser) isUnderlinedHeader(data []byte) int {
219 // test of level 1 header
220 if data[0] == '=' {
221 i := 1
222 for data[i] == '=' {
223 i++
224 }
225 for data[i] == ' ' {
226 i++
227 }
228 if data[i] == '\n' {
229 return 1
230 } else {
231 return 0
232 }
233 }
234
235 // test of level 2 header
236 if data[0] == '-' {
237 i := 1
238 for data[i] == '-' {
239 i++
240 }
241 for data[i] == ' ' {
242 i++
243 }
244 if data[i] == '\n' {
245 return 2
246 } else {
247 return 0
248 }
249 }
250
251 return 0
252}
253
254func (p *parser) html(out *bytes.Buffer, data []byte, doRender bool) int {
255 var i, j int
256
257 // identify the opening tag
258 if data[0] != '<' {
259 return 0
260 }
261 curtag, tagfound := p.htmlFindTag(data[1:])
262
263 // handle special cases
264 if !tagfound {
265 // check for an HTML comment
266 if size := p.htmlComment(out, data, doRender); size > 0 {
267 return size
268 }
269
270 // check for an <hr> tag
271 if size := p.htmlHr(out, data, doRender); size > 0 {
272 return size
273 }
274
275 // no special case recognized
276 return 0
277 }
278
279 // look for an unindented matching closing tag
280 // followed by a blank line
281 found := false
282 /*
283 closetag := []byte("\n</" + curtag + ">")
284 j = len(curtag) + 1
285 for !found {
286 // scan for a closing tag at the beginning of a line
287 if skip := bytes.Index(data[j:], closetag); skip >= 0 {
288 j += skip + len(closetag)
289 } else {
290 break
291 }
292
293 // see if it is the only thing on the line
294 if skip := p.isEmpty(data[j:]); skip > 0 {
295 // see if it is followed by a blank line/eof
296 j += skip
297 if j >= len(data) {
298 found = true
299 i = j
300 } else {
301 if skip := p.isEmpty(data[j:]); skip > 0 {
302 j += skip
303 found = true
304 i = j
305 }
306 }
307 }
308 }
309 */
310
311 // if not found, try a second pass looking for indented match
312 // but not if tag is "ins" or "del" (following original Markdown.pl)
313 if !found && curtag != "ins" && curtag != "del" {
314 i = 1
315 for i < len(data) {
316 i++
317 for i < len(data) && !(data[i-1] == '<' && data[i] == '/') {
318 i++
319 }
320
321 if i+2+len(curtag) >= len(data) {
322 break
323 }
324
325 j = p.htmlFindEnd(curtag, data[i-1:])
326
327 if j > 0 {
328 i += j - 1
329 found = true
330 break
331 }
332 }
333 }
334
335 if !found {
336 return 0
337 }
338
339 // the end of the block has been found
340 if doRender {
341 // trim newlines
342 end := i
343 for end > 0 && data[end-1] == '\n' {
344 end--
345 }
346 p.r.BlockHtml(out, data[:end])
347 }
348
349 return i
350}
351
352// HTML comment, lax form
353func (p *parser) htmlComment(out *bytes.Buffer, data []byte, doRender bool) int {
354 if data[0] != '<' || data[1] != '!' || data[2] != '-' || data[3] != '-' {
355 return 0
356 }
357
358 i := 5
359
360 // scan for an end-of-comment marker, across lines if necessary
361 for i < len(data) && !(data[i-2] == '-' && data[i-1] == '-' && data[i] == '>') {
362 i++
363 }
364 i++
365
366 // no end-of-comment marker
367 if i >= len(data) {
368 return 0
369 }
370
371 // needs to end with a blank line
372 if j := p.isEmpty(data[i:]); j > 0 {
373 size := i + j
374 if doRender {
375 // trim trailing newlines
376 end := size
377 for end > 0 && data[end-1] == '\n' {
