summaryrefslogtreecommitdiff
path: root/js/lib/blocks.js
blob: 53fe2b96c798e2fc6b947cce65f53a72ab0b3d6a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
var C_GREATERTHAN = 62;
var C_SPACE = 32;
var C_OPEN_BRACKET = 91;

var InlineParser = require('./inlines');
var unescapeString = new InlineParser().unescapeString;

// Returns true if string contains only space characters.
var isBlank = function(s) {
    return /^\s*$/.test(s);
};

// Convert tabs to spaces on each line using a 4-space tab stop.
var detabLine = function(text) {
    if (text.indexOf('\t') == -1) {
        return text;
    } else {
        var lastStop = 0;
        return text.replace(/\t/g, function(match, offset) {
            var result = '    '.slice((offset - lastStop) % 4);
            lastStop = offset + 1;
            return result;
        });
    }
};

// Attempt to match a regex in string s at offset offset.
// Return index of match or -1.
var matchAt = function(re, s, offset) {
    var res = s.slice(offset).match(re);
    if (res) {
        return offset + res.index;
    } else {
        return -1;
    }
};

var BLOCKTAGNAME = '(?:article|header|aside|hgroup|iframe|blockquote|hr|body|li|map|button|object|canvas|ol|caption|output|col|p|colgroup|pre|dd|progress|div|section|dl|table|td|dt|tbody|embed|textarea|fieldset|tfoot|figcaption|th|figure|thead|footer|footer|tr|form|ul|h1|h2|h3|h4|h5|h6|video|script|style)';
var HTMLBLOCKOPEN = "<(?:" + BLOCKTAGNAME + "[\\s/>]" + "|" +
        "/" + BLOCKTAGNAME + "[\\s>]" + "|" + "[?!])";
var reHtmlBlockOpen = new RegExp('^' + HTMLBLOCKOPEN, 'i');

var reHrule = /^(?:(?:\* *){3,}|(?:_ *){3,}|(?:- *){3,}) *$/;


// DOC PARSER

// These are methods of a DocParser object, defined below.

var makeBlock = function(tag, start_line, start_column) {
    return { t: tag,
             open: true,
             last_line_blank: false,
             start_line: start_line,
             start_column: start_column,
             end_line: start_line,
             children: [],
             parent: null,
             // string_content is formed by concatenating strings, in finalize:
             string_content: "",
             strings: [],
             inline_content: []
           };
};

// Returns true if parent block can contain child block.
var canContain = function(parent_type, child_type) {
    return ( parent_type == 'Document' ||
             parent_type == 'BlockQuote' ||
             parent_type == 'ListItem' ||
             (parent_type == 'List' && child_type == 'ListItem') );
};

// Returns true if block type can accept lines of text.
var acceptsLines = function(block_type) {
    return ( block_type == 'Paragraph' ||
             block_type == 'IndentedCode' ||
             block_type == 'FencedCode' );
};

// Returns true if block ends with a blank line, descending if needed
// into lists and sublists.
var endsWithBlankLine = function(block) {
    if (block.last_line_blank) {
        return true;
    }
    if ((block.t == 'List' || block.t == 'ListItem') && block.children.length > 0) {
        return endsWithBlankLine(block.children[block.children.length - 1]);
    } else {
        return false;
    }
};

// Break out of all containing lists, resetting the tip of the
// document to the parent of the highest list, and finalizing
// all the lists.  (This is used to implement the "two blank lines
// break of of all lists" feature.)
var breakOutOfLists = function(block, line_number) {
    var b = block;
    var last_list = null;
    do {
        if (b.t === 'List') {
            last_list = b;
        }
        b = b.parent;
    } while (b);

    if (last_list) {
        while (block != last_list) {
            this.finalize(block, line_number);
            block = block.parent;
        }
        this.finalize(last_list, line_number);
        this.tip = last_list.parent;
    }
};

// Add a line to the block at the tip.  We assume the tip
// can accept lines -- that check should be done before calling this.
var addLine = function(ln, offset) {
    var s = ln.slice(offset);
    if (!(this.tip.open)) {
        throw({ msg: "Attempted to add line (" + ln + ") to closed container." });
    }
    this.tip.strings.push(s);
};

