forked from golang/tools
-
Notifications
You must be signed in to change notification settings - Fork 0
/
parse.go
725 lines (657 loc) · 18.1 KB
/
parse.go
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
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package present
import (
"bufio"
"bytes"
"errors"
"fmt"
"html/template"
"io"
"io/ioutil"
"log"
"net/url"
"regexp"
"strings"
"time"
"unicode"
"unicode/utf8"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/renderer/html"
"github.com/yuin/goldmark/text"
)
var (
parsers = make(map[string]ParseFunc)
funcs = template.FuncMap{}
)
// Template returns an empty template with the action functions in its FuncMap.
func Template() *template.Template {
return template.New("").Funcs(funcs)
}
// Render renders the doc to the given writer using the provided template.
func (d *Doc) Render(w io.Writer, t *template.Template) error {
data := struct {
*Doc
Template *template.Template
PlayEnabled bool
NotesEnabled bool
}{d, t, PlayEnabled, NotesEnabled}
return t.ExecuteTemplate(w, "root", data)
}
// Render renders the section to the given writer using the provided template.
func (s *Section) Render(w io.Writer, t *template.Template) error {
data := struct {
*Section
Template *template.Template
PlayEnabled bool
}{s, t, PlayEnabled}
return t.ExecuteTemplate(w, "section", data)
}
type ParseFunc func(ctx *Context, fileName string, lineNumber int, inputLine string) (Elem, error)
// Register binds the named action, which does not begin with a period, to the
// specified parser to be invoked when the name, with a period, appears in the
// present input text.
func Register(name string, parser ParseFunc) {
if len(name) == 0 || name[0] == ';' {
panic("bad name in Register: " + name)
}
parsers["."+name] = parser
}
// Doc represents an entire document.
type Doc struct {
Title string
Subtitle string
Summary string
Time time.Time
Authors []Author
TitleNotes []string
Sections []Section
Tags []string
OldURL []string
}
// Author represents the person who wrote and/or is presenting the document.
type Author struct {
Elem []Elem
}
// TextElem returns the first text elements of the author details.
// This is used to display the author' name, job title, and company
// without the contact details.
func (p *Author) TextElem() (elems []Elem) {
for _, el := range p.Elem {
if _, ok := el.(Text); !ok {
break
}
elems = append(elems, el)
}
return
}
// Section represents a section of a document (such as a presentation slide)
// comprising a title and a list of elements.
type Section struct {
Number []int
Title string
ID string // HTML anchor ID
Elem []Elem
Notes []string
Classes []string
Styles []string
}
// HTMLAttributes for the section
func (s Section) HTMLAttributes() template.HTMLAttr {
if len(s.Classes) == 0 && len(s.Styles) == 0 {
return ""
}
var class string
if len(s.Classes) > 0 {
class = fmt.Sprintf(`class=%q`, strings.Join(s.Classes, " "))
}
var style string
if len(s.Styles) > 0 {
style = fmt.Sprintf(`style=%q`, strings.Join(s.Styles, " "))
}
return template.HTMLAttr(strings.Join([]string{class, style}, " "))
}
// Sections contained within the section.
func (s Section) Sections() (sections []Section) {
for _, e := range s.Elem {
if section, ok := e.(Section); ok {
sections = append(sections, section)
}
}
return
}
// Level returns the level of the given section.
// The document title is level 1, main section 2, etc.
func (s Section) Level() int {
return len(s.Number) + 1
}
// FormattedNumber returns a string containing the concatenation of the
// numbers identifying a Section.
func (s Section) FormattedNumber() string {
b := &bytes.Buffer{}
for _, n := range s.Number {
fmt.Fprintf(b, "%v.", n)
}
return b.String()
}
func (s Section) TemplateName() string { return "section" }
// Elem defines the interface for a present element. That is, something that
// can provide the name of the template used to render the element.
type Elem interface {
TemplateName() string
}
// renderElem implements the elem template function, used to render
// sub-templates.
func renderElem(t *template.Template, e Elem) (template.HTML, error) {
var data interface{} = e
if s, ok := e.(Section); ok {
data = struct {
Section
Template *template.Template
}{s, t}
}
return execTemplate(t, e.TemplateName(), data)
}
// pageNum derives a page number from a section.
func pageNum(s Section, offset int) int {
if len(s.Number) == 0 {
return offset
}
return s.Number[0] + offset
}
func init() {
funcs["elem"] = renderElem
funcs["pagenum"] = pageNum
}
// execTemplate is a helper to execute a template and return the output as a
// template.HTML value.
func execTemplate(t *template.Template, name string, data interface{}) (template.HTML, error) {
b := new(bytes.Buffer)
err := t.ExecuteTemplate(b, name, data)
if err != nil {
return "", err
}
return template.HTML(b.String()), nil
}
// Text represents an optionally preformatted paragraph.