378 end--
379 }
380 p.r.BlockHtml(out, data[:end])
381 }
382 return size
383 }
384
385 return 0
386}
387
388// HR, which is the only self-closing block tag considered
389func (p *parser) htmlHr(out *bytes.Buffer, data []byte, doRender bool) int {
390 if data[0] != '<' || (data[1] != 'h' && data[1] != 'H') || (data[2] != 'r' && data[2] != 'R') {
391 return 0
392 }
393 if data[3] != ' ' && data[3] != '/' && data[3] != '>' {
394 // not an <hr> tag after all; at least not a valid one
395 return 0
396 }
397
398 i := 3
399 for data[i] != '>' && data[i] != '\n' {
400 i++
401 }
402
403 if data[i] == '>' {
404 i++
405 if j := p.isEmpty(data[i:]); j > 0 {
406 size := i + j
407 if doRender {
408 // trim newlines
409 end := size
410 for end > 0 && data[end-1] == '\n' {
411 end--
412 }
413 p.r.BlockHtml(out, data[:end])
414 }
415 return size
416 }
417 }
418
419 return 0
420}
421
422func (p *parser) htmlFindTag(data []byte) (string, bool) {
423 i := 0
424 for isalnum(data[i]) {
425 i++
426 }
427 key := string(data[:i])
428 if blockTags[key] {
429 return key, true
430 }
431 return "", false
432}
433
434func (p *parser) htmlFindEnd(tag string, data []byte) int {
435 // assume data[0] == '<' && data[1] == '/' already tested
436
437 // check if tag is a match
438 closetag := []byte("</" + tag + ">")
439 if !bytes.HasPrefix(data, closetag) {
440 return 0
441 }
442 i := len(closetag)
443
444 // check that the rest of the line is blank
445 skip := 0
446 if skip = p.isEmpty(data[i:]); skip == 0 {
447 return 0
448 }
449 i += skip
450 skip = 0
451
452 if i >= len(data) {
453 return i
454 }
455
456 if p.flags&EXTENSION_LAX_HTML_BLOCKS != 0 {
457 return i
458 }
459 if skip = p.isEmpty(data[i:]); skip == 0 {
460 // following line must be blank
461 return 0
462 }
463
464 return i + skip
465}
466
467func (p *parser) isEmpty(data []byte) int {
468 // it is okay to call isEmpty on an empty buffer
469 if len(data) == 0 {
470 return 0
471 }
472
473 var i int
474 for i = 0; i < len(data) && data[i] != '\n'; i++ {
475 if data[i] != ' ' && data[i] != '\t' {
476 return 0
477 }
478 }
479 return i + 1
480}
481
482func (p *parser) isHRule(data []byte) bool {
483 i := 0
484
485 // skip up to three spaces
486 for i < 3 && data[i] == ' ' {
487 i++
488 }
489
490 // look at the hrule char
491 if data[i] != '*' && data[i] != '-' && data[i] != '_' {
492 return false
493 }
494 c := data[i]
495
496 // the whole line must be the char or whitespace
497 n := 0
498 for data[i] != '\n' {
499 switch {
500 case data[i] == c:
501 n++
502 case data[i] != ' ':
503 return false
504 }
505 i++
506 }
507
508 return n >= 3
509}
510
511func (p *parser) isFencedCode(data []byte, syntax **string, oldmarker string) (skip int, marker string) {
512 i, size := 0, 0
513 skip = 0
514
515 // skip up to three spaces
516 for i < 3 && data[i] == ' ' {
517 i++
518 }
519
520 // check for the marker characters: ~ or `
521 if data[i] != '~' && data[i] != '`' {
522 return
523 }
524
525 c := data[i]
526
527 // the whole line must be the same char or whitespace
528 for data[i] == c {
529 size++
530 i++
531 }
532
533 // the marker char must occur at least 3 times
534 if size < 3 {
535 return
536 }
537 marker = string(data[i-size : i])
538