// Add block of type tag as a child of the tip.  If the tip can't
// accept children, close and finalize it and try its parent,
// and so on til we find a block that can accept children.
var addChild = function(tag, line_number, offset) {
    while (!canContain(this.tip.t, tag)) {
        this.finalize(this.tip, line_number);
    }

    var column_number = offset + 1; // offset 0 = column 1
    var newBlock = makeBlock(tag, line_number, column_number);
    this.tip.children.push(newBlock);
    newBlock.parent = this.tip;
    this.tip = newBlock;
    return newBlock;
};

// Parse a list marker and return data on the marker (type,
// start, delimiter, bullet character, padding) or null.
var parseListMarker = function(ln, offset) {
    var rest = ln.slice(offset);
    var match;
    var spaces_after_marker;
    var data = {};
    if (rest.match(reHrule)) {
        return null;
    }
    if ((match = rest.match(/^[*+-]( +|$)/))) {
        spaces_after_marker = match[1].length;
        data.type = 'Bullet';
        data.bullet_char = match[0][0];

    } else if ((match = rest.match(/^(\d+)([.)])( +|$)/))) {
        spaces_after_marker = match[3].length;
        data.type = 'Ordered';
        data.start = parseInt(match[1]);
        data.delimiter = match[2];
    } else {
        return null;
    }
    var blank_item = match[0].length === rest.length;
    if (spaces_after_marker >= 5 ||
        spaces_after_marker < 1 ||
        blank_item) {
        data.padding = match[0].length - spaces_after_marker + 1;
    } else {
        data.padding = match[0].length;
    }
    return data;
};

// Returns true if the two list items are of the same type,
// with the same delimiter and bullet character.  This is used
// in agglomerating list items into lists.
var listsMatch = function(list_data, item_data) {
    return (list_data.type === item_data.type &&
            list_data.delimiter === item_data.delimiter &&
            list_data.bullet_char === item_data.bullet_char);
};

// Analyze a line of text and update the document appropriately.
// We parse markdown text by calling this on each line of input,
// then finalizing the document.
var incorporateLine = function(ln, line_number) {

    var all_matched = true;
    var last_child;
    var first_nonspace;
    var offset = 0;
    var match;
    var data;
    var blank;
    var indent;
    var last_matched_container;
    var i;
    var CODE_INDENT = 4;

    var container = this.doc;
    var oldtip = this.tip;

    // Convert tabs to spaces:
    ln = detabLine(ln);

    // For each containing block, try to parse the associated line start.
    // Bail out on failure: container will point to the last matching block.
    // Set all_matched to false if not all containers match.
    while (container.children.length > 0) {
        last_child = container.children[container.children.length - 1];
        if (!last_child.open) {
            break;
        }
        container = last_child;

        match = matchAt(/[^ ]/, ln, offset);
        if (match === -1) {
            first_nonspace = ln.length;
            blank = true;
        } else {
            first_nonspace = match;
            blank = false;
        }
        indent = first_nonspace - offset;

        switch (container.t) {
        case 'BlockQuote':
            if (indent <= 3 && ln.charCodeAt(first_nonspace) === C_GREATERTHAN) {
                offset = first_nonspace + 1;
                if (ln.charCodeAt(offset) === C_SPACE) {
                    offset++;
                }
            } else {
                all_matched = false;
            }
            break;

        case 'ListItem':
            if (indent >= container.list_data.marker_offset +
                container.list_data.padding) {
                offset += container.list_data.marker_offset +
                    container.list_data.padding;
            } else if (blank) {
                offset = first_nonspace;
            } else {
                all_matched = false;
            }
            break;

        case 'IndentedCode':
            if (indent >= CODE_INDENT) {
                offset += CODE_INDENT;
            } else if (blank) {
                offset = first_nonspace;
            } else {
                all_matched = false;
            }
            break;

        case 'Header':
        case 'HorizontalRule':
            // a header can never container > 1 line, so fail to match:
            all_matched = false;
            if (blank) {
                container.last_line_blank = true;
            }
            break;

        case 'FencedCode':
            // skip optional spaces of fence offset
            i = container.fence_offset;
            while (i > 0 && ln.charCodeAt(offset) === C_SPACE) {
                offset++;
                i--;
            }
            break;

        case 'HtmlBlock':
            if (blank) {
                container.last_line_blank = true;
                all_matched = false;
            }
            break;

        case 'Paragraph':
            if (blank) {
                container.last_line_blank = true;
                all_matched = false;
            }
            break;

        default:
        }

        if (!all_matched) {
            container = container.parent; // back up to last matching block
            break;
        }
    }

    last_matched_container = container;