type Text struct {
Lines []string
Pre bool
Raw string // original text, for Pre==true
}
func (t Text) TemplateName() string { return "text" }
// List represents a bulleted list.
type List struct {
Bullet []string
}
func (l List) TemplateName() string { return "list" }
// Lines is a helper for parsing line-based input.
type Lines struct {
line int // 0 indexed, so has 1-indexed number of last line returned
text []string
comment string
}
func readLines(r io.Reader) (*Lines, error) {
var lines []string
s := bufio.NewScanner(r)
for s.Scan() {
lines = append(lines, s.Text())
}
if err := s.Err(); err != nil {
return nil, err
}
return &Lines{0, lines, "#"}, nil
}
func (l *Lines) next() (text string, ok bool) {
for {
current := l.line
l.line++
if current >= len(l.text) {
return "", false
}
text = l.text[current]
// Lines starting with l.comment are comments.
if l.comment == "" || !strings.HasPrefix(text, l.comment) {
ok = true
break
}
}
return
}
func (l *Lines) back() {
l.line--
}
func (l *Lines) nextNonEmpty() (text string, ok bool) {
for {
text, ok = l.next()
if !ok {
return
}
if len(text) > 0 {
break
}
}
return
}
// A Context specifies the supporting context for parsing a presentation.
type Context struct {
// ReadFile reads the file named by filename and returns the contents.
ReadFile func(filename string) ([]byte, error)
}
// ParseMode represents flags for the Parse function.
type ParseMode int
const (
// If set, parse only the title and subtitle.
TitlesOnly ParseMode = 1
)
// Parse parses a document from r.
func (ctx *Context) Parse(r io.Reader, name string, mode ParseMode) (*Doc, error) {
doc := new(Doc)
lines, err := readLines(r)
if err != nil {
return nil, err
}
// Detect Markdown-enabled vs legacy present file.
// Markdown-enabled files have a title line beginning with "# "
// (like preprocessed C files of yore).
isMarkdown := false
for i := lines.line; i < len(lines.text); i++ {
line := lines.text[i]
if line == "" {
continue
}
isMarkdown = strings.HasPrefix(line, "# ")
break
}
sectionPrefix := "*"
if isMarkdown {
sectionPrefix = "##"
lines.comment = "//"
}
for i := lines.line; i < len(lines.text); i++ {
if strings.HasPrefix(lines.text[i], sectionPrefix) {
break
}
if isSpeakerNote(lines.text[i]) {
doc.TitleNotes = append(doc.TitleNotes, trimSpeakerNote(lines.text[i]))
}
}
err = parseHeader(doc, isMarkdown, lines)
if err != nil {
return nil, err
}
if mode&TitlesOnly != 0 {
return doc, nil
}
// Authors
if doc.Authors, err = parseAuthors(name, sectionPrefix, lines); err != nil {
return nil, err
}
// Sections
if doc.Sections, err = parseSections(ctx, name, sectionPrefix, lines, []int{}); err != nil {
return nil, err
}
return doc, nil
}
// Parse parses a document from r. Parse reads assets used by the presentation
// from the file system using ioutil.ReadFile.
func Parse(r io.Reader, name string, mode ParseMode) (*Doc, error) {
ctx := Context{ReadFile: ioutil.ReadFile}
return ctx.Parse(r, name, mode)
}
// isHeading matches any section heading.
var (
isHeadingLegacy = regexp.MustCompile(`^\*+( |$)`)
isHeadingMarkdown = regexp.MustCompile(`^\#+( |$)`)
)
// lesserHeading returns true if text is a heading of a lesser or equal level
// than that denoted by prefix.
func lesserHeading(isHeading *regexp.Regexp, text, prefix string) bool {
return isHeading.MatchString(text) && !strings.HasPrefix(text, prefix+prefix[:1])
}
// parseSections parses Sections from lines for the section level indicated by
// number (a nil number indicates the top level).
func parseSections(ctx *Context, name, prefix string, lines *Lines, number []int) ([]Section, error) {
isMarkdown := prefix[0] == '#'
isHeading := isHeadingLegacy
if isMarkdown {
isHeading = isHeadingMarkdown
}
var sections []Section
for i := 1; ; i++ {
// Next non-empty line is title.
text, ok := lines.nextNonEmpty()
for ok && text == "" {
text, ok = lines.next()
}
if !ok {
break
}
if text != prefix && !strings.HasPrefix(text, prefix+" ") {
lines.back()
break
}
// Markdown sections can end in {#id} to set the HTML anchor for the section.