539 // if this is the end marker, it must match the beginning marker
540 if oldmarker != "" && marker != oldmarker {
541 return
542 }
543
544 if syntax != nil {
545 syn := 0
546
547 for data[i] == ' ' {
548 i++
549 }
550
551 syntaxStart := i
552
553 if data[i] == '{' {
554 i++
555 syntaxStart++
556
557 for data[i] != '}' && data[i] != '\n' {
558 syn++
559 i++
560 }
561
562 if data[i] != '}' {
563 return
564 }
565
566 // strip all whitespace at the beginning and the end
567 // of the {} block
568 for syn > 0 && isspace(data[syntaxStart]) {
569 syntaxStart++
570 syn--
571 }
572
573 for syn > 0 && isspace(data[syntaxStart+syn-1]) {
574 syn--
575 }
576
577 i++
578 } else {
579 for !isspace(data[i]) {
580 syn++
581 i++
582 }
583 }
584
585 language := string(data[syntaxStart : syntaxStart+syn])
586 *syntax = &language
587 }
588
589 for data[i] == ' ' {
590 i++
591 }
592 if data[i] != '\n' {
593 return
594 }
595
596 skip = i + 1
597 return
598}
599
600func (p *parser) fencedCode(out *bytes.Buffer, data []byte) int {
601 var lang *string
602 beg, marker := p.isFencedCode(data, &lang, "")
603 if beg == 0 || beg >= len(data) {
604 return 0
605 }
606
607 var work bytes.Buffer
608
609 for {
610 // safe to assume beg < len(data)
611
612 // check for the end of the code block
613 fenceEnd, _ := p.isFencedCode(data[beg:], nil, marker)
614 if fenceEnd != 0 {
615 beg += fenceEnd
616 break
617 }
618
619 // copy the current line
620 end := beg
621 for data[end] != '\n' {
622 end++
623 }
624 end++
625
626 // did we reach the end of the buffer without a closing marker?
627 if end >= len(data) {
628 return 0
629 }
630
631 // verbatim copy to the working buffer
632 work.Write(data[beg:end])
633 beg = end
634 }
635
636 syntax := ""
637 if lang != nil {
638 syntax = *lang
639 }
640
641 p.r.BlockCode(out, work.Bytes(), syntax)
642
643 return beg
644}
645
646func (p *parser) table(out *bytes.Buffer, data []byte) int {
647 var header bytes.Buffer
648 i, columns := p.tableHeader(&header, data)
649 if i == 0 {
650 return 0
651 }
652
653 var body bytes.Buffer
654
655 for i < len(data) {
656 pipes, rowStart := 0, i
657 for ; data[i] != '\n'; i++ {
658 if data[i] == '|' {
659 pipes++
660 }
661 }
662
663 if pipes == 0 {
664 i = rowStart
665 break
666 }
667
668 // include the newline in data sent to tableRow
669 i++
670 p.tableRow(&body, data[rowStart:i], columns, false)
671 }
672
673 p.r.Table(out, header.Bytes(), body.Bytes(), columns)
674
675 return i
676}
677
678// check if the specified position is preceeded by an odd number of backslashes
679func isBackslashEscaped(data []byte, i int) bool {
680 backslashes := 0
681 for i-backslashes-1 >= 0 && data[i-backslashes-1] == '\\' {
682 backslashes++
683 }
684 return backslashes&1 == 1
685}
686
687func (p *parser) tableHeader(out *bytes.Buffer, data []byte) (size int, columns []int) {
688 i := 0
689 colCount := 1
690 for i = 0; data[i] != '\n'; i++ {
691 if data[i] == '|' && !isBackslashEscaped(data, i) {
692 colCount++
693 }
694 }
695
696 // doesn't look like a table header
697 if colCount == 1 {
698 return
699 }
700
701 // include the newline in the data sent to tableRow
702 header := data[:i+1]
703
704 // column count ignores pipes at beginning or end of line
705 if data[0] == '|' {