    // This function is used to finalize and close any unmatched
    // blocks.  We aren't ready to do this now, because we might
    // have a lazy paragraph continuation, in which case we don't
    // want to close unmatched blocks.  So we store this closure for
    // use later, when we have more information.
    var closeUnmatchedBlocks = function(mythis) {
        // finalize any blocks not matched
        while (!already_done && oldtip != last_matched_container) {
            mythis.finalize(oldtip, line_number);
            oldtip = oldtip.parent;
        }
        var already_done = true;
    };

    // Check to see if we've hit 2nd blank line; if so break out of list:
    if (blank && container.last_line_blank) {
        this.breakOutOfLists(container, line_number);
    }

    // Unless last matched container is a code block, try new container starts,
    // adding children to the last matched container:
    while (container.t != 'FencedCode' &&
           container.t != 'IndentedCode' &&
           container.t != 'HtmlBlock' &&
           // this is a little performance optimization:
           matchAt(/^[ #`~*+_=<>0-9-]/,ln,offset) !== -1) {

        match = matchAt(/[^ ]/, ln, offset);
        if (match === -1) {
            first_nonspace = ln.length;
            blank = true;
        } else {
            first_nonspace = match;
            blank = false;
        }
        indent = first_nonspace - offset;

        if (indent >= CODE_INDENT) {
            // indented code
            if (this.tip.t != 'Paragraph' && !blank) {
                offset += CODE_INDENT;
                closeUnmatchedBlocks(this);
                container = this.addChild('IndentedCode', line_number, offset);
            } else { // indent > 4 in a lazy paragraph continuation
                break;
            }

        } else if (ln.charCodeAt(first_nonspace) === C_GREATERTHAN) {
            // blockquote
            offset = first_nonspace + 1;
            // optional following space
            if (ln.charCodeAt(offset) === C_SPACE) {
                offset++;
            }
            closeUnmatchedBlocks(this);
            container = this.addChild('BlockQuote', line_number, offset);

        } else if ((match = ln.slice(first_nonspace).match(/^#{1,6}(?: +|$)/))) {
            // ATX header
            offset = first_nonspace + match[0].length;
            closeUnmatchedBlocks(this);
            container = this.addChild('Header', line_number, first_nonspace);
            container.level = match[0].trim().length; // number of #s
            // remove trailing ###s:
            container.strings =
                [ln.slice(offset).replace(/^ *#+ *$/, '').replace(/ +#+ *$/,'')];
            break;

        } else if ((match = ln.slice(first_nonspace).match(/^`{3,}(?!.*`)|^~{3,}(?!.*~)/))) {
            // fenced code block
            var fence_length = match[0].length;
            closeUnmatchedBlocks(this);
            container = this.addChild('FencedCode', line_number, first_nonspace);
            container.fence_length = fence_length;
            container.fence_char = match[0][0];
            container.fence_offset = first_nonspace - offset;
            offset = first_nonspace + fence_length;
            break;

        } else if (matchAt(reHtmlBlockOpen, ln, first_nonspace) !== -1) {
            // html block
            closeUnmatchedBlocks(this);
            container = this.addChild('HtmlBlock', line_number, first_nonspace);
            // note, we don't adjust offset because the tag is part of the text
            break;

        } else if (container.t == 'Paragraph' &&
                   container.strings.length === 1 &&
                   ((match = ln.slice(first_nonspace).match(/^(?:=+|-+) *$/)))) {
            // setext header line
            closeUnmatchedBlocks(this);
            container.t = 'Header'; // convert Paragraph to SetextHeader
            container.level = match[0][0] === '=' ? 1 : 2;
            offset = ln.length;