// This is nicer than the default #TOC_1_2-style anchor.
title := strings.TrimSpace(text[len(prefix):])
id := ""
if isMarkdown && strings.HasSuffix(title, "}") {
j := strings.LastIndex(title, "{#")
if j >= 0 {
id = title[j+2 : len(title)-1]
title = strings.TrimSpace(title[:j])
}
}
section := Section{
Number: append(append([]int{}, number...), i),
Title: title,
ID: id,
}
text, ok = lines.nextNonEmpty()
for ok && !lesserHeading(isHeading, text, prefix) {
var e Elem
r, _ := utf8.DecodeRuneInString(text)
switch {
case !isMarkdown && unicode.IsSpace(r):
i := strings.IndexFunc(text, func(r rune) bool {
return !unicode.IsSpace(r)
})
if i < 0 {
break
}
indent := text[:i]
var s []string
for ok && (strings.HasPrefix(text, indent) || text == "") {
if text != "" {
text = text[i:]
}
s = append(s, text)
text, ok = lines.next()
}
lines.back()
pre := strings.Join(s, "\n")
raw := pre
pre = strings.Replace(pre, "\t", " ", -1) // browsers treat tabs badly
pre = strings.TrimRightFunc(pre, unicode.IsSpace)
e = Text{Lines: []string{pre}, Pre: true, Raw: raw}
case !isMarkdown && strings.HasPrefix(text, "- "):
var b []string
for {
if strings.HasPrefix(text, "- ") {
b = append(b, text[2:])
} else if len(b) > 0 && strings.HasPrefix(text, " ") {
b[len(b)-1] += "\n" + strings.TrimSpace(text)
} else {
break
}
if text, ok = lines.next(); !ok {
break
}
}
lines.back()
e = List{Bullet: b}
case isSpeakerNote(text):
section.Notes = append(section.Notes, trimSpeakerNote(text))
case strings.HasPrefix(text, prefix+prefix[:1]+" ") || text == prefix+prefix[:1]:
lines.back()
subsecs, err := parseSections(ctx, name, prefix+prefix[:1], lines, section.Number)
if err != nil {
return nil, err
}
for _, ss := range subsecs {
section.Elem = append(section.Elem, ss)
}
case strings.HasPrefix(text, prefix+prefix[:1]):
return nil, fmt.Errorf("%s:%d: badly nested section inside %s: %s", name, lines.line, prefix, text)
case strings.HasPrefix(text, "."):
args := strings.Fields(text)
if args[0] == ".background" {
section.Classes = append(section.Classes, "background")
section.Styles = append(section.Styles, "background-image: url('"+args[1]+"')")
break
}
parser := parsers[args[0]]
if parser == nil {
return nil, fmt.Errorf("%s:%d: unknown command %q", name, lines.line, text)
}
t, err := parser(ctx, name, lines.line, text)
if err != nil {
return nil, err
}
e = t
case isMarkdown:
// Collect Markdown lines, including blank lines and indented text.
var block []string
endLine, endBlock := lines.line-1, -1 // end is last non-empty line
for ok {
trim := strings.TrimSpace(text)
if trim != "" {
// Command breaks text block.
// Section heading breaks text block in markdown.
if text[0] == '.' || text[0] == '#' || isSpeakerNote(text) {
break
}
if strings.HasPrefix(text, `\.`) { // Backslash escapes initial period.
text = text[1:]
}
endLine, endBlock = lines.line, len(block)
}
block = append(block, text)
text, ok = lines.next()
}
block = block[:endBlock+1]
lines.line = endLine + 1
if len(block) == 0 {
break
}
// Replace all leading tabs with 4 spaces,
// which render better in code blocks.
// CommonMark defines that for parsing the structure of the file
// a tab is equivalent to 4 spaces, so this change won't
// affect the later parsing at all.
// An alternative would be to apply this to code blocks after parsing,
// at the same time that we update <a> targets, but that turns out
// to be quite difficult to modify in the AST.
for i, line := range block {
if len(line) > 0 && line[0] == '\t' {
short := strings.TrimLeft(line, "\t")
line = strings.Repeat(" ", len(line)-len(short)) + short
block[i] = line
}
}
html, err := renderMarkdown([]byte(strings.Join(block, "\n")))
if err != nil {
return nil, err
}
e = HTML{HTML: html}
default:
// Collect text lines.
var block []string
for ok && strings.TrimSpace(text) != "" {
// Command breaks text block.