706 colCount--
707 }
708 if i > 2 && data[i-1] == '|' && !isBackslashEscaped(data, i-1) {
709 colCount--
710 }
711
712 columns = make([]int, colCount)
713
714 // move on to the header underline
715 i++
716 if i >= len(data) {
717 return
718 }
719
720 if data[i] == '|' && !isBackslashEscaped(data, i) {
721 i++
722 }
723 for data[i] == ' ' {
724 i++
725 }
726
727 // each column header is of form: / *:?-+:? *|/ with # dashes + # colons >= 3
728 // and trailing | optional on last column
729 col := 0
730 for data[i] != '\n' {
731 dashes := 0
732
733 if data[i] == ':' {
734 i++
735 columns[col] |= TABLE_ALIGNMENT_LEFT
736 dashes++
737 }
738 for data[i] == '-' {
739 i++
740 dashes++
741 }
742 if data[i] == ':' {
743 i++
744 columns[col] |= TABLE_ALIGNMENT_RIGHT
745 dashes++
746 }
747 for data[i] == ' ' {
748 i++
749 }
750
751 // end of column test is messy
752 switch {
753 case dashes < 3:
754 // not a valid column
755 return
756
757 case data[i] == '|' && !isBackslashEscaped(data, i):
758 // marker found, now skip past trailing whitespace
759 col++
760 i++
761 for data[i] == ' ' {
762 i++
763 }
764
765 // trailing junk found after last column
766 if col >= colCount && data[i] != '\n' {
767 return
768 }
769
770 case (data[i] != '|' || isBackslashEscaped(data, i)) && col+1 < colCount:
771 // something else found where marker was required
772 return
773
774 case data[i] == '\n':
775 // marker is optional for the last column
776 col++
777
778 default:
779 // trailing junk found after last column
780 return
781 }
782 }
783 if col != colCount {
784 return
785 }
786
787 p.tableRow(out, header, columns, true)
788 size = i + 1
789 return
790}
791
792func (p *parser) tableRow(out *bytes.Buffer, data []byte, columns []int, header bool) {
793 i, col := 0, 0
794 var rowWork bytes.Buffer
795
796 if data[i] == '|' && !isBackslashEscaped(data, i) {
797 i++
798 }
799
800 for col = 0; col < len(columns) && i < len(data); col++ {
801 for data[i] == ' ' {
802 i++
803 }
804
805 cellStart := i
806
807 for (data[i] != '|' || isBackslashEscaped(data, i)) && data[i] != '\n' {
808 i++
809 }
810
811 cellEnd := i
812
813 // skip the end-of-cell marker, possibly taking us past end of buffer
814 i++
815
816 for cellEnd > cellStart && data[cellEnd-1] == ' ' {
817 cellEnd--
818 }
819
820 var cellWork bytes.Buffer
821 p.inline(&cellWork, data[cellStart:cellEnd])
822
823 if header {
824 p.r.TableHeaderCell(&rowWork, cellWork.Bytes(), columns[col])
825 } else {
826 p.r.TableCell(&rowWork, cellWork.Bytes(), columns[col])
827 }
828 }
829
830 // pad it out with empty columns to get the right number
831 for ; col < len(columns); col++ {
832 if header {
833 p.r.TableHeaderCell(&rowWork, nil, columns[col])
834 } else {
835 p.r.TableCell(&rowWork, nil, columns[col])
836 }
837 }
838
839 // silently ignore rows with too many cells
840
841 p.r.TableRow(out, rowWork.Bytes())
842}
843
844// returns blockquote prefix length
845func (p *parser) quotePrefix(data []byte) int {
846 i := 0
847 for i < 3 && data[i] == ' ' {
848 i++
849 }
850 if data[i] == '>' {
851 if data[i+1] == ' ' {
852 return i + 2
853 }
854 return i + 1
855 }
856 return 0
857}
858
859// parse a blockquote fragment
860func (p *parser) quote(out *bytes.Buffer, data []byte) int {