        } else if (matchAt(reHrule, ln, first_nonspace) !== -1) {
            // hrule
            closeUnmatchedBlocks(this);
            container = this.addChild('HorizontalRule', line_number, first_nonspace);
            offset = ln.length - 1;
            break;

        } else if ((data = parseListMarker(ln, first_nonspace))) {
            // list item
            closeUnmatchedBlocks(this);
            data.marker_offset = indent;
            offset = first_nonspace + data.padding;

            // add the list if needed
            if (container.t !== 'List' ||
                !(listsMatch(container.list_data, data))) {
                container = this.addChild('List', line_number, first_nonspace);
                container.list_data = data;
            }

            // add the list item
            container = this.addChild('ListItem', line_number, first_nonspace);
            container.list_data = data;

        } else {
            break;

        }

        if (acceptsLines(container.t)) {
            // if it's a line container, it can't contain other containers
            break;
        }
    }

    // What remains at the offset is a text line.  Add the text to the
    // appropriate container.

    match = matchAt(/[^ ]/, ln, offset);
    if (match === -1) {
        first_nonspace = ln.length;
        blank = true;
    } else {
        first_nonspace = match;
        blank = false;
    }
    indent = first_nonspace - offset;

    // First check for a lazy paragraph continuation:
    if (this.tip !== last_matched_container &&
        !blank &&
        this.tip.t == 'Paragraph' &&
        this.tip.strings.length > 0) {
        // lazy paragraph continuation

        this.last_line_blank = false;
        this.addLine(ln, offset);

    } else { // not a lazy continuation

        // finalize any blocks not matched
        closeUnmatchedBlocks(this);

        // Block quote lines are never blank as they start with >
        // and we don't count blanks in fenced code for purposes of tight/loose
        // lists or breaking out of lists.  We also don't set last_line_blank
        // on an empty list item.
        container.last_line_blank = blank &&
            !(container.t == 'BlockQuote' ||
              container.t == 'Header' ||
              container.t == 'FencedCode' ||
              (container.t == 'ListItem' &&
               container.children.length === 0 &&
               container.start_line == line_number));

        var cont = container;
        while (cont.parent) {
            cont.parent.last_line_blank = false;
            cont = cont.parent;
        }

        switch (container.t) {
        case 'IndentedCode':
        case 'HtmlBlock':
            this.addLine(ln, offset);
            break;

        case 'FencedCode':
            // check for closing code fence:
            match = (indent <= 3 &&
                     ln.charAt(first_nonspace) == container.fence_char &&
                     ln.slice(first_nonspace).match(/^(?:`{3,}|~{3,})(?= *$)/));
            if (match && match[0].length >= container.fence_length) {
                // don't add closing fence to container; instead, close it:
                this.finalize(container, line_number);
            } else {
                this.addLine(ln, offset);
            }
            break;

        case 'Header':
        case 'HorizontalRule':
            // nothing to do; we already added the contents.
            break;

        default:
            if (acceptsLines(container.t)) {
                this.addLine(ln, first_nonspace);
            } else if (blank) {
                // do nothing
            } else if (container.t != 'HorizontalRule' &&
                       container.t != 'Header') {
                // create paragraph container for line
                container = this.addChild('Paragraph', line_number, first_nonspace);
                this.addLine(ln, first_nonspace);
            } else {
                console.log("Line " + line_number.toString() +
                            " with container type " + container.t +
                            " did not match any condition.");

            }
        }
    }
};

// Finalize a block.  Close it and do any necessary postprocessing,
// e.g. creating string_content from strings, setting the 'tight'
// or 'loose' status of a list, and parsing the beginnings
// of paragraphs for reference definitions.  Reset the tip to the
// parent of the closed block.
var finalize = function(block, line_number) {
    var pos;
    // don't do anything if the block is already closed
    if (!block.open) {
        return 0;
    }
    block.open = false;
    if (line_number > block.start_line) {
        block.end_line = line_number - 1;
    } else {
        block.end_line = line_number;
    }

    switch (block.t) {
    case 'Paragraph':
        block.string_content = block.strings.join('\n').replace(/^  */m,'');
        // delete block.strings;