// Section heading breaks text block in markdown.
if text[0] == '.' || isSpeakerNote(text) {
lines.back()
break
}
if strings.HasPrefix(text, `\.`) { // Backslash escapes initial period.
text = text[1:]
}
block = append(block, text)
text, ok = lines.next()
}
if len(block) == 0 {
break
}
e = Text{Lines: block}
}
if e != nil {
section.Elem = append(section.Elem, e)
}
text, ok = lines.nextNonEmpty()
}
if isHeading.MatchString(text) {
lines.back()
}
sections = append(sections, section)
}
if len(sections) == 0 {
return nil, fmt.Errorf("%s:%d: unexpected line: %s", name, lines.line+1, lines.text[lines.line])
}
return sections, nil
}
func parseHeader(doc *Doc, isMarkdown bool, lines *Lines) error {
var ok bool
// First non-empty line starts header.
doc.Title, ok = lines.nextNonEmpty()
if !ok {
return errors.New("unexpected EOF; expected title")
}
if isMarkdown {
doc.Title = strings.TrimSpace(strings.TrimPrefix(doc.Title, "#"))
}
for {
text, ok := lines.next()
if !ok {
return errors.New("unexpected EOF")
}
if text == "" {
break
}
if isSpeakerNote(text) {
continue
}
if strings.HasPrefix(text, "Tags:") {
tags := strings.Split(text[len("Tags:"):], ",")
for i := range tags {
tags[i] = strings.TrimSpace(tags[i])
}
doc.Tags = append(doc.Tags, tags...)
} else if strings.HasPrefix(text, "Summary:") {
doc.Summary = strings.TrimSpace(text[len("Summary:"):])
} else if strings.HasPrefix(text, "OldURL:") {
doc.OldURL = append(doc.OldURL, strings.TrimSpace(text[len("OldURL:"):]))
} else if t, ok := parseTime(text); ok {
doc.Time = t
} else if doc.Subtitle == "" {
doc.Subtitle = text
} else {
return fmt.Errorf("unexpected header line: %q", text)
}
}
return nil
}
func parseAuthors(name, sectionPrefix string, lines *Lines) (authors []Author, err error) {
// This grammar demarcates authors with blanks.
// Skip blank lines.
if _, ok := lines.nextNonEmpty(); !ok {
return nil, errors.New("unexpected EOF")
}
lines.back()
var a *Author
for {
text, ok := lines.next()
if !ok {
return nil, errors.New("unexpected EOF")
}
// If we find a section heading, we're done.
if strings.HasPrefix(text, sectionPrefix) {
lines.back()
break
}
if isSpeakerNote(text) {
continue
}
// If we encounter a blank we're done with this author.
if a != nil && len(text) == 0 {
authors = append(authors, *a)
a = nil
continue
}
if a == nil {
a = new(Author)
}
// Parse the line. Those that
// - begin with @ are twitter names,
// - contain slashes are links, or
// - contain an @ symbol are an email address.
// The rest is just text.
var el Elem
switch {
case strings.HasPrefix(text, "@"):
el = parseAuthorURL(name, "http://twitter.com/"+text[1:])
case strings.Contains(text, ":"):
el = parseAuthorURL(name, text)
case strings.Contains(text, "@"):
el = parseAuthorURL(name, "mailto:"+text)
}
if l, ok := el.(Link); ok {
l.Label = text
el = l
}
if el == nil {
el = Text{Lines: []string{text}}
}
a.Elem = append(a.Elem, el)
}
if a != nil {
authors = append(authors, *a)
}
return authors, nil
}
func parseAuthorURL(name, text string) Elem {
u, err := url.Parse(text)
if err != nil {
log.Printf("parsing %s author block: invalid URL %q: %v", name, text, err)
return nil
}
return Link{URL: u}
}
func parseTime(text string) (t time.Time, ok bool) {
t, err := time.Parse("15:04 2 Jan 2006", text)
if err == nil {
return t, true
}
t, err = time.Parse("2 Jan 2006", text)
if err == nil {
// at 11am UTC it is the same date everywhere
t = t.Add(time.Hour * 11)
return t, true
}
return time.Time{}, false
}
func isSpeakerNote(s string) bool {
return strings.HasPrefix(s, ": ") || s == ":"
}
func trimSpeakerNote(s string) string {
if s == ":" {
return ""
}
return strings.TrimPrefix(s, ": ")
}
func renderMarkdown(input []byte) (template.HTML, error) {
md := goldmark.New(goldmark.WithRendererOptions(html.WithUnsafe()))
reader := text.NewReader(input)
doc := md.Parser().Parse(reader)
fixupMarkdown(doc)
var b strings.Builder
if err := md.Renderer().Render(&b, input, doc); err != nil {
return "", err
}
return template.HTML(b.String()), nil
}
func fixupMarkdown(n ast.Node) {
ast.Walk(n, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
switch n := n.(type) {
case *ast.Link:
n.SetAttributeString("target", []byte("_blank"))
// https://developers.google.com/web/tools/lighthouse/audits/noopener
n.SetAttributeString("rel", []byte("noopener"))
}
}
return ast.WalkContinue, nil
})
}