861 var raw bytes.Buffer
862 beg, end := 0, 0
863 for beg < len(data) {
864 end = beg
865 for data[end] != '\n' {
866 end++
867 }
868 end++
869
870 if pre := p.quotePrefix(data[beg:]); pre > 0 {
871 // skip the prefix
872 beg += pre
873 } else if p.isEmpty(data[beg:]) > 0 &&
874 (end >= len(data) ||
875 (p.quotePrefix(data[end:]) == 0 && p.isEmpty(data[end:]) == 0)) {
876 // blockquote ends with at least one blank line
877 // followed by something without a blockquote prefix
878 break
879 }
880
881 // this line is part of the blockquote
882 raw.Write(data[beg:end])
883 beg = end
884 }
885
886 var cooked bytes.Buffer
887 p.block(&cooked, raw.Bytes())
888 p.r.BlockQuote(out, cooked.Bytes())
889 return end
890}
891
892// returns prefix length for block code
893func (p *parser) codePrefix(data []byte) int {
894 if data[0] == ' ' && data[1] == ' ' && data[2] == ' ' && data[3] == ' ' {
895 return 4
896 }
897 return 0
898}
899
900func (p *parser) code(out *bytes.Buffer, data []byte) int {
901 var work bytes.Buffer
902
903 i := 0
904 for i < len(data) {
905 beg := i
906 for data[i] != '\n' {
907 i++
908 }
909 i++
910
911 blankline := p.isEmpty(data[beg:i]) > 0
912 if pre := p.codePrefix(data[beg:i]); pre > 0 {
913 beg += pre
914 } else if !blankline {
915 // non-empty, non-prefixed line breaks the pre
916 i = beg
917 break
918 }
919
920 // verbatim copy to the working buffeu
921 if blankline {
922 work.WriteByte('\n')
923 } else {
924 work.Write(data[beg:i])
925 }
926 }
927
928 // trim all the \n off the end of work
929 workbytes := work.Bytes()
930 eol := len(workbytes)
931 for eol > 0 && workbytes[eol-1] == '\n' {
932 eol--
933 }
934 if eol != len(workbytes) {
935 work.Truncate(eol)
936 }
937
938 work.WriteByte('\n')
939
940 p.r.BlockCode(out, work.Bytes(), "")
941
942 return i
943}
944
945// returns unordered list item prefix
946func (p *parser) uliPrefix(data []byte) int {
947 i := 0
948
949 // start with up to 3 spaces
950 for i < 3 && data[i] == ' ' {
951 i++
952 }
953
954 // need a *, +, or - followed by a space
955 if (data[i] != '*' && data[i] != '+' && data[i] != '-') ||
956 data[i+1] != ' ' {
957 return 0
958 }
959 return i + 2
960}
961
962// returns ordered list item prefix
963func (p *parser) oliPrefix(data []byte) int {
964 i := 0
965
966 // start with up to 3 spaces
967 for i < 3 && data[i] == ' ' {
968 i++
969 }
970
971 // count the digits
972 start := i
973 for data[i] >= '0' && data[i] <= '9' {
974 i++
975 }
976
977 // we need >= 1 digits followed by a dot and a space
978 if start == i || data[i] != '.' || data[i+1] != ' ' {
979 return 0
980 }
981 return i + 2
982}
983
984// parse ordered or unordered list block
985func (p *parser) list(out *bytes.Buffer, data []byte, flags int) int {
986 i := 0
987 flags |= LIST_ITEM_BEGINNING_OF_LIST
988 work := func() bool {
989 for i < len(data) {
990 skip := p.listItem(out, data[i:], &flags)
991 i += skip
992
993 if skip == 0 || flags&LIST_ITEM_END_OF_LIST != 0 {
994 break
995 }
996 flags &= ^LIST_ITEM_BEGINNING_OF_LIST
997 }
998 return true
999 }
1000
1001 p.r.List(out, work, flags)
1002 return i
1003}
1004
1005// Parse a single list item.
1006// Assumes initial prefix is already removed if this is a sublist.