        // try parsing the beginning as link reference definitions:
        while (block.string_content.charCodeAt(0) === C_OPEN_BRACKET &&
               (pos = this.inlineParser.parseReference(block.string_content,
                                                       this.refmap))) {
            block.string_content = block.string_content.slice(pos);
            if (isBlank(block.string_content)) {
                block.t = 'ReferenceDef';
                break;
            }
        }
        break;

    case 'Header':
    case 'HtmlBlock':
        block.string_content = block.strings.join('\n');
        break;

    case 'IndentedCode':
        block.string_content = block.strings.join('\n').replace(/(\n *)*$/,'\n');
        block.t = 'CodeBlock';
        break;

    case 'FencedCode':
        // first line becomes info string
        block.info = unescapeString(block.strings[0].trim());
        if (block.strings.length == 1) {
            block.string_content = '';
        } else {
            block.string_content = block.strings.slice(1).join('\n') + '\n';
        }
        block.t = 'CodeBlock';
        break;

    case 'List':
        block.tight = true; // tight by default

        var numitems = block.children.length;
        var i = 0;
        while (i < numitems) {
            var item = block.children[i];
            // check for non-final list item ending with blank line:
            var last_item = i == numitems - 1;
            if (endsWithBlankLine(item) && !last_item) {
                block.tight = false;
                break;
            }
            // recurse into children of list item, to see if there are
            // spaces between any of them:
            var numsubitems = item.children.length;
            var j = 0;
            while (j < numsubitems) {
                var subitem = item.children[j];
                var last_subitem = j == numsubitems - 1;
                if (endsWithBlankLine(subitem) && !(last_item && last_subitem)) {
                    block.tight = false;
                    break;
                }
                j++;
            }
            i++;
        }
        break;

    default:
        break;
    }

    this.tip = block.parent || this.top;
};

// Walk through a block & children recursively, parsing string content
// into inline content where appropriate.  Returns new object.
var processInlines = function(block) {
    var newblock = {};
    newblock.t = block.t;
    newblock.start_line = block.start_line;
    newblock.start_column = block.start_column;
    newblock.end_line = block.end_line;

    switch(block.t) {
    case 'Paragraph':
        newblock.inline_content =
            this.inlineParser.parse(block.string_content.trim(), this.refmap);
        break;
    case 'Header':
        newblock.inline_content =
            this.inlineParser.parse(block.string_content.trim(), this.refmap);
        newblock.level = block.level;
        break;
    case 'List':
        newblock.list_data = block.list_data;
        newblock.tight = block.tight;
        break;
    case 'CodeBlock':
        newblock.string_content = block.string_content;
        newblock.info = block.info;
        break;
    case 'HtmlBlock':
        newblock.string_content = block.string_content;
        break;
    default:
        break;
    }

    if (block.children) {
        var newchildren = [];
        for (var i = 0; i < block.children.length; i++) {
            newchildren.push(this.processInlines(block.children[i]));
        }
        newblock.children = newchildren;
    }
    return newblock;
};

// The main parsing function.  Returns a parsed document AST.
var parse = function(input) {
    this.doc = makeBlock('Document', 1, 1);
    this.tip = this.doc;
    this.refmap = {};
    var lines = input.replace(/\n$/,'').split(/\r\n|\n|\r/);
    var len = lines.length;
    for (var i = 0; i < len; i++) {
        this.incorporateLine(lines[i], i+1);
    }
    while (this.tip) {
        this.finalize(this.tip, len - 1);
    }
    return this.processInlines(this.doc);
};


// The DocParser object.
function DocParser(){
    return {
        doc: makeBlock('Document', 1, 1),
        tip: this.doc,
        refmap: {},
        inlineParser: new InlineParser(),
        breakOutOfLists: breakOutOfLists,
        addLine: addLine,
        addChild: addChild,
        incorporateLine: incorporateLine,
        finalize: finalize,
        processInlines: processInlines,
        parse: parse
    };
}

module.exports = DocParser;