1007func (p *parser) listItem(out *bytes.Buffer, data []byte, flags *int) int {
1008 // keep track of the indentation of the first line
1009 itemIndent := 0
1010 for itemIndent < 3 && data[itemIndent] == ' ' {
1011 itemIndent++
1012 }
1013
1014 i := p.uliPrefix(data)
1015 if i == 0 {
1016 i = p.oliPrefix(data)
1017 }
1018 if i == 0 {
1019 return 0
1020 }
1021
1022 // skip leading whitespace on first line
1023 for data[i] == ' ' {
1024 i++
1025 }
1026
1027 // find the end of the line
1028 line := i
1029 for data[i-1] != '\n' {
1030 i++
1031 }
1032
1033 // get working buffer
1034 var raw bytes.Buffer
1035
1036 // put the first line into the working buffer
1037 raw.Write(data[line:i])
1038 line = i
1039
1040 // process the following lines
1041 containsBlankLine := false
1042 sublist := 0
1043
1044gatherlines:
1045 for line < len(data) {
1046 i++
1047
1048 // find the end of this line
1049 for data[i-1] != '\n' {
1050 i++
1051 }
1052
1053 // if it is an empty line, guess that it is part of this item
1054 // and move on to the next line
1055 if p.isEmpty(data[line:i]) > 0 {
1056 containsBlankLine = true
1057 line = i
1058 continue
1059 }
1060
1061 // calculate the indentation
1062 indent := 0
1063 for indent < 4 && line+indent < i && data[line+indent] == ' ' {
1064 indent++
1065 }
1066
1067 chunk := data[line+indent : i]
1068
1069 // evaluate how this line fits in
1070 switch {
1071 // is this a nested list item?
1072 case (p.uliPrefix(chunk) > 0 && !p.isHRule(chunk)) ||
1073 p.oliPrefix(chunk) > 0:
1074
1075 if containsBlankLine {
1076 *flags |= LIST_ITEM_CONTAINS_BLOCK
1077 }
1078
1079 // to be a nested list, it must be indented more
1080 // if not, it is the next item in the same list
1081 if indent <= itemIndent {
1082 break gatherlines
1083 }
1084
1085 // is this the first item in the the nested list?
1086 if sublist == 0 {
1087 sublist = raw.Len()
1088 }
1089
1090 // is this a nested prefix header?
1091 case p.isPrefixHeader(chunk):
1092 // if the header is not indented, it is not nested in the list
1093 // and thus ends the list
1094 if containsBlankLine && indent < 4 {
1095 *flags |= LIST_ITEM_END_OF_LIST
1096 break gatherlines
1097 }
1098 *flags |= LIST_ITEM_CONTAINS_BLOCK
1099
1100 // anything following an empty line is only part
1101 // of this item if it is indented 4 spaces
1102 // (regardless of the indentation of the beginning of the item)
1103 case containsBlankLine && indent < 4:
1104 *flags |= LIST_ITEM_END_OF_LIST
1105 break gatherlines
1106
1107 // a blank line means this should be parsed as a block
1108 case containsBlankLine:
1109 raw.WriteByte('\n')
1110 *flags |= LIST_ITEM_CONTAINS_BLOCK
1111 }
1112
1113 // if this line was preceeded by one or more blanks,
1114 // re-introduce the blank into the buffer
1115 if containsBlankLine {
1116 containsBlankLine = false
1117 raw.WriteByte('\n')
1118 }
1119
1120 // add the line into the working buffer without prefix
1121 raw.Write(data[line+indent : i])
1122
1123 line = i
1124 }
1125
1126 rawBytes := raw.Bytes()
1127
1128 // render the contents of the list item
1129 var cooked bytes.Buffer
1130 if *flags&LIST_ITEM_CONTAINS_BLOCK != 0 {
1131 // intermediate render of block li
1132 if sublist > 0 {
1133 p.block(&cooked, rawBytes[:sublist])
1134 p.block(&cooked, rawBytes[sublist:])
1135 } else {
1136 p.block(&cooked, rawBytes)
1137 }
1138 } else {
1139 // intermediate render of inline li
1140 if sublist > 0 {
1141 p.inline(&cooked, rawBytes[:sublist])
1142 p.block(&cooked, rawBytes[sublist:])
1143 } else {
1144 p.inline(&cooked, rawBytes)
1145 }
1146 }
1147
1148 // render the actual list item
1149 cookedBytes := cooked.Bytes()
1150 parsedEnd := len(cookedBytes)
1151
1152 // strip trailing newlines
1153 for parsedEnd > 0 && cookedBytes[parsedEnd-1] == '\n' {
1154 parsedEnd--
1155 }
1156 p.r.ListItem(out, cookedBytes[:parsedEnd], *flags)
1157
1158 return line
1159}
1160
1161// render a single paragraph that has already been parsed out
1162func (p *parser) renderParagraph(out *bytes.Buffer, data []byte) {
1163 if len(data) == 0 {
1164 return
1165 }
1166
1167 // trim leading spaces
1168 beg := 0
1169 for data[beg] == ' ' {
1170 beg++
1171 }
1172
1173 // trim trailing newline
1174 end := len(data) - 1
1175
1176 // trim trailing spaces
1177 for end > beg && data[end-1] == ' ' {
1178 end--
1179 }
1180
1181 work := func() bool {
1182 p.inline(out, data[beg:end])
1183 return true
1184 }
1185 p.r.Paragraph(out, work)
1186}
1187
1188func (p *parser) paragraph(out *bytes.Buffer, data []byte) int {
1189 // prev: index of 1st char of previous line
1190 // line: index of 1st char of current line
1191 // i: index of cursor/end of current line
1192 var prev, line, i int
1193
1194 // keep going until we find something to mark the end of the paragraph
1195 for i < len(data) {
1196 // mark the beginning of the current line
1197 prev = line
1198 current := data[i:]
1199 line = i
1200
1201 // did we find a blank line marking the end of the paragraph?
1202 if n := p.isEmpty(current); n > 0 {
1203 p.renderParagraph(out, data[:i])
1204 return i + n
1205 }
1206
1207 // an underline under some text marks a header, so our paragraph ended on prev line
1208 if i > 0 {
1209 if level := p.isUnderlinedHeader(current); level > 0 {
1210 // render the paragraph
1211 p.renderParagraph(out, data[:prev])
1212
1213 // ignore leading and trailing whitespace
1214 eol := i - 1
1215 for prev < eol && data[prev] == ' ' {
1216 prev++
1217 }
1218 for eol > prev && data[eol-1] == ' ' {
1219 eol--
1220 }
1221
1222 // render the header
1223 // this ugly double closure avoids forcing variables onto the heap
1224 work := func(o *bytes.Buffer, pp *parser, d []byte) func() bool {
1225 return func() bool {
1226 pp.inline(o, d)
1227 return true
1228 }
1229 }(out, p, data[prev:eol])
1230 p.r.Header(out, work, level, "")
1231
1232 // find the end of the underline
1233 for data[i] != '\n' {
1234 i++
1235 }
1236 return i
1237 }
1238 }
1239
1240 // if the next line starts a block of HTML, then the paragraph ends here
1241 if p.flags&EXTENSION_LAX_HTML_BLOCKS != 0 {
1242 if data[i] == '<' && p.html(out, current, false) > 0 {
1243 // rewind to before the HTML block
1244 p.renderParagraph(out, data[:i])
1245 return i
1246 }
1247 }
1248
1249 // if there's a prefixed header or a horizontal rule after this, paragraph is over
1250 if p.isPrefixHeader(current) || p.isHRule(current) {
1251 p.renderParagraph(out, data[:i])
1252 return i
1253 }
1254
1255 // if there's a list after this, paragraph is over
1256 if p.flags&EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK != 0 {
1257 if p.uliPrefix(current) != 0 ||
1258 p.oliPrefix(current) != 0 ||
1259 p.quotePrefix(current) != 0 ||
1260 p.codePrefix(current) != 0 {
1261 p.renderParagraph(out, data[:i])
1262 return i
1263 }
1264 }
1265
1266 // otherwise, scan to the beginning of the next line
1267 for data[i] != '\n' {
1268 i++
1269 }
1270 i++
1271 }
1272
1273 p.renderParagraph(out, data[:i])
1274 return i
1